Community Corner

Wednesday Weather: Forecasters Talk of Derecho Conditions in Northern Virginia

Meteorologists are in disagreement: Some say weather patterns are right for a straight-line windstorm this week; others say it's unlikely.

Manassas residents won't soon forget last year's deadly derecho that struck the area June 29.

That late Friday-night storm brought high winds and heavy rain. It killed at least two people and knocked out power to more than a quarter-million homes in Northern Virginia. The downed trees, multi-day power outages, problems with 911 that centered in Arlington, cell phone service interruptions and triple-digit temperatures created a grueling mix for the area.

Now, some meteorologists are talking about a weather system that may have the potential to spawn another derecho, possibly late Wednesday or Thursday.

Find out what's happening in Manassaswith free, real-time updates from Patch.

Fortunately, any power outages related to these coming storms may be easier to handle, as high temperatures are projected to be in the low to mid-80s over the next 10 days—not 100-plus degrees.

Of course, meteorologists don't always agree on weather forecasts.

Find out what's happening in Manassaswith free, real-time updates from Patch.

Here's a breakdown of who's saying what:

Alex Sosnowski, senior meteorologist from AccuWeather: 

"Complexes of strong, drenching and locally severe thunderstorms will reach from parts of South Dakota and Nebraska to Illinois, Ohio, western Pennsylvania and the Virginias during the middle of this week.

Part of this area could be hit by an intense thunderstorm complex, known as a derecho."

Sosnowski, replying to comments about possible fear-mongering by uttering the word "derecho" in his forecast, said: "It is our duty to warn people of potential dangerous weather conditions. The weather pattern favors multiple MCSs (Mesoscale Convective System) spanning late Tuesday to Thursday afternoon. Of these there is a 'chance' one morphs into a derecho. Because forecasting the exact starting point of an MCS is difficult and exactly where the complexes will turn to the right of the flow, we can't say dead on which locations will be hit the hardest."

Larry Cosgrove, whose Twitter bio describes him as a meteorologist specializing in the prediction of extreme weather events, tweeted:

"Severe weather risk across much of Corn Belt, Mid-Atlantic region Tuesday night - Thursday. Derecho or MCS threat"

Jason Samenow, Capital Weather Gang in a post Monday headlined "Ratcheting down the derecho hype, but recognizing the risk (late Wednesday)"

The Capital Weather Gang's Jason Samenow examines the forecasts and concludes that he is "unconvinced there’s reasonable confidence D.C. will experience derecho conditions, and I cringe at sounding the alarm so soon."

Capital Weather Gang's Matt Rogers does not mention the "d word," but possible "strong winds" for late Wednesday:

"Another super-soaker system surges into the area  with potentially widespread heavy storms yet again (which *might* contain some strong winds). The models vary on timing and details, but we should be especially wary anytime after 8 p.m."

Greg Forbes, The Weather Channel forecast for Wednesday:

"Scattered severe thunderstorms, possibly in clusters or even a derecho (widespread damaging wind event associated with a bow echo thunderstorm pattern) in northeast IA, south WI, north half IL, north IN, south MI, OH, southwest PA, north and central WV, MD, DC, north VA."

Do you think meteorlogists are sounding the alarm too early, or do you like advance warning even if dire weather forecasts change for the better? Tell us in the comments. 


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