ABOUT JAN 3-4…. and Beyond

Posted by wxrisk | GENERAL,WINTER 2011-12 | Wednesday 28 December 2011 6:53 pm

1800  EST    28 DEC ….    STARDATE  201112.28

 

As somebody who works in his own home office  and   owns  theor own business…  I don’t get a lot of days off.  Even when the weather in the Middle Atlantic states is fairly quiet there  is  ALWAYS weather  to talk about which I have to cover for energy  and  grain clients.  So the holidays for me is a big slowdown and much   needed one.  Unless of course you have a major East Coast snowstorm or blizzard like we did last year…  In which case it’s a lot of fun but it’s very intense and it’s not really a break.

Even in this relatively quiet in on eventful winter so far across the eastern half of the CONUS I am watching the developing second heat wave of the growing season for Argentina…  Another round of flooding rainfall likely for much of eastern  and central Brazil…  as well   weather  in Australia and South Africa.. and the   winter  wheat crop  in the Ukraine and  sw Russia… and … and … and…

 

By now mostly you  have probably heard about the potential for a significant if not major East Coast snowstorm on January  3-4.     On Monday and Tuesday  the  0z and 12  runs of of the European model one bonkers with the development of a major storm on are just off the East Coast and a huge amount of snow.     The 12z  European model on Tuesday  12/27 showed a huge amount of snow  — 12 to 18″ in a band from the Virginia North Carolina border all way up the Boston.

I debated about whether not to post this map because I know is going to cause problems one way or the other.  But I decided to post a map for number of different reasons.  There were 3   primary  reasons   WHY  I decided to issue the European snow map from yesterday.

  1.  as I  am sure you and all of your friends and family KNOW …it has  been  a really mild winter so far  especially given  the last two winters    (which were pretty active if not downright severe the times).  So if we were to suddenly see a significant or major East Coast winter storm it could catch a lot of people by surprise.
  2.  The European model yesterday showed a lot of snow not just a few inches…  so I wanted people to understand the gravity of the potential significance of the storm if it in fact develops.  I suppose some people are going to accuse me of issuing of that  snow map from yesterday’s European model in some sort  efforts to increase the web site in the face book the viability/ visibility and or  Donations…  but really that has little to do with it.
  3.  I try not to talk down to people if I can avoid it.  That’s not to say I won’t rip somebody in new body cavity   if they deserve it.   I  certainly  will do that I  think I need to.   But when I issued the European snow map from yesterday’s model run I stated quite clearly that this was NOT a forecast of some of projection.  For the most part most people understand what I am talking about.  If you are stupid you probably shouldn’t be on the Internet anyway and decides the great thing about stupid people is that it gives me an opportunity to   crap on them.  I could have played it safe and not issued the map because I know that it would cause some confusion…  But quite frankly the culture is stupid enough as it is and I rather not be a part of that since I am supposed to be a scientist and not a    game show host.

Of course once I issued the snow map I guess it was inevitable that the model data early on Wednesday morning and on Wednesday afternoon would turn the other direction and shift the potential major   East coast Low   further off the coast  ( to the east).  Given that this event is still 6  or 7 days away I don’t consider this sort of model shift or variation to be of any significance.  The important thing is that the system is still there  on  all the weather models.

On the other hand it  should be kept in mind that this is NOTHING  like the last two winters.     Over the last two winters the pattern set up early and locked in and a really did not change until spring or late February.     In the winter of 2009-10  and 2010-11   if  you farted too loudly  it would  might cause and East Coast snowstorm to develop.   That is certainly not the case so far this winter.

I have  been asked a number of times to comment  with regard to  the debate as to whether not   the pattern  NEEDS  to   have a  -NAO  to a   East coast snowstorm.  Like many things in life there are several nuances to this question.

If the question is does there   “need”    to be  a -NAO   for any accumulating snow    in the  Northeast  ( VA to  MAINE)    then the answer is clearly no.     We certainly can get accumulating snow of the few inches  with a  +NAO.

But IF  the question is     does there NEED    ( required)   to have a -NAO  to have    S.E.C..S   (significant East Coast snowstorm)   a  M.E.C.S.      (major East Coast snowstorm)  or H.E.C.S.     (historic East Coast snow storm)       then the answer is yes you do need one  9 times out of 10.

For example if we take a look at the   OCT 29-30 NOREASTER that dropped the historic early season snowfall over the higher  terrain   of the northeast and caused tremendous damage in places such as interior Connecticut and western and Central Massachusetts…  we can a  very clearly  see  a   defined  -NAO and  a clearly defined   50/50 Low as well.

Without those two features the October 29-30 NOREASTER would   have come much further inland.  Indeed that has been the problem with all the potential Low pressure area systems so far this winter coming out of the Midwest.  The AO and NAO have both been consistently positive and the times extremely positive almost off the chart…  So Low pressure systems coming out of Midwest have tracked up either through the eastern Great Lakes OR up the spine of the Appalachian Mts.

Indeed this chart shows the actual status  of the   AO and the  NAO since September 30.  As you can see only   TWICE  in the last 90 days has either the Arctic oscillation or the North American oscillation dropped below zero and a negative territory.      And  one of those two times …in late October ..allowed the historic NOREASTER to develop with the inland heavy snow.

In this next image we can take a look of the day 9 European vs. the GFS   from  12/26…  Valid  for January 5.  The map and less hand side is the European the map of the right hand side is the GFS.

 

Clearly these two maps  do NOT  match as the European model is showing a major trough on the East Coast and the GFS to showing a huge ridge covering the entire country.   But as we can see now from the current GFS model ….  here we  are just two days later and suddenly the GFS has a monster trough on the East Coast  with all sorts of arctic air  coming south covering all the Midwest and northeast and pushing into the Deep South .

