Numerous Severe Storms Possible Tuesday Afternoon

The Storm Prediction Center (SPC) has placed portions of the immediate Washington Metropolitan Area under an “Enhanced Risk” of Severe Thunderstorms” on Tuesday afternoon. 

What does an enhanced risk mean?

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Afternoon Damaging Wind Threat for DC Region

The Washington Region remains under a “slight risk” for severe thunderstorms this afternoon. Increasing lapse rates out ahead of an approaching upper level trough along with ample daytime heating will produce the ingredients necessary for storms capable of producing damaging winds in excess of 60 – 70 mph. Cloud to ground lightning, torrential rain and hail are also possible in these storms.

The high resolution NAM model (image above courtesy Tropical Tidbits) predicts that a line of thunderstorms will approach the Shenandoah Valley around 2pm, pushing eastward into the Washington Region between 3 and 6 pm. I would not be surprised to see a Severe Thunderstorm Watch issued for our region during the early afternoon hours.


Update on Flash Flooding Probability

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Waves of torrential rainfall will move northward out of central Virginia impacting the entire Washington Region through the day on Thursday.  With the ground being so hard from a lack of rain, water will easily run off into streams, creeks, low-lying areas, poor drainage areas (underpasses) etc. 

Here is a look at the latest full suite of short-range high-resolution models.  Keep in mind that it is very hard to pinpoint exactly who receives the jackpot, but if you live in a flood prone area please make preparations for facing rapidly rising water overnight into the evening hours on Thursday.

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Tornado and Hail Threat:

A low-level jet stream will provide enough spin that some storms may become severe with hail and isolated tornadoes being the primary threat.  I say isolated because we have not had any sunshine to really destabilize the atmosphere, however wind shear values (helicity) are running marginal so an isolated spin up tornado is not out of the question this evening, hence the Storm Prediction Center has issued a Severe Thunderstorm Watch for our region this evening.

Rainfall Totals: 

When analyzing the current high-resolution models one thing is clear:  A widespread 3 to 5″ of rain is likely for all with the locations receiving “training thunderstorms” possibly picking up 5 to 12″ of rain!  

Please monitor the latest forecasts from the National Weather Service and if a Flash Flood Warning is issued for your area have a plan to move to higher ground.