2200  EDT  OCT   24 ,2012…  STRADATE    201210.24

The latest recon as of 10:00 PM this evening showed that hurricanes sandy was becoming a category 3  hurricane with the Los pressure now reaching 955MB.  From the satellite pictures you can see that she is bombing out very nicely and continuing to intensify into a massive hurricane as the European and other models have been depicting for the past several model runs.  This is an impressive looking hurricane for late October and it’s very large.

 
The announcement that NWS offices up and down the East Coast will launch additional weather sounding balloons to obtain more information about the atmosphere in the hope that the weather models can use this new information to get a better handle on what is happening with the atmosphere is an indication of how important in serious the potential is with this hurricane/ monster coastal storm.
Most of the time when something like this is done it  is usually because there is a lot of model uncertainty.  And that is usually  caused by the GFS model  screwing up again.  Over the years I seen this many times where the GFS model has a solution which no other model seems to be showing so in order to get a better handle on the situation  they launched these intermediate weather balloons for additional atmospheric soundings and this information gets put into the  the various  weather computer models.

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The idea here is to hope that the crappie GFS model  finally gets a clue about the basic laws of the universe and physics with all this new additional information in the model.  The problem is that you can only shine up   a pile of SHIT  so much.   So all the high expectations were hope that this new data is somehow going to affect the GFS model over the next few runs usually ends up being a total bust and let down.

Let us take a look about why the GFS model is screwing this up so badly.  And this is really important because so many TV meteorologists both within the weather channel and on your local media and even on many private web pages rely extremely heavily on the GFS weather model.

And because the GFS model even this afternoon continues to show a hurricane staying well off the coast until it gets up into southeastern New England…  Many of the TV & Media outlets up and down the East Coast are downplaying the threat or talking about the very complicated situation or expressing some other boilerplate expression of uncertainty.

For those  that are not weather geeks    and  don’t know…   it has been documented many times that the  GFS model has a cold bias.  What that means is that if the temperature is going to reach 80° for example…  The GFS model will show the temperature reaching 75.   But in the atmosphere at the high levels it has other more serious implications.  The cold bias of the GFS in the jet stream levels means that it Mishandles things like  TROUGHS   and   RIDGES very badly.  In other words if the numerical value of a particular weather feature the jet stream is to say   100…  The GFS will show this feature to be   90.  And by weakening the feature and underplaying it it ends up distorting the entire pattern as you go further out in time .
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Let’s take a look.
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This next image shows you the European model from this afternoon valid for 96 hours or October 28.  We can see a mighty hurricane SANDY  just  off SC   GA   coast moving  due North.  But we can also see a massive system sitting out there in the Central North Atlantic Ocean.

It is a basic law of physics and weather that you CANNOT  have two large enormous  Low pressure areas located in close proximity to each other.  For some reason that we cannot quite figure out the GFS seems to have problems understanding that basic laws of the weather physics.
This next image is the 72 hr Wednesday afternoon European model and it so shows the Jetstream pattern.  I have highlighted the key features but what is important   to  understand is that there  is a bulge or mountain of the air which exists between the huge ocean Low and the central north Atlantic and SANDY off the Georgia Coast.

This  feature…called a  RIDGE …has a certain intensity or to value which we can measure…  That number IS  576DM.
However when we compare this to the upper air map from the GFS model we see something different.
In this next image I present the GFS jet stream map valid for the exact same time — 72 hours some now or October 27.  I again I have  highlighted the key features on we can clearly see that same  RIDGE   existing between sandy and the huge ocean low in the North Central Atlantic Ocean.  But the numerical value of this feature is significantly lower or weaker on the GFS model  ( that cold bias I referred to above)… 570DM.

And because  this   RIDGE  is  weaker the GFS model … the  GFS Model allows SANDY to move further out into the Atlantic Ocean and closer to the ocean Low in the north central Atlantic.  This is a meteorological impossibility and it is why the model needs to be rejected as a viable solution with this particular situation.

By 120 hours or five days some now (October 29) the European model has captured hurricane SANDY  which is now a super large and very powerful coastal storm and pulled it towards the Virginia Maryland New Jersey Coast.

The GFS model is sitting there without a clue has SANDY  hundreds of miles offshore not affecting anybody except for some fish.  Its solution is absurd and ludicrous and should be totally disregarded.

Even the   NOGAPS  sees the pattern correctly

That being said we can point out that the GFS  Hurricane ensembles appear to be getting a clue  as they finally show a more dramatic shift to the west with each new passing model run.
This image shows the GFS hurricane  ensembles  plots or tracks  from early Wednesday morning.  Notice how all of them or turning sandy towards the coast with a sharp turn to the northwest.  Of course the problem here is that the GFS   Hurricane ensemble  STILL   swing  SANDY way too far to the   out to the east before the hurricane / huge coastal storm begins to get captured.

However 12 hours later  we see that the GFS hurricane  ensemble shows a much closer track to the coast and in much sharper turn  to the WEST with numerous LANDFALLS between New York City and wallops island Virginia …  Including the lower Maryland Eastern shore and New Jersey .
Note that these tracks are significantly further south or down the coast then what the previous image showed .   This is more proof that the European and navy or Nogaps model will likely be correct.

Finally one of the key points in figuring out where sandy is going to turn to the west and strike the coast …  Will be her position relative to Florida and the Bahamas on Friday .  The closer to Florida that  SANDY is located then be close issue will be to the coast and the more likely we are to see a turn into  North Carolina Virginia or Maryland .

On the other hand the further off the Florida  coast  SANDY is…  The more likely she used to swing    “WIDE”  are out into the Atlantic off the southeast coast then turn north     THEN  nw    back  into  the East Coast probably making landfall somewhere up by New Jersey New York City Long Island were Connecticut.

2130 EDT   SEPT  3  2012

One of the things that really bothers me about hurricane forecasting is the  bit of wisdom or  wise tale that suggests that hurricanes  have   “minds of their own “….as if   they  were people. That    ”saying”    has been used for many many years because of the poor understanding of the atmosphere we used to have with respect to the all tropical cyclones. But it’s not really accurate to still make that claim.  Hurricanes do not have minds of their own … they obey the laws of physics.
Now that doesn’t mean we always get the hurricane forecast correct. All sorts of things can happen in the last 60 hours before landfall and Isaac is a pretty good example of this.    That being said let’s talk about Leslie.    Back on Friday night I posted this over on the face book page and it’s a pretty good place to start.

***ABOUT LESLIE… A THREAT TO EAST COAST?… No it will not be… well *PROBABLY* not.. First as I said several days ago LESLIE will NOT be a early week curvature storm ( when many other were sayung Just that) .   Once she clears 60 degrees West longitude  and passes  well north of Puerto Rico..   then typically   after turning due North …  most  Tropical cyclones this would typically go out to sea probably east of Bermuda .  BUT with Leslie SHOULD a major ridge will form over the central North Atlantic early next week…. which essentially will trap  or block   LESLIE   preventing her from going out to sea.   As the ridge in the jet stream expands she be FORCED s-l-o-w-l-y westward… Towards the EAST COAST!!! sounds ominous, no?
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Coming out of Labor day …. all of the weather models show a very IMPRESSIVE trough developing over Midwest and the East coast . Now TYPICALLY most major troughs like this in the jet stream force any hurricane in the western Atlantic back out to sea. That is PROBABLY what will happen here with LESLIE. The data shows LESLIE coming west BUT at a rather high LATITUDE. Thus the trough (as it sweeps through the Midwest and the East Coast ) Kicks LESLIE e out to sea SEPT 8-9
BUT there have been a few RARE but well known cases where there is a big trough over the Midwest / Appalachian mountains and the hurricane interaction is JUST the PERFECT position so as to “GRAB” the hurricane and pull it TO the coast…. See for example the great east coast Hurricane of OCT 1878. ..the 1938 hurricane… The 1933 Chessy bay cane… HAZEL 1954 and ISABEL 2003. These sort of “uncommon” cases ONLY occur when the hurricane is SOUTH of 30 north latitude AND … AND enters the trough base in the SOUTHEAST SIDE side of the trough. As   of right now … no data shows this right now. When Leslie begins to maker move towards the coast she  comes in  s much further north then 30 N latitude.

