WEEKEND VA WEATHER 4/30-5/1-5/2… 5/7-5/8-5/9

Posted by wxrisk | GENERAL | Wednesday 28 April 2010 11:09 am

1105   APRIL 28

Back in early April the Middle Atlantic states experienced and three days of pretty warm temperatures… Upper 80s to L 90s. However South Central Virginia including Richmond and historic did see temperatures into the middle 90S  on April 6 and 7.

APRIL  30- MAY 1-  MAY 2

It looks like we are going to see that   sort of Heat again come this weekend as the models are stronger and higher with the impressive ridge  in the Jet stream  that  develops over the eastern third of the nation.   The Wednesday run of the 0z European model shows that the temperatures could reach 95° on Sunday and Monday– MAY 2-3.  Not surprisingly the 0z GFS does not have that much heat because of its natural cold bias and also because it is a lot faster with the cold front on May 2 moving through the Midwest into the East Coast. Since the models faster with the front it has a lot more clouds which of course this time a year old is going to greatly restrict temperatures.

And given the overall pattern and that most of the GFS and Euro ensemble data is depicting it is pretty clear to me that the cold front is not gonna reach the east coast until Monday MAY 3rd at the earliest… And may not reach eastern VA eastern MD eastern NC until late Monday night.

Of course if temperatures to reach the middle 90s it is possible that when the cold font does arrives some of the thunderstorms accompanying the frontal passage could be strong a severe. However right now this does not look like a classic Spring season severe weather event .

MAY   7 – 8 – 9

For the second forecast weekend of MAY 7-8-9 the data shows a fairly dry and warm weekend. However there is significant uncertainty or a variable that we have to deal with first. 13 figure this out will have a very good idea of what the weekend of May 7-9-9… will be like.

The pattern repeats itself because a another strong trough moves into the Pacific Northwest and the Central California Coast MAY 4-5. This trough moves into the plains and rides a surface cold front into the central plains and the Midwest MAY 6-7. Again because the overall pattern we are going to be facing a fairly strong ridge over the southeastern states which means that this cold front is also likely to slow down or stall over the Lower Plains- TN Valley — and into the Middle Atlantic region.

As a result the second weekend –MAY 7-8-9 is looking fairly wet across a large portion of the Midwest and the Middle Atlantic states. Based upon the data it looks like that of the three days May 9 would be the driest.


1110  EDT  APRIL 26

All last week I suggested that most of this just past weekend -APRIL 23-24-25 would be rain free for central and Southern Virginia and that the warm front would only bring significant rains Friday night and Saturday over northern into the DC area and over the northern neck.

As we now know that is exactly what happened. Except for few early morning sprinkles Saturday AM the warm front pass through most of the commonwealth without any significant rain.  The warm front stalled across NW … northern and northeast VA. To be sure there were lots of clouds around the for the most part the rains did not affect most of the commonwealth.

I was concerned that there could be significant showers and thunderstorms across most of a state Saturday night into Sunday morning… but theses storm did not develop.  The large low pressure area over the Midwest was stronger and deeper than forecasted which affected the overall pattern across the Middle Atlantic region.  Most of this past Sunday was generally cloudy and warm except for the Piedmont with the sun not breaking out until the afternoon hours.  By then of course it was too late for any sort of significant shower and thunderstorm activity to develop.

That big low over the Ohio Valley will be moving into Pennsylvania by this evening.  It’s associated cold front will drive into the Middle Atlantic states and will probably will see some showers and thunderstorms this afternoon across the commonwealth .  Not a huge outbreak butter will be dry either .


The pattern for this coming weekend along the east coast and especially the Middle Atlantic states will be strongly determined by the developing powerful large scale trough in the jet stream that forms this week over the West coast and the northern & central Rockies.

In response to this massive trough the atmosphere will develop a very strong ridge over the Deep South which will build only into New England by this weekend. As a result the deep trough over the western Conus will only be able to push into the Plains and the Midwest.  The surface cold front will stall while strong southerly winds feed moisture from the Gulf of Mexico into the stalled Midwest front.