If we keep this sort of model failure by the GFS in mind…  Then if the 12z gfs  model today has  no storm near the East Coast  I have to allow for the possibility given the poor performance of the model over the past 48 hours …..that the GFS is probably not handling the situation for January 3 correctly.

That being said the European model also is further East off the coast

as is the 12z   Wednesday Canadian.

   

But again as it mentioned above at this point in time the issue is whether not this low was still there at all.  And the system is still clearly there.

What about the  + NAO?  Well that’s a good point.    As I stated above if you want to have a really big east coast of snowstorm     one needs to have  either the   AO  and / or the NAO  in negative territory or at least very close to neutral .

Interestingly    as these   charts   from DR Ryan Mauve’s fabulous website shows  the NAO and the NAO   do actually dropped very close to neutral early in January at the time of this potentially   east coast Low.  It is still possible though unlikely  that the  NAO MIGHT   drop into  -NAO  …  Just barely into negative territory–   as we saw in  OCT 28-29.

 

Regardless of whether not the East Coast snowstorm actually develops or whether it stays out to sea the interaction between the large cold High coming down from Canada and the coastal Low… will produce a strong and prolong lengthy   North wind  from Quebec Canada down to Georgia JAN 3-4.  The cold air that gets pull down because of   depth of the trough  and  the strong North winds is going to shock  a lot of people.  The coldest morning   the East Coast will depend on whether not there is an East Coast storm so it might be  January 4 or January 5  once the winds drop  off .  I would not be all be surprised to see a lot of temperature readings in the single digits from Virginia up into the big cities of the northeast.

Taking a step further out …  we are beginning to see some signs that the pattern may be changing a little bit.  Right now everybody and his mom has January as a blowtorch but if you look at the 11 to 15 day GFS  and  European  ensemble  means they are not that warmed east the Mississippi River.

The European and the European  ensemble at day 10…  show the development of a strong ridge over Central Asia that pushes its way northward across the Arctic circle  and  into   and over the North Pole  by  day 10.  The  12z GFS ensemble  has this as well.

These image  Here   SHOW  how   the BULGE in the     Jet stream over  central  Siberia  Builds into the  Arctic    very  rapidly and strongly   Day  5  to day 10.

 

This feature does several things.  First it forces the polar vortex to split apart into different sections which in turn weakens the very strong and persistent +AO.  If this projection of higher  heights were to push into Greenland for example it could cause entire pattern to rapidly shift around.

Indeed  if you look at these MECS images you will see a persistent downward trend on all the models with regard to the AO and NAO  over the next two weeks.  It’s a slow steady drop not a massive swing or   oscillation which is one of the reasons why it’s probably going to be the correct overall trend.

 

 

XMAS DAY EAST COAST STORM… and update on SSWE

Posted by wxrisk | GENERAL,WINTER 2011-12 | Tuesday 20 December 2011 6:17 pm

1800 EST   20 DEC 2011…. STARDATE   201112.20

 

There are two things to talk about in this update as the head into the long holiday weekend.  First the potential for East Coast storm of some type during Christmas day.    Earlier in the week I   thought the system would stay flat and undeveloped and not really be a problem for the East Coast but clearly that  is not going to be the case.  The last several runs of the European model of been pretty bullish with the system developing as a wave of low pressure on the cold front on December 23-24 over the southeast   states.  Initially there is  a large cold High centered over Maine and the atmosphere appears to be cold enough for the precipitation to begin as snow   from DCA to   NYC …  but  ONLY  if  some  precipitation breaks out   ahead of the main Low.   This  kind of precipitation event is refer to as overrunning in the weather business.  So  it is possible that IF  the precipitation begins early enough from DC northward into New York City early on the 25th it might begin as snow.  But this is just a maybe and not  yet   a  “probable”  event.

However the overall data clearly shows that the cold High pressure area is not going to stay over southeastern Canada.  Because there is no blocking over the Canadian maritime provinces because there is no blocking in the jet stream over Greenland the cold area of high pressure slides off the coast of very rapidly as the low pressure area is coming up from Georgia and the Carolinas.

The interaction between the Low pressure area and the HIGH  moving off the Maine Coast produces a southeast wind which is the proverbial kiss of death for anybody wanting a snowstorm in the I- 95 corridor.  In order for this to be a snow event for the I-95 cities  the cold High pressure area has to stay over southeastern Canada   AND  the Low   has to track NOT over  Atlanta  but along the GA  SC   NC  coast.

 

 

One could argue that pay it still four days away and maybe something will change.  But if that’s what you are thinking then you’re not thinking very clearly.   The issue is not  which side of   Philly   the  r/s   snow line will set up.   At 120  or 108 hrs the weather models are really quite good at this  distance  in seeing he major large scale synoptic features and it is these large scale features which is what sets up snowstorms and nor’easters.  In other   word its  not going to  change   too much.

In the 6-10  day  things still look   like   crap if you like snow and  cold and stormy patterns

     

 

 

The second issue has to do with the longer term pattnern  and  speculations about  the rest of  WINTER 2011-12.  The models continue to show that the  SSW   event is   still developing and it will continue to do so as you move into January.  But one of the things we have to keep in mind is that there are   several  cases   where  of SSW– significant stratospheric warming-  events that have not led to major pattern changes.


