From the ABC 7 Weather team

Severe Weather: Now likely Saturday in D.C.

September 7, 2012 - 09:45 PM
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A strong cold front is heading our way with severe storms tonight and likely DC area Saturday

9:45 Update- from Bob Ryan- Alex's blog below still shows all the reasoning why we are now likely to be under severe watches and warnings Saturday afternoon.  There are watches out across parts of the Midwest until 3AM and likely will be more later tonight.  Look at the latest NASA GOES image 

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of the storms exploding across the Midwest.  One of the simulations of the weather we really look at is the ensemble of many "models" and that is also showing a line of strong storms coming through Saturday about 5PM

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">Courtesy PSU  Eyewall page

and we know the cold front coming will bring a dramatic change to the air.  So the combination of everything we are looking means there is a risk of severe storms Saturday, the highest risk in the DC area is 3-10PM 

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so stay informed and don't take any chances Saturday afternoon.  If you hear thunder, you are at risk of being struck by lightning.  Stay safe and we'll keep you posted

 

 

Let's get this out of the way first...this week has been downright brutal. With dew points in the 70s through the majority of the week, the humidity levels have been off the charts, and showers and precipitation have been common occurrances through the week. Now we end the week with 90 degree temperatures, but big changes are only 24 hours away.

A strong cold front is beginning to take shape over the Midwest, with a few severe thunderstorm warnings already out ahead of the front issued over Illinois and Indiana. That system will advance quickly through the day towards the Ohio Valley, where it should be located tomorrow morning. Below is the Storm Prediction Center's Moderate Risk for severe storms outlook. Our region is squarely in the risk area which extends from the NC-SC border north through the entire Northeast.

SPC Thunderstorm Outlook for Saturday

When to expect it? The timing for severe weather appears like it will be somewhere between 3 p.m. and 8 p.m. Saturday, though it should be even later east of town. With that being said, the beaches may not experience bad weather until the overnight hours, which would be good for beachgoers!

Simulated Reflectivity 5pm Saturday from the 4km NAM

What are the severe threats? As far as the type of severe weather, at this current time the thinking is for damaging winds as the primary threat. The thought is a line of thunderstorms will be ongoing during the morning over the Ohio Valley then cross the mountains and move into the D.C. area during the afternoon.

I do have to say that an isolated tornado may not be out of the question, as there is enough shear to support it. Though we are not anticipating an outbreak of tornadoes by any means, the chance for one or two is there. If a line of storms sets up, there is the chance for rotation within the line, but at this time I do not think there will be a huge threat of discreet supercells out ahead of the front. The best chance for supercells and potential tornadoes looks to be through eastern Pennsylvania, New Jersey and New York, which was why the risk outlook was upgraded to moderate.

Storms should push east through the late evening hours tomorrow, giving way to cooler temperatures, lower humidity and clear skies. The forecast for Sunday through early next week returns the D.C. area back to the 70s to near 80 degrees. get ready to get back outside!

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