Posted by wxrisk | GENERAL | Thursday 31 May 2012 10:03 pm

2230  EDT  31  MAY

Yes  Virginia  we  ARE  going to see  what could be   SIGNIFICANT    and widepsread   severe weather outbreak affecting most of North Carolina …Virginia …West Virginia …Maryland …central and eastern Pennsylvania …and Delaware on Friday June 1.  There are several reasons why this  particular severe weather threat  COULD  be more a significant  severe  weather.

The Thursday  evening  weather map shows a area of LOW pressure developing over  KENTUCKY..   There are numerous Moderate to heavy storms over IND   OH  KY  with Moderate   rain over southern MI.  The  LOW pressure area  will  track NE  from  KY to  Cleveland   then into the  eastern Great Lakes.   The upper level support or the Jet stream that is supporting this Low  …is going to  develop a certain angle   as it  reaches the East Coast.   In the weather  business this is called a NEGATIVE   TILT ;   that is to say the trough alignment  be running northwest to southeast   ( from Michigan to  Virginia).  This alignment in the upper level trough  will enable thunderstorms to develop more rapidly than  they might typically do  with a Ordinary cold front .  In addition this system will  be  pulling up a lot of warm humid air from the Deep south and from the Gulf stream     off the Southeast coast.   Initially skies should be clear    to   Partly cloudy for most of Friday and that could allow temperatures to get close to 90° or 92  especially over central and eastern  Virginia …Maryland and North Carolina.


With each passing model run the data becomes stronger with  regard to the  severity of the thunderstorms as a cold front moves into  far western North  Carolina …West Virginia …and far western portions of Virginia  on Friday morning.


The  KEY  aspect to this  POSSIBLE  widespread  sever  threat  will be the developement of  2nd   LOW  on the  Cold    where the WARM front  Intersect  or  met.  This feature is a  called   a  TRIPLE POINT   Iin the weather  Busioness  and  the 0z  NAM  1JUNE   model  has the   TRIPLE point showing up nicely.    If  the   TRIPLE POINT    develops as the NAM/ WRF  is  showing and  tracks    WEST of Richmond area  thid would palce the worst  storms over the Piedmont into the    DCA Metro area and  northwest VA.

In addition one of the aspects of severe weather here on the East Coast which often gets overlooked is the timing.  In the Midwest and   Plains  the timing issue is   often not that big of a deal…   but on the East coast it is    In this particular case the approach or timing of the cold front will be ideally situated to get maximum amount of heating as the thunderstorms  approach and the cold front crosses these states.  Most of the thunderstorm  should be at or just west of I–95 in North Carolina ..Virginia ..and Maryland   by 7:00 or 8:00 PM Friday.






SPC -  storm prediction center—has been  talking about this threat for 24 hours already.  In the Thursday morning  discussion they mentioned that they might raise the threat  to    MODERATE   RISK for severe /  torandic  storms   for most of North Carolina
…Virginia …and Maryland and this upgrade may occur this evening  or Friday morning before the event actually begins.

Based upon the data I am  looking  late   Thursday …it looks like the biggest threat areas will be from Charlottesville up towards Washington, DC including locations such as Strasburg   Harrisonburg   front Royal   Warrenton     Culpeper   Leesburg  and then into western and Central Maryland including all of  Northern VA/
Washington, DC /Baltimore  metro areas.  A second area may develop from Richmond east into the Northern neck and Middle peninsula areas and perhaps into Hampton roads.

I suspect a large portion of Virginia and Maryland will be placed under a TORNADO  Watch during the day tomorrow.  The potential for   rains up to 2 inches is pretty high especially over central and eastern portions of North Carolina …Virginia … and Maryland and the HAIL  potential also quite high.







This whole system should be off the coast and done with  during the predawn hours on Saturday  AND   this coming  weekend looks   spectacular… but the rains and storms  will  continue   over  NJ NYC  CT  and Much of New England  through Saturday.

For next week JUNE  3-9….  temperatures will run below normal over the entire eastern half of  the CONUS.  This Low  which is going to hit us tomorrow   will  continue to travel up the New England  then stall off the southeast coast of  Canada.  It will be blocked from moving any further to the east the cause of a blocking feature in the Jet stream over northern and northeastern Canada.

This will force the jet stream to plunge from Minnesota down to Kentucky into  North Carolina  all next week.  A boundary or front  will set up next week from Georgia to Louisiana to Kansas and there will be numerous showers and  thunderstorms over the Deep South and the Delta because of this front.   But for Virginia …North Carolina …West Virginia Maryland … and Delaware …conditions will be pretty good  with  generally  fair skies and normal or  below normal temperatures for the entire week.

Beyond  JUNE  2-9  the pattern and data clearly indicates that  Mid  and late JUNE   is going to turn hotter.  Once the blocking feature over  northern  Canada leaves ….  the   cooler air mass over the eastern U.S. will also leave.   Heat building in   over  the SW  conus and the Lower / central Plains will spread into the Midwest by  JUNE 10 and into  the  Middle Atlantic  by JUNE   12-13  and this   hot   pattern  could last to JUNE 25-30.   Rainfall  may also become quite as scarce as well . 







