1100  JUNE  2

The model data continues to shift here as we go through the middle portion of a week.   Earlier it looked like a major trough was going to move through the Midwest and the northeast this weekend– mainly on Sunday June 6 and Monday June 7.  But each subsequent run of the various models — such as the GFS Euro and CMC– is showing that this trough is weaker because the energy coming in from the Pacific is so strong that the trough is really is not getting a chance to amplify as it moves through the Great Lakes and the Northeast.  It looks like a pretty good cold front for the Great Lakes and from Pennsylvania northward into New England on June 6-7 .  But as things  stand right now for the Lower Middle Atlantic states this cold front may not get far enough south to bring about any sort of significant shower thunderstorm activity  SUNDAY   June  7.

Coming out of the weekend the forecast is going to get complicated.

The model data shows that of the strong ridge over the southwest states will attempt a slide into the Lower Plains and the Delta region for several days starting on June 5… nad lasting through June 8.

Indeed the model data from the European and the GFS shows temperatures greater than 100°… and in some locations as high as 105° over large portions of eastern NM TX OK A and M- U 90s into southern half of COL KS ARK and LA.

Typically when you get a ridge like this forming over the Lower Plains as it comes out of the southwest states… the ridge likes to build north and east into the central Plains and the Midwest.   But in this particular situation the very strong Pacific jet stream will be racing across the top of the ridge essentially in a west east direction through the Central Plains the Midwest and into the northeast all next week.

This does TWO things… FIRST this sort of strong active Pacific jet stream ensures that the heat over the lower plains will not get any further north then say interstate 70. Second this sort of strong flow becomes DIFFLUENT aloft on the synoptic scale.   In other words pieces of energy moving in the jet stream (vot maxes) will cause thunderstorm development and thunderstorm clusters to form over the central Plains and the Midwest… and possibly into the Middle Atlantic region.

JUNE 11-12-13

As we approach the second weekend JUNE 11-12-13… Which in turn will allow for the strong ridge over the southwest states to begin to slide or expand eastward.  Without the trough lingering over the northeast the ridge will have a much better chance to expand into the central plains and the Midwest .  This could be the beginning of the first significant hot. For most of the Midwest the Deep South the Tenn valley and the Middle Atlantic region.  The euro and GFS ensemble data is quite impressive here showing the ridge to the setting up over the these areas whiile on the West Coast the trough stays put.

The West coast trough the serving as an anchor in the overall pattern because as long as the trough stays strong and deep over the west coast / Pacific NW the Ridge stays strong and Deep over the Plains and Midwest and East Coast.

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1200 EDT   MAY 31

Although most of the commonwealth has not seen significant showers and thunderstorms over this long weekend there have been a few areas which are been hit pretty hard. Here in downtown Chester– mind you there is no such place as downtown Chester it’s just sort of a phrase I use– we been hit with two significant thunderstorms and the last three days– one during the early morning hours of Friday 1-2am — and again Saturday evening when a series of storms cells kept “popping ” up over the region.

And judging by the Monday afternoon radar looks like we will probably see some more storms later on this afternoon and on Tuesday.

　JUNE  4-5-6

Last week many of the weather models are showing a pretty strong cold front associate with a fairly strong upper trough moving through the Midwest and the northeast JUNE 3-4.  That still appears to be the case to the model data here on the 0z and 12 runs Monday appeared to be somewhat weaker with this front.  This means that Friday, June 4 is likely be a fairly stormy start to the weekend especially in the afternoon in the evening.  At this point most of the model data is driving the frontal off the coast which should mean that June 5 and June 6 would be decent days with less humidity somewhat cooler temperatures and dry conditions.

However the European and the GFS models here at midday are showing a bit of a change.  Theese models   take of the next big shortwave in the jet stream across the Upper Plains and moving through the Great Lakes where surface Low pressure develops. The Low tracks ENE thru the Great Lakes into New York State Sunday, June 6 then up into Maine on June 7. Normally this sort track is not a big thunderstorms threat for the Middle Atlantic region and especially for Virginia.

But because of the shape or configuration of the jet stream…  (the 0z GFS and euro show a very diffulent aloft jet stream pattern)…   the thunderstorm potential for Sunday afternoon June 6 over the commonwealth appears to be pretty strong.   Right now the model data is favoring central and Southern Virginia being hit with a series of thunderstorms… But it is still too far out in to be certain of this.

WEEKEND  # 2   JUNE 11-12 -13.

Right now the early call on the second weekend shows a significant ridge developing in the jet stream over the central lower plains and the delta region.  The GFS and the GFS ensemble is pretty bullish with this pattern building the ridge into the heart of the Midwest and forcing the jet stream north of VA.  This was set up a somewhat drier more, pattern and potentially bring significant heat into Western portions of Virginia. However… The European ridge is somewhat flatter and not as amplified so the Middle Atlantic region could still be in a fatal location for thunderstorm development because of the jet stream not shifting to the north.