The Storm Prediction Center has released a new severe weather outlook for Monday. A few severe thunderstorms are probable late this afternoon and evening across portions of the Edwards Pleateau, Hill Country, Central Texas, North Texas, and Northeast Texas. Sonora, Brady, Brownwood, Granbury, the D/FW Metroplex, Sherman, Paris, Texarkana, Longview, Palestine, Buffalo, Waco, Temple, and Kerrville are a few towns included in the main risk zone. Surrounding that is an area where we may see an isolated severe storm but the probability is lower.
As described in my blog post Sunday evening wind shear aloft will be weak today. The only reason we’re talking about a severe weather threat today is because instability values will help compensate somewhat for the lower wind-shear. The result could be a few severe thunderstorms capable of producing hail up to the size of ping-pong balls and localized damaging winds over 60 MPH. A brief tornado cannot be ruled out but weak wind shear and high cloud bases greatly limit the threat of tornadoes.
The threat of severe storms will be highest during the very late afternoon hours and especially into the evening as a cold front moves into the region and helps provide the lift necessary to make more storms develop. The overall threat of severe weather is not expected to become significant or widespread, but I do expect we will have several severe thunderstorm warnings today. The good news is some will get rain today.
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1233 AM CDT MON APR 21 2014
VALID 211200Z – 221200Z
…THERE IS A SLGT RISK OF SVR TSTMS ACROSS PARTS OF THE RED RIVER
TO THE EDWARDS PLATEAU OF TX…
ISOLATED SEVERE STORMS MAY DEVELOP FROM PARTS OF THE RED RIVER TO
THE EASTERN EDWARDS PLATEAU OF TEXAS THIS AFTERNOON AND EVENING.
A WEAK SHORTWAVE TROUGH CENTERED OVER KS/OK WILL DAMPEN AS IT MOVES
E/SEWD…AS A NRN-STREAM SHORTWAVE TROUGH OVER THE SRN CANADIAN
PRAIRIES PROGRESSES TO THE GREAT LAKES. THIS WILL AID IN A COLD
FRONT PUSHING EWD ACROSS THE GREAT LAKES AND SWD INTO THE SRN
PLAINS. A DRYLINE SHOULD MIX TOWARDS THE BIG COUNTRY AND EDWARDS
A TSTM CLUSTER CURRENTLY OVER NW TX SHOULD BE ONGOING OVER SE OK/FAR
N-CNTRL TX AT 12Z. CONVECTIVE OUTFLOW FROM THIS ACTIVITY WILL LIKELY
MODULATE THE NERN EXTENT OF SEVERE RISK DURING THE AFTERNOON. TO THE
SW…DIURNAL HEATING SHOULD BE ROBUST WITHIN A PLUME OF 50S TO LOWER
60S SURFACE DEW POINTS. WITH STEEP MID-LEVEL LAPSE RATES…MLCAPE
SHOULD INCREASE TO 1500-2500 J/KG ACROSS CNTRL TX.
THE MOST LIKELY AREA FOR AFTERNOON CONVECTION SHOULD BE ALONG
REMNANT OUTFLOW AMIDST WEAK LOW-LEVEL WAA. ISOLATED STORMS SHOULD
ALSO FORM BY LATE AFTERNOON SWWD NEAR THE DRYLINE AND OVER THE
MOUNTAINS OF COAHUILA. WITH THE DAMPENING SHORTWAVE IMPULSE EXPECTED
TO BE OVER THE OZARK PLATEAU IN THE AFTERNOON…500 MB W/NWLYS WILL
LARGELY BE WEAKENING TO AROUND 25-30 KT. BUT GIVEN THE DEGREE OF
INSTABILITY…MULTICELL CLUSTERS ARE PROBABLE WITH PERHAPS A COUPLE
OF SUPERCELLS. LARGE HAIL AND ISOLATED SEVERE WINDS SHOULD BE THE
PRIMARY RISKS. TORNADO THREAT APPEARS LIMITED GIVEN WEAK LOW-LEVEL
SHEAR AND LARGE SURFACE DEW POINT DEPRESSIONS /ESPECIALLY WITH SWRN