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Mesoscale Discussion 15 |
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MESOSCALE DISCUSSION 0015
NWS STORM PREDICTION CENTER NORMAN OK
0318 AM CST SAT JAN 11 2014
AREAS AFFECTED...SERN LA/SERN MS/SERN AL/WRN FL PANHANDLE
CONCERNING...SEVERE POTENTIAL...WATCH POSSIBLE
VALID 110918Z - 111115Z
PROBABILITY OF WATCH ISSUANCE...40 PERCENT
SUMMARY...INCREASING CONVECTION WITHIN A MARGINALLY UNSTABLE BUT
STRONGLY SHEARED PRE-FRONTAL ENVIRONMENT SUGGESTS ISOLATED SEVERE
RISK. WHILE A WW IS NOT IMMINENT...ISSUANCE MAY BE REQUIRED OVER
THE NEXT COUPLE OF HOURS AS CONDITIONS EVOLVE.
DISCUSSION...LATEST SURFACE ANALYSIS SHOWS A COLD FRONT -- NOW JUST
E OF THE MID MS VALLEY -- CONTINUING TO MARCH STEADILY EWD...WHILE
SLY BOUNDARY-LAYER FLOW CONTINUES ADVECTING LOW TO MID 60S DEWPOINTS
NWD ACROSS THE LOWER MS VALLEY/CENTRAL GULF COASTAL REGION.
LARGE-SCALE ASCENT -- ASSOCIATED WITH AN ADVANCING UPPER TROUGH --
CONTINUES TO OVERSPREAD THE REGION...AND IS LIKELY CONTRIBUTING TO A
MODEST INCREASE IN CONVECTION NOTED ACROSS SRN LA OVER THE PAST HOUR
OR SO. THOUGH INSTABILITY REMAINS MARGINAL ACROSS THIS
AREA...MODEST/ADDITIONAL LOW-LEVEL MOISTENING IN CONJUNCTION WITH
SUBTLE COOLING AT MID LEVELS WITH TIME SUGGEST POTENTIAL FOR SOME
INCREASE IN CAPE. AS A RESULT...SOME ADDITIONAL CONVECTIVE
STRENGTHENING/ORGANIZATION IS POSSIBLE OVER THE NEXT FEW HOURS --
GIVEN THAT BACKGROUND DEEP-LAYER SHEAR REMAINS LIKEWISE SUPPORTIVE
OF ORGANIZED UPDRAFTS.
ASSUMING SOME DEGREE OF LOCAL UPDRAFT INTENSIFICATION/LONGEVITY
INDEED OCCURS...OBSERVED 0-1 KM SHEAR AROUND 30 KT SUGGESTS THAT A
CONCURRENT INCREASE IN TORNADO POTENTIAL IS POSSIBLE. THIS RISK --
ALONG WITH POTENTIAL FOR LOCALLY GUSTY/DAMAGING WINDS WITH STRONGER
STORMS -- MAY EVENTUALLY NECESSITATE WW ISSUANCE. WE WILL CONTINUE
TO MONITOR AIRMASS EVOLUTION AND CONVECTIVE TRENDS FOR SIGNS OF
INCREASING SHORT-TERM SEVERE RISK.
..GOSS/MEAD.. 01/11/2014
ATTN...WFO...TAE...BMX...MOB...JAN...LIX...LCH...
LAT...LON 29179162 29699167 30639078 31748925 32788758 32748628
31318605 30138640 29938866 29708893 29078892 28788930
28948983 28879093 29179162
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