Well here we Monday afternoon evening and that analysis still apparently holds true.  I am not at all surprised by the constant Westward  d adjustment of Leslie.   Once again we have a problem with the hurricane models because they are run off the GFS grid.    As I stated many times once you get a tropical cyclone north of 30° north latitude the cold bias of the GFS model which tends to overdo develop troughs   and/ or   phase two different  into one big system ….really begins to come into play here.
It is these very reasons why the GFS model consistently took Isaac into Florida and up the East Coast for many many model cycles until finally getting a clue 72 hours before landfall.  We are seeing the exact same problem here with a hurricane models and how they are handling tropical cyclone Leslie . It is no surprise that the model which does not have the cold bias — the European model– has been further west than any other model with the track of Leslie and so far has the best overall accuracy score with regard to the track of Leslie.

Broadly speaking one cane to break down most East Coast hurricane events into three groups.

1. The first group pass to do with the curvature between the East Coast and Bermuda. This sort of track is refer to by the old timers as a   “SLOT HURRICANE:“.
2. The second group refers to the typical East Coast landfall track… where the tropical cyclone essentially goes along the coast following the path of least resistance usually making landfall at or near Cape Hatteras and paralleling the Middle Atlantic and New England Coast up towards Cape Cod. This group can be referred to as the EAST COAST TRACK. Most East Coast hurricanes fallen this track and we can refer to a few them by name to give you a general idea. Hurricane bob in 1991… Hurricane Gloria 1985… Hurricane Floyd 1999… Hurricane Irene 2011 hurricane Belle 1976.
3. The third group is a lot less common but far more dangerous which I refer to as the NW TRACK. Some are more dangerous and historic East Coast hurricanes are in this group…. Such as the September 1938 New England hurricane… Hurricane hazel… Hurricane Donna… Hurricane Isabel Chessy bay 1933 Hurricane just to name a few.

By looking at a few of the cases we can see what exactly is   the  threat is with regard to Leslie.

First let’s take a look at the typical East Coast hurricane track. This first image refers to hurricane GLORIA   in late September 1985.    This was the first big hypermedia event at the dawn of the new electronic age in media. In this image we can see the actual track in the black it background image.  And we can see below that the upper air and surface maps explaining WHY Gloria which was forecasted come inland over New Jersey and New York City in fact did not come inland but paralleled the coast. On Thursday, September 26, 1985    the upper air map showed a major trough over the Midwest that was positively tilted (SW to NE).    And on the surface map we can see Gloria approaching the Southeast U.S. Coast. It was thought that the trough would deepen and take a negative tilt (NW to SE) which would pull Gloria it into the coast .   Instead the Midwest trough did go negative BUT the trough did NOT deepen ( plunge south) .    Thus the Midwest   trough  acted as a ” KICKER”     which forced Gloria to stay on or just off the coast

Next   let  us look at hurricane FLOYD   September 1999. In this image we can see the actual track which was very similar to Gloria from 1985. The upper air map shows a deep trough over the Midwest but the trough is positively tilted ( SW to NE). And on the surface map and the upper air map we can see Floyd just off the Florida coast.    We can clearly see that from this position the trough is only going to act as a kicker and not allow Floyd to come inland . Which is exactly what happened.  The rains over Eastern North Carolina and Eastern Virginia were torrential and historic flooding occurred but Floyd did not come inland.

We can   look briefly at HURRICANE EARL from 2011.   Here is the upper air map and again we can see very clearly are pretty big  trough over the Midwest and EARL off the Virginia North Carolina Coast.    The problem is of course at the trough is “progressive ”     —that is to say moving from west the east and it is NOT  deepening.    So it drives EARL off the coast which is exactly what happened.

Now it’s compare that to some of the more famous East Coast hurricanes and see what difference is we can detect.

We will start out with the most famous of all East Coast hurricanes which arguably might be the September New England hurricane of 1938. In this image we can see the actual cape verde classic hurricane track…. which is quite impressive in his own right.

In this next  image we can see the actual surface track and the upper air track from the early upper air maps which were available at the time.    The key point here is that there was a massive trough over the Midwest but unlike what we sought with GLORIA EARL or FLOYD …  this trough was actually deepening as opposed to moving from west the east.   That is to say the trough was actually driving down    towards Alabama and Mississippi as opposed to sweeping towards East Coast.

This is critically important because it changes the entire pattern. With a trough a deepening towards the gulf coast it allows the the western Atlantic ridge ( “Bermuda High”) to expand the get pulled towards the coast and this in turn force is the hurricane to move into the coast as opposed to paralleling it ON the coast or Just offshore .

In this next example we can see the upper air and the surface Maps of mighty hurricane Hazel OCT 1954    which I think has been the storm of record for the East Coast outside of New England over the last 100 years.  In this first map of HAZEL’s approach to the East coast in mid October 1954 the upper air map shows a Upper Low embedded in deep trough over the Midwest .  At first glance it would seem a high probability that this large deep trough would easily knock HAZEL offf the coast and out to sea. But that is on what happens.

In this set of maps we can see that the upper air map clearly showed the West Coast ridge  over North America amplify — that is to say pushing    NORTH  towards the Yukon and Alaska.   This in turn allow the deep trough and the Upper Low to move from Wisconsin down into Tennessee!    This dramatic movement of course changes the entire pattern on the East Coast and over the Western Atlantic Ocean.    The trough deepening –as opposed to moving from west the east — allows HAZEL to be pulled into the trough.    The upper Low over   the Midwest  was so deep in itself that   in combination with HAZEL…   there was an extremely rare and rapid transition from hurricane to monster nor’easter which developed in a 12 hour time frame.    As a result HAZEL did not lose energy as she raced through North Carolina Virginia Maryland Pennsylvania and up into the eastern Great Lakes.

In our third special case we look at mighty hurricane Donna from September 1960 which was also a classic CAPE VERDE hurricane which did not behave as forecasted.  Donna pass north the Puerto Rico then turned due west passing between the Florida Straits in Cuba…. then taking a sharp right turn making landfall south of Tampa and warring up the East Coast.
In this first image we can see a ordinary looking trough in the Jet stream dropping into the Dakotas as Donna it is off the west coast of Florida.   In the middle map we can see that the trough is beginning to change and instead of moving from west the east across the great lakes we see a dropping down towards Arkansas.   This movement causes the pattern over the East Coast and the Western Atlantic Ocean to change…. by increasing the western Atlantic ridge and pulling it toward the East Coast.  In the third map … we now have a massive trough extending from the western great lakes all way down to Louisiana!   The trough has clearly taken on a ” negative tilt ” . Not surprisingly this is forced Donna on the coast and allowed the system to maintain much of its energy .

ISABEL SEPT 2003.
This next image shows mighty hurricane Isabel which was   major event for North Carolina and Virginia in September 2003. On the TOP map we can see the actual track of Isabel passing north of Puerto Rico and striking Eastern North Carolina and Eastern Virginia.    The middle map shows the upper air pattern as Isabel approach the U.S. east coast. We have a pretty deep trough over the Pacific Northwest and the northern Rockies and we have a very strong western Atlantic Ridge ( Bermuda High). The third map shows that the cause the deep trough over the Rockies continue to amplify as it pushed into the Midwest it caused he strong western Atlantic ridge ( Bermuda High ) to get pulled INTO the U.S. East coast.   Notice  here the THICK BLACK LINE which pushes all the way into Pennsylvania lake Huron and north of the state of Maine. Obviously Isabel only had one possible path which was to strike Eastern North Carolina Eastern Virginia.   Not surprisingly  h many of the GFS models showed a land fall further up the coast be cause the cold bias of the GFS showed a weaker Bermuda High.

So what have we learned?     There are plenty more cases here to show but what we have seen from the 1938 hurricane hazel 1954 and Donna  is that the tropical cyclone has to be in a certain position off the southeast coast at the time that a trough of the Midwest is dropping southward or deepening.    
If …on the other hand … the Midwest trough is progressive — that is to say moving from west the east — then you end up with a situation where the trough acts as a KICKER and drives the hurricane off the coast and out to sea.

