MESO: Mesoscale Discussion 2099

ACUS11 KWNS 041934
SWOMCD
SPC MCD 041934
SCZ000-GAZ000-FLZ000-042200-

MESOSCALE DISCUSSION 2099
NWS STORM PREDICTION CENTER NORMAN OK
0134 PM CST SUN NOV 04 2012

AREAS AFFECTED...PORTIONS ERN/SRN GA...CENTRAL/SRN FL
PANHANDLE...ERN/SRN SC.

CONCERNING...SEVERE POTENTIAL...WATCH UNLIKELY

VALID 041934Z - 042200Z

PROBABILITY OF WATCH ISSUANCE...20 PERCENT

SUMMARY...TSTM COVERAGE IS FCST TO INCREASE GRADUALLY ACROSS
DISCUSSION AREA THROUGH REMAINDER AFTERNOON...AS PEAK PERIOD OF
DIURNAL BOUNDARY-LAYER INSTABILITY BECOMES INCREASINGLY JUXTAPOSED
WITH FAVORABLE DEEP-LAYER LIFT. A FEW STG-SVR TSTMS WITH HAIL AND
DAMAGING GUSTS ARE EXPECTED.

DISCUSSION...SURFACE MESOANALYSIS SHOWS FRONTAL-WAVE LOWS OVER OUTER
BANKS AND WRN/UPSTATE SC...CONNECTED BY WAVY FRONTAL ZONE THAT
EXTENDS ACROSS CENTRAL/SRN SC AND SERN NC. FARTHER W...FRONTAL ZONE
IS EVIDENT IN TWO SEGMENTS...NRN ONE HAVING STRONGER BAROCLINICITY
BUT SRN ONE BEING MOST INFLUENTIAL ON CONVECTIVE POTENTIAL. SRN
FRONTAL SEGMENT WAS DRAWN FROM CENTRAL SC SWWD OVER SWRN
GA...EXTREME SERN AL AND WRN PORTIONS FL PANHANDLE. CAROLINAS FRONT
AND LEADING GA/AL/FL BOUNDARY ARE EXPECTED TO CONTINUE MOVING SLOWLY
SEWD THROUGH REMAINDER AFTERNOON. VIS SATELLITE ANIMATIONS DEPICT
CONVECTION GRADUALLY DEEPENING OVER WARM SECTOR -- PRIMARILY
CORRESPONDING TO SERIES OF NARROW/PARALLEL CORRIDORS WHERE
HORIZONTAL BOUNDARY-LAYER ROLLS INITIATE TOWERS AMIDST NEGLIGIBLE
MLCINH. VEERED PREFRONTAL SFC FLOW WILL CONTINUE TO LIMIT MASS
CONVERGENCE...SO TSTM GROWTH/EXPANSION SHOULD REMAIN GRADUAL.
DEEPEST DEVELOPMENT SO FAR HAS BEEN WHERE SRN FRONTAL ZONE IMPINGES
ON THOSE ROLLS OVER ERN/SRN GA...ROUGHLY FROM ABY AREA TO EMANUEL
COUNTY. THIS TREND SHOULD CONTINUE WITH SOME ENEWD AND SWWD
EXTENSION OF DEVELOPMENT...RESULTING IN SCATTERED TSTMS IN PRIMARY
CONVECTIVE BAND...AND ISOLATED COVERAGE TO ITS E.

PRIMARY TSTM MODE SHOULD BE MULTICELLULAR WITH CLUSTERED TO
QUASI-LINEAR STRUCTURES...THOUGH BRIEF/WEAK SUPERCELLS ARE POSSIBLE.
EXISTING 25-35 KT EFFECTIVE SHEAR MAGNITUDES OVER REGION MAY
INCREASE SLIGHTLY AS MID-UPPER LEVEL TROUGH APCHS FROM CENTRAL GULF
COAST/MS DELTA REGION. PRECONVECTIVE/WARM-SECTOR MLCAPE SHOULD
INCREASE INTO 500-1000 J/KG RANGE. MAIN FACTORS LIMITING GREATER
CAPE ARE LACK OF ROBUST MIDLEVEL LAPSE RATES...AND SFC MIXING/DRYING
THAT HAS LOWERED DEW POINTS INTO UPPER 40S TO MID 50S F RANGE IN
IMMEDIATE PREFRONTAL CORRIDOR. HOWEVER...FCST SOUNDINGS INDICATE
THAT PROCESS ALSO HAS INCREASED DCAPE AND YIELDED SUBCLOUD
INVERTED-V THERMODYNAMIC PROFILES MORE SUITABLE TO MAINTAIN STG-SVR
DOWNDRAFT GUSTS GENERATED ALOFT.

..EDWARDS/HART.. 11/04/2012

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

ATTN...WFO...ILM...CHS...CAE...JAX...FFC...TAE...

LAT...LON 33807864 33537898 33137921 31958088 30968145 30558315
29578498 29698518 30438572 31678373 32668233 33408158
33968050 33807864

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