Gusty squall likely late Friday morning into early afternoon

A high-energy cold front will sweep across the region  Friday, bringing a brief, but hard-hitting round of downpours and strong winds.

The National Weather Service’s Storm Prediction Center places the eastern half of our region (along and east of I-95) under a “slight risk” of severe thunderstorms, with the main potential hazard damaging winds.


Area under a slight risk of severe storms Friday shaded in yellow (NWS SPC)

A squall line may enter the western suburbs as early as 9-10 a.m., with an arrival around noon for D.C.’s eastern suburbs (timeline subject to some tweaking).


High resolution NAM model shows squall line just west of I-95 at noon (WeatherBell.com)

“The vigor and speed of the line could take people by surprise,” says Jeff Halverson, Capital Weather Gang’s severe weather expert.

The showers and storms will blow through quickly – within a couple hours, but may put down a quick 0.25-0.5″ of rain, with locally higher amounts.  Storm drains and gutters may experience some overflow due to lingering snow and related winter debris.


GFS model simulates roughly a half inch of rain around the metro region Friday. (WeatherBell.com)

Winds, especially east of the District, are likely to gust over 30 mph, with an outside shot at 50 mph or higher gusts.

Halverson says the storms probably won’t produce much lightning due to a relative shortage of instability.  Their morning arrival won’t give the atmosphere much time to heat up, although slightly more instability is likely in Southern Maryland and east of the Chesapeake Bay.

Related: Slight risk of severe weather in D.C. region Friday

By 2 to 3 p.m., the line of activity will have crossed the Bay, and sunshine will return.

This same front is expected to produce a significant severe weather outbreak in the South and Tennessee Valley later today, with a small chance of tornadoes, and a much higher risk of damaging straight-line winds.  Memphis, Nashville, and Louisville are among the cities with the greatest risk of hazardous weather. Wind gusts in that area could exceed 70 mph. Nearly 45 million people – from New Orleans to Cincinnati – may contend with strong to severe thunderstorms today.


Severe weather summary graphic for Thursday (National Weather Service)
Jason is currently the Washington Post’s weather editor. A native Washingtonian, Jason has been a weather enthusiast since age 10.
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Kevin Ambrose · February 20, 2014