HOW DOES THIS RELATE TO LESLIE ?
As I stated above at the beginning of this essay … over the past few days the European model –especially last week –has been showing Leslie not being pushed out to sea but getting forced back towards NORTHWEST and int the general direction of the NORTHEAST US Coast because of a developing ridge in the jet stream over the middle of the North Atlantic Ocean.   For example here is the August 30 European run for day 9 and 10 and we can clearly see the model trying to drive LESLIE to the east coast to get around the developing BIg ridge in the North Atlantic.

The problem here is that even though we have a deep trough over the Midwest LESLIE is already    MUCH further NORTH than what we saw in the cases of the 1938 New England hurricane…. Hurricane Hazel and Hurricane Donna.

Not surprisingly today the 12z GFS Model   showed no change from it has been handling LESLIE.  The model shows an ordinary trough moving through the Midwest at DAY 6… which at the surface appears to be a ordinary cold front. These features sweep off the East Coast and drive Leslie harmlessly out to sea.   BUT  the  18z  GFS   takes a step towards the    12z  EUROPEAN  model solution  ( see  below)

However the afternoon European model continues to show a more ominous looking scenario and has a lot of people all excited. As impressive as the European model is as I stated above and quite clearly shown above in all cases where we seen a major East Coast hurricane strike… The tropical cyclone was located off the southeast coast below 30 degrees north latitude as the trough over the Midwest begins to deepen.
On the 12z MONDAY SEPT 3 run of the European model we can see the pattern set up at DAY 5-6. The model shows a much deeper trough over the Midwest the what we’re seeing on the GFS and not surprisingly be also see a stronger ridge out in the north Atlantic which prevents LESLIE from turning out to see. On September 9 the European model actually forms a large upper low ( ULL) over the Ohio Valley which continues to drop towards Georgia. This only increases the strength of the RIDGE in the northwest Atlantic… which in turn forces LESLIE to head towards the southeast coast of Massachusetts!!!!

on DAY 7 / SEPT 10 the European model shows this amazing ULL diving towards the Georgia Coast and in doing so shows a Fujiwara EFFECT taking place.    ( two fairly strong Low being very close to another one alters the movement and track of eash other).    http://en.wikipedia.org/wiki/Fujiwhara_effect

Notice now that the RIDGE in the northwest Atlantic is pushed all way into Boston and New York City… Yikes!!!! According to the European model LESLIE would be located due east of Cape Hatteras at 35 N latitude and 70° W Lange to at an amazing strength of 922 MB which of course would be a historic category five hurricane.  This is a very likely to be way overdone by the European model.

DAY 8/ SEPT 11 this amazing and highly unlikely meteorological dance of death continues with the UPPER LOW reaching the Georgia South Carolina Coast and LESLIE striking very close to Cape Cod. Again the European model still has this intense hurricane at 930MB which is a very strong category four hurricane… Extremely highly unlikely.

And by day 10 the European model has a system striking Halifax nova Scotia with arguably one of the strong as hurricanes they have ever seen in that part of southeastern Canada.

The European scenario is extremely unlikely.. BUT   the Synoptics makes sense with with respect to the Upper air patterns that allow for Major East Coast hurricanes to strike and or come Inland.    The problem  with this scenario as I stated before is that Leslie is not coming INTO the U.S. east coast at a fairly far south latitude… which was the case with the 1938 New England hurricane…. Hurricane hazel …hurricane Donna and hurricane Isabel in 2003.
At this point in time I can not completely rule out the European scenario but in order for the European to work out we must see a large trough over the Midwest drop into the Tennessee Valley… preferably with a large upper low forming over Tennessee and Georgia. Only if that happens would be European scenario be viable. There is no margin for error here…. ANY change in the European scenario would mean that LESLIE would stay further off the coast

1930  EDT  25 AUGUST  

I think I have  made it clear over the last several years that I have clear preference for the European model as opposed to the GFS.  While I do own up to that (and the data and the model cores clearly show ths ) there is an important caveat : my preference for the European over the GFS extends beyond 72 hours.   I have said many times during the winter season and other hurricane seasons that I do not have a problem with the GFS once you get within 84 hours.   The research and the data shows that the GFS accuracy is a lot better within 84 hrs and the European model actually loses a LITTLE bit of accuracy within 72 hrs.   So I don’t mind being tagged with the label “European model lover”    ( as opposed to say marxist leninst)      as long as that label also comes with the acknowledgment that I do like the GFS once you get with in 84 hours.
I mention this because we are rapidly approaching that point now within 84 hours of landfall with Isaac.  After six days — 2x a day — with the European model showing a land fall between Pensacola and New Orleans ….the 12z Saturday, August 25 run suddenly jumped east and now shows landfall in Apalachicola Florida. To say that I was surprised by this would be understatement but then when I considered the time frame (within 84 hours) … it just might be that the 12z Aug 25 is a ” hiccup”.   Indeed the 12z EUROPEAN ensemble MEAN position does still show a land fall between Pensacola and Mobile Alabama.    On the other hand the 12z GFS continued its westward jog with the track of Isaac.   This is also the case for the last 2   runs of Canadian and British models.

I stated reasons in Friday 6pm discussion on the website quite clearly .    The cold front at the surface and the trough in the jet stream that is currently moving through the Midwest is NOT going to be able to GRAB Issac and pull him into the floor to Panhandle at Apalachicola … and it is not going to pull the remains of Isaac into GA…. SC NC and VA.   And because the cold front misses Isaac the heat dome from the Southwest states and the Rockies builds into the central Plains which forces Isaac to bend to the LEFT or back to the WNW.    I said this yesterday … and I am still saying it today and the data is clearly going in that direction.

And this next image we can see the clear shift both on the operational hurricane models them cells. I placed here the last 4 hurricane model plots starting from 0Z run of AUG 25.. 6z 12z and now the 18z hurricane model plots.  This image speaks for itself because you can clearly see the pronounced westward shift which is increasing as you are getting closer towards landfall. This point is VERY IMPORTANT: we are getting closer to the point where models should become increasing more accurate because we only dealing over the next three days — not 6 — and they are now picking up on the trend back to the WNW / LEFT.

In fact we can even see this more clearly on the GFS hurricane ensemble.    This image shows us the last three runs of the GFS hurricane ensembles… and this shift here has been absolutely stunning over the last 18 hours.

There has been a lot of speculation locallly here the middle Atlantic states that some portion… perhaps a good deal …of the rains from tropical storm Isaac will come up either from the southeast     ( GA SC ) or from Tennessee … and into the Carolinas Virginia Maryland .    That whole concept is based upon the idea that Isaac was going to make landfall in floor to somewhere between Pensacola  and Apalachicola.     From there its rains would move into Georgia and then quickly be pulled up the coast and therw would be a VERY nice significant rain for the Carolinas and Virginia.    This sort of forecasts has been said by a lot of forecasters both on the weather channel at some the other private weather services and on a lot of the local TV stations up and down the East Coast.

The problem with this forecast is that is is based completely on the GFS and Canadian Models as well as the early hurricane model projections back on Wednesday Thursday and Friday.    But as we have seen above that the GFS has switched much further to the west so that the forecast of significant rains coming up from Georgia into the Carolinas Virginia … is much reduced.
The point here is that the further west Isaac goes the more likely it is for the remains of Isaac ( heavy rains) will go up into Mississippi Alabama Tennessee Kentucky and then into the Midwest… and NOT into SC NC VA MD DE PA NJ. And as we can see with this trend to the west… it is this latter scenario which appears to be more likely .    Hey if you want to ignore this trend feel free. But when your forecast busts and the remains of Isaac ‘ havy rains  do   not come up from the  Florida   panhandle into the Carolinas / Virginia… don’t come crying to me.

1800 EDT  24 AUGUST   2012

If you been following any of the weather models OR my discussions and posts over face book wxrisk … Or anybody else ‘s weather forecasts and discussions for that matter then I am sure you have deduced by now we have quite a bit of uncertainty as to what’s going to happen with Isaac when he finishes crossing Cuba. The system is finally beginning to really taking off and developing but of course it’s not going to do that once it crosses the land mass of Cuba. That being said because the tropical storm is now actually developing an intensifying it probably will come off Cuba and a lot better shape.

