Northwest Flow And Storms

May 21st, 2014 at 9:05 am by under Weather

We have a unique, although not rare, weather pattern which is setting up for the next couple of days over the eastern U.S.  The upper level winds will be flowing from northwest to southeast.  This makes for some difficult forecasting, and also some active weather at times.  Here’s the latest satellite/radar with the upper level winds shown on top:

Jet Stream & SatRad

Jet Stream & SatRad

So what happens during these setups is simple.  Showers and storms will form over the Great Lakes and Midwest states.  Then they’ll follow the upper level winds and move southeast.  The upper level winds act as a steering current for the clusters of storms.  A good example of this is the Derecho storm that moved from Illinois to North Carolina within about 12 hours back in 2012.   Here’s my old blog about it after it happened. Derecho Blog.

While I don’t think we’ll see anything like that this time, the setup is there for storms to quickly move to the southeast.  Today we have more warmth and humidity in the region than yesterday. Temps will be in the 80s and dew points are in the 50s.  So unlike yesterday, the storms will be able to survive in our region today and tonight.  The problem is that many of the computer models have a tough time forecasting these types of storms.  This is due to their size and speed.  The storms that form are on a much smaller scale than fronts and Mid-latitude cyclones (areas of low pressure).  So they can give you a good idea of where the zone is that will be affected, but they don’t handle the exact timing or placement very well.  So at this time let’s just say that today we’ll have a couple of those storm systems move from Ohio and Pennsylvania into Virginia and Maryland.  These storms may contain strong, possibly damaging, winds as well as large hail.  Most of the models actually have the storms passing just to our east and possible affecting the Eastern Shore.  However, a couple of the models bring the storms right into the viewing area.  Here is what our Future Trak model shows for this evening:

Future Trak (7pm)

Future Trak (7pm)

Keep in mind that an earlier version had more coverage and heavier rain than this version.  Either way follow this common motto…Hope for the best and prepare for the worst.  So keep an eye to the sky and/or the weather reports later this afternoon.  At this time I’d say the highest chance for rain will be between 5 and 10pm, but that could easily change.  We are on the edge of a slight risk area for severe weather, but I would assume that anybody in our viewing area could see the gusty winds.

Tonight any storms that do form will move through by the late evening.  Then we’ll see partly cloudy skies and lows in the 60s.

Tomorrow the models show a little higher chance for scattered t’storms forming during the afternoon.  It will be warm again with highs in the mid-upper 80s, but a cold front will move through late in the day.  This could help to create some of those showers and storms.  Then we’ll cool-down and dry-out on Friday behind the system.  Overall the Memorial Day weekend still looks good.  Skies will be partly sunny with highs in the 70s and 80s.  There may be a stray shower Saturday night.  There will probably be an update on that over the next day or two.

Again keep an eye to the sky later today.

Meteorologist: Jeremy Wheeler

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