Friday, January 20, 2012

Chance of strong storms in the metro this evening

The Storm Prediction Center has just placed the metro area on the far western edge of a slight risk for severe thunderstorms for tonight (see image below).While "garden-variety" thunderstorms have been in the MWN Forecast for tonight, this represents a minor increase in the chance that some of these storms could be strong.  A warm front is currently lifting north through the metro and temps and moisture trapped behind the front are spreading over the city.  In fact, at 3pm, mid 60s could be found south of the boundary (including at Memphis International) with dewpoints soaring into the 50s.  Meanwhile on the north side of the front, conditions are still fairly cool. With the spread of the warm sector (warmer/moister air) over the region and increasing wind aloft, some storms that form have the potential to be strong.

Slight Risk area for Friday evening, courtesy SPC

The most likely severe weather threat tonight will be damaging thunderstorm wind.  SPC places us in a 15% area for this threat (see image below).  Basically that means we have a 15% chance of seeing 58 mph wind or greater within 25 miles of any point.  Due to the turning wind with height (wind shear) in the lower levels, there is also a small, though not negligible, chance of a tornado as well.

As the warm front retreats north, a low pressure system will move along the front from west to east, reaching the area around midnight and accompanied by a cold front. The passage of the front will end any chance of strong to severe storms.  So, the timing for potential strong storms appears to be in a small window from about 8pm to midnight, give or take an hour.  The best CHANCE for severe weather will actually be across north MS/AL and TN east of the metro.

Risk for damaging wind (58 mph+) tonight, courtesy SPC
After a cool day in the wake of the front tomorrow, the atmosphere will once again prime for the possibility of severe weather on Sunday with strong storms possible again Sunday night.  More details on this event will be forthcoming once we get past tonight's storms, but for now the SPC has again placed the entire region in a slight risk (see image below).  Initially, the threat on Sunday appears to be greater than the one for tonight.  The MWN Forecast and MWN Storm Center will keep you updated on the latest information and we'll be nowcasting any and all severe weather on our social media feeds listed below.

Slight Risk area for Sunday night, courtesy SPC
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