The key appears to be whether not the warming at the top levels of atmosphere  – 10 mb  30mb   50 mb  can  move  down into  the   200  300 or  500 MB level.        Keep in mind when we talk about a Greenland block   or the -NAO that what we are actually referring to   is a buildup of warm air at the high latitudes in or near the Arctic regions which causes the Jetstream pattern to shift or change.  It is literally a bubble or mountain of warm air   –relative to the rest of the air around it –and the Jetstream is correspondingly altered .


This image shows what we need to see happen over the next 10 or 12 days   in order to salvage something of the winter.  The BOTTOM hart shows the most important image….  Right now the winds continue to blow from south to north at the high levels of the atmosphere.  Over the last several days we  have seen a slow shift  in these  arrows   from   SE/ NW   to  its  current  South to NE  .   Ideally we want to see the arrows continue  swing  around in a clockwise direction so that they are blowing in a   west to  east or NW to SE   or  even North to south direction.    If this happens then will  see the warm air associated with the SSW  work its way down to the  200 mb  300 mb and 500 mb level and alter the pattern.

Keep in mind however that even IF this is the case and this does happen ….it would not happen before January 10.  Then it would take  another 10 days  after that  before we would see any changes in the pattern.
This is why you some other private forecasters are  now  talking about January 2012  featuring more  very mild  temps  and  a relatively calm pattern.   Even if we do see a shift in the winds at 10mb  30mb  and 50 MB  and the warming getting down to the  200   and 500 MB levels  it  is not going to appear  on the Models  before the middle of January at the earliest.

And there  is also an equally good possibility that the winds never swing around  to a   NW- SE   direction.

 

 

 

 

 

 

 

 

WHY THE MLD PATTERN HAS NOT CHANGED

Posted by wxrisk | GENERAL,WINTER 2011-12 | Tuesday 13 December 2011 9:40 pm

2200  EST   13  DEC    …STAR DATE    201112.13

There has been a lot of talk recently from various whether sources and  some of   my   competitors about potential for a pattern change   coming  after the  Holidays.  This talk in part has been based upon the appearance  of a significant bubble  or pool of warm air which appears  in many of the   weather Models   late in the  6-10 day and in the 11-15 day at  the top of the atmosphere   (the  50 mb  level).  The technical name for this phenomenon is called a Significant Stratospheric Warming Event    — which can be referred to as either SSW  or  SSWE — event.

Back in the late 1980s and throughout the 1990s there was a lot of research done on this phenomenon because it appears to have some fairly strong correlation to colder patterns developing over North America.  Without getting too technical the argument or theory goes that the rapid warming in these  very top layers of  the atmosphere enables the middle and lower levels the atmosphere too warm and  thus form blocking patterns.    Keep in mind  for  example that   the -NAO  is   ACTUALLY  a  mountain of  air  that is  much   warmer   (relatively speaking )  then the air  around it.   Then research shows    that about 10 to 14 days after  the  SSWE   reaches  the   high northern latitudes or the arctic circle  the  AO and NAO  turns    negative.

This link shows you the actual breakthrough study when it first appeared back in 1986.

http://journals.ametsoc.org/doi/abs/10.1175/1520-0493%281988%29116%3C0162%3ASSWAAU%3E2.0.CO%3B2

These two images show the impact of the SSW on the Low  pressure tracks  in  JAN  and  FEB.  In both images the top map refers to  NON  SSW  events   and the bottom maps   refer to   Low pressure tracks  for  SSW  events.   As you can see the the tracks are significantly altered in SSW   events  to the south which in turn allows for colder weather patterns and more wintery precipitation.

 

 

In this next image we can see   the difference in the month of January and February between temperatures with SSWE    and  Non  SSWE.  In both months large portions of the eastern  half of the CONUS are significantly colder…

 

This is   GRAPH that   shows   what was  a  MAJOR   SSWE   back in the Middle of winter  of 2008-09 .  As you can see  the RED line  shows the  temps at   50 MB   dropping   in OCT  NOV  DEC… then a     massive rapid   warming   that occurred in   early January  and  the patern shifted.

 

Here is the  TEMP anomaly  map from DEC  2008  …  and  you can clearly see   temps   much above Normal  over  the  East coast  into the southeast… and    BELOW/ MUCH BELOW  NORMAL   temps over    the Upper  Plains and    Upper  Miss valley .  If you look at the   Upper air maps   you see  +A0 and +NAO   and a  deep persistent Midwest trough    ( sound familar??)

Now   here are  the  Temp anomalies  for     JAN 2009… and  you can see   temps MUCH  BELOW Normal over the    Ohio valley and   New  England and    BELOW  NORMAL  from TN and  NC  northward.    And the maps shows   clear – AO and -NAO and  there were 2   significant  East coast winter  storms in JAN  2009.

 

If we take a LOOK at the  current   AO  and NAO  trends… we  see  that since   SEPT 21 .. only Twice   have the  AO and the NAO    reached  negative values and even then it  was  for  very brief  time.

These maps show   the  GFS    the CMC and   the much   improved NOGAPS  models forecasts of the AO and NAO.  As you look at these    graphs    Note  how many FALSE  trends   we saw with these models…  how many times     the GFS or   CMC showed a  downward trend  with the   AO    and / or the  NAO… only to be 100%  totally  WRONG.

    

 

WHY have these models  THIS winter  been   soooo  bloody  awful with   getting the AO and  NAO  trends  when last winter these same Models  were VERY good???

IMO    it   has  been the   HUGE  massive pool of super cold air  at    the  top of the atmosphere  ( 50mb level)    that has    been a stonewall  against   any attempt   to get the   super +AO and  super  +NAO  from   dropping into the   Negative   phase.

