Tuesday, October 27, 2009

DAY1SVR: Day 1 Convective Outlook

ACUS01 KWNS 271244
SWODY1
SPC AC 271243

DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0743 AM CDT TUE OCT 27 2009

VALID 271300Z - 281200Z

...THERE IS A SLGT RISK OF SVR TSTMS OVER PARTS OF THE FL
PANHANDLE...NW FL...AND SRN GA...

...SYNOPSIS...
POTENT SHORTWAVE TROUGH NOW OVER THE RED RVR VLY HAS ASSUMED A BIT
OF A NEGATIVE TILT. THE TROUGH SHOULD ACCELERATE ENE INTO WRN TN BY
THIS EVE BEFORE CONTINUING INTO WRN MD/PA EARLY WED. AT THE SAME
TIME...POWERFUL JET STREAK NOW CROSSING THE NRN SIERRA EXPECTED TO
EVOLVE INTO A DEEP CLOSED LOW OVER SRN UT/NRN AZ.

AT LWR LVLS...WEAK SFC WAVE AND INVERTED TROUGH ASSOCIATED WITH RED
RVR UPR SYSTEM SHOULD REDEVELOP ENE ACROSS THE TN/LWR OH VLYS
TODAY/TONIGHT. HOWEVER...FRONT EXTENDING E/NE FROM THE WAVE LIKELY
WILL SHOW MORE LIMITED NWD MOTION AS SHALLOW WEDGE AIR MASS REMAINS
ALONG AND JUST S/E OF THE SRN APPALACHIANS.

...FL PANHANDLE INTO NW FL/SRN GA...
AREA VWP PLOT AND PATTERN OF SHOWER/STORM DEVELOPMENT OVER THE NERN
GULF OF MEXICO SUGGEST PRESENCE OF A N/S 850 MB CONFLUENCE ZONE
LOCATED ROUGHLY 250 MILES E OF THE COLD FRONT TRAILING SSW FROM N
CNTRL GULF SFC WAVE. THE CONFLUENCE ZONE...AND ITS INTERSECTION
WITH WARM/STNRY FRONT INVOF THE FL PANHANDLE... SHOULD CONTINUE TO
BE A SOURCE OF ENHANCED CONVECTIVE DEVELOPMENT THROUGH THE DAY.

NW FL/SRN GA AND THE FL PANHANDLE WILL REMAIN WELL REMOVED FROM
STRONGEST FORCING FOR ASCENT ASSOCIATED WITH RED RVR VLY UPR SYSTEM.
BUT GLANCING INFLUENCE OF THAT DISTURBANCE...AND ASSOCIATED VEERING
OF DEEP FLOW OVER THE CNTRL GULF CST MAY...AT LEAST BETWEEN NOW AND
MID AFTN...ENHANCE THE POTENTIAL FOR STORM DEVELOPMENT ALONG THE
CONFLUENCE ZONE AND FRONT BEFORE UPR SYSTEM MOVES FARTHER N INTO THE
TN VLY.

WITH PW REMAINING AOA 2 INCHES AND WIND PROFILES EXHIBITING A 30-40
KT SLY LLJ BENEATH 40-50 KT SWLY MID LVL FLOW...WAA SETUP COULD
YIELD SCTD SUPERCELLS WITH LOW LVL ROTATION/ISOLD TORNADOES.
ALTHOUGH WEAK LOW LVL LAPSE RATES AND LIMITED UPR LVL FORCING SHOULD
MITIGATE OVERALL SVR THREAT...POTENTIAL FOR AT LEAST A FEW SUSTAINED
STORMS AND TORNADOES APPEARS GREAT ENOUGH TO WARRANT A SLIGHT RISK
FOR LATER THIS MORNING INTO THE AFTN.

...PARTS OF CENTRAL/NRN FL PENINSULA INTO SERN GA...
SOMEWHAT GREATER SFC HEATING WILL OCCUR OVER THE FL PENINSULA...S
AND E OF FRONT/CONFLUENCE ZONE AFFECTING THE NW PART OF THE STATE.
AT THE SAME TIME...HOWEVER...LOW TO MID LVL SHEAR WILL BE
WEAKER...WITH ONLY MODEST VEERING IN THE LWR LVLS. NEVERTHELESS
...SCTD DIURNAL STORMS SHOULD FORM OVER CNTRL AND NRN PARTS OF THE
PENINSULA. THESE SHOULD MOVE/DEVELOP MAINLY ENE TOWARD THE FL E CST
AND SE GA...AND MAY POSE A THREAT FOR LOCALLY DMGG WIND AND PERHAPS
A BRIEF TORNADO BEFORE WEAKENING EARLY THIS EVE.

..CORFIDI/GRAMS.. 10/27/2009

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