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Which leads us to the forecast problem of what’s going to happen . We have two very distinct scenarios and this is not complicated in terms of following it and figure out what’s going to happen.      Back on Thursday afternoon the 12z GFS has shifted does strongly to the west and was showing a land fall near mobile Alabama which is almost as far west as the European model has been showing over the past 12 runs. However since then the GFS has gone back to the east and as result many other forecasts … on the weather channel…accu weather… NHC .. etc etc have shifted back to the east showing a land fall over Apalachicola and tracking very close to the southwest coast of Florida.

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Let me be clear I think that forecast is wrong.    It’s possible but I think it’s the wrong way to go and I think the GFS is making a serious error here which I hope to explain shortly.

The first key point or benchmark is where it leaves the Cuban Coast. This is a enlarged view from stormvista.com   of the 12z FRIDAY AUG 24 RUN of the GFS . Notice that the bottle has Isaac actually cutting across southwest Florida — Naples and fort Myers and then tracking one along the coastal areas of Tampa perhaps maybe 25 miles offshore. From there it makes landfall in the Apalachicola area.

Now here   is  the European model…. the 12z AUG 24 run… And this is very consistent with what the European has been showing for days and days and days. The model has eyes into coming off the Cuban Coast further to the west so would never touches southwest Florida at all.

That is a key point.  When  Monday rolls around  …  if Isaac is not going across southwest Florida — fort Myers and Naples– it means that the European solution is probably going to be correct.  
Since the European model is further to the west won at least Cuba in ends up going through the open portions of the Eastern Gulf of Mexico… And then the model r turns Isaac back to the northwest… so it makes landfall at Mobile Alabama.

Now these are two very different solutions. So why do the models don’t agree?
The answer has to do with a large scale features across North America which again far too many meteorologist ignore and  just  try  to focus on the local hurricane model. So I hope this explanation will give you a better understanding of what is going on and why the European and the GFS models are in such a big fight.

Most of these maps are pretty self explanatory and I put a lot of detail into them so you can follow along . Basically however the dilemma is that the GFS model is merging or phasing Isaac on theFL panhandle with a trough or cold front that moves through the great lakes and the northeast early next week. The model does not seem to understand that these are two separate systems and this over phasing tendency is very common with the GFS.

The European model moves the front through much faster   so that   Isaac  if left  hanging back.    Then the model develops a new heat dome from the southwest on the Rockies back into Missouri Kansas and Illinois — which is going to happen anyway regardless of whether not Isaac was going to form and hit the gulf coast.    However the movement of this heat dome traps or blocks Isaac from moving any further inland. As a result the European does not show significant rains getting up the East Coast at all.    Instead the   rains get into   MS  AL  TN  KY  ILL IN  and OH.

Here are  the  0z  and 12z   EURO  ensembles …  the left side maps are the 500  mb maps  and the   right side are the   surface maps. Again we can see  Why the   euro is  soooo far to the  west than the other models .

0700   EST  23 AUGUST   2012

One of the really big rules in forecasting in the medium and extended range  has  to do with basic  principles of understanding of how the  weather Models  are  SUPPSOE  to work.  The problem is that a lot of TV meteorologists and some private sector meteorologists don’t really seem to grasp this.  Let’s assume you have one particular solution from one weather model.  Lets call  it the  ABC .  Now all the other weather models are showing something else besides ABC.  One weather model is showing  XYZ..  another is showing MNO  another    QRS.. etc .  Obviously  this can cause quite a bit of confusion and variability or uncertainty in the forecast .  Of course there are a number of ways and techniques good forecasters can use to get around or reduce this uncertainty or variability but for the most part … a A lot of forecasters are bamboozled when they come across a large array of possible solutions .

Fair enough.
However if we keep in mind that the basic premise of forecasting with weather models is that as you get closer to the event … each day    model accuracy should increase and you should have model consensus.  This concept  in  taught  in most of the undergrad meteorology schools and it is a very important concept.  In other words weather models which are dealing with 48 hours now should be a lot more accurate and in a lot better agreement   then   7 days  from now.
Got it? .

That being  so HERE is the BIG rule.   When the other weather models begin to turn towards one particular weather model … say the ABC  solution … it usually means that this particular weather model  solution is going to be  end up  being correct .  In other words as you get close to  the  Day 1  … if  other the weather models turned towards the Canadian model solution  ( for example)   it usually means that the Canadian model solution will be correct.  Or if the weather models turned towards the European model solution or the GFS model it usually means those model and that being the correct solution after all.

OK taking this idea and applying  it  to what is  going on with Isaac…we see a very clear and distinct trend that all the models.: They are  shifting towards the the European model solution of the past four days which is
1    Issac  NOT   going  cut  directly across   Haiti and eastern Cuba
2 .. NOT going into south or eastern Florida 
3   NOT coming  up the  southeast US  coast… 
4    Issac will move into the Eastern Gulf of Mexico.

The European model has remained very consistent   –unlike all the other models –for the past four days.  We can see again that the model takes the system south of  Haiti and Eastern Cuba and finally turns across Western Cuba into the Eastern Gulf of Mexico.  From there the 0z Thursday AUG 23  run  the European model  shows a land fall either in the far western portions of the Florida panhandle or in Southern Alabama…  as a category 3  hurricane.

The Canadian model which has consistently   taken Isaac into the Bahamas then up the Southeast U.S. Coast …suddenly now shows a Florida  landfall which is something  this Model has not shown before.  This is a major shift towards the European solution.

The British model  ( the Ukmet ) now shows a Eastern Gulf of Mexico track which again is a major change to cause this model has not shown that one time over the past four days.

and with the 0z   GFS and  GFS  based hurricane models…  We now see a track that is now not even on the West Florida Coast  — which is  what the GFS Models were showing yesterday .  — but now   the 0z  GFS Model  also has a track in the eastern Gulf of Mexico.  So again we see a another shift to a west  and a big step towards the European solution
Of course as I am writing this out.. the new   and wretched  6z GFS  Model  comes  out  with a new   ” issue”.     Yes the 6z   GFS  is significantly west of yesterday’s GFS model runs …which   was  west of what we saw on Tuesday ….which   was  west of what we saw  on Monday.  But  the  6z  GFS  model  run  has to come up with the  idiotic solution.      The 6z GFS takes  Issac   (after taking Isaac into Western Florida very close to Tampa )   then up towards Northern Florida…   then the model phases or merges  it with the jet stream over the Great Lakes and pulls  the  remains of Issac  north into the Carolinas and Virginia with extremely heavy rains.

This is BULLSHIT.

We know it is BS   because the solution makes no sense to meteorologically.     We know it is BS because the GFS model is famous for over phasing or over developing coastal systems.  And  We know it is BS  because   no other model is showing anything like the  6z GFS.    It is obvious and self evident that the model after 138 hours views the remains of tropical storm Isaac as a coastal storm located off the coast of Georgia…  And that somehow another the calenda  is now November as opposed to late August.

If we compare this solution to the very  persistent and consistent European model  which has shown any Eastern Gulf of Mexico track since Monday…  without  any serious variance  whatsoever  — unlike the GFS   the Ukmet  and the  Canadian — the contrast is quite amazing.  But more importantly there  are  tenn of Millions if not hundreds of millions of dollars riding on this forecast because the European model takes the remains of Isaac up into the drought ridden areas of the Upper Delta  then into the heart of the Midwest with widespread significant rainfall.  So if you are going to follow the 6z  GFS and you bought a lot of soybean   futures and you forecast more dry conditions  in the 6-10 day you are about to end up in the poor house.

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2240  19 AUGUST  2012

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As a general rule I do not update the web site at all on Monday because it’s such a busy day for me     with regard to the commodity trades that I simply don’t have time.   Unfortunately with the system   94L  developing  in   the tropical Atlantic combined with some realy exceedingly bad forecasts out there on the Internet… I guess I am going to have to find the time to break my rule and update.

First let’s talk about the date.   Last year August 27, 28 29 was the landfalling dates of hurricane IRENE. Specifically over eastern North Carolina and into eastern Virginia it was August 28 2011.    Not only was that a very important day for me and WXRISK.COM and the Facebook page but it also affected me along with many Virginians and eastern North Carolina residents in a major way.    So naturally with this system possibly becoming ISSAC  which should be yet a another   ” I ” storm…  along with IRENE last August 28-29 and ISABEL in SEPT 18 . 2003 … we are starting to see a lot of concern regarding 94L and if it becomes ISSAC.     I mean if 94L does become ISSAC   … and IF it hits NC VA …what are the odds of the three significant landfalling hurricanes in the lower Middle Atlantic states all being the 9th named tropical cyclone ( the “I’ storm)?

