Posted by wxrisk | SEASONAL FORECASTS | Monday 31 May 2010 1:01 pm

27  MAY   2200   EDT

  sorry I could  NOT  release  this  forecast earlier…..


Posted by wxrisk | GENERAL | Monday 24 May 2010 8:42 am

0836   EDT   24  MAY

MAY 28-29-30-31

 We are rapidly approaching the first big weekend of the summer months that being a long memorial day holiday weekend. Like so many things that are important and significant in this country the holiday of Memorial Day was founded the cause of the trauma of the civil war…. As was baseball the Red Cross and Rapid mass movement of armies by railroad.

The pattern going into this week   will feature a strong ridge/ dome over the Midwest which will bring about several warm/ hot days for that portion of the nation.  However the warmth will not really get into the Middle Atlantic states this week as the ridge is actually retrograde– moving WEST towards the Plains and not towards the East coast.

Of some concern is the development of a low pressure area in the southwest Atlantic which has been showing up on the various global weather models for the last several days. There’s been some talk from private weather services– such as Joe Bastardi up in accu weather land — at this system could become a significant tropical feature but that in fact it really is fantasy and not likely to happen.

There is a small chance this feature could become a subtropical low but even when you are always dealing with the the “extreme” scenario that JB loves to do… Reality has to be a factor. In this case the reality has to do with amazingly cold water which continues to exist over the southwest Atlantic Ocean. This large pool of cold water in the southwest Atlantic Ocean can be seen here. 

If you think  that this system has  a chance to  develop with of SSTA that are running anywhere from 1-3° below normal in the southwest Atlantic in late May… You probably need to slow down and rethink that.

Assuming this sort of sub tropical Low does in fact stay off the middle Atlantic Coast this weekend the long Holiday weekend should be OK for the Middle Atlantic region.  There will be a weak cold front moving through PA NH MD DE VA traveling from north to south that will bring a few passing showers to the area Friday afternoon and evening.  Parenthetically it is THIS cold front on Friday that will ensure the Low over the southwest Atlantic Ocean will be driven out to sea.

The rest of the holiday weekend looks to be pretty decent with warm temperatures but no serious heat and no significant rain threats on either Saturday Sunday or Monday. In summary at this point looks to be ideal.

JUNE 4-5-6

The retrogression of the ridge will continue as we move into early June 2010 and will eventually reach the West coast. This would generally support some sort of trough position being located over some portion of the eastern Conus. This is strongly indicated by the European ensemble mean position…. Which shows are significant positive height anomaly over central and Southern California and other one over Eastern Canada.

The 0z GFS ensemble mean is mcuh more scattered and all over the Place. Some other individual members have a pretty significant trough over the Midwest and the northeast… while other members show a flat wide ridge over CA and the sw states and a strong Pacific jet coming into the Pacific NW and sw Canada. The jet then spreads as it moves into the Plains and Midwest—- the flow becomes more diffluent aloft– which could set up a fairly strongly pattern for the Midwest and the Middle Atlantic states.


Posted by wxrisk | GENERAL | Wednesday 12 May 2010 11:01 am

12 MAY  1101  EDT

WEEKEND   MAY 14-15-16

At this point the forecast for this coming weekend of MAY 14-15-16 seems to be in pretty good shape.  The second major rain system for the Midwest in three days will be developing tonight and Thursday and this is likely to be a major rain event for that area and even into the Tennessee Valley— where they do NOT need rain.  The question for the weekend weather in VA is how does the front react when it crosses were reaches the East coast and specifically the Middle Atlantic region?

Friday looks HOT with L to M 90s possible over the southern half of the state .  The data shows the moving through front Friday night .  You would think that was the sort of temperature contrast and heat ahead of the front that weather models would show more shower and thunderstorm activity with the front passage.  However once again it looks like that the front will be weakening as it moves through the area and the associated Low-pressure region over the Ohio Valley will be tracking up into Pennsylvania and New York and away from VA.  This has all the makings that of a weakening front which is one reasons why the data is so dry with the cold front passage.

Right now it appears to be that the best chance for seeing any sort of shower thunderstorm activity will be over the western third of the state and into West Virginia late Friday night. And all the data shows the front clearing the North Carolina border by Saturday morning with high pressure building into the region.  Assuming this doesn’t change it means that most of Saturday and all Sunday should be mighty nice across the Middle Atlantic region in general and especially across the commonwealth.

