MESO: Mesoscale Discussion 0116

ACUS11 KWNS 172345
SWOMCD
SPC MCD 172344
ARZ000-MSZ000-LAZ000-TXZ000-OKZ000-180215-

MESOSCALE DISCUSSION 0116
NWS STORM PREDICTION CENTER NORMAN OK
0544 PM CST TUE FEB 17 2009

AREAS AFFECTED...SRN/CENTRAL AR AND ARKLATEX REGION -- PORTIONS NE
TX...NWRN LA...SWRN AR...EXTREME SERN OK.

CONCERNING...SEVERE POTENTIAL...WATCH POSSIBLE

VALID 172344Z - 180215Z

TSTMS ARE FCST TO DEVELOP AND INCREASE IN COVERAGE GRADUALLY THROUGH
EVENING -- SPREADING FROM SW-NE ACROSS ARKLATEX REGION TOWARD LOWER
MS VALLEY. MAIN CONCERN WILL BE HAIL.

SFC MESOANALYSIS INDICATES DIFFUSE/FRAGMENTED WARM FRONTAL ZONE
EVIDENT FROM S-CENTRAL OK SWD THEN EWD ACROSS CENTRAL/E-CENTRAL
TX...S OF TYR...TO CENTRAL LA. WARM FRONT SHOULD CONSOLIDATE
SOMEWHAT AND LIFT NEWD ACROSS MUCH OF E TX AND LA THROUGH 06Z.
MEANWHILE STG ELEVATED WAA REGIME IS MAINTAINED TO ITS NE ALONG
SLOPED FRONTAL/ISENTROPIC SFC...AND AMIDST STRENGTHENING/45-60 KT
LLJ. INCREASINGLY MOIST PARCELS -- EMANATING FROM COASTAL AREAS
WITH DEW POINTS UPPER 60S F AT SFC AND 10-13 DEG C AT 850 MB -- WILL
BE LIFTED TO LFC BENEATH MUCAPES BETWEEN 500-1000 J/KG. AS BUOYANCY
ALOFT STRENGTHENS/DEEPENS WITH TIME...SO WILL BOTH EFFECTIVE SHEAR
AND EFFECTIVE SRH -- 50-60 KT AND 200-300 J/KG RESPECTIVELY --
AVAILABLE TO THOSE ELEVATED INFLOW PARCELS. STORM ORGANIZATION
SHOULD INCREASE ACCORDINGLY...WITH MOST FAVORABLE LARGE HAIL
POTENTIAL FROM TSTMS THAT CAN MAINTAIN THEIR IDENTITY LONG ENOUGH TO
BUILD LOW-MIDDLE LEVEL MESOCYCLONES. ROBUST STABLE LAYER NEAR SFC
WILL BE MAINTAINED OVER DISCUSSION AREA THROUGH EVENING...WITHOUT
APPRECIABLE DRYING ABOVE...WHICH SHOULD MINIMIZE POTENTIAL FOR
ORGANIZED SVR WIND. HOWEVER...ISOLATED GUSTS APCHG SVR LEVELS
CANNOT BE RULED OUT FROM MOST INTENSE TSTMS -- ESPECIALLY OVER NE TX
WHERE PRE WARM-FRONTAL STABLE LAYER WILL BE SHALLOWEST.

..EDWARDS.. 02/17/2009

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

ATTN...WFO...MEG...JAN...LZK...SHV...TSA...FWD...

LAT...LON 31799375 31609449 31749536 32079558 33079566 34139523
34899415 35329215 35239107 34619067 34069089 33329171
32519259 31799375

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