It’s one of those things that make you look and wonder if there is something else at work beside science but actually it’  i the human mind which is making these sorts of connection.     To begin with 94L has taken a lot longer to develop then what anybody thought   and this includes the folks at the National hurricane center.   The morning satellite picture here on the 20th did not look very good. As you can see from this picture the immense Sahara dust cloud has in fact been entrain or pulled into the system.    At the end of last week it look like 94 L would stay south  of the  Dust  cloud and not really be affected by it.    Clearly that is not the case and it is significantly impacting 94L’s ability to develop rapidly.

Because of this amount of dust entering 94L….  the European model over this past weekend backed off of the idea of a very powerful tropical cyclone / hurricane hitting the Southeast US coast    (If you recall the European model last Friday was quite bullish on 94L becoming a big threat for the Southeast U.S. Coast).     During this past weekend every single run of the European model showed no development at all and some of the European model runs actually kill the system completely over the next seven days!!     Interestingly even though the GFS last week did not even see 94L and showed NO development…. during this past weekend the GFS models began to jump up and down about 94L even though it appeared to be struggling.
And because 94L   looks weaker and is taking longer to develop…    94L is for more likely to head in a westerly direction which would take it into the Caribbean and very close to the big island’s of Hispanola and Cuba. This of course would interfere in its ability to develop rapidly were into a significant hurricane for an extended period of time.

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This is vastly different from what we sought with IRENE or ISABEL   . Those East Coast hurricane as did  NOT   come up through and over the big island’s in the northern Caribbean. Here  is the European model surface maps from the Penn state E-wall site…  and we can clearly see the model shows a very weak tropical cyclone move into the Northwest Caribbean into the eastern or southeastern portion of the Gulf of Mexico and hitting Florida.

On the other hand if we look at the 0Z Monday GFS at 180 hrs ( day 7.5) and 216 hrs ( day 9) we see a moderate intensity tropical cyclone probably not a hurricane moving across the far southeast portions of the Gulf of Mexico and hitting the western side of Florida. From there the system lingers over Florida — remember that after 192 hours the model resolution on the GFS becomes a pile of crap so it’s going to handle tropical systems a lot more poorly and with a lot less detail.

The Canadian model and the Canadian model ensembels .. was a bit more bullish with a tropical cyclone and showed a stronger system but one that was off the Southeast U.S. Coast. The Canadian model was not taking this system through the Caribbean or into Florida but paralleling the U.S. east coast and then heading out to sea: a very reasonable and viable solution even though the Canadian model is not a particular good model with regard to handling t ropical cyclones.

The 6z GFS showed more of the same thing … a TC of moderate intensity moving through or over Cuba and the Northwest Caribbean and making landfall on the west side of Florida
( ft Myers according to the 6z GFS)  AUG 27 … then lingering over the west coast of Florida .

Here is the 12 the GFS…. And as you can see at day six the model has 94L as ISAAC but it is located over Central Cuba and by August 28 is located over west Central Florida
( HELLO GOP  CONVENTION!!!..  didn’t this happen in 2008?)

 
In looking at the 12z hurricane models we see some important features.   Notice that most of the models take this system through the big island’s over the Northern Caribbean. This is not good for those  forecasting   significant or rapid    development.   And not surprisingly the models hurricane intensity charts are also showing very weak and slow development. Yet despite all this there were several interesting forecasts and speculation from some meteorologists and people who stayed at a holiday inn last night that 94 L/ Isaac would become a major hurricane .

That of course is a distinct possibility but as you can see there are a lot a reasons for that not to be the case.
Next the 12Z Canadian model came out and it showed a very powerful hurricane headed right for the North Carolina Virginia Coast in a manner very similar to what we sought with IRENE and ISABEL .

Those 2 hurircanes came across from the tropical Atlantic passing east and northeast of the Bahamas -they did not come up to the Caribbean.   So the Canadian at least it is showing a scenario very similar to what we saw with IRENE and ISABEL.    That being said the Canadian solution is unrealistic because the model takes 94L/ ISSAC across the western side of the W.A.R. ( the Bermiuda HIGH) which does not make a lot of sense meteorologIically speaking.
If we look at the Canadian ensmbles to see how many members support or  MATCH the 12z operational Canadian and its big hit to the East coast scenario we find a few members supporting it but not a lot.   Again this is a warning sign that the operational Canadian scenario is probably not correct.

On the other hand many people saw the 12z GFS Hurricane ensembles .. and went ..”WOW east coast hurricane !!..”      This is also a track very similar to what we saw with IRENE and ISABEL.     But here we have to remember that the GFS ensemble is run at a lower resolution then the operational model and as result the model appears to be phasing or merging the hurricane and a trough in the jet stream coming in from the Great Lakes   . This causes the hurricane  to come up the East Coast according to the GFS ensembles.

The Monday afternoon evening satellite pictures are little more promising and we can clearly see a closed circulation even though there is a gap in the convection on the northwest side of the disturbance.

  
Indeed the 12z European model came out and actually showed a somewhat better developed 94L that was no longer disintegrating into an open wave . The European model was now detecting an actual tropical cyclone (ISSAC) in the Southeast Gulf of Mexico and threatening the west coast of Florida.

 What we do have really good agreement on is that the European Ensembles AND the GFS ensembles show some sort of decent size tropical cyclone in and around Florida or the Eastern Gulf of Mexico or just off the southeast coast AUG 28-29-30. But it does not look particularly strong or well organized.

SUMMARY… 94L is NOT developing as fast as what I   and many others thought it would. It has been pulling a lot of  dust and dry air which has inhibited its development and is allowing the system to take a more westerly track so that it  passes  south the Puerto Rico in   all probability. This means that the system is going to interact with the big island’s and the Northern Caribbean and will probably interfere will restrict its ability to rapidly develop into a significant hurricane. Those calling for a major hurricane for the Florida and or the Southeast U.S. Coast at this time are doing so without any basis in fact and are ignoring the significance of the model data and the overall track. 94L will likely become a tropical storm and it will be given the name of ISAAC. But this system’s track is significantly different from what we saw with IRENE and with ISABEL … and folks in Virginia North Carolina at this time are probably looking at the remains of tropical storm or weak hurricane coming up from Florida and Georgia — in other words no big deal.

There is of course the possibility that the system could rapidly intensified over the Eastern Gulf of Mexico before it came into the west side of Florida… And there is even a small possibility that the system might end up tracking north of the big island’s in the Northern Caribbean and approach the southeast U.S. Coast from the Bahamas. This obviously would also oppose a much bigger threat to the southeast coast. But these are very small possibilities at this time.

2000 EDT  17 AUGUST  2012

In my last update in the tropical section I went to some detail about how the pattern and set up in the MDR  -  the Main Development Rregion — of the Atlantic Basin was still set up quite favorably and was going to remain that way probably through the end of the month.

Since I made that update a few days ago things   have clearly trended    with continued above normal activity.   The strong tropical wave which came off Africa last week–  the feature which the operational GFS consistently blew up into a major East Coast hurricane– turned out to sea harmlessly earlier in this week.  In doing so it showed that the GFS was off by about 2000 miles.   In any  event that system developed into a tropical storm GORDON a few days ago .  The remains of tropical discretion #7  held  together and regenerated in the bay of Campeche Sea yesterday and was upgraded to tropical storm  HELENE this afternoon .    Of course even though we are seeing above normal activity …none of this tropical activity so far has  become a  really big deal.  After all it is a El Nino …. or at least so we are told but as you can tell from the overall weather patterns   (the crippling  heat /  drought in the CONUS …  the  lack of rain in Southern Brazil in South America….  and in Australia…  this is  turning  out to be a pretty abnormal El Nino event .

