Sunday, November 22, 2009

DAY1SVR: Day 1 Convective Outlook

ACUS01 KWNS 221922
SWODY1
SPC AC 221920

DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0120 PM CST SUN NOV 22 2009

VALID 222000Z - 231200Z

...NO SVR TSTM AREAS FORECAST...

...20Z OUTLOOK UPDATE...

EARLIER LOW SEVERE POTENTIAL ACROSS PARTS OF NORTHERN FLORIDA/
FLORIDA PENINSULA APPEARS TO BE IN THE PROCESS OF DIMINISHING AS A
WEAKENING MID-LEVEL CIRCULATION/TROUGH CONTINUES TO LIFT TOWARD THE
TENNESSEE VALLEY/SOUTHERN APPALACHIANS. A TENDENCY TOWARD
WEAKENING/VEERING OF LOW-LEVEL WIND FIELDS NOW APPEARS UNDERWAY...
AND A SUBSIDENT MID-LEVEL REGIME MAY INHIBIT THE RISK FOR ADDITIONAL
STORMS TO THE NORTH OF ONGOING CONVECTIVE BAND STILL TO THE
NORTH/WEST OF A TAMPA/DAYTONA BEACH LINE. THIS BAND APPEARS FOCUSED
ALONG A LOWER/MID TROPOSPHERIC CONFLUENCE ZONE WHICH MAY ONLY SLOWLY
ADVANCE INTO/THROUGH THE TAMPA/ST. PETERSBURG AND ORLANDO/MELBOURNE
AREAS LATE THIS AFTERNOON AND EVENING...AS AN UPSTREAM SUBTROPICAL
IMPULSE ACCELERATES ACROSS THE EASTERN GULF OF MEXICO.

OTHERWISE...FORCING AHEAD OF THE FRONTAL WAVE NOW BEGINNING TO LIFT
UP THE SOUTH ATLANTIC COAST IS EXPECTED TO PROVIDE THE FOCUS FOR ANY
OTHER CONVECTIVE DEVELOPMENT OF CONCERN. BEYOND THE NEXT HOUR OR
SO...ACTIVITY WILL PROBABLY BE CONFINED TO THE ELEVATED WARM
ADVECTION REGIME ABOVE THE FRONTAL INVERSION OVER INLAND AREAS
NORTHEAST OF COASTAL GEORGIA. DESPITE THE WEAK CAPE...THERMODYNAMIC
PROFILES MAY BE COOL ENOUGH TO SUPPORT THE RISK FOR SMALL HAIL IN
THE MOST VIGOROUS UPDRAFTS.

..KERR.. 11/22/2009

.PREV DISCUSSION... /ISSUED 1010 AM CST SUN NOV 22 2009/

...NRN/CENTRAL FL PENINSULA AND EXTREME SERN GA...
UPPER LOW OVER AL IS FORECAST TO WEAKEN AND LIFT NEWD INTO THE OH
VALLEY TONIGHT...IN RESPONSE TO UPPER TROUGH SHIFTING EWD FROM THE
ROCKIES INTO THE MS VALLY. AT THE SURFACE...WEAK AREA OF LOW
PRESSURE STRETCHED FROM SRN LA EWD INTO THE WRN FL PANHANDLE.
OCCLUDED/WARM FRONT WAS LOCATED WITHIN THIS AREA OF LOW PRESSURE
FROM SERN LA INTO FAR NRN FL...WITH A WEAK COLD FRONT EXTENDING N-S
IN THE NERN GULF...WEST OF THE FL PENINSULA. AT MID MORNING...
STRONG THUNDERSTORMS WERE LOCATED ABOUT 60 NW OF PIE. WHILE MODERATE
INSTABILITY PERSISTED OVER THE NERN GULF WATERS...INSTABILITY WAS
WEAK OVER INLAND AREAS. THIS HAS RESULTED IN STORMS TO BACKBUILD AND
REMAIN OFFSHORE. THIS TREND IS EXPECTED TO CONTINUE FOR THE NEXT FEW
HOURS. THICKER CLOUDS FROM CONVECTION ARE LIKELY TO RESTRICT
WARMING/INSTABILITY ACROSS PORTIONS OF NRN FL. HOWEVER...AS
TEMPERATURES WARM INTO THE 80S NEAR THE SRN EDGE OF THE THICKER
CLOUDS...SUFFICIENT INSTABILITY MAY EXIST FOR STORMS TO MOVE/DEVELOP
INLAND THIS AFTERNOON. WHILE DEEP LAYER SHEAR MAY SUPPORT A SEVERE
STORM OR TWO...LOW LEVEL MASS CONVERGENCE AND UPPER FORCING SHIFTING
NWD AWAY FROM THIS REGION SHOULD KEEP ANY SEVERE THREAT ISOLATED.

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