For example  here is the  CURRENT    50 MB   temp  map….  as You can see there is a huge pool of cold air   over  GREELAND … hello  super  + NAO)  and  the   arctic circle  which is  EXACTLY   where the  PV has    been and wehre all these  super    powerful large  Ocean Low   in the northeast Atlantic   have been forming and  battering Ireland  the UK and Northwest Europe.   But  also note the   large  Bubble of  warm temps over    eastern  Asia / Japan

By Day 10  we  can see  Massive     changes  at  500 MB… the   Massive warm  Bubble has   reach  northwest Canada  and the  pool of super  cold air   that was  over  Greenland  and   left the entire westerm Hemisphere  for the 1st time   60  days.

The  day 10    euro   shows  this    huge  bubble of warm air  moving  deeply into  Northern Canada  and buidling into  Greenland  ( a map which I cannot show)

 

The  11-15  day  on the  euro ensemble are MAXED  out… and off the charts  over   far North  Canada  and beginning to spread into  the  Canadian side of the  arctic circle  and   Greenland.

 

SUMMARY  this sort of massive warming  MEANS  something.   It  is hard to see   how this pattern  will not be  altered   by this  SSWE.  ASSSUMING   that is  true  the   model data  should  begin to show a   pattern  change    DEC 26-31.    The potential    exists  for the pattern   to  turn much   colder  but   it is far too  early to   commit to that at this time.

 

 

 

 

NOVEMBER 2011 NAO…. EXTREMELY POSITIVE…

Posted by wxrisk | GENERAL | Friday 9 December 2011 9:42 am

1000  EST   DEC  9…  STARDATE   201112.9

 

MODIFIED  1900 EST 

In case you did not  know it… the  final NOV   NAO   figures have come in… and the  actual NOV number   showed the NAO at +1.30.  Only 7   times    has  NOV  NAO been above  +1.0 

NOV 1952……  +1.04
NOV 1958……  +1.64
NOV 1977……..+3.04
NOV 1982 ……. +1.60
NOV 1986…….  +2.29
NOV  1992…..  .+1.19
NOV 1993……   +2.56
What did the NAO  do in the following   DJF periods?   Some  of the  NAO turned positive some   stayed negative  and  some split ….. with DEC staying positive while JAN  FEB turned  negative
NOV 1952……  DEC   -0.47    JAN  +0.37    FEB   +0.74
NOV 1958……  DEC   -0.70    JAN  -0.87     FEB   +0.68
NOV 1977……..DEC   -1.57    JAN  +1.38    FEB   +0.67
NOV 1982 …….DEC   -1.29    JAN  +1.59     FEB    -0.53
NOV 1986……. DEC  +0.99    JAN  -1.15      FEB   -0.73
NOV 1992…..   DEC   +0.47    JAN  +1.60    FEB  +0.50
NOV 1993……  DEC   +1.56   JAN  +1.04     FEB   +0.46

Keep in  Mind   we  have    weak to moderate  La Nina   event  underway  and   weaker  than last  winter.  Of course 1982-83   was   raging very strong El Ninio…. strongest ever    so that  is   NOT  really  relvant…    1986-87  was a moderate   El Nino  so again   I wouldnt   give that winter   much consideration  and  1977-78  was a weak  El NIno  winter.

1952-53  was   a neutral year as was  1958-59 and 1992-93   and 1993-94…so again  not good matches

Thus right now  we do not really have any  good analogs  of    strongly   Positive NAO and  La  Nina.  But  it  is also a  FACT   that  there  has  never been a   winter with a WEAK / Moderate La Nina    SHORT  DURATION   events    (  1962-63   1964-65   1984-85   1995-96    2010-11 )     where the NAO   has stayed  positive in all 3  months    DEC  JAN FEB   

 

Over in EUROPE   we can see the   continuing affects   of the super positive NAO  by the   frequent  development of these huge  ocean Lows  that   have  deen  dropping mdown to 960 and 950  mb.    I posted  on one of these monsters   Thursday afternoon  on the FACEBOOK  page.      The     Parade  of BIG  Ocean Lows  does NOT end  as the     day 5   Models  all show   another  a 950 mb Low    tracking   very close to the Ireland and Scotland at  950 MBs.

EURO  http://meteocentre.com/models/ecmwf_eur_00/GZ_PN_096_0000.gif

GFS   http://meteocentre.com/models/ukmet_eur_00/GZ_D5_PN_120_0000.gif

UKMET  http://meteocentre.com/models/gfs_eur_00/GZ_D5_PN_120_0000.gif

 

I raise  the  European  monster low tracks  because     the Primary reason why   NW   Europe — especially the UK and Norway -are   getting  battered by these  huge  Hurricane like ocean Lows …   is because of the   strongly  Positive   NAO.

The PSD   GFS  and  EURO  ensemble means keep the PNA  negative…  while the NAO  is  in   general   trend towards neutral
http://www.esrl.noaa.gov/psd/forecasts/teleconn/images/compare.pn.png

BUT keep in  mind all of the forecast Models have been  AWFUL…  I mean truly  wretched  this season  in forecasting the   NAO.  This image says it all…  on the  top graph  we can see the  NAO  actual  TRACK… and its   EXTREMELY positive      values   since mid NOV..

   

 

The  Bottom two   charts  shows  the GFS  ens PREDICTION at day 10 and at day 14 …  and   the   forecast  has   been  extreme in  the other  way…  consistenly  showing   the  exact WRONG   phase and intensity.