This first image shows us the current MJO impulse   from the British European and GFS models.  As you can see they all forecast the MJO to move steadily through phase 1 and 2  over the next 10 days.  By the  beginning of September   the MJO might actually reach phase 3.   As I stated several times  over the past few weeks  research clearly shows that there a much higher than normal probability of tropical cyclone development IF  and ONLY IF…  there is some sort of tropical feature which might develop.  In other words  MJO does not cause  tropical cyclone development…  It just enhances the likelihood that a feature might develop.

In addition the latest  200 Mb  vertical velocity plots from CPC shows more extremely favorable conditions moving into the MDR.  I have been talked about this development  for few weeks and  things are  really looking  favorable over the next 10 to 14 days.  A particular importance is a cluster of strong rising motion in the atmosphere   (lots of green) that is moving into the Gulf and the Caribbean over the next few days.  Eventually this energy will move into the tropical Atlantic just as any potential system coming in from Africa heads towards the Caribbean or the Bahamas.

The problem is that we have a very strong system which is come off the southwest African Coast and the past  36 hours or so.  You can see some the images here of this impressive system  (94L)which is a large a massive tropical wave with a tremendous amount convection already in the system.

It’s also are fairly low latitude…  And as you can see from the satellite image   from CIMSS…   the dust coming off of Northwest Africa appears to be fairly far to the north of the system.  if so… then  this tropical disturbance designated  94 L  should   not be impacted by the dust as so many systems so far this season have .

In addition as we can see the ward temperatures continue to warm nicely in the tropical eastern and central Atlantic…  Which should also in the developer of the system.

The latest  WIND SHEAR  maps from CIMSS shows really like shear conditions across the entire tropical Atlantic especially  south of  15N.

But decides the system being fairly far to the south the pattern is set up so that there will be   large and powerful western Atlantic   Ridge covering much of the central and Western Atlantic Ocean.   This are ridge is known as the W.A.R. or western Atlantic rage that you may know of  the more common name  –   ” the BERMUDA HIGH”.

This is very important because 94L  is  really  far south  and by staying at a  fairly low latitude as it approaches the Northeast Caribbean   ( 60 degrees west Longitude)   the  strong ridge or dome in the Western Atlantic Ocean  get a chance to Build    towards the  USA   East coast.   In doing so  the  WAR  will protect  it  from any sort of  cold fronts or troughs  that might come off the East Coast.

The European model has been particularly bullish on the system now for several days.  Here  is an image of the last three runs of the operational European …  And as you can clearly see the trend is towards the Bahamas and wore the Southeast U.S. Coast at day 10.

Now keep in mind the European model is not showing the landfall here but the trend is towards the coast and that is what’s important given that this event is still 10 days out.

Here  is a comparison of the 12Z   Friday European operational and the European  ensemble  at   120  hrs / 5 days.  As you can see we have a large huge dome in the Central Atlantic Ocean which will prevent this system from turning out to sea too early.

Next we have the  day 10  European model also from  12z  FRIDAY .  What’s noticeable here is the remarkable agreement between the operational   euro and the  ensemble.  The key as you can clearly see on the model is how strong the western flank of the Bermuda high ideas.  This is always a critical aspect in forecasting any East Coast hurricane threat.

Indeed if we look at some the spaghetti diagrams of the European ensemble  from m0z  FRIDAY  and 12z   FRIDAY  that you can get from STORMVISTA.COM     (you really have to get an accoutn there… there model stuff  is  best   there is) …  We can also see this shift towards the Bahamas and the southeast coast  at 204   hrs  and to a lessor degree  at 240 hrs.

And looking at the actual operational European model at day 10 we can see the tropical cyclone possibly intense major hurricane nearing the Bahamas off the floor to coast.  We also see what appears to be a decent sized trough over the East Coast.  Now it’s 10 days out   so  one  has to wonder IF that trough  is for real or …..is it being overdone by the model??   We also see a new heat dome developing over the lower planes and the southwestern states….  And if that heat dome builds and faster   then  the  trough  along the East Coast would be weaker   and this in turn would increase the chances of the hurricane hitting the Southeast U.S. Coast.

As you can see there a lots of possibilities here.

what about the    GFS  Model?  Quite frankly I don’t care with this model has to say about  94L and its   development.  There are several reasons for this.  First  let me remind you that the GFS model has a resolution problem after 192 hours which is day 8.  If you don’t know what that means it refers to  the GFS Model which has a different resolution after 192 hours out to  384 hrs  ( day 16).  This simply is not enough computing power over at  HPC/ EMC to run the GFS model at the same resolution all way through  to  384   /  Day 16.  As a result the model is famous for having these massive flip flops and inconsistencies  AFTER   192 hrs.  The European and Canadian models for example do not have this problem but the only one the model 2x a  day.    This is critically important when you are considering  why the GFS model past day 8   does so poorly in figuring out the development and tracks of tropical systems.

SECOND  as I  mentioned earlier the  GFS  model  did an absolutely atrocious job  in  forecasting the strong tropical wave from last week  that came off the African Coast.  If you recall the model developed into a major hurricane that threatened to hit the U.S. east coast around August  21-22.   The   system did not develop into a major hurricane and the GFS model    was off by more than 2000 miles.  Why would anybody give a rat’s an us about the GFS this far out in time.?

 At this point you may ask … what about the   vaunted European model…  How did that  model handle that system which later on became tropical storm  GORDON?  In fact the European took the system and turned it harmlessly out to sea in the Central Atlantic Ocean and then curve to back up towards the azores….  which is pretty darn close to what the GORDON  has actually done.

Anyway if you really do want to take a look at the  GFS models with regard to 94L… here they are.  First we can take a look of the GFS model and see what it  is doing differently on a large scale from the European model.  It has the hurricane or tropical cyclone nearing the Leeward islands in the Northeast Caribbean as a pretty big system  August 25 but be cause the model has a much weaker western Atlantic Ridge  the GFS turns the tropical cyclone out to sea east of Puerto Rico.

Not surprisingly all since all of the hurricane models are based primarily off the GFS and the GFS grid it should not be a surprise that all of the hurricane models from this morning turned this tropical cyclone out to sea east of Puerto Rico.   Monkey   see  Monkey do  right ?

It  turns   out  however   that the 18z hurricane models have turn   much closer to the European solution in showing a track much further to the southwest and implying a  closer  track towards the northeast Leeward  islands.

SUMMARY:   there appears to be a high probability of a significant tropical cyclone in the cape verde    hurricane pipeline coming down which could be develop into a category 3+  hurricane at some point in its lifecycle over the next 10 or 12 days.    In general ….looking at the overall pattern  AT THIS TIME….  it does not appear to be what I would call favorable for East Coast hurricane strike and if I had to make a bet right now I would favor a near miss with the tropical cyclone passing between Bermuda and the East Coast.     But there are still a ton of possibilities out there and a ton of variables.  I do believe that this is NOT going to turn out to sea EARLY  and that the dust will not affect it and it has a high potential to become a significant hurricane.  There are several additional benchmarks to watch….  For example if this TC   ere to pass through the Northeast Caribbean / Leewards  islands … THAT  would greatly increase the chance of a U.S. landfall.  Likewise if this system were to pass close to the Bahamas  THAT    also would increase the chances of the U.S. landfall.

And lastly I have notice the date of possible close passage to the East coast which should be around August 28 or 29 ….  one year ago to the day that Irene came into Eastern Virginia and Eastern North Carolina.

2200  EDT  13  AUGUST  2012 
Over the past week   we had two fairly significant tropical features  in the  tropical Atlantic.   One   was a strong tropical wave  (Designated 92L by the NHC)     which became tropical depression #7…   and the other was a fierce looking tropical wave that came off the southwest coast of Africa last week and was being forecasted by the GFS   model  to become a huge Atlantic hurricane and threaten the East Coast with either near miss or direct hit sometime around August 21-22.

Of course   when I posted on this potential last week here and over on the FACEBOOK  page   I posted that long shot GFS  scenario was because a number of other weather sources were talking about this potential on various websites and face book pages.   And some of the hype was getting a little out of control.   Of course one can make the argument that the very fact I was talking about those features last week proved that I too was involved in the hype.     Of course if you make that argument it would kind of mean that you are not that bright because there is a difference between Hype and sensationalism and Knocking it down .
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Anyway lets take a look and see what happened to the 2 big features and see what if anything it tells us about the second half of August.

