SWODY1
SPC AC 211945
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0145 PM CST SAT NOV 21 2009
VALID 212000Z - 221200Z
...NO SVR TSTM AREAS FORECAST...
...SERN LA...
EARLY AFTERNOON SURFACE OBSERVATIONS/VISIBLE SATELLITE IMAGERY
INDICATED SOME BREAKS IN THE CLOUD COVER OVER SERN LA...BOOSTING
SURFACE TEMPERATURES. HOWEVER...ENELY SURFACE TRAJECTORIES ARE
MAINTAINING MODEST LOW LEVEL MOISTURE /SURFACE DEWPOINTS LOWER-MID
50S/ OVER INLAND LOCATIONS. SURFACE ANALYSIS SHOWED AN OCCLUDED LOW
PRESSURE AREA HAS REMAINED OFFSHORE...THUS FAR...BUT IS EXPECTED TO
MOVE ACROSS SERN LA THIS FORECAST PERIOD. REGIONAL RADARS INDICATED
A COUPLE OF STRONGER STORMS HAD FORMED SINCE THIS MORNING IN THE
VICINITY OF THE OCCLUDED LOW...BUT WEAKENED ONCE THEY TRACKED NWD
INTO A MORE STABLE BOUNDARY LAYER.
ADDITIONAL STORMS WERE LOCATED OVER THE CENTRAL GULF WITHIN THE WARM
SECTOR. ALTHOUGH THE OCCLUDED LOW SHOULD MOVE OVER SERN LA...
EXTENSIVE CLOUDS/PRECIPITATION LOCATED OVER THE NORTH CENTRAL GULF
/ALONG AND E OF THE MS DELTA REGION/ SHOULD MAINTAIN A MORE STABLE
AIR MASS OVER THIS AREA...AND THUS PRECLUDE THE TRIPLE POINT AND
WARM SECTOR FROM MOVING VERY FAR NWD. THERE ARE NO CHANGES TO THE
SEVERE WEATHER PROBABILITIES WITH THIS OUTLOOK ISSUANCE...BUT THE
GENERAL TSTM LINE HAS BEEN SHIFTED N/NWWD ACROSS SRN/SERN LA TO
ACCOUNT FOR TRENDS OF ELEVATED STORMS TRACKING INLAND IN ADVANCE OF
THE OCCLUSION.
..PETERS.. 11/21/2009
.PREV DISCUSSION... /ISSUED 1003 AM CST SAT NOV 21 2009/
......SERN LA...
AS UPPER TROUGH SHIFTS EWD FROM THE INTERMOUNTAIN WEST INTO THE
NRN/CENTRAL ROCKIES...UPPER LOW...OVER SRN TX THIS MORNING...IS
FORECAST TO EJECT EWD THROUGH THE LOWER MS VALLEY REGION THROUGH THE
PERIOD. SATELLITE AND SURFACE OBSERVATIONS SHOWED A SURFACE LOW WAS
LOCATED ABOUT 100 MI SOUTH OF LCH...WITH A WARM FRONT STRETCHING
FROM THE LOW ESEWD TO FL KEYS. THIS SURFACE LOW IS EXPECTED TO SHIFT
MOSTLY EWD AND MAY EVEN CROSS THE FAR SERN PORTIONS OF LA LATE THIS
AFTERNOON/EVENING. HOWEVER...SATELLITE IMAGERY SUGGESTS THE SURFACE
LOW HAS ALREADY BECOME OCCLUDED AS A TRAILING COLD FRONT AND
ASSOCIATED CONVECTION APPEAR TO BE SURGING EWD FASTER THAN THE LOW
PRESSURE SYSTEM. THIS TREND SHOULD CONTINUE AS STRONGER WINDS
ALOFT...OVER THE CENTRAL/NRN GULF WATERS...PUSH DRIER AND COOLER AIR
EWD AND PINCH OFF THE RICHER GULF MOISTURE...SOUTH OF THE WARM FRONT
AND EAST OF THE COLD FRONT IN THE GULF. THEREFORE...EVEN AS THE LOW
MOVES INLAND LATER TODAY...ANY THREAT FOR SEVERE STORMS SHOULD
REMAIN CONFINED SOUTH AND EAST OF LA OVER THE NRN GULF WATERS.
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