as of   30  AUG  2200  EDT

 
INTERNATIONAL WEATHER –      Models   show Massive   Low  to  develops over  Ukraine and   western Russia   AUG 31- SEPT 2 while  western Europe  stays dry but   Major low could  hit  IR  FR SP  and UK   SEPT 6-7-8…    heavy rains coming   this  weekend for  SE Brazil and   eastern  Argentina…  China looks Ideal  dry…  More  good rains coming this  weekend for Australia… large  rather cool air mass  moves into central &  eastern Canada  SEPT 3-4-5  but  western  Canada    stays  in a wet pattern ..  India Monsoon   shifts to  north  India Plains   by   SEPT 2…  

NORTH AMERICA WEATHER -      Say Good Bye   to DANIELLE… EARL now a CAT  4    is going to TRY and make a  run up the  East coast  from eastern NC to Southeast MASS   but the  KEY  is   does he pass  EAST of Hatteras  or  West of Hatteras???    SEE   HURRICANE    SECTION…  Tropical Storm   FIONA  is  born   but   will be  SLOW  to develop   until  EARL   pulls away…. Models shift  FIONA threat  away from   FL  and  towards   the SE US Coast …  COOL  autumn Like air mass  comes into Midwest  SEPT 3  and  into the Northeast  SEPT  4….  but  cool airmass will NOT last  as    Mean trough  in Jet stream  stays over  West Coast and  Rockies   so  Ridge   stays over   Deep South  with More  Warmer  than Normal temps extending  into Midwest and  Middle Atlantic  region    SEPT  6 – 11 

It doesn’t take a meteorologist for anyone to know how beastly hot the Summer of 2010 has been across the Commonwealth. And not just over Virginny…. but for all of Maryland Delaware the Carolinas and through the Deep South it’s been a beastly hot Summer.  And not surprisingly it also been quite dry with much of the mid Atlantic region moving into various drought stages as date to date by  folks at   USDA  / NOAA’s drought monitor index.

At Richmond June and July 2010 set the record for the most 100+ degree days ever recorded (now at 11) .   But all that is about to change and it is  very probable— but not yet certain— that the period from say August 15/16  to August 30 will not see any more of these 100+ degree  max temperature days.

The change to a much much wetter  pattern  begins when a Major Low pressure develops over Hudson’s Bay and Eastern Canada on AUG 13 and 14.   This Low will carve out a Major trough in the Jet stream over the eastern half of the Conus and send a strong cold front sweeping south and east through the Midwest. This front will reach the Appalachian Mountains AUG 15-16.   At this point the cold front will stall on a line from Georgia to New York State and in doing so this stalled front will become a focusing mechanism for widespread heavy showers and thunderstorms up and down the front.

In this prolonged interval ….from say AUG 15-16 to AUG 20-21… it is NOT going to rain ALL the time.   But in this type of pattern the strong inflow from the Gulf and Atlantic Ocean off the SE Coast will feed abundant moisture into this front. At times the rainfall especially from I-95 west into the mountains will be the very heavy.

This link shows the POSSIBLE rainfall from the Wednesday Midday GFS ensemble mean just for the period from AUG 16 to the 20th.     More importantly  as  we move closer to the  event  the   model data is  increasing the   rainfall amounts and coverage . Some areas of this 7 day period   could see 5-10″ of rain  and more over the elevated terrain in Northern GA far northern SC western NC and western half of VA.    There are of course of several aspects to this unfolding event that are uncertain. . First is possible that the front could move through North Carolina Virginia and Maryland faster than what the model data right now is depicting. If that happens… it would end the rains much but significant rains are still fall across the most of commonwealth NC MD DE eastern PA and southern NJ.

It is also quite possible that the front will stay stalled over the East coast as the Bermuda High/western Atlantic Ridge builds into the East coast. Indeed this is what the 12z GFS and European weather models are depicting to occur after August 21. This would continue the rainy pattern fpr a few more days.

1000 EDT    14  JULY

The Wednesday 0z operational European model is showing a significantly different pattern than the 0z GFS and the 0z CMC. These models continue to develop a pretty powerful dome over the Plains and the Midwest in the 6-10 day. To the European begins to form a dome during this time frame.

The Canadian however develops a pretty serious trough over the northeast which keeps the dome centered over the Mississippi Valley of the plains states. That trough appears to be…according to the 0z Wed Canadian …. strong enough to keep most of the East coast (including Virginia) in a much cooler weather pattern and this would also affect the Ohio Valley as well.

The GFS shoves the dome in the Midwest SOUTH as the Model develops a weak cold front over the Great Lakes and Northern New England. The front presses south JULY 24-25-26 and brings about some showers and thunderstorms to the great lakes and the northeast. At this point it is impossible to say if the storms will reach Virginia. The Models keep the Dome over the Deep South … whiich again IF correct would bring in several days of U 90s and L 100s degree temperature readings.

The 0z Wednesday Europran continues to show the dome further south and any of the models. And because of the model has the dome so far to the south a pretty significant cold front moves into the upper plains and a good portion of the Midwest July 24-25 and into the Northeast July 26-27. The 0z Euro ensembles are not nearly as far south as the operational run.

No matter which of these possible solutions is correct the all show that the dome is either going to come due east from the Midwest region into the Ohio Valley and the Middle Atlantic states… or the dome gets shoved south … then comes east. There are of these possible so areas looks like a very hot last 10 days of July for the commonwealth…. a 3rd round of temps near or above 100 degrees seems a good bet.

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1100   EDT JULY  12

As I am sure most of you know it’s been a very hot summer throughout the commonwealth as well as the Middle Atlantic states and  in  fact the entire eastern third of the Conus.    June 2010 was the hottest or one of the hottest June months on record .    Minor drought conditions had begun to develop across the commonwealth and if the current hot and fairly dry pattern continues then it looks like the drought conditions will probably worsen as we go through the second half for July and into August .

　The weather models over the weekend and early this month morning continue to show the developing potential of a major heat dome for the Midwest and the Plains states developing in the 6 to 10 day period.    All the models are showing this dome and given that we are now in any rapidly developing an increasing LA NINA pattern this sort of pattern development is a supported by the overall seasonal trend .

But beyond that this new pattern has significant implications for Virginia and the the entire Middle Atlantic region.

JULY 16-17-18.

 This looks like a warm weekend pretty typical for what will see in mid July with temperatures likely range in the low to mid 90s across the entire commonwealth. A cold front attached to a fairly strong area of Low-pressure and Eastern Canada will move through the big cities of the East coast Saturday night or Sunday.  This front should be strong enough to provide significant showers and thunderstorms to much of the commonwealth as well as the big cities of I -95.

This cold front will be followed by another fairly vigorous cold front moving through the NE Conus JULY 20-21. It is during this period that the heat dome over the southwest states will begin to slide east expanding into the Central and Lower Plains and into the Midwest BY DAY 9-10…. JULY 21-22.

JULY 23-24-25

The entire forecast for this weekend for Virginia… as well as MD DE WVA and NC…. depends on the development and the position of this massive Dome in the Jet stream that all of the weather models are currently developing over the Plains and the Midwest after July 20.  The day 10  ECMWF   0z  run….  has this Dome centered over the Midwest and the Delta. There is a weak trough off the New England Coast and the model makes it clear that the dome is rapidly building into Western Virginia western NC and into the Lower Ohio valley.

If this sceanrio is right VA could see its 3rd round of 100+ degree temps starting in this weekend . The heat may Not make it past DCA or BWI as the models all keep a weak trough over New England.

This would bring back eight another significant interval of 100° plus temperatures

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