This image gives us a wide shot of the infrared satellite from August 12 — t I have highlighted the remains of TD # 7…. and the strong tropical wave which came off the southwest Africa last week.    What is interesting to note here is that if you take a look at the previous post …. the GFS Model depiction of the strong tropical wave coming off Africa  was    going to develop into a hurricane  by  AUG   14-15  …  and it  would eventually strike the Southeast U.S. Coast .   The European models  showed no such threat and had this system turning harmlessly out to sea east of Bermuda.    As you can see from the satellite picture it looks like the European model is going to be correct and the GFS was jumping the gun and overreacting once again.  This system coming off Africa was allowed to turn to the northwest because of the trough in the jet stream which existed in the Middle Atlantic Ocean.

That same trough produced strong southwest winds across the Central Atlantic Ocean  and turned the    aw African  wave  to the  NW  early … also   killed  Tropical Depression #7    last week.  The shear was so strong that it eventually killed the TD  forcing it into an open wave  at the end of last week.     As you can see the remains of TD#7 is still going essentially east to west through the Caribbean Basin and it still has some convection associated with it but it is not likely to develop.

But in a larger sense one of the problems with these two systems is that the pattern still had not yet turned favorable. In the previous post I showed the 200 MB vertical velocity fields maps. During the month of July most of the Atlantic Basin was in     SINKING AIR   (the brown stuff)    which greatly reduces the threat of SIGNIFICANT tropical development.     As you can see HERE as of AUG 4… there was a huge concentration or ” blob” of the   brown stuff    (sinking air)   over the entire Gulf Carribean basin central America and the sw Atlantic .    It should NOT of beena    surprise that TD#7 died and the strong tropical wave coming off the sw coast of Africa turned out to be a massive GFS model flop.

LESSON? its pretty basic… REALITY over Models

So where do we stand now?     Looking at the NEW AUG 10 200 MB Vertical Velocity plots we see a MAJOR change. Note the HUGE large intense area of GREEN or RISING air surging into the Gulf and Craibbean basin  . One can surmise that this GREEN area/ rising air which ENHANCES tropical development will moves into the tropical Noth Atlantic in several days.

Now if there was only some sort of new strong tropical Low / wave coming off the sw coast of Africa.

oh look there is.... In fact as you can see from these satellite pictures… there is a pretty strong tropical wave about to move off the coast of southwest Africa. The IR satellite picture shows a lot of convection here but not all of the convection is going to survive once the system moves off the land mass and into the immediate coastal waters between of the African Coast and the Cape Verde islands.   Still the sea surface temperatures continue to warm and the far eastern Atlantic and this feature does have some potential.
In addition this next satellite picture shows an enormous cluster of heavy thunderstorms which appears to have a cyclonic circulation already in the system centered over the NIGERIA and NIGER .

To be sure some of this is speculative and right now there is no system which is close to developing and certainly there is no threat at all of any kind to any portion of the Caribbean Basin or the U.S. coastal areas.   But I have been using this 200 mb vertical velocity method to determine favorable windows of tropical development for several years and it works pretty good. So let’s see.

lastly  there  is the  CURRENT  MJO   which will be in phase  1 and 2    through the end of the Month  and  as I showed before  research shows ENHANCED  tropical  activity  in the  Atlantic Basin  when the MJO  is   in  phase 1and 2 .

1545 EDT   8 AUGUST

Over the past few days some of the operational weather models have been indicating a fairly strong system coming off the southwest African Coast and developing into a significant tropical cyclone / hurricane.   At first it was thought that the tropical wave system which is currently designated as 92L…. was the feature that most of the operational models were jumping on and showing as a potentially significant tropical wave that might develop into a significant Atlantic hurricane. That is still a possibility although all looking at the midday satellite picture here on Wednesday AUG 8 … 92 L does not look very well developed.

However as a some others have noted and I have been watching now for couple of days….  there  has been a very strong cluster of heavy thunderstorms which has developed just north of equatorial Africa.    This feature is large  and well organized  and it appears to be holding together. It is  moving towards the southwest coast of Africa and is likely come off the African Coast on Thursday or Friday. It is somewhat unusual to see a tropical wave this massive fairly early this early   in  the season but it is not unheard of.

We can take a look at some of the impressive satellite pictures   and   model data to see this bad boy in all its Glory. This first picture is from August 7 and we can see the enormous tropical wave with apparently feeder bands are clearly evident.  This is indicative of strong cyclonic circulation  already in the system.

Here is the early morning IR picture and again we can see how impressive this features looking especially when you compare    or contrast  it   to the rather to be looking  average  looking  92L tropical wave to the west  at 30-35   degrees W Longitude.

Here is the latest photograph from the BRITS which use a combination of infrared and  visible.    The advantage of using these images from the DUNDEE UK satellite web site is that the images here are huge and the detail is quite impressive.    In  this image I have highlighted some of the features and the cyclonic curvature evident within the massive tropical wave.

The downside to all this is that unfortunately we are already seeing a lot of the usual hypsters and scaremongers in the private weather business talking about this feature as a potential East Coast hurricane threat…. sometime after August 21. I have even seen some TV stations here the middle Atlantic    region talk about this.     Let’s face it… the primaries reason WHY they are mentioning this is because of the GFS model.
Here are some of the recent runs of the GFS model would show this feature tracking across the tropical Atlantic…   and slamming into the Southeast U.S. Coast after AUG 21 . This image is from the 0z GFS AUG 8 run… and the 6z GFS is showing the same sort of thing.

   
The problem here is that the European model also   shows this strong tropical wave developing  BUT   the euro   turns  it   out to sea either at or to the east of the Longitude of Bermuda.    Keep in mind that the European model early on handle and ERNRSTO better than the GFS. Eventually the GFS big switch course and showed a persistent track into the Yucatan.

It is  way the too early to engage  in any sort of informed speculation about this potential significant system.   The ocean where temperatures off the west coast of Africa out warmed dramatically over the past two with three weeks.

But the problem   is  that  we don’t know where this system is going to come off the African Coast ,,,,AND we do not know the latitude of where it passes with respect to make a CAPE VERDE islands .    This is absolutely critical to the potential track .   The history of  Cape Verde  (CV)   Island    Tropical  cyclones  shows that systems that pass south of the Cape Verde Islands   close   to 10° north latitude have a far greater chance of reaching   or   at least  threatening the U.S. mainland….   as opposed to tropical systems that pass south of the cape Verde islands but at 13 or 14 degrees N latitude.     Even though it may not seem like the difference between 3° latitude  is a big deal …the implications further out and time are huge .

But besides all that   …   we have no idea what the pattern is going to look like in the Western Atlantic Ocean after August 17.    Yesterday most the model data was showing a strong western Atlantic Ridge –often refer to as the Bermuda high– that was extending into the Bahamas and just off the FL – GA -SC Coast.     When the Bermuda high is displaced into the southwest  Atlantic  ocean  like this..  it often favors Atlantic hurricanes making the U.S.  East coast landfall.    But today the data does not show that at all — in fact some of the data shows a new cold front moving through the East Coast after AUG 17-18.     If that is the case then it does  NOT make a difference how strong this system is going to be coming off the southwest coast of Africa …   or where it passes with respect to the CV island s.   If there is a strong cold front coming off the East Coast …IF… this system will be kicked harmlessly out to sea.

1345   EDT  5 AUGUST

I receive a lot of questions lately about tropical storm Florence which formed on Friday in the far far eastern portions of the tropical  North Atlantic… eEven to the east of the cave ready islands.  This is only the third time that we have reached the six the names stomed in a hurricane season this early.  The last time was 2005 and back in 1936 both of which were extremely active hurricane years.

That being said    despite the early and impressive development of tropical storm Florence  ( FLO)     she   has no real future and is certainly not going to be a classic  Cape Verde  Hurricane.  There are two real problems with the system and its potential future.  First…  is that tropical storm Florence came off the African Coast too far to the north and ran into a wall of massive Sarandon dust.  The early development of Florence allow the system to track more WNW   then  west.  Tropical storm Ernesto being a weaker system…  tracked   due west and avoided the massive plume of Sahara dust which is dominated much of the central and eastern north Atlantic over the past 60 days.  However with  Florence the tropical cyclone has developed a bit faster which has allowed for the more WNW  track.. so that   she has gained enough latitude to run into the southern edge of the massive Sahara dust cloud .

