Update: Strongest storms are passing south and east of the city


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Update at 6:33 p.m. ET: The severe thunderstorm watch has been discontinued from the District and to the north and west.   Heavy storms continue in southern Maryland, and a severe thunderstorm warning covers St. Mary’s, Calvert, southeast Prince George’s and southeast Charles counties until 7:30 p.m. for damaging winds to around 60 mph.  General rain and a bit of thunder stretches from the eastern side of the Beltway to around Annapolis.  All of this activity should push off to the east of the Bay between 7:30 and 8 p.m.  This is the last update in this post.

Update at 6:13 p.m. ET: Central Charles county is taking the brunt of the storms as they move east into Calvert County. Winds are probably fairly gusty in La Plata right now, possibly peaking above 60 mph.  Warnings are still in effect for both of these counties until 6:45 p.m. ET.  A 53 mph wind gust was reported in Quantico, and a 59 mph gust was reported in Montclair, both in Prince William County. Quarter-size hail was reported as well in Dumfries, VA.  Behind these storms, lingering rain — and in some places, heavy rain – is still present, but this should push out of the area over the next couple of hours.

Update at 5:40 p.m. ET: The strongest storms continue to be south of the city, where warnings remain in effect for Prince George’s, Charles, southern Fairfax, and Prince William counties. Gusts in these storms could be severe, and there is a potential for hail. These storms are moving east at 30 mph and will avoid D.C. to the south. Within the Beltway, and possibly north and west of the city, there will probably be some moderate rain for a while, but the severe weather threat seems to have passed for D.C. itself.

Update at 5:14 p.m. ET: The strongest storms are located from the border of Prince William and Fairfax Counties down to northern Stafford County. A weak line of rain is moving through D.C. right now that is most likely becoming an annoyance for the commute. Severe thunderstorm warnings are still in effect for portions of Prince William and Fauquier Counties.

Radar as of 5:10 p.m. ET. (Map credit: Weather Underground)

Radar as of 5:10 p.m. ET. (Map credit: Weather Underground)

Update at 4:57 p.m. ET: A weak line of showers are entering the beltway from the west. These are not the storms that are still to our southwest (and still have warnings in effect for counties including Fauquier and Prince William) but are out ahead of them. The storms themselves are starting to take on a track that is more southeast. The southern D.C. metro region will be impacted by these storms, however, it’s not totally clear that D.C. itself will take a hit from the severe storms. At the very least, the commute will be a little rainy and roads could be slick for the drive home as these weaker showers move through.

Showers move through D.C. ahead of the main storms which are still to the west-southwest. (Map credit: Weather Underground)

Showers move through D.C. ahead of the main storms which are still to the west-southwest. (Map credit: Weather Underground)

 

Update at 4:23 p.m. ET: Against odds, we have been issued a severe thunderstorm watch, which is in effect until 10 p.m. ET.

A severe thunderstorm watch is in effect until 10 p.m. ET. (SPC)

A severe thunderstorm watch is in effect until 10 p.m. ET. (SPC)

In addition, a new severe thunderstorm warning has been issued which includes southern Fauquier County. This warning is in effect until 5:00 p.m. ET. We are also seeing some scattered reports of damage to small trees around Marshall, Virginia, as these storms rolled through. Strong gusts could be possible, as well as some small hail.

A severe thunderstorm warning (lower yellow polygon) is in effect until 5:00 p.m., which includes southern Fauquier County. (Map credit: Weather Underground)

A severe thunderstorm warning (lower yellow polygon) is in effect until 5:00 p.m., which includes southern Fauquier County. (Map credit: Weather Underground)

 

Update at 4:00 p.m. ET: The Storm Prediction Center has released a mesoscale discussion which includes the D.C. metro area. The probability of a severe thunderstorm watch being issued is only 20% at this point, though they mention that marginally severe wind gusts are possible as storms begin to enter the area from the west.

Severe thunderstorm warning for portions of northeast Virginia. This warning expires at 4:45pm ET. (Map credit: Weather Underground)

Severe thunderstorm warning for portions of northeast Virginia. This warning expires at 4:45 p.m. ET. (Map credit: Weather Underground)

A severe thunderstorm warning is in effect until 4:45 p.m. for central Fauquier and northwest Prince William Counties, which includes the city of Manassas. Expect winds in this storm to approach 60 mph in the stronger gusts, as well as the potential for some hail.

Original Post:

While a few thunderstorms, some of them on the strong side, have already started to pop in Maryland and northern Virginia this afternoon, our chance for organized severe weather in the D.C. area is relatively low.

Scattered, mostly moderate-intensity storms will likely move through the area late this afternoon and evening (most likely timing window in immediate D.C. area 5-10 p.m.).  Isolated storms may be severe with a damaging wind threat but the highest chance for severe weather is to the south and east of the metro region where the sun is having an opportunity to break through the clouds, destabilizing the atmosphere.  Generally, storms should not be as strong or widespread as Tuesday.

From our severe weather expert, Jeff Halverson:

This afternoon and evening, I expect showers and thunderstorms to develop again. A frontal boundary straddles the region, with a surface pressure trough across VA-MD, and abundant low-level moisture. However, unlike yesterday, we do not foresee development of a strong squall line moving through the D.C. metro region. Scattered to overcast clouds will limit destabilization of the atmosphere.

Surface forecast for 8pm on Wednesday, July 9, 2014. (NWS)

Surface forecast for 8pm on Wednesday, July 9, 2014. (NWS)

The high resolution models suggest that convection will be most widespread to the south and east of the immediate D.C. metro area. Scattered storms may still develop in our vicinity. Because there is significant wind shear, in regions that experience enough afternoon sun, some of these storms could be locally strong to severe, including strong multi-cell storms and short, bowing line segments. The NOAA Storm Prediction Center (SPC) outlines just a 5% risk of wind damage – a very low end probability. However, locally heavy rain and lightning remain definite possibilities.

Forecast radar for 8pm ET Wednesday from the High Resolution Rapid Refresh model. (NOAA)

Forecast radar for 8pm ET Wednesday from the High Resolution Rapid Refresh model. (NOAA)

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