Thursday, December 22, 2011

MESO: Mesoscale Discussion 2388

ACUS11 KWNS 221350
SWOMCD
SPC MCD 221350
ALZ000-MSZ000-LAZ000-221445-

MESOSCALE DISCUSSION 2388
NWS STORM PREDICTION CENTER NORMAN OK
0750 AM CST THU DEC 22 2011

AREAS AFFECTED...ERN LA AND SRN/CENTRAL MS

CONCERNING...TORNADO WATCH 898...

VALID 221350Z - 221445Z

THE SEVERE WEATHER THREAT FOR TORNADO WATCH 898 CONTINUES.

13Z SURFACE ANALYSIS SHOWS AN ELONGATED AREA OF LOW PRESSURE
EXTENDING FROM E CENTRAL LA /45 WNW BTR/ INTO SRN MS /30 SSE JAN/
WITH THE WARM FRONT STRETCHING NEWD THROUGH CENTRAL AL TO NRN GA.
SLY LOW LEVEL FLOW S OF THIS FRONT IS CONTINUING TO DESTABILIZE THE
WARM SECTOR DESPITE WEAK LAPSE RATES WITH MUCAPE OF 500-1000 J/KG.
WATER VAPOR IMAGERY SUGGESTS A LEAD IMPULSE MAY BE TRACKING NEWD
ACROSS THE LOWER MS VALLEY ATTM AND SUPPORTING THE CONVECTIVE
CLUSTER OVER WEST CENTRAL/CENTRAL MS AND SWD EXTENDING WIND SHIFT.
MEANWHILE...THE IMMEDIATELY UPSTREAM SHORTWAVE TROUGH IS BECOMING
NEGATIVELY TILTED AS IT TRACKS INTO E TX. INCREASING LARGE SCALE
ASCENT AHEAD OF THIS LATTER TROUGH WILL FURTHER ENHANCE THE
DEVELOPMENT OF TSTMS ALONG THE LEAD WIND SHIFT AND DISCRETE STORMS
WITHIN THE WARM SECTOR.

ALTHOUGH LOW LEVEL WINDS OVER CENTRAL MS ARE CALM TO NLY...DEEP
LAYER WIND PROFILES SUGGEST THE RELATIVELY COOLER SURFACE AIR MASS
IS NOT VERY DEEP N OF THE SURFACE LOW/WARM FRONT...WITH SLY WINDS
JUST OFF THE SURFACE...INCREASING AND VEERING TO SWLY WITH HEIGHT.
A FEW DEGREE INCREASE OF SURFACE TEMPERATURE/DEW POINT IN THIS TYPE
OF ENVIRONMENT /STRONGLY SHEARED THROUGH A DEEP LAYER AND LOWER
LEVELS/ WILL SUPPORT AN ORGANIZED STORM PRODUCING DAMAGING WINDS
AND/OR AN ISOLATED TORNADO.

..PETERS.. 12/22/2011

...PLEASE SEE WWW.SPC.NOAA.GOV FOR GRAPHIC PRODUCT...

ATTN...WFO...BMX...MOB...MEG...JAN...LIX...LCH...

LAT...LON 29479253 31179157 31799078 32489057 33458953 33678940
33778851 33568816 31848850 31138914 30158965 29208999
28689023 28619093 29009194 29269257 29479253

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