However for the Middle Atlantic region and especially for the commonwealth the strong ridge over the East coast will ensure that this is going to be a VERY WARM and dry weekend. Friday temperatures will reach into the Low 80s over the southern half of the commonwealth. Saturday and Sunday will see readings in at least the M 80s across the southern half of the state and 78-83 over the northern half of the commonwealth.  And it looks like most of the region will be dry all three days .

MAY 7-8-9

Eventually of course the cold front from the Midwest will reach the Middle Atlantic states but that probably won’t be until May 4 or May 5.

For the weekend of MAY 7-8-9 the operational 0z European and 0z GFS models are diametrically opposed to each other. By day 9-10 the 0z European weather model is developing a new piece of energy which slides down the British Columbia Coast into Oregon and Northern California. This in turn would cause a new ridge to form over the southeastern states and allow temperatures to run either near normal or above normal … And if the ridge over the southeast is strong enough it would provide for another dry weekend.
 BUT the 0z GFS offers a totally different solution. The 0z GFS has no new trough over the SW states. Instead the 0z GFS model develops a strong ridge over the eastern Pacific and deep trough over the Midweast and East coast. This would do two things.

1) shut off the parade of storms coming in from the Pacific. Thus the central portions of the nation would turn drier . 
2) The eastern US would turn much colder in this weekend of MAY 7-8-9 .

As you can see these two models are diametrically opposed to each other. Given the overall pattern I am inclined to go there with the European especially given that the Canadian model looks very much like the European model.

VA WEEKEND WEATHER 4/23 – 4/24 – 4/25 and 4/30 – 5/1 – 5/2

Posted by wxrisk | GENERAL | Thursday 22 April 2010 11:05 am

1100  22 APRIL

APRIL  23 – 24 -25

The first weekend is fast approaching and it is time to nail down the forecast and see what going on. The humongous Upper and surface Low pressure area that is currently moving out of the southwest states and the Rockies will be doing a number this weekend over much of the plains and the Midwest. Those areas are gonna see a lot of rain this weekend. The concern for the Middle Atlantic region and specifically for the Virginia commonwealth is whether not the rain reach is us by Sunday the 25th..

As the major Low tracks thru the central Plains and into ILL its associated warm front …which this morning can be seen over the weather maps cutting through Southern Kansas and Missouri… will also with lift northeast into the Ohio valley and Middle Atlantic states on Friday. The warm front passage could bring some showers to much of commonwealth Friday. These showers do NOT appears to be significant and will be moving fairly rapidly from southwest to northeast. At this time none of the model data is showing any thunderstorms embedded in these showers with a warm front passage. Right now this looks to be a 30 to 40% coverage event and amounts under 0.35″ . In other words a nuisance rain but not a soaking rain or even a steady rain. By Friday afternoon rains will have ended and the sun may be out over the southwest third of the commonwealth.

Saturday looks to be a decent day with some clouds and some sun and most of the day will be dry across most of the commonwealth.   At that point the main surface Low will be located over the Central Illinois tracking close to adjust to the east of Chicago by Sunday.

This Low’s associated cold front will be weakening as it crosses the Appalachian mountains on Sunday. Because the Low is tracking well to the NW… and lifting away from the area… the cold front will not have any impact or much push behind it as it sweeps through the commonwealth.    Areas to the north — such as Pennsylvania New York and New Jersey will probably see significant rain on Sunday but not for VA .    Most forecasters    will have SOME showers across a good portion of the state on Sunday but again I need to emphasize that this rain will not be significant and if you have any outdoor plans you probably will be able to work through the and most today over most areas will be dry .

 APRIL 30 – MAY1 – MAY2:

There is no doubt that the pattern is stuck and we are ina a repeating cycle —another massive piece of energy in the Pacific jet stream is going to drop out of the Gulf of Alaska next week and form a huge system over California and the SW states by 4/28.    That portion of the e nation of having just a terrible Spring season as this will be the fifth major system to impact central and Southern California and the Great Basin area in the last 30 days .

This is one of the reasons why much of March and April 2010 have been quite mild —because here has been a persistent ridge over the eastern Conus in response the trough over the West coast.