The  EPO  currently pos  moves  into   Moderate   negative values  but the  euro ensemble  does not support that .
http://www.esrl.noaa.gov/psd/forecasts/teleconn/images/compare.we.png

PSD  6-10 day  ens  mean is  very warm over the   eastern US … far warmer than   any of the recent GFS and  EURO ens  means
http://www.esrl.noaa.gov/psd/forecasts/reforecast/images/pentad2/hgt500fcstanom_2011120900.png

The 8-14   day  shows  more of the same BUT  it implies  that   with the   strong    se  ridge  and   strong neg   5h ( 500MB) aomalies  over the    eas
tern Canada … systems   may come out of the sw states   and tack into the   Ohio valley then into  New  England http://www.esrl.noaa.gov/psd/forecasts/reforecast/images/week2/hgt500fcstanom_2011120900.png

Of course given how   BADLY the  PSD  did last week   this   solution  is not one that I think is  correct.  In addition the   PSD  esn has NO support from any other model

LET LOOK AT THE  MJO…

GFS  ens  for  MJO curls    the  current impulse inwards then back out to phase 4http://www.cpc.ncep.noaa.gov/products/precip/CWlink/MJO/foregfs.shtml

OP GFS kills  the current  Impulse  off  totally
http://www.cpc.ncep.noaa.gov/products/precip/CWlink/MJO/foroper.shtml

0z UKMET  does the  same
http://www.esrl.noaa.gov/psd//mjo/Forecasts/images/bmo.mjo.latest.png

as  does the  ECMWF  ens MJO  model
http://www.cpc.ncep.noaa.gov/products/precip/CWlink/MJO/CLIVAR/ecmm.shtml

SUMMARY..  the  pattern for   rest   of DECEMBER  looks      QUIET..  without any hints of major  winters storms for the   EASTERN Conus . On the other hand  the   the pattern  does NOT look  nearly  as warm  as  it did  last week.   Its a   Blah pattern… with a bias of  SEASONALY mild temps over the    Deep south and   Mid Atlantic .    On the other hand the  western US   into the Rockies     ( and Upper Plains)  look cold… not severe  or  even major  cold..   but     cold and  very  wet .     If  we can get the current  MJO  impulse to   NOT   turn into the circle of  death  and ake it to phase 7  we could  see the patetrn finally shift. to one   where the mean trough  moves into the   eastern US…   But  right now that is   not   supported  by the   data.

DEC 8 INLAND SNOW EVENT

Posted by wxrisk | GENERAL,WINTER 2011-12 | Wednesday 7 December 2011 8:17 am

LAST   CALL   MAP

This   LAST CALL map   has some  changes on it…   the   these  two  imnages  show  why.   The  first image shwos the     change in the NAM model with regard to the 850  mb Low… the  closed    Low   which  was NOT on the   12z DEC  6 NAM    …  IS  over    central MD     at the  same time   on the 0z  DEC 7   NAM   run. This  has   serious implications  as the   warm air   ( the red lines)    surges  deeper  into   eastern  PA   and into   NYC  and  southern new  England.     As a general rule having an 850 Low     track   North of  DCA and   over  PHL….   The  SECOND   map   shows  how much faster   this   Low   is   coming   up the coast  and that  means LESS    snow    time  once the cold air   arrives.

 

 

1ST   CALL MAP … usually issued   36  to  48 hrs before the event begins

In a lot of ways this is turning out to be interesting little event because it will be instructive for those wishing to understand the intricacies of forecasting snowstorms and the northeast U.S..  There are several interesting aspects to this event has is developing.
One of the things you find from meteorology students and those weather hobbyists that are severe weather fanatics  and those  that in general focus   on    the  short term… is that their general ignorance   or lack of focus on the large scale synoptic features can often lead  them  into  ” trouble”  when it comes time to actually making the forecast.  The applies  in particular  Winyter  weather events and    tropical cyclones.
In this particular case  all of the models today have slowed down the arrival the cold air in the big cities of the Northeast.  So obviously the question is why and is this solution viable  and  correct?  Often times you  will see weather hobbyists and inexperienced meteorologists argue     about  the various weather models as to which solution is correct.   And   can  that approach  can  be useful   even for  veteran    Meteorologists.   BUT   if you are aware of the   synoptic pattern  some of these uncertainties  can be answered.
For example currently the temperatures across much of central and Eastern Virginia are in the mid  60s  and a few places have reached  70.   And that is with overcast skies!  That is considerably warmer than what some of the forecast models are calling for just a day or two ago and it represents the strength and the power of the strong rage over the southeastern U.S.
Meanwhile the cold air west of the front over the Midwest and the Ohio Valley is not looking that impressive. Its  there   but  it  is clearly in  no   hurry to come east.  And if take a step back and look at the even larger scale..  We see several real problems here as to why this is not a  I-95  snowstorm.  The extremely positive  AO and NAO… the lack of   50/ 50 Low… the fact that the Low comes up the front BEFORE  the cold air arrives…   and the    veryt fast     track  of the Low Up the coast …all of these things indicate reasons why the snow mounts forecasts even for the high  terrain  to the north and west of the big cities of the Northeast have to be kept on the low side.  We are not in the same winter that we saw last year   or even the year before….  so  it is   imperative that forecasters do not become   Bad  Gnerals and forecast the last battle   or   the last war.

WHAT CAN GO WRONG ?  Is it possible that the cold air might come and faster so that there’s more out of the snow window over the big cities of I -95?  While perhaps but we are getting very close to the that now and so far of anything the model trend is going the other way.  And again here the  the Synoptics are  very  strong  against the idea of the cold air coming in sooner.  You can hang your hat on that miracle if you want to but that’s not the way  I am  going.

