MESO: Mesoscale Discussion 1781

ACUS11 KWNS 180053
SWOMCD
SPC MCD 180053
MSZ000-LAZ000-ARZ000-TXZ000-OKZ000-180300-

MESOSCALE DISCUSSION 1781
NWS STORM PREDICTION CENTER NORMAN OK
0753 PM CDT FRI AUG 17 2012

AREAS AFFECTED...CNTRL MS...SRN AR...NRN LA...FAR NERN TX...FAR SERN
OK

CONCERNING...SEVERE POTENTIAL...WATCH UNLIKELY

VALID 180053Z - 180300Z

PROBABILITY OF WATCH ISSUANCE...20 PERCENT

SUMMARY...ISOLATED THUNDERSTORMS WILL POSE A RISK FOR SVR HAIL/WIND
DURING THE NEXT FEW HOURS. THE ANTICIPATED SHORT DURATION AND
ISOLATED NATURE OF THE SVR THREAT SHOULD PRECLUDE WW ISSUANCE.

DISCUSSION...THUNDERSTORMS CONTINUE TO DEVELOP WITHIN A W-E-ORIENTED
BAROCLINIC ZONE DRAPED ACROSS THE ARKLATEX AND ARKLAMISS REGIONS.
MID-LEVEL LAPSE RATES OF 6.5-7 C/KM ATOP SFC DEWPOINTS IN THE LOWER
70S PER JACKSON MS/SHREVEPORT LA 00Z RAOBS ARE SUPPORTING MLCAPE OF
1500-2500 J/KG. AND...WITH MODEST HIGH-LEVEL FLOW...EFFECTIVE BULK
SHEAR MAGNITUDES OF 25-30 KT WILL CONTINUE SUPPORTING ORGANIZED
STORM STRUCTURES AND PERHAPS MARGINAL/TRANSIENT SUPERCELLS. THE
STRONGEST STORMS WILL BE CAPABLE OF PRODUCING SVR WIND/HAIL.
HOWEVER...WITH THE ONSET OF NOCTURNAL STABILIZATION...THE SVR THREAT
SHOULD BE RELATIVELY SHORT LIVED AS STORMS GRADUALLY TRANSITION SWD.
SVR COVERAGE SHOULD BE LIMITED BY THE LACK OF STRONGER FORCING FOR
ASCENT AND WEAKER INSTABILITY WITHIN CONVECTIVELY OVERTURNED AIR
FARTHER SOUTH.

..COHEN/THOMPSON.. 08/18/2012

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

ATTN...WFO...JAN...LZK...SHV...

LAT...LON 32478900 32338986 32519145 32739250 32789316 32959402
33249462 33579485 33859481 34139447 33949360 33789268
33579208 33419122 33179026 33038951 32908890 32478900

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