The Second  problem is the overall pattern.  The tropical north Atlantic is dominated by a strong Bermuda Ridge / surface High in the southwest Atlantic Ocean just off the Easter Southeast U.S. Coast and a strong  Ridge/ surface HIGH in the tropical Atlantic Ocean.

However in between these two features is a gap in the central Atlantic ocean and this gap extends fairly far to the south.  This gap is actually a trough in the jet stream….  and like all troughs the eastern side of it has wins which are running from southwest and northeast

Thus as a  result Florence which is now gaining some latitude is starting to see the affect of the trough   and the strong southwesterly winds.  This produces   strong shear which moves away the thunderstorms/ convection and allows a system to weaken.  When you combine that this inhibiting factor along with a strong massive dust cloud that the tropical cyclone is now running into…

Well  it  pretty much kills any future that tropical storm force might have but then

2 AUG 1630 EDT ….

The hurricane reconnaissance flight found flight level wins at 52 knots when they investigate Tropical Depression #5   early this afternoon around 3:00 or 4:00 PM   EDT.  The estimated the surface level winds to be around 40 knots which seems reasonable and  NHC    is going to upgrade the depression two tropical storm  ERNESTO    at  5PM EDT

There  has  been some speculation based upon the the hurricane models and the GFS that next week the TD #5   /  tropical storm will bend to the right as moves into the Northwest Caribbean and either just clip   the northern extension the Yucatan  Peninusla or pass through the Yucatan channel then head towards the Texas gulf coast..

The remains a possibility although the data and the overall trends do  NOT  support  that and let me explain why and why I think    ERNESTO  will    hit  the Yucatan then cut across the bay of Campeche Sea and move into Northern Mexico south of the Rio Grande river and Brownsville Texas.

We can see on the midday satellite picture that the depression is looking a lot better than it did last night.

This image I find  to be especially useful because it gives you an idea of where the system is with respect to the  northern coast of Venezuela and Colombia on the south American continent.

Because of the strong zonal or east to west flow at this latitude  TD 5/ ERNESTO is moving along at a really good clip.  Usually we see a tropical system like this  fast    it is   difficult for the system to develop as steady pace.    IF  ERNESTO picks up any more Forward peed the low level center may in fact get pulled away from the main convection and a system could shear apart.   This has happened several times over the past few years with various tropical systems in the North Atlantic.

The close proximity to the South American Coast is really important point which needs to be stressed.     If you come up the northeast coast of Brazil … headed towards Venezuela and Colombia you will see that the   north coast  of South America gains latitude …reaching   12° N latitude in several locations and reaching close to 13° N latitude at a few areas  but far more importantly is that a system tracking into the southeast portions of the Caribbean is going to interact with the South American .

The large circulation of a tropical depression or a  tropical storm or a   hurricane is going to pull in a lot of dry non tropical air from off the Highlands and mountains of Colombia and Venezuela .  This   air gets entrained into a a tropical cyclone  and   causes  the system to stabilize in  its  development / intensification.    In some cases we can  see a TC  weaken  dramatically .  As a result if  when  you look at the hurricane climatology over the past 100 years …   you will see that many tropical cyclones do  NOT    intensify over the Southeast Caribbean even though the warm sea surface temperatures would seem to be ideal.

Now that being said ….you  should notice  that once we cross   the  72 degree west longitude    line… the South American Coast turns to the southwest …  into the Gulf of Panama.  But more importantly the entire western portions of the Caribbean opens up or expands as you approach the Gulf of Mexico and the Yucatan channel.  The combination of the opening of the geographical region combined with the climatology of extremely warm water  and    HIGH pressure off  the se  US  coast  ( the ” Bermuda High “)   which aids in the ventilation of developing tropical systems ….all favor the Western Caribbean as an area for explosive development of tropical cyclones.

But the point is that if Eernesto tracks close to the north coast of Venezuela we  are not going to see any sort of significant development / intensification   over  the next two or three days.  Indeed if we look at the  various models which forecast tropical cyclone intensification we can see that there is very little growth on all these models with respect to the Wind field or the pressure   thru the next 60-72  hrs.   Then after 72 hours we see significant and citation which is precisely the point at which ERNESTO reaches a portion of the  western Caribbean which expands or opens up.

With regard to the latest hurricane models….  the 12z  GFS   and the  12z  Hurricane  models   are in strong agreement but then again since all the hurricane models are run off the GFS great anyway there is not much of a reason to expect a significant difference.  The 12z  hurricane models match what the  12z  GFS   model over  North America and the western hemisphere showing— the ERNESTO  is going to turn northwest  for  some unknown reason ….  and track through the Yucatan channel and head towards the Texas Coast.

What I think we are seeing here is the infamous   GFS cold bias.  If you are just a hurricane weather  nut and you  have  not  been tracking the models on a daily basis like I do in daily operational forecasting …  then are probably unaware of how badly performing the GFS has been during this incredibly hot and drought summer over the Plains  and  Midwest.  The model has consistently been far too wet and far too cold with the over development of massive  troughs  in the Jet stream   and  strong cold fronts  and the surface and large areas of thunderstorms    especially in the     day 4  to day 15  time frame.     This link shows the cold bias of the last week in the last 30 days of the GFS quite nicely.

The reason why this is important is that all the hurricane models are run off the GFS grid   …. so…. if the GFS is over developing big troughs along the East Coast  then hurricane models are going to reflect this bias and assumed that the GFS is correct:     that there is going to be a much deeper trough on the East Coast.   The idea here is that if there is a fairly good sized trough on the East Coast and allow ERNESTO   to turn to the northwest   as he approaches the Yucatan channel  —which is what all the GFS  and Hurricane   models are showing.

However the European model is showing a much shallower trough over the East Coast early next week…  which means that there is no poll to the northwest and the system crashes into the Yucatan Peninsula….  And possibly into Northern Mexico south of the Rio Grande.

But  there are two other factors to taking into consideration.     If we take a look at the climatology of    all TC  located near or at the same position that TD#5/ ERNESTO is located at …  (based on 12z postion)…  we can see a number of them showing turns through the Yucatan channel or Cuba and into the eastern Gulf or up along the East Coast.  However that being said notice there are a number of tracks which do take a system into the Yucatan and south of Brownsville.

Of these 10 analog tracks …the  tracks    where the tropical cyclone moving through the Caribbean at or above 15° N  Latitude  ended up tracking either through the Yucatan channel or into the Gulf of Mexico or Florida.  The other systems which came in the Caribbean at a much lower latitude….  were essentially   tropical cyclones  which passed south of Jamaica and into the Yucatan channel.

Finally in a  very recent   study…  in what I consider to be a very significant study ….done on hurricane trends and climatology…  almost all tropical cyclones in the   North Atlantic can be divided into four different  CLUSTER  or types.

CLUSTER 1  are tropical cyclones that form  over the open waters of the north Atlantic…  Usually where the  SSTs  are not the warmest and almost always feature an early re-  curvature .

CLUSTER  2….  can be called refer to as the  “Homegrown    TC” because they often form in association with a stalled cold front and /or closed upper Low.  The systems often formed in the Western Caribbean or Gulf of Mexico and have a pretty high probability of some sort of  US landfall.

CLUSTER    3 is the     classic CAPE VERDE   hurricane   that forms in the southern portions of the tropical north Atlantic .  These sorts of tropical cyclones have a high probability of a land fall in the U.S.  and often reach category  3-4-5   status  at some point in their development and life cycle .

CLUSTER   4  is the Caribbean hurricane track…. wWhich features a development just to the east of the lesser Antilles   / 60 degrees W Longitude   and a track south of Puerto Rico and Jamaica with a  2   common  landfalls  — the Yucatan peninsula / bay of Campeche Sea area    and / or  the   western Gulf of Mexico / Texas.

FULL STUDY  CAN BE  FOUND HERE      http://www.ssec.wisc.edu/~kossin/articles/Kossin_et_al_2010_JofC.pdf

Clearly TD #5 /  ERNESTO is a cluster for type of tropical cyclone that we are dealing with here.  And all of the forecasting should be based upon this premise from this point on.