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MESOSCALE DISCUSSION 0796
NWS STORM PREDICTION CENTER NORMAN OK
0246 PM CDT MON MAY 11 2009
AREAS AFFECTED...EXTREME SRN SC...SERN GA...ERN FL PENINSULA
CONCERNING...SEVERE POTENTIAL...WATCH UNLIKELY
VALID 111946Z - 112045Z
THE THREAT FOR ISOLATED SEVERE WIND GUSTS EXISTS DURING THE
AFTERNOON OVER PORTIONS OF THE ERN AND SRN FL PENINSULA...AND
EXTREME SRN SC INTO SERN GA. THE MARGINAL NATURE OF THE THREAT IS
EXPECTED TO PRECLUDE A WW.
SUBJECTIVE SURFACE ANALYSIS INDICATES SEA BREEZE BOUNDARIES OVER THE
WRN AND ERN FL PENINSULA...WITH STRONGEST LOW LEVEL CONVERGENCE
OCCURRING BETWEEN THESE TWO BOUNDARIES OVER CENTRAL PORTIONS OF THE
PENINSULA. ADDITIONAL REGION OF SURFACE CONVERGENCE EXISTS OVER SERN
GA INTO EXTREME SRN SC ALONG SYNOPTIC COLD FRONT. RECENT VISIBLE
SATELLITE IMAGERY AND LIGHTNING DATA INDICATE THUNDERSTORM
INITIATION TAKING PLACE WITHIN THESE CONVERGENCE ZONES...MAINLY
ALONG THE WRN PERIPHERY OF AIRMASS CHARACTERIZED BY UPPER 60S TO LOW
70S DEWPOINTS. THIS MOISTURE COMBINED WITH TEMPERATURES RISING
THROUGH THE 80S IS AIDING IN THE DEVELOPMENT OF A MODERATE TO VERY
UNSTABLE ATMOSPHERE...WITH RUC MLCAPE VALUES UP TO 2500 J/KG.
VERTICAL WIND SHEAR PROFILES ARE FORECAST TO REMAIN RELATIVELY WEAK
THROUGH THE AFTERNOON...FAVORING MULTICELL THUNDERSTORMS THAT WILL
REMAIN FOCUSED ALONG LOW LEVEL BOUNDARIES AND STORM SCALE OUTFLOW
INTERACTIONS. DUE TO THE WARM/MOIST BOUNDARY LAYER AIRMASS OVER
LAYED BY A DEEP LAYER OF DRY MID LEVEL AIR...LARGE THETA-E
DIFFERENCE /AOA 30 K/ WILL EXIST...FAVORING ISOLATED DAMAGING WIND
GUSTS AND PERHAPS MARGINALLY SEVERE HAIL WITH THE STRONGER UPDRAFT
CORES.
..GARNER.. 05/11/2009
ATTN...WFO...CHS...MFL...MLB...TBW...JAX...FFC...
LAT...LON 27058023 26548033 26408078 26498124 26778154 27048160
28898166 32128256 32718210 32798112 32448050 32018085
31098138 29958131 27788039 27058023
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