MAY 21-22-23

There is no doubt now that the overall pattern is about to undergo significant change as we move closer and closer to the beginning of Summer 2010.  One of the reasons why the pattern has been so wet across the Midwest over the last several weeks is that the mean trough position has been located over the West coast.  This of course is significantly different from what we saw over this past Winter and very different from the pattern we saw on the Autumn of 2009 the Summer of 2009 and the Spring of 2009– all of which featured the mean trough being located over the East coast or Midwest.

In response to the mean trough being located over the West coast– and if you know anybody on the West Coast I am sure they have told you how cold and wet the Spring of 2010 has been for that area– the atmosphere is developing ridge over the southeastern states.

Systems coming out of the mean trough or tracking in a ENE or NE direction across the Plains into the Midwest and then into the Northeast.  During the Spring months this sort of pattern can be very wet pattern because a southeast ridge allow persistent High pressure to be located off the SE Coast.  The low level circulations from that High feed moisture from the Gulf of Mexico into the Midwest so that when these areas of Low pressure and get ejected from California and the Great Basin… they have a lot of moisture work with.

Hence the wet pattern. ya Follow?

However as we move into mid and late May the jet stream is now shifting further to the north– as it always does.  As a result the mean trough is no longer dropping as far south as Southern California and Vegas.  Instead the mean trough on the West coast now only drops as far south as the Pacific Northwest.  Keeping the overall pattern the same but displacing it to the north means at the southeast ridge is now getting a chance to build into the Plains and the Midwest.  This is exactly what happened in week two across the Conus .

The problem is that also leaves a weakness along the East coast for some sort of trough to develop.  The formation of a deep trough over the East coast which is what the GFS is depicting… Which trap the strong ridge in place over the Plains & Midwest for several days and allow the first series heat of the season to develop in that area.  For the East coast however and for this particular weekend a strong trough over the East coast would mean below normal temperatures and possible showers.

Not surprisingly the operational gfs is the most aggressive of all the models with a solution for the strong trough and a possible Low pressure area along the East coast.  The European & Canadian also have a trough there but not nearly as strong and the coastal Low-pressure area is very weak.  At this point all I can tell you is that looks like temperatures will be below normal on the East Coast and it could be some scattered showers across either the middle Atlantic and New England depending on the possible formation of any Low pressure development.

If you are west of the Appalachians however is going to turn hot and dry for several days to the last 3rd and 4th week of MAY 2010.


10 MAY 1100 EDT

The weekend turn out to be pretty well with regard to the actual forecaster made from last week. Saturday was the warmest day of the week for much of the state SOUTH of I-64 . There was lots of sunshine and very strong winds which made the day quite comfortable if you don’t mind when the conditions. The front it comes to the state almost completely dry.

MAY 14-15-16
Over the next three days there going to be too major low pressure areas coming out of the western Conus — specifically the Great Basin region. These Low will bring widespread significant rain to much of the plains and the Midwest as well as the Great Lakes and Northern New England. In response to this persistent trough over the western third of the US… The atmosphere is countering it by developing another strong ridge over the southeast states this week. As a result of these two Low pressure areas will track through the Great Lakes and into New England and not really impact the Middle Atlantic region and the commonwealth of Virginia. This is southeast ridge will cause temperatures to run Above Normal from Tuesday into Friday over VA and all of the Middle Atlantic region.

It is the second Low pressure area that in tracking through New England will eventually send its weak cold front into the Middle Atlantic region the on MAY 14.   The front will probably have some showers and thunderstorms with its passage on the 15th.   Right now most the models show the cold front will have pushed into NC and the Deep South by Sunday May 16.   If so that it looks like Sunday will be pretty nice day especially over the northern half of the state.    I still have some concern that the front is going to hang up across the southern half of the commonwealth Saturday night into Sunday…. So there is a decent risk that the forecast for Sunday which right now look pretty good for the southern half of Virginia might be considerably wetter.

MAY 21-22-23

The weather models are definitely showing the change the pattern developing in WEEK 2.   The weather models are moving the persistent ridge over the southeast coast West…into the Plains and Rockies …starting MAY 15.    This in turn will force some sort of trough to develop over the eastern Third of the US and especially over the East coast. As a result temperatures for the weekend of MAY 21-22-23 will likely run below normal   . It is possible that we could also see some sort of coastal Low development as well along the SE or Middle Atlantic coastal areas .   If this does happen then the weekend of MAY 21-22-23 could turn out to be pretty wet.