The models this morning are showing a piece of energy getting ejected out of the southwest into the central and Upper Plains by 4/29 and into the Great Lakes by 4/30.  This will allow High pressure to linger off the East coast and set up a strong south or southwest wind flow across the East coast 4/30 and 5/1. Temperatures should run quite mild if not outright warm .

Again since this Low will be tracking to our N and W away from us and riding over the top of the ridge off the eastern US… this Low’s associated cold front will move through the northeast on MAY 1 in a weakening state.  Over the Northeast Conus that area may see significant showers and thunderstorms from this cold front on May 1 but for the Middle Atlantic region and especially for Virginia this front may come through dry… or mostly dry.

1100  APRIL 20

APRIL 23-24-25

The model data from over the weekend and early this morning as not really changed significantly with regard to the weather concerns for this first upcoming weekend of 4/23 – 4/24 – 4/25. The main driving feature will be the MAJOR Low pressure area which crashes into the central and Southern California coast Wednesday and Thursday. This system is going to become a major and rather slow moving Low pressure area for much of the Central Plains and the Midwest this weekend.

Friday over the Middle Atlantic region should be pretty nice with the high pressure area moving off the SE Coast and winds turning southerly. Saturday will start out nice but it looks like the significant rains over the Midwest will begin to move into eastern TN NC WVA and western VA sometime during the morning and reach eastern VA/ Chessy bay and DCA by the afternoon. At this point it does not look like heavy rain on Saturday 3/24 but certainly will be more than just a few Passing showers.

Sunday on the other hand looks like it’s completely in the craper. The 0z European and GFS models show a major system located over Missouri and Illinois on the 25th over which has stalled over that area on the 26th. Normally when you CA low pressure area about forks the west it usually does not bring significant precipitation into the Middle Atlantic region if the system is not moving . However in this case the data shows and the overall pattern supports this that the initial band of heavy rain over the Midwest will race out east into NC WVA and VA on Sunday 4/25. Therefore there is a high probability — but NOT yet a certainty– that Sunday 4/25 will be total wash out.


Coming out of the weekend the trough position over the eastern third of the Conus will still be there but the models are showing a new surge of energy on the powerful Pacific jet diving out of the Gulf of Alaska and developing another large slow moving Low for California 4/27 and 4/28. This feature will also be very strong aloft and at the surface and will bring much of central and Southern California significant rain as well as the southwest states.

This feature also has the potential to bring significant rain into the Plains and the Midwest by 4/30 and into the Middle Atlantic region MAY 1-2. It Is possible this system may hang up over the Plains and Midwest long enough to allow for a decent early may weekend but the overall pattern doesn’t support this idea. Right now the odds favor least some portion of the 4/30-5/1-5/2 weekend seeing significant rain over VA NC and MD.

VA WEEKEND WEATHER APRIL 16-17-18 and APRIL 23-24-25

Posted by wxrisk | GENERAL | Thursday 15 April 2010 11:01 am

APRIL  15  1100

The model data looks pretty straightforward as we go into the weekend.. APRIL 16 -17-18.   It  is pretty obvious that Friday and Saturday will definitely be the nicer days for the weekend over the Middle Atlantic states but not so nice across the northeast.    The large upper  Low in the jet stream WILL  drop out of eastern Ontario  and  track across the eastern Great Lakes on Friday and then through the Northeast this weekend. At the surface this feature will have a fairly decent     Low pressure area which will also move to the New England Coast Saturday night and Sunday. Thus for the northeast and especially New England this is not gonna be a great weekend.    However south of the MD -PA  State line tomorrow looks quite mild and sunny and then the cold front should sweep through fairly quickly through the commonwealth Saturday morning and into northern NC by midday Saturday.   There may be a brief passing shower with this cold front passage but for the most part this front comes thru Virginia and North Carolina dry .

Sunday   4/25  looks     FAIR ( sun   and cloudsn)  over   VA   and NV   but    very chilly and   dry.  

APRIL 23-24-25

That    weekend will be be determined by the action which develops over the West coast and southwest states early next week.   The weather models are in strong agreement that a major surge of energy in the Pacific jet stream will drive a strong feature from the Gulf of Alaska south along the West coast with this system eventually closing off as a large Upper Low in the Jet stream over central and Southern California 4/20.    It has been a pretty nasty WET and chilly Spring for the West coast especially for the Sacramento Valley as well as the Great Basin.   This new strong system will bring more very cold temperatures and a lot of rain for these areas on 4/20… 4/21 and 4/22.

