wpostServer: http://css.washingtonpost.com/wpost

The Post Most: Local

Posted at 04:05 PM ET, 05/30/2012

Weather Service aggressive in highlighting severe storm potential Friday


Percent chance of severe weather within 25 miles of a given point on Friday (National Weather Service Storm Prediction Center)
It’s a long way off - meaning subject to change - but the National Weather Service Storm Prediction Center (SPC) is using strong language to describe the threat of severe thunderstorms Friday in the Washington, D.C. area.

Consider these excerpts from its write-up (bold text indicates my added emphasis) discussing the severe weather potential:

* SEVERE POTENTIAL THE FIRST DAY OF JUNE WILL GENERALLY BE TIED TO THE EAST-NORTHEASTWARD ADVANCEMENT OF A POTENT UPPER TROUGH OVER THE EASTERN THIRD OF THE CONTINENTAL U.S.

* AS THE PARENT UPPER SYSTEM TRENDS TOWARD A SLIGHT NEGATIVE TILT ON FRIDAY...AMPLE FORCING FOR ASCENT/VERTICAL SHEAR WILL CONTRIBUTE TO SUSTAINED STRONG/SEVERE THUNDERSTORMS

* DAMAGING WINDS /POTENTIALLY WIDESPREAD/ AND SEVERE HAIL WILL BE THE PRIMARY HAZARDS FROM WHAT SHOULD MAINLY BE A MULTICELLULAR/LINEAR CONVECTIVE MODE. SOME SUPERCELLS...PERHAPS EVEN A TORNADO THREAT...COULD OCCUR PROVIDED SUFFICIENT DESTABILIZATION NEAR THE AFOREMENTIONED WARM FRONT.

SPC indicates a “slight risk” of severe storms but a 30% probability of severe weather within 25 miles of a point for the entire D.C. metro region - which is quite high for a 3-day outlook.

The NWS office in Sterling also supports the storm threat idea. Here are excerpts from its latest discussion:

* EXPECT HEAVY THUNDERSTORMS AND POTENTIAL FLASH FLOODING

* THE LOW LEVEL SHEAR /IN BOTH 12Z NAM AND GFS FORECAST SOUNDINGS/ IS FAVORABLE FOR TORNADOES

Severe weather is not a given. For severe weather to materialize, the timing and spacing of certain features will have to come together just right. But, at the moment, this appears to be the most favorable set up for severe weather so far this year.

We will keep you updated on this potential and provide additional analysis Thursday into Friday.

By  |  04:05 PM ET, 05/30/2012

 
Read what others are saying
     

    © 2011 The Washington Post Company