Here is the latest SPC Day One Convective Outlook….
Can the instability reach I-20 this evening? One way or another, my main concern remains the pressure gradient winds, not involved with thunderstorms.
It will be very interesting to watch developments during the next 36 hours. The next of the outlook is below…
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0649 AM CST THU DEC 24 2009
VALID 241300Z – 251200Z
…THERE IS A SLGT RISK OF SVR TSTMS THROUGH TONIGHT FROM LA/MS EWD
ACROSS SRN AL/SWRN GA TO THE FL PANHANDLE…
…SYNOPSIS…
AN INTENSE MID LEVEL SHORTWAVE TROUGH OVER CENTRAL TX THIS MORNING
WILL EJECT NEWD TO THE LOWER OH VALLEY BY CHRISTMAS MORNING AS A
SEPARATE CLOSED LOW DIGS SSEWD OVER THE NRN HIGH PLAINS. THE TX
WAVE WILL BE PRECEDED BY A DEEPENING CYCLONE WHICH WILL TRACK NEWD
FROM EXTREME NE TX THIS MORNING TO THE MID MS VALLEY OVERNIGHT. IN
CONJUNCTION WITH THE DEEPENING CYCLONE…A WARM FRONT WILL MOVE NEWD
FROM LA THIS MORNING TO THE I-20 CORRIDOR IN MS/AL BY THIS
AFTERNOON/EARLY TONIGHT…WHILE A COLD FRONT SURGES EWD ACROSS LA/MS
TODAY TO AL AND SW GA OVERNIGHT. THE PRIMARY FOCUS FOR SEVERE
STORMS WILL BE ALONG THE COLD FRONT AND WITHIN THE WARM SECTOR
THROUGH TONIGHT.
…LA/MS TODAY TO AL/SRN GA/N FL OVERNIGHT…
A STRONGLY FORCED SQUALL LINE WILL CONTINUE TO CONSOLIDATE ALONG THE
COLD FRONT INTO WRN LA THROUGH THE MORNING…SE LA AND MS THIS
AFTERNOON…AND CENTRAL/SRN AL AND THE FL PANHANDLE TONIGHT. THERE
WILL BE A CONTINUED THREAT FOR MORE ISOLATED/PRE-FRONTAL SUPERCELLS
AND A COUPLE OF TORNADOES TODAY IN THE UNSTABLE WARM SECTOR WITH
STRONG VERTICAL SHEAR ACROSS LA /MLCAPE OF 1000-1500 J/KG AND
EFFECTIVE SRH AOA 400 M2 PER S2/. EMBEDDED SUPERCELL AND LEWP
STRUCTURES CAN BE EXPECTED DURING THE AFTERNOON INTO CENTRAL/SRN MS
AND SE LA AS THE FRONTAL SQUALL LINE OVERTAKES THE PRE-FRONTAL
CONVECTION. THEREAFTER FROM LATE AFTERNOON INTO TONIGHT…THE
PRIMARY SEVERE THREAT WILL BECOME DAMAGING WINDS WITH A RELATIVELY
LOW-TOPPED/STRONGLY FORCED SQUALL LINE. VERY STRONG FLOW /70 KT/
WITHIN A FEW THOUSAND FEET OF THE GROUND AND A LARGE PRESSURE
FALL/RISE COUPLET WITH THE FRONT SUGGEST THAT THE SQUALL LINE WILL
BE CAPABLE OF TRANSPORTING HIGH-MOMENTUM FLOW TO THE
GROUND…DESPITE RATHER WEAK INSTABILITY /MUCAPE OF ONLY A FEW
HUNDRED J PER KG/.
THE SQUALL LINE IS EXPECTED TO GRADUALLY WEAKEN EARLY FRIDAY ACROSS
GA/N FL AS THE PRIMARY SYNOPTIC WAVE AND FORCING FOR ASCENT MOVE NW
OF THE REGION…AND INSTABILITY REMAINS MARGINAL. STILL…FORECAST
HODOGRAPHS SUPPORT DAMAGING WIND AND POSSIBLE EMBEDDED/SHALLOW
ROTATING STORMS.