Eventually this system is going to come east and bring a significant rain event for much of the Plains and the Midwest.   The issue that we have to solve is what direction does this Low take as it moves through the Plains and the Midwest.

Most of the model data is taking this Low northeast through the Midwest and into the eastern Great Lakes while High pressure area moves off the SE Coast.   The reason for this sort of track is that more energy is coming into the West coast while this system is tracking through the central portion of the nation.   In response to this new surge of energy over the California Coast the atmosphere counters that by developing ridge off the SE.

 This sort of development which can be seen here at the surface means that much of the Middle Atlantic region for the weekend of 4/23- 4/24-4/25 will have mild conditions but rainy as the front stalls over the region and south or se winds bring in significant low level mositure from the Gulf.

APRIL  16-17-18

We have been on a real break here over the last several weekends with some spectacular springtime weather. And of course much of the Middle Atlantic region has deserved this great start to the early Spring so I am sure nobody is really complaining. But that’s about the change as all of the Model data shows a significant pattern Change IS coming  Starting this weekend and continuing for the second half of April.

This first image shows the current Jet stream pattern.  As you can see we have a pretty strong trough over the  WESTERN   Conus.

 The atmosphere has countered that by developing a strong ridge over the Plains of the Mississippi with our valley.   We also have a pretty deep and strong trough over the northeast Conus and Quebec Canada.  That will keep High pressure coming down from Central Canada and into the Great Lakes and the Northeast for most of this week So temperatures should stay either Normal or Below Normal from the Carolinas to the Great Lakes and up into the Northeast.

Eventually by the weekend the trough over Quebec and Canada and New England will begin to retrograde — that is moved backwards towards the Great Lakes.   And a ridge over the Midwest will begin to retrograde back towards the Plains then the Rockies and eventually Western Canada.

This will allow a strong piece of energy to drop southeast on Friday into Eastern Ontario and the Great Lakes.  All the models developing a fairly strong coastal Low from this Trough. The 0z ECMWF shows the surface Low developing in the Gulf of Maine 4/18 then installing over southeastern Canada for several days.    The 0z GFS is similar but of course it’s much stronger and much deeper so the surface Low was of course further south and poses a threat for seeing significant rains over the Northeast US.   Not surprisingly the updated 6z GFS is much closer towards the European solution than the overdone 0z GFS.

In any event this weekend looks to be a colder  and wet weekend for some portion of the Middle Atlantic states.    I don’t think the significant rain will get as far south as the commonwealth but it certainly will be a cooler cloudy weekend with some scattered showers about especially Friday evening into Saturday morning.    Meanwhile the energy from the powerful Pacific jet stream will continue to dominate the pattern across North America. 

APRIL 23-24-25

 By early next week the ridge that which was located over the Mississippi River Valley will be found over Western Canada. More energy will undercut the ridge with widespread significant rains likely for much of California and the Great Basin into the Rockies 4/19 4/20 and 4/21.

The model data supports a significant area of low pressure coming out of the lower for central plains on the 22nd and tracking through the heart of the Midwest with widespread significant rain. The 0z GFS which of course over does the trough… frces most of this rain to stay well to the south     (south of interstate 40).   However 0z GFS ensembles and the 6z GFS is Much furthr north with this heavy rain.    Not only does this make sense in the overall pattern but if it’s correct and means that the weekend of 4/23 4/24 4/25 looks very wet for the entire Middle Atlantic region. 



Posted by wxrisk | GENERAL | Thursday 8 April 2010 11:02 am

1100 EDT   APRIL 8

It doesn’t take a brain surgeon to see that the morning radar has the fairly strong cold front moving through the Ohio Valley and Tennessee valleys with pretty good showers and thunderstorms for early in the day.

It looks like the cold front will move through late this Thursday afternoon over the western portions of the commonwealth and reach eastern half of VA late tonight along the East coast. By that time it should have a pretty good band of showers and thunderstorms with its passage.

