MESO: Mesoscale Discussion 0397

ACUS11 KWNS 311729
SWOMCD
SPC MCD 311729
TNZ000-GAZ000-ALZ000-MSZ000-MOZ000-ARZ000-311900-

MESOSCALE DISCUSSION 0397
NWS STORM PREDICTION CENTER NORMAN OK
1229 PM CDT SAT MAR 31 2012

AREAS AFFECTED...WRN/MIDDLE TN...NRN AL/MS...ERN AR

CONCERNING...SEVERE POTENTIAL...WATCH LIKELY

VALID 311729Z - 311900Z

THUNDERSTORM DEVELOPMENT IS PROBABLE ACROSS WRN/MIDDLE TN BY
18-19Z...WITH STORMS INCREASING IN COVERAGE OVER NRN AL/MS AND
PERHAPS ERN AR DURING THE REMAINDER OF THE AFTERNOON. LARGE HAIL AND
DAMAGING WINDS WILL BE POSSIBLE WITH THIS ACTIVITY...AND A WW WILL
LIKELY BE NEEDED OVER PORTIONS OF THE REGION.

MIDDAY WV IMAGERY SHOWS AN UPPER DISTURBANCE MOVING SEWD TOWARD THE
LWR/MID OH VALLEY...WITH A POSITIVE TILT TROUGH AXIS EXTENDING SWWD
INTO ERN TX. AT THE SURFACE...AN AREA OF LOW PRESSURE IS EXITING THE
MID-ATLANTIC...WITH A COLD FRONT TRAILING WWD INTO TN...WHICH
TRANSITIONS INTO A WARM FRONT EXTENDING NWD INTO THE LWR MO VALLEY.
VISIBLE SATELLITE IMAGERY SHOWS MOSTLY CLEAR SKIES ALONG THE TN
PORTION OF THE COLD FRONT...WHICH IS ALLOWING SURFACE TEMPERATURES
TO WARM INTO THE MID TO UPR 70S ACROSS THE REGION. THIS
HEATING/DESTABILIZATION COMBINED WITH LOW TO MID 60S DEWPOINTS AND
MIDLEVEL LAPSE RATES IN EXCESS OF 7.5 C/KM WILL FAVOR STRONG
INSTABILITY THIS AFTERNOON...WITH MLCAPE VALUES NEAR 2500 J/KG.
GIVEN THE PRESENCE OF WEAK LOW-LEVEL CONVERGENCE ALONG THE FRONT AND
POSSIBLE LARGE-SCALE FORCING FOR ASCENT WITH THE UPPER
TROUGH...THUNDERSTORM INITIATION APPEARS PROBABLE OVER WRN/MIDDLE TN
DURING THE NEXT HR OR TWO. STORMS ARE THEN FORECAST TO SPREAD S INTO
PORTIONS OF NRN AL/MS DURING THE REMAINDER OF THE AFTERNOON. THOUGH
LOW-LEVEL FLOW IS NOT PARTICULARLY STRONG...MIDLEVEL NWLY WINDS FROM
30-40 KT WILL YIELD SUFFICIENT DEEP-LAYER VERTICAL WIND SHEAR FOR
ORGANIZED MULTICELL CLUSTERS. LARGE BUOYANCY AND STEEP LAPSE RATES
WILL FAVOR SVR HAIL...IN ADDITION TO DAMAGING DOWNBURST WINDS.

..GARNER.. 03/31/2012

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

ATTN...WFO...MRX...FFC...OHX...BMX...HUN...MEG...JAN...LZK...

LAT...LON 36169026 36578560 34938530 34008681 33669136 34979180
36169026

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