Is it possible that the coastal Low may slow down some?  Yes that is also Possible …  but again absolutely no model data showing that occurring and the pattern is  strongly  against  that idea.
The biggest concern for potential busted forecast here is that the precipitation shuts off BEFORE  the cold air arrives.  This would occur if the coastal low war to move faster   or    if  the cold air crossing  the mountains would   be delayed.   Given the overall setup here I think this is the biggest concern   that   would  lead to  a ” busted forecast”.

 

 

1ST    GUESS  MAP

 click  on the image for  full size

 

FINAL WINTER FORECAST

Posted by wxrisk | GENERAL,SEASONAL FORECASTS | Sunday 4 December 2011 8:46 pm

4  DEC    1600  EST  …

 

http://1664596.sites.myregisteredsite.com/seasonalforcst/WINTER1112/WINTER1112version1.htm

MID DECEMBER UNDECIDED…#2

Posted by wxrisk | GENERAL | Friday 2 December 2011 5:55 pm

 1700  EST   2  DEC  2011… STARDATE   201112.02  

 

One of the primary    reasons why a lot of meteorologists have turned sour on the winter is because of the belief in some of the longer range weather models which go out to three in four weeks.  Specifically I am referring to the European weeklies.      Back in the winter of 2009-10 and   last winter …European weekly  models  did a very good job in latching onto the pattern early.  They got the timing of the coal pattern when develop exactly right and the European weeklies also got the timing and the method in which the cold patterns will break down in February of last year.
Given that the European weekly forecasts are a relatively new product these models have developed a significant following a specially given the very good forecast we saw from this model over the last two winters.

As  we moved    through November more and more of the European   weekly  models showed no cold air of any kind reaching any portion of the central and eastern  CONUS.    Week after week –  twice a   week now– the European weekly showed nothing but a Moderate to deep trough over the West Coast  (-PNA) and a strong +NAO.  However as I pointed out a couple times already the European weeklies completely messed the upcoming cold shot next week for the Plains  the Midwest and the Northeast where  was  the     CFS vs2  did  not.  That model has correctly predicted that temperatures would actually run  a little below normal during the first 10 or 12 days of December for much of the country east of the Rockies.
However there’s another model which can be used in trying to figure out the patterns in the   week 2   and week 3  time  frame besides the European weeklies.

So may I introduce to you,  The one an only Billy Shears…. opps I mean the  one and only PSD  Model  from  ESRL….. ( Sargent Pepper’s Lonely Hearts Club band)….

What is the PSD?  As many of us know the Operational GFS  past 180 hrs is NOT very good.    The Model resolution shifts   (truncation) . The GFS ensemble (GEFS) helps  but the GEFS have the same problems the op GFS has. The PSD version of the GFS is an UPGRADED version of the old MRF from 1998 BUT…. with all the Model biases and corrections.      The  PSD  — aka    “reforecast “  model is an ensemble of 16 members  and  it  been shown have significantly better skill than the op-GFS and somewhat better skill than the GEFS in the 6-10 day and 11-15 day.
http://www.esrl.noaa.gov/psd/forecasts/reforecast/

 

There   is not much doubt that much of the country eastern Rockies will turn pretty cold next week and once the cold front cross of the East Coast on December 7 it will turn cold  there for at least a few days.  However the operational European model completely breaks down the West Coast ridge  DEC  11-12…  which ends up shutting off the supply of cold air into the central and eastern CONUS.
The   12z operational GFS is a little better  and slower with a delay of the strong rage on the West Coast but it also a clearly appears to be weakening.
However if we take a look at the PSD   ensemble we see a very different solution. The PSD at 240  is depicting a much stronger ridge along the West coast of North America with a strong flow of cold or even arctic air into a good portion of the central and eastern CONSU : The PSD  is a  cold  looking map.

If we look further out in time….  I can tell you that the 12z  European  ensemble at day 15 is not a good looking map if you want cold temperatures and were possible winter storms for the central and / or eastern CONUS.  The model shows the entire pattern or flow going flat and zonal with no ridge on the West Coast or the eastern Pacific…  no supply of cold air into any portion of the central or eastern U.S.  and mild Pacific air overrunning most the country.

Again however the PSD model is significantly different and shows a very strong ridge e covering the West coast of North America with a strong flow of cold war even arctic air into a central and eastern CONUS.     I do not know which of these models / solution   is  or will be correct.  But I  can ell you that the PSD reforecast   model has been doing pretty good and it’s been doing better than the European weeklies   in some respects.  Clearly however that can be no compromise between these two models as they are showing diametrically opposing solutions

 

 

 

0845   EST  30 NOV  2011…. STARDATE  201111.30

for those of you that get the much heralded eECMWF weeklies… which now come out rwice a week   (Monday and Thurday at 1710 CST) … it is  important   to keep in mind for weeks   and  weeks   EVERY run  of the  euro weeklies have been showing a large   -PNA pattern and nothing but mild to warm temps over the central and eastern US.     Even LAST week Euro weeklies showed the week   3  — DEC 4-10– map with NO cold air anywhere.

Yet we now KNOW that the week of  DEC 4-10 IS going to be pretty darn cold. I raise this because once again the euro weeklies are very mild for all of the US from the Rockies east to the Coast in week 3 and 4 for most of DECEMBER.   Sure the new NOV 29 euro weeklies NOW show DEC 4-10 as finally being cold…  but the euro weeklies  have been   all that  good as of late.

