Tuesday, November 2, 2010

MESO: Mesoscale Discussion 2035

ACUS11 KWNS 021657
SWOMCD
SPC MCD 021657
ALZ000-MSZ000-LAZ000-021930-

MESOSCALE DISCUSSION 2035
NWS STORM PREDICTION CENTER NORMAN OK
1157 AM CDT TUE NOV 02 2010

AREAS AFFECTED...PORTIONS LOWER MS DELTA REGION -- SERN LA...EXTREME
SRN MS...COASTAL AL.

CONCERNING...SEVERE POTENTIAL...WATCH UNLIKELY

VALID 021657Z - 021930Z

SVR POTENTIAL FCST TO INCREASE SOMEWHAT DURING NEXT FEW HOURS...IN
FORM OF MRGL CONVECTIVE WIND THREAT AND POSSIBILITY OF BRIEF/WEAK
TORNADO.

PRIMARY CONVECTIVE BAND IS EVIDENT FROM ST JAMES PARISH SWD ACROSS
TERREBONNE PARISH AND OVER GULF...GENERALLY TRANSLATING EWD 10-15 KT
WITH LOCAL ACCELERATIONS NEAR SMALL BOWING SEGMENTS. BROAD AND/OR
WEAK CIRCULATIONS ALOFT HAVE BEEN EVIDENT SO FAR IN RADAR VELOCITY
DATA. A FEW TSTMS ALSO HAVE FORMED FARTHER NE...EMBEDDED WITHIN
BROADER AREA OF PRECIP OVER WASHINGTON/ST TAMMANY PARISHES. SFC
MESOANALYSIS SHOWS WARM FRONT EXTENDING ESEWD FROM ST TAMMANY PARISH
ACROSS MOUTH OF MOBILE BAY...DRIFTING NWD. WEAK MESOLOW IS EVIDENT
ALONG MAIN TSTM BAND OVER LA COAST...THOUGH PRESSURE CHANGES AHEAD
OF IT ARE RATHER WEAK. AS NOTED IN 1630Z DAY-1 OUTLOOK...OBSERVED
VERTICAL SHEAR IS NOT PARTICULARLY STG...WITH 0-3 KM AGL SRH
GENERALLY NEAR 100 J/KG PER LIX VWP. THIS IS LOWER THAN RECENT RUC
FCST SOUNDINGS FOR THAT LOCATION...ALTHOUGH AREAS SLIGHTLY FARTHER W
NEAR MAIN CONVECTIVE BAND AND N NEAR WARM FRONT MAY EXPERIENCE
ENHANCED INFLOW AND HODOGRAPH SIZE NOT SAMPLED BY OBSERVATIONAL
PLATFORMS.

MEANWHILE...VIS IMAGERY INDICATES SUSTAINED CLOUD BREAKS OVER
NEAR-COASTAL AREAS OF MS/AL...PERMITTING DIABATIC SFC HEATING AND
EFFECTIVELY SHUNTING SFC WARM FRONT INLAND. LOW-LEVEL MOISTURE
BECOMES WEAKER WITH EWD EXTENT ACROSS AL INTO FL PANHANDLE. THIS
TENDENCY SHOULD BE MAINTAINED THROUGH AT LEAST 21Z AS RELATIVELY
BACKED SFC WINDS MAINTAIN TRAJECTORIES FROM LOWER-THETAE AIR MASS N
OF WARM FRONT. FRONT ITSELF SHOULD SHIFT SLIGHTLY INLAND ACROSS AL
ALSO. MODIFIED FCST SOUNDINGS SUGGEST MLCAPE NEAR 500 J/KG ALONG
AND S OF WARM FRONT THROUGH AFTERNOON.

..EDWARDS.. 11/02/2010

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

ATTN...WFO...MOB...JAN...LIX...

LAT...LON 29099082 29749070 30179093 30439033 31068989 31168956
31108893 30848859 30588830 30248762 30228831 30218841
30238876 30198894 30188916 30048881 29858879 29608896
29468921 29398932 29348916 29208898 29068905 29048913
28988912 29108924 28918935 28928945 29148940 29258962
29328986 29089014 29029045 29099060 29099082

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