Severe Thunderstorms Possible Saturday

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Saturday is shaping up to be an interesting day across the Washington Region with temperatures soaring into the upper 90s, dew points just shy of 80 degrees, an upper level (500-mb) disturbance slated to cross our region, high surface CAPE (convective available potential energy) and very strong wind shear (some models forecasting values approaching 50 knots)! An area of low pressure will also be passing just to our north and east as a cold front approaches from the northwest.  If these trends continue and timing of the features is accurate, our region could be under the gun for damaging winds, hail and possibly even some tornadoes.

Dew points will be Oppressive and this saturated air mass will be fuel for deep moist convection:

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Severe Thunderstorms Likely Friday Afternoon

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A cold front will cross the Washington Region on Friday afternoon touching off widespread showers and thunderstorms.  While not everyone is guaranteed to get hit with damaging winds and hail, some locations will certainly be under the gun with higher wind shear values and plenty of instability.  The image above shows the latest NAM model’s future-cast “radar simulation” from 3PM through 11PM. However, this is just one model, so thunderstorms are possible anytime on Friday afternoon through the evening hours.

The Storm Prediction Center has placed the entire Washington Region under a Slight Risk for Severe Thunderstorms (image above).  What classifies a thunderstorm as severe? Wind gusts in excess of 58 mph, and hail greater than 1″ in diameter. With wind shear values coinciding with peak heating during the afternoon, an isolated tornado can not be ruled out.

The weekend will feature partly cloudy skies, much lower humidity and temperatures in the mid to upper 80s.