The 0z GFS ensemble mean 6-10 day 500 Mb height  anomalies– the very Positive  anomaly can be seen over the Gulf of Alaska just west of the AK panhandle  http://raleighwx.americanwx.com/models/gfsensemble/00zENS6-10day500mbHeightAnomalyNA.gif

the 11-15 day GFS ensemble 500 mb height anomalies has shifted well WEST which pulls   the trough   thatbi  over the Midwest back into the Plains / Rockies and Pac NW and allows for a new but weak  Ridge to  re-form   over the southeast US ridge.
http://raleighwx.americanwx.com/models/gfsensemble/00zENS11-15day500mbHeightAnomalyNA.gif

0z EURO day 7 has the West coast Ridge but  withn a  new  LL over the sw states (model bias)http://raleighwx.americanwx.com/models/euro/00zeuro500mbHGHTNH168.gif

By day 10 the 0z Euro breakdowns down the entire West coast pattern . Even so one just has to take glance to see a much more “relaxed” flow of the Pac jet over the N Pacific  http://raleighwx.americanwx.com/models/euro/00zeuro500mbHGHTNH240.gif

Here we can see very different day 9 Maps. The 0z Euro argues that the cold blast is going to be very short lived as it breaks down the entire West coast ridge / -EPO very quickly which results in ZONAL flow and any cold air flow getting into the Conus. The day 9 Op-GFS still has -EPO / West coast Ridge and fairly deep trough over the eastern half of the US. Both models shows  a strong -NAO.  http://www.meteo.psu.edu/~gadomski/ECMWF_0z/hgtcomp.html

Look at the teleconnection trends we see the EPO strongly negative   that then moves  rapidly back to neutral by DEC 12-13
http://www.esrl.noaa.gov/psd/forecasts/teleconn/images/compare.we.png

while the PNA which starts Positive moves steadily deeper as the -EPO weakens and moves towards nautral
http://www.esrl.noaa.gov/psd/forecasts/teleconn/images/compare.pn.png

I am seeing some changes in the pattern over in Europe and Russa that may have more significant implications for the NAO phase and that many are over looking.    Over the past 30 days NOV 2011 has featured VERY stormy conditions over Iceland into the UK the North Sea and into Norway and Sweden.   These Low have NOT been crashing into western central and eastern Europe because of a strong Ridge in the Jet stream stretching from Spain to the Ukraine.   The Ukraine and sw Russia winter wheat crop is in big trouble because of lack of all precip . But that ridge is moving — the temps in central and western Russia have turned warmer

This weekend the Biggest most intense Low on this current wavetrain may hit N Scotland then pass into southwest Norway — Monday data saw 944 mb but the 0z data today shows 940s.   Once this big Low passes it is possible that the ridge over western and central Europe will get the chance to ” JUMP”" into the Azores in the northeast Atlantic.    From there the 500 MB ridge will have to be watched to see IF she can build towards iceland.

0z GFS MJO plots  pushes current MJO into phase 5…. which is very warm for DC over the Plains and Midwest
http://www.cpc.ncep.noaa.gov/products/precip/CWlink/MJO/ensplume_full.gif

CA -AR-PC MJO models show significant weakening as the MJO moves through phase 3 then  4   then into  5
http://www.cpc.ncep.noaa.gov/products/precip/CWlink/MJO/forca.shtml

UKMO which KILLS the current Impulse as soon as it enters phase 4
http://www.esrl.noaa.gov/psd//mjo/Forecasts/images/bmo.mjo.latest.png

ECMWF ens mean same sort of thing
http://www.cpc.ncep.noaa.gov/products/precip/CWlink/MJO/CLIVAR/ecmm.shtml

This  is  leaves open  the possibility that  IF  the MJO impulse  does collapse   the  pattern  could  suddenly   turn   cvery different   – PROBABLY colder  — very  rapidly.

“…..WAS IT OVER WHEN THE GERMANS BOMBED PEARL HARBOR !?….”

Posted by wxrisk | GENERAL,WINTER 2011-12 | Thursday 1 December 2011 10:15 pm

2050 HRS  EST   1  DECEMBER  2001… STARDATE  201112.01

 Being on the wrong side of a cold front is not a disaster.  Being on the wrong side of a ridge  and having the cold air fairly close to your location—-  and assuming you are a winter  weather lover–  is also not a disaster.  You know what that’s called?    It’s called life ….or in this case weather life.  The important thing to see  is

1)  is there is any colder being generated and  
2) if  so… is the cold   air coming south
3)   and  is  it  reaching  into any portion of  your region.

If  you  are a  winter  weather lover  I am sure  you can recall  that there  have been some notable winters over the last 20 years which have been quite mild and very little snowfall.    What  could  be call a “disaster winter”    if you happen to love winter weather.  For example the winter of 2001 -02…  clearly qualifies as a “disaster winter “.  There was  no cold air being generated and when the cold  fronts    came south     they  had  no  “kick”   to it .     The same thing can be said for the winter of 2007-08.

So even though there are many winter weather lovers…  some of them    in the  various weather forums …   seem to be  about  ready to put a gun  to their   deformed  skulls  because December 1 and they do not have  2 feet of snow on the ground.    Iin my view there  is absolutely no reason to panic or really get worried.

That being said I do have to admit that the entry I made a couple days ago on the FACEBOOK  about the potential for serious cold in the eastern U.S.  is probably not going be nearly as significant as what it appeared.        The primary  reason   for this   is  the     first   cold front which I originally thought  was coming  through  the East Coast December  5-6….   is  NOT  coming  through until  DEC 7-8.     The Upper  Low over the southwest states which alll the Models   have coming out this weekend and brings  significant rain and snow to the drought areas of Texas Oklahoma and Kansas …  is going to come out in one big piece.     It is likely to generate a significant surface Llw over the Delta and Midwest DEC  6-7….  which in turn causes the cold front to slow down and helps pull up mild air across the East Coast.     On the other side are front this system has the potential to bring pretty good snow in areas such as  MO… St. Louis    central and Northern ILL…  Chicago into the western Great Llakes.

