SWODY1
SPC AC 230556
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1256 AM CDT TUE OCT 23 2007
VALID 231200Z - 241200Z
..NO SVR TSTM AREAS FORECAST...
..CENTRAL GULF COAST...
00Z NAM-WRF/GFS AND 12Z ECMWF/UKMET ARE IN FAIRLY GOOD AGREEMENT
THROUGH DAY 1 PERIOD WITH SRN EXTENT OF CENTRAL U.S. UPPER TROUGH
CONTINUING TO EVOLVE INTO A CUT-OFF LOW AS IT TRACKS SEWD AND STALLS
OVER THE LOWER MS VALLEY. PORTION OF COLD FRONT LOCATED EAST OF THE
UPPER LOW IS EXPECTED TO TRACK EWD ACROSS AL AND THE FL PANHANDLE
TODAY...AND SHOULD REACH GA TO THE NWRN FL PENINSULA BY 12Z
WEDNESDAY.
CURRENT QLCS SHOULD BE LOCATED ACROSS PARTS OF ERN AL TO THE WRN FL
PANHANDLE AT 12Z TODAY...WITH POTENTIAL FOR A FEW EMBEDDED ROTATING
UPDRAFTS ALONG LLJ AXIS WHERE LOW LEVEL SHEAR WILL BE MAXIMIZED.
UPPER FORCING AHEAD OF THE CLOSED LOW IS EXPECTED TO REMAIN
SUFFICIENT INTO THE EARLY AFTERNOON FOR A CONTINUATION OF ONGOING
TSTMS EWD TOWARD WRN GA AND THROUGH THE FL PANHANDLE. MODELS
SUGGEST SWLY MID LEVEL FLOW OF AT LEAST 50 KT ACROSS AL TODAY THAT
WILL SUPPORT EFFECTIVE BULK SHEAR SUFFICIENT FOR ORGANIZED STORMS.
HOWEVER...THERE IS UNCERTAINTY WITH THE POTENTIAL SEVERE THREAT
TODAY SINCE THE LLJ IS EXPECTED TO WEAKEN THROUGH THE PERIOD AS
UPPER FORCING/DEEP LAYER SHEAR BEGIN TO LAG THE COLD FRONT AS THE
CLOSED LOW STALLS OVER THE LOWER MS VALLEY. ANOTHER LIMITING FACTOR
FOR SEVERE IS THE EXTENT TO WHICH THE EXTENSIVE CLOUDINESS ATTENDANT
WITH CURRENT AL CONVECTIVE SYSTEM LIMITS WARM SECTOR
DESTABILIZATION. DESPITE WEAK LAPSE RATES/INSTABILITY...VERY MOIST
BOUNDARY LAYER CONDITIONS AND AMPLE DEEP LAYER SHEAR DO WARRANT AT
LEAST LOW PROBABILITIES FOR ISOLATED DAMAGING WIND GUSTS OR PERHAPS
A TORNADO DURING THE FIRST HALF OF THE FORECAST PERIOD.
.PETERS/CROSBIE.. 10/23/2007
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