VA WEEKEND WX MAY 7-8-9 and MAY 14-15-16

Posted by wxrisk | GENERAL | Wednesday 5 May 2010 11:03 am

1105 EDT  MAY 5  

 The main concern for the Middle Atlantic region and the commonwealth of Virginia this coming weekend will be the area of L ow pressure that develops on Thursday night and Friday over the Midwest.   The Low itself is not going to track anywhere near the Middle Atlantic region.    Instead the  Low will track through the eastern Great Lakes and up  across   the Saint Lawrence river valley and   then through   Northern  New England.

Its associated cold front will sweep through to the  East coast some time during the day on Saturday.   This is going to be one of the situations were forecasters are probably going to overemphasize the threat of showers and thunderstorms.   This happens for number different reasons.   For one there is a subset of meteorologists who loved to go bananas was severe weather events which can be a real problem with regard to   ”overplaying “     or hyping these events in the northeast   US.     That is because a lot of times the same atmospheric conditions which will produce significant or major severe weather outbreaks in the Midwest or the Plains often has a lot less impact   in the northeast US.

This bias towards over forecasting severe weather events especially early in  the  season can give off the wrong impression as to how much rain might fall with a cold front passage like this.    In addition because a lot of meteorologists have this bias toward severe weather events they Mis read  the synoptic setup.

This Low is pulling AWAY  from VA NC on Saturday and it is weakening.    This means WEST winds are likely Saturday…. which means DOWN SLOP which in turn means less humidity and Lowering Dew points

In any event most of Friday will be fabulous day with temperatures in the L to M 80s and low humidity. MOST of Saturday across most of the commonwealth will be rain free.   The cold front will probably have already reached the Shenandoah and southwest Virginia — say interstate -81- by 10 am.    It will be moving rapidly so the timing of the cold front passage will occur in the middle portion of the day… As opposed to late afternoon which is why we have maximum heating.

It would not surprise me at all IF the commonwealth did not see a single drop of rain from this cold front passage.

MAY 14-15-16

For the weekend of MAY 14-15-16… Right now it looks pretty dry.    Besides this system moving through the Midwest on Friday there are s going to be two other significant Low pressure areas coming out of the mean trough located over the west coast in the next seven days.    The first Low will be on MAY 11-12 followed by the second event MAY 14-15.

The systems will be forced to track through the upper Mississippi Valley and into the Great Lakes because in response to this trough the atmosphere is developing a strong ridge over the Gulf coast and southeastern states.

Temperatures will run warmer than normal for much of the Deep South but also it will turn dry.

It is possible that eventually this cold front over the Midwest on MAY 13-14 will push into the East coast by MAY 16-17… but I doubt it.


3 MAY  1103 EDT

The clouds came into much faster than I had originally anticipated last week for this past weekend Last week I mentioned the possibility the temperatures could reach into the middle nineties on Sunday over much of central and Southern Virginia. However that was premised on the idea that the clouds would not move rapidly and until Sunday night or Monday. Clearly that did not happen.

On the other hand early last week I did correctly forecast the torrential rainfall for this past weekend over Tennessee and Kentucky.

MAY 7-8-9

The main change in the weather models on this Monday morning has to do with the development of a new system MAY 6 over the central Plains which tracks ENE into the eastern Great Lakes on May 7.  That sort track means that the Middle Atlantic region will stay in southwesterly winds which will bring two fairly warm days until the Low’s associated cold front moves through late on MAY 8.  This front should have some showers and thunderstorms with it on Saturday and Saturday night.

At the same time the next major piece of energy drops into the West coast over this coming weekend…MAY 7-8-9.   This is going to be a major weather feature for the next 10-12 say because of this deep trough over California is going to eject several pieces of significant energy ENE in the 6-10 day.

MAY  14-15-16

The first one comes out through the central plains MAY 10-11.  The Low will also Track ENE mainly be cause the models in response to this deep trough over the West coast start to develop a pretty strong ridge over the southeastern states.  As a result the system as it moves through the Plains into the Midwest MAY 11-12 will track fairly far to the north.

This Low falls apart over the great lakes as the next strong piece of energy tries to come out of the West coast and Great Basin MAY 13-14.  However the models continue to show a fairly strong ridge over the southeast so there’s a lot of uncertainty as to how fast this big West coast Low will come east.  The European hangs this trough backed well west of the Mississippi River so that everyone East of the Mississippi is dry.  The GFS is much faster with this Low and if it is correct this system will bring significant rains to portions of the Middle Atlantic states MAY 14-14-16