Eventually of course once the Low pressure area does move up off the New England Coast the associated cold front sweeps through and the cold air reaches the East Coast DEC  8-9-10.

Up until this point all models agree.  Then things fall to hell in a handbasket. 

Let’s start up are taking a look at the  WRETCHEDLY  bad   operational GFS at 12z   DEC 1  run…. at  240 and  at  360 hrs.     In this image we can see a comparison between the operational GFS  500 MB   map  (left  side)    and the GFS  ensemble  BOTH  valid at day 10.  ( right side).    Clearly the operational run has a solution which the ensemble mean  does NOT support at all.  The operational run shows one conditions covering much of the eastern U.S….  Very warm over the Deep South in fact and all the cold air bottled up across central and Eastern Canada.      MEANING –   reject the operational GFS.

Next lets  take a look at the day 15 operational GFS a compare to the  GFS  day 15  ensemble.  Again we see the same sort of thing where the operational run is vastly different from what the GFS ensemble is showing.


 Lets look at the   operational European  in detail. vs  european ensemble.      This image shows us the  Day  10  500 MB    map of the operational European  (left side)   and the  surface  map for the day 10 european ( right ).     As you can see there   is a lot of cold air  coming south of the European  behind the cold front.     East of the front is a lot of warm air over the southeastern states push and all the way up the East Coast past VA and up into New England.  On the other hand this looks like   a major snowstorm for the upper Midwest and the western Great Lakes.

This image compares the   day 9  operational european Model  (left side)   vs the   day 9  operational GFS model.  In the overall sense both models are very close to each other in the pattern across the entire northern hemisphere.  The only difference is that the GFS has much more ridging over the eastern CONUS    than the European does.


With the European model we see some of the same sort of thing.  The  ensemble    is colder than the  operational or regular.    The euro  emsemble at Day 10   much like the  GFS   ensemble  shows a stronger ridge  over Western Canada and the eastern Pacific and a deeper trough over the central U.S.    The strong southeast ridge g   appears to have moved out into the Atlantic Ocean and there is a   strong   PV over Baffin island   (+AO).

All this is telling me that the 6-10 day timeframe  – dec  7-11…  is probably going to be colder than the operational run of the European or the GFS is currently depicting.  It could be very cold for the upper Pplains the Midwest and seasonally cold for the Northeast.

Looking at some of the   Teleconnection indices.  We can see that in fact the  current  +PNA does weaken over the next several days but tries to make a comeback by the end of the  week 2    on both the European and the GFS  Ensemble .       All of the NAO  indicies stay very positive on all the models…  and the  EPO  turns  slightly negative over the next several days as the West Coast ridge tries to make a reappearance   then turns Positive   as the   west coast ridge  weakens.

  

 
So again if you  are the northeast   and  looking for a really great early winter pattern there is nothing here which indicates that its  coming.      On the other hand as long as you are  smart enough  to  NOT  pay attention to the operational GFS   past day 7…   there is nothing  in the data which supports  a prolonged  serious warm  periods  — called a  “torch”   in  the weather  Biz.    In fact   for good portion Midwest and the Plain states …the next 2 weeks  looks pretty cold  with a couple of possible significant  winter storms.

In order to break this pattern we need of course  to   get    -AO and or  -NAO  to form .  There is   NOTHING   on the model data which shows   that  happening over the next two weeks.     If we take a look at some of the MJO plots…  we might get a clue as to when the next phase  or development in the winter pattern will occur.  This image shows the current MJO impulse as of November 30 and as you can see  it is in Phase  3. In  December Phase 3 corresponds to a pretty mild pattern  but we are trying to figure out where the  MJO  is going to track.

 

This next image has four different  MJO  forecast plots on it.  Ideally we wanna get the current MJO impulse to swing around in the phase  7  phase 8 and  phase 1….  This would trigger a significant change in the overall pattern across in northern hemisphere.  As you can see from most of these  MJO plots  they all KILL   the current   MJO   impulse once it moves into phase 4.  They turn the impulse into the circle of death where dissipates.  From there it’s possible we may get a whole new impulse …OR   there  many be  a  new  MJO  impulse    that re-emerges  in another quadrant.

 One last thing… In case  you did not know–  and I am sure many of you do not– the global models in Europe  — the European the GFS the Canadian the British the navy model– are all showing a humongous and extremely intense low pressure area tracking across the northern tip of Scotland and slamming into southwest Norway and day 8.   The 0z GFS  has a MSLP of 933 MB!!!!

 The PSD    Version of   the  GFS shows how this  might lead to something  significant on the road.  During the 6 to 10 day…  As this huge storm moves across the northern tip of Scotland and into southwestern Norway an equally strong positive  500 MB height anomaly will be over the northwest Atlantic.  After the huge storm crashes into Norway it  will track to the Baltic Sea into Southern Finland   or  northwestern Russia during the 8 to 14 day.   This of course will leave a gap  or a  ” void’  in the pattern which will allow the positive  500 MB  anomaly over the northwest Atlantic to move east or  Northeast.

If this  feature moves NORTHEAST   …IF…IF…     it could reach Greenland and trigger a   -NAO   phase / event.  If this happens it would not be until after week 2.    Then   once the  positive  500 anomaly  reaches  Greenland (hypothetical )…  It would take 8 to 10 days before it would affect the pattern over North America .  So if this hypothetical does in fact work out we would not see a significantly colder or more favorable winter weather lover pattern  until around Christmas .     On the other hand it’s also quite possible that this  500  positive anomaly may move due east across the north Atlantic into the UK and never reached Greenland.