Thursday, April 24, 2014

Showers Tomorrow; Severe Storms Possible Across Central/South-East VA

Friday (4/25) 7:15am Update
Latest HRRR run continues to show the potential for the development of severe storms across portions of central and southeast Virginia later this afternoon and evening.

8z HRRR for 6pm via NOAA
The overnight outlook from the Storm Prediction Center includes much of the same area as yesterday's day 2 outlook.  Although the damaging wind and hail are the biggest threats, they are now mentioning the threat for a tornado or two across far southeastern VA into northeast North Carolina as well.  This is where there the atmosphere may be conducive for super cell development.

Day 1 Severe Outlook from the SPC

Day 1 Tornado Outlook from the SPC
End Update

Thursday (4/24) 9:45pm
A low pressure system currently affecting parts of the upper Mississippi Valley with severe weather will track across the Ohio Valley into the northern mid-Atlantic during the day Friday. It's trailing cold front will swing through bringing showers and storms to the entire region.  

Forecast Surface Map for 2pm Friday via the WPC
Ingredients may come together to produce some severe weather with this frontal passage, especially east of the Blue Ridge mountains. The highest chances will be the farther east you go towards I-95 and coastal areas of the state.  Deep layer shear values will approach 30-40 knots which is plenty to help maintain and even strengthen any line segments that do develop.

SFC-500 mb Bulk Shear via Twisterdata
With that being said, the uncertainty lies with how much instability there will be for initial storm development.  Areas across western Virginia will likely be too stable from early morning cloud cover.  Instability will increase the further east you ago as the line won't move through here until after the peak heating hours of the day.  Cape values may approach 750-1000 J/kg across portions of the piedmont.

Cape Values 5pm via Twisterdata
Where these ingredients collide will bring the best shot at severe weather. The greatest threats appear to be damaging straight line winds although some embedded hail can't be ruled out.  The 12z wrf from this afternoon shows some bowing line segments quite nicely.

WRF Radar Forecast 5pm Friday via Wright-Weather
Here's the current outlook from the Storm Prediction Center showing where the greatest potential exists.  Be sure to keep an eye to the sky; especially if you live in any of these areas.  The front will clear the area by late Friday night allowing high pressure to work back in.  This will set the stage for a very sunny, warm weekend.  Enjoy it because next week is looking rainy.

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