I’m watching this severe weather risk for Friday closely as a cold front is expected to push through the area in the Friday/Saturday timeframe, bringing some more needed rain but also possibly bringing a damaging wind threat. SPC was pretty gangbusters about it yesterday, coming in with a 30% risk; they’ve since dialed this back to about 15% given significant timing differences in the models (about 8-12 hours, which is the difference between a frontal passage during peak heating and overnight). Available instability is certainly the question, which has been a recurring theme for all of this winter’s severe weather threats so far.
From NWS Charleston’s forecast discussion this morning:
DEEP MOISTURE AND FORCING FROM THE RIGHT REAR QUADRANT OF A 125+ KT
UPPER LEVEL JET WILL SUPPORT SCATTERED TO NUMEROUS SHOWERS ACROSS
THE AREA BY FRIDAY AFTERNOON ALONG WITH ISOLATED THUNDERSTORMS. WEAK
LAPSE RATES AND LIMITED INSTABILITY ARE BOTH NEGATING FACTORS FOR
ANY SEVERE THUNDERSTORMS…BUT GIVEN WHAT COULD BE IMPRESSIVE LOW
LEVEL WIND FIELDS IN ADVANCE OF THE FRONT…THERE CERTAINLY IS A
MARGINAL DAMAGING WIND THREAT AND SPC HAS THE ENTIRE FORECAST AREA
IN A SLIGHT RISK. IF THE FRONT COMES THROUGH DURING THE DAY THAT IS
CERTAINLY MORE FAVORABLE TIMING FOR SEVERE WEATHER…BUT IT SEEMS AS
IF THE ECMWF IS THE MOST ROBUST BUT ITS FRONTAL TIMING IS AT NIGHT.
WHILE NOT TOTALLY CONVINCED THAT A SEVERE WEATHER EVENT IS GOING TO
BE A BIG CONCERN ON FRIDAY…WILL ADD MENTION TO THE HAZARDOUS
WEATHER OUTLOOK GIVEN THE NON-ZERO POTENTIAL.
Will continue to monitor trends as needed as this situation is still very fluid. Going to try to get an update out later today with the 12z global model runs.