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Mesoscale Discussion 1451 |
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MESOSCALE DISCUSSION 1451
NWS STORM PREDICTION CENTER NORMAN OK
0228 PM CDT THU JUN 30 2011
AREAS AFFECTED...PORTIONS OF SRN MS...ERN/CNTRL LA...FAR SRN
AR...FAR SWRN AL...
CONCERNING...SEVERE POTENTIAL...WATCH UNLIKELY
VALID 301928Z - 302200Z
A FEW STORMS COULD PRODUCE DMGG WIND GUSTS THIS AFTERNOON.
EARLY AFTERNOON MESOANALYSIS DEPICTS A STATIONARY FRONT STRETCHING
FROM JUST EAST OF EL DORADO AR TO NEAR VICKSBURG MS TO NEAR MOBILE
AL. FRONTAL CONVERGENCE COMBINED WITH SUFFICIENT DEEP-LAYER MOISTURE
-- I.E. PWAT VALUES BETWEEN 1.4 AND 1.7 INCHES PER 12Z OBSERVED
JACKSON...SHREVEPORT...AND SLIDELL SOUNDINGS -- AND AMPLE SFC
HEATING HAVE SUPPORTED THE DEVELOPMENT OF BUILDING CUMULUS AND
ISOLATED CONVECTION PARTICULARLY NEAR AND JUST SW OF THE FRONT. THE
AIR MASS SW OF THE FRONT HAS BECOME MODERATELY TO VERY
UNSTABLE...WITH MLCAPE VALUES IN EXCESS OF 3000 J/KG ACROSS PORTIONS
OF ERN LA AND SWRN MS...WHICH WILL FOSTER ADDITIONAL
DEVELOPMENT/INTENSIFICATION OF CONVECTION. WITH NELY LOW/MID-LEVEL
FLOW OF 15 TO 20 KT EVIDENT PER JACKSON/SHREVEPORT/SLIDELL VWP
DATA...PULSE CONVECTION WILL DRIFT SWWD WITHIN A WEAKLY SHEARED
ENVIRONMENT. ADDITIONAL CONVECTION COULD DEVELOP ALONG SEA BREEZE
CIRCULATIONS NEAR THE GULF COAST...WHICH MAY HAVE A TENDENCY TO
PROPAGATE INLAND. STEEP LOW-LEVEL LAPSE RATES SUPPORTIVE OF DCAPE
VALUES OF 1000 TO 1300 J/KG WILL SUPPORT INTENSE MICROBURSTS CAPABLE
OF PRODUCING DMGG WIND GUSTS. THIS THREAT MAY BE EXACERBATED BY DRY
AIR ENTRAINMENT AND EVAPORATIVE COOLING PROCESSES OWING TO THE
PRESENCE OF RELATIVELY DRY AIR ABOVE THE 780-MB LEVEL EVIDENT IN THE
12Z OBSERVED SOUNDINGS.
..COHEN.. 06/30/2011
ATTN...WFO...MOB...JAN...LIX...LZK...LCH...SHV...
LAT...LON 32739302 33279267 33299220 33099184 32439118 31759045
31048884 30748817 30558774 30278788 30278855 29938909
29388964 29219026 29239088 29369145 30049257 31099300
32739302
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