This more rapid movement of the front ensures that the weekend of APRIL 9-10-11 for the Middle Atlantic region as well as the commonwealth will be a pretty decent one. Earlier it looked like the cold front might linger along the east coast so that Saturday morning could shut off pretty cold from NC to New England but the new data has the trough lifting out rapidly Friday night. This means that most of a colder should be gone from the East Coast early Saturday morning . There will be a fairly strong High pressure area over WVA and VA so the morning might start off a little on the net the side but under strong brilliant sunshine and blue skies temperatures will recover nicely. Max temperatures should be in the middle and upper 60s across most of the state. Sunday should be back into the low to mid 70s across the entire region.

APRIL 16-17-18:

Weather models continue to show a major surge of energy in the Pacific jet stream crashing into the Wwest coast early next week. This will allow for a large upper Low to form over the West coast which will slowly push into the Great Basin by 4/16. This deep and unusual trough will bring central and Southern California Much Below normal temperatures and a lot of rain for April. However over the Midwest the atmosphere will develop a strong ridge.

 Earlier in the week it looked  D  like this ridge was going to extend into the Northeast which would mean yet another round of much above normal temperatures from NC into New England. However the models today are developing a large coastal storm over southeastern Canada on 4/15. This feature becomes so powerful and strong in the upper levels of the atmosphere that it forces the jet stream the plunge from Central Quebec southward across the eastern Great Lakes and down into PA and VA 4/16 and 4/16. If this is correct we would see a shot a fairly cool air for that weekend.

1100 EDT APRIL 5

This first image shows you the temperatures we saw for Friday Saturday and Sunday afternoons and what is notable is the temperature is pushing into the L 80s across much of the commonwealth. The Easter long holiday weekend was spectacular with all three days featuring brilliant sunshine and rather low humidity… exactly as I forecasted on 3/28 and 3/29.

But now it is a new forecast cycle and it Is time to focus on this coming weekend and of course the weekend for the middle of April .

Today — April 5– and Tuesday will actually be even warmer than what we saw over the weekend as the models continue to show the development of a major area of Low-pressure over the Central Plains which will track into be upper Mississippi Valley and the Great Lakes over the next three days. This track will bring significant rain to much of the upper Midwest and then into the Ohio Valley as the systems trailing cold front feeds on the moisture and the warm temperatures.

The models were in disagreement over this past weekend with regard to how fast of the cold font reach the East coast. The European model had the cold front coming through Thursday night into early Friday morning.

The 0z GFS was slower with the cold front coming through a bit later with more showers and thunderstorms Friday afternoon and evening. However this morning both models are much stronger agreement with regard to the timing of the front which is sometime during Friday afternoon and evening.

There also in good agreement that once the cold front clears the area ….Saturday and Sunday should be a fairly decent weekend across the commonwealth and most of the Middle Atlantic states. Of course it will be nearly as warmth and is delightful as what we just saw… But it shouldn be dry weekend with seasonal temperatures. Of the three days right now it looks like Sunday is going to be the warmest of the three.

APRIL 16-17-18

Right now the weekend of 4/16 – 4/17 – 4/18 is of course rather far off into the future but we can see some things which he was a clue about what this 2nd weekend forecast should Look like.

This image shows the day 9 Jet stream Maps. The image on the left hand side is the European and on the right hand side is the GFS. Both models show a large vortex centered over eastern Siberia Alaska and the Aleutian islands and both models also show above Normal Heights north of Hawaii.

The interaction of these two features means that the Pacific jet stream is going to once again become very active and powerful and we can see that by all those THICK Black Lines which are compacted over the Pacific from Japan into the eastern Pacific near the West coast. I have highlighted this Pacific jet by the WHITE arrows which shows the energy coming in.

In response to this new surge of Pacific Energy the models are developing a ridge over the eastern third of the Conus. We can see that by the brigjht RED shading g over the East coast. If this ridge becomes strong … we could see another interval of above normal temperatures over the Middle Atlantic states as well as much of the eastern third of the Conus. Certainly this 2nd weekend also looks to be fairly dry as well since a strong ridge over the eastern third of Conus would greatly restrict any sort of rainfall.