Posted by wxrisk | GENERAL | Saturday 19 May 2012 9:29 pm

1630   EST   19  MAY  2012     STARDATE  201205.19


Suddenly in the weather business it has gotten very busy.   Most people probably think that in the weather business during the middle and late Spring and in the Autumn seasons it’s usually not that busy except for the occasional severe weather outbreak or a hurricane in the Autumn.    For the most part that is generally true but sometimes a bunch of different things can come together which can a lot of pressure on you especially if you are a extended range forecaster in the private sector like yours truly.    Besides having to worry about the Memorial Day long weekend –which is looking extremely hot for the Midwest and a good portion of the Plains and the delta region — there is also the sudden development of this tropical system on the North Carolina coast.   Then we have the issue of trying to figure out whether not the Midwest heat is going to get into the East Coast during the Memorial Day weekend.
In the short term we have to deal with the potential tropical development of this hybrid system from the southeast North Carolina Coast.    I will the dealing with this feature mostly through the FACEBOOK page.  I do want the state however that I believe that the system COULD become a full tropical or “warm core” system it keep it.  Yes 93L is located right over the warm waters of the Gulf of Mexico but it IS embedded within a large upper Low which is developing over the entire southeast and Middle Atlantic states this weekend.

Indeed over the past few days I have been telling my clients that this Upper Low over the   southeast  is likely to bring significant showers and thunderstorms to much of the lower Middle Atlantic states (WVA VA NC MD DE ) May 22 -23.   It is also possible for example that this feature might become a tropical depression or tropical storm then as it gets captured by the upper Low.. lose its warm core characteristics. At any rate it’s interesting feature to watch but it is not going to become a hurricane or anything of real significance with regard to people’s lives or property.

OK…. let’s talk about the Memorial Day weekend. In the weather business you have to get the big holiday periods correct. It is just the nature of the game and if you don’t well then you suck. You can get all 90 days of the summer season correct with sky conditions rainfall and temperatures. But if you get the July 4 holiday or the July 4 holiday weekend wrong… well GOD help ya.

The Model data is looking much hotter for ALL of the eastern half of the Conus for the long Memorial day weekend (MAY 25-29) … from the eastern Plains through all of the Midwest and into Northeast US. This includes all of the lower Middle Atlantic states (WVA NC VA MD DE).   That being said there is still quite a bit of uncertainty as to how hot it is going to get EAST of the Appalachian Mts along the East Coast from North Carolina up into New England.  Right now it looks like that the core of the heat is going to be west of the Appalachians … as far west as base of the Rockies covering most of the Midwest as well as the Delta and the central and Lower Plains
With the collpase of the MJO in early and mid MAY… what is driving the overall weather pattern over North America is the large amount of cold water in the eastern Pacific AND a large pool of remarkably warm water a few 100 miles southeast of Newfoundland Canada in central North Atlantic. That pool of cold water has been persistent there for most of last year and every day so far in 2012 and in the weather business is refer to as the negative phase of the PDO ( -PDO). The affect of this -PDO is that it is forcing the Jetstream to come further south than it normally does in the month of MAY . The Pacific Northwest as well as British Columbia has seen a pretty wet and chilly APRIL and MAY 2012 mainly because of the number of strong systems and the persistent deep trough that has been hitting that part of the North America.


Early next week (MAY 21-23) there will be another strong deep trough in the Jet stream slamming into the West Coast of North America…. bringing below normal temperatures and significant rains to the Pacific Northwest and the northwest Rockies MAY 22-23-24.    The appearance of this extremely deep and powerful trough for late MAY over the West coast means that the atmosphere will counter this by developing a strong Ridge over the eastern CONUS.    This time the Ridge will develop over the eastern third of the Conus… mainly centered over the Midwest during the long Memorial holiday weekend which means much above normal temperatures … Possibly record HEAT temperatures for many in the Midwest region.

The issue however for folks on the East Coast is whether not the heat is going to get east of the Appalachian Mts and for how long.   Complicating this feature has been the development on the last few model runs    (on all the weather models)     showing another ULL– UPPER LEVEL LOW –over the southeast or the Middle Atlantic states  as we approach the Memorial Day weekend.    This feature appears to keep the dome centered WEST of the Appalachian Mts and in doing so prevents severe heat from reaching the big cities of the I 95 corridor.

Earlier in the week it was clear that the GFS model was missing the pattern and the European model was outperforming it once again.    These models for May 17 show that the GFS had a Ridge over the eastern U.S. but the Model was rapidly advancing the massive West coast trough from the Pacific Northwest east into the Plains and the Upper Midwest.   This movement prevented any sort of heat Ridge or Dome from forming.    The European model on the other hand from MAY 16-17 was already detecting the development of the heat dome over a large portion of the central and or eastern CONUS. The difference is that the GFS was simply mishandling or not detecting the nature of the deep trough over the western portion of U.S. and Canada.

Starting on Friday the GFS turned dramatically and strongly towards the European scenario and now in fact shows a massive heat dome for most of the 6 to 10 day period covering a large portions of the eastern Plains …the Midwest and at times into the East Coast areas. However the problem is that the GFS model resolution turns into crap after 192 hours so trying to figure out what happens in the 6-10 day with the operational GFS is often a waste of time.

To be more specific ..all the models are showing a strong block developing over the United Kingdom and Iceland this week and next  . This feature is a form of the North Atlantic oscillation– the NAO. Since we are dealing with positive anomalies the over the UK… the NAO in the negative phase BUT based to the East  . Over the next 10 days the European model as well as the European ensemble keeps the -NAO feature over Iceland and the UK.  The GFS and to a lesser degree the GFS ensemble grabs the EAST based -NAO and pulls it westward towards Greenland and then into Eastern Quebec and labrador Canada. This movement however does not occur until after the model resolution of the GFS turns into garbage another words after 192 hours.  This leads me to strongly believe that the GFS is simply mishandling the eastern based -NAO feature.  As a result the model ends of breaking down the entire heat dome pattern over the Midwest way to quickly by Day 10 and into the 11 to 15 day as well.

0z   and  12z  MAY 19  ECMWF  MODEL RUNS


12Z gfs   operational   GFS MODEL  RUN