[Tropical] Tropical Weather Discussion

EMWIN Server emwin at nashvilleweather.net
Wed Dec 21 11:48:37 CST 2011


AXNT20 KNHC 211748
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
105 PM EST WED DEC 20 2011

TROPICAL WEATHER DISCUSSION FOR NORTH AMERICA...CENTRAL
AMERICA...GULF OF MEXICO...CARIBBEAN SEA...NORTHERN SECTIONS OF
SOUTH AMERICA...AND ATLANTIC OCEAN TO THE AFRICAN COAST FROM THE
EQUATOR TO 32N. THE FOLLOWING INFORMATION IS BASED ON SATELLITE
IMAGERY...WEATHER OBSERVATIONS...RADAR...AND METEOROLOGICAL
ANALYSIS.

BASED ON 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
1700 UTC.

...THE ITCZ/THE MONSOON TROUGH...

THE MONSOON TROUGH EXTENDS INLAND OVER W AFRICA TO THE COAST OF
LIBERIA NEAR 6N11W CONTINUING TO 6N13W. THE ITCZ CONTINUES FROM
6N13W ALONG 5N20W 6N29W 4N37W 6N49W. SCATTERED
MODERATE/ISOLATED STRONG CONVECTION IS FROM 4N-7N BETWEEN
14W-28W...AND FROM 6N-7N BETWEEN 43W-49W.

...DISCUSSION...

GULF OF MEXICO...
A FRONTAL BOUNDARY CONTINUES TO IMPACT THE N AND WRN PORTIONS OF
THE GULF OF MEXICO TODAY WITH A COLD SECTION EXTENDING FROM THE
MISSISSIPPI COAST NEAR 30N90W ACROSS SE LOUISIANA TO 28N92W
WHERE IT BECOMES STATIONARY AND CONTINUES ALONG 25N96W 21N97W
23N100W. AN AREA OF WIDESPREAD SHOWERS/ISOLATED THUNDERSTORMS IS
AHEAD OF THE FRONT IMPACTING THE NE CORNER OF THE GULF N OF 28N
BETWEEN 83W-89W. POSSIBLE ISOLATED SHOWERS ARE ALSO ALONG THE
FRONTAL BOUNDARY. THE ERN GULF REMAINS UNDER SURFACE RIDGING
EXTENDING FROM A HIGH PRESSURE SYSTEM IN THE W ATLC. THIS
PATTERN IS PROVIDING MAINLY SE-S FLOW AHEAD OF THE FRONT. DUE TO
THE STRONG PRESSURE GRADIENT BETWEEN THE FRONT AND THE
HIGH...WIND SPEEDS ARE BETWEEN 15-20 KTS WITH HIGHER GUSTS.
ALOFT...MAINLY SWLY FLOW DOMINATES WITH A WEAK SHORTWAVE TROUGH
EMBEDDED IN THE FLOW NEAR THE W COAST OF FLORIDA WHICH IS
ENHANCING THE SHOWER ACTIVITY IN THE NE GULF. BESIDES THE
MOISTURE PRESENT NEAR THE AFOREMENTIONED SHOWER ACTIVITY...THE
REMAINDER OF THE BASIN IS COVERED BY DRY AIR ALOFT WHICH IS
HELPING PROVIDE FAIR CONDITIONS ACROSS MUCH OF THE SRN GULF.
EXPECT THE NRN PORTION OF THE FRONT TO CONTINUE TO MOVE EWD
WHILE THE STATIONARY PART RETREATS TO THE NW BEFORE A SECOND
COLD FRONT MOVES INTO THE NW GULF TOMORROW.

CARIBBEAN SEA...
WINDY CONDITIONS ARE ACROSS THE CARIBBEAN TODAY WITH MAINLY NE-E
TRADEWIND FLOW OF 20-25 KTS REACHING 30 KTS IN THE CENTRAL
CARIBBEAN AND GALE FORCE NEAR THE COAST OF COLOMBIA. ISOLATED
SHOWERS ARE EMBEDDED WITHIN THE TRADEWIND FLOW WITH SOME
STRONGER ACTIVITY N OF VENEZUELA. ALOFT...A WEAK SHORTWAVE UPPER
TROUGH IS OVER THE FAR NW CARIBBEAN EXTENDING FROM JUST W OF
FLORIDA. UPPER RIDGING COVERS THE REMAINDER OF THE AREA WITH
AXIS EXTENDING FROM THE FAR SE CORNER OF THE BASIN TO HISPANIOLA
AND INTO THE W ATLC. SURFACE HIGH PRESSURE OVER THE W ATLC IS
EXPECTED TO REMAIN STATIONARY WHICH WILL CAUSE THE STRONG
PRESSURE GRADIENT...AND THUS HIGH WINDS...TO PERSIST OVER THE
CARIBBEAN FOR THE NEXT COUPLE DAYS.

ATLANTIC OCEAN...
SURFACE RIDGING AROUND A 1028 MB HIGH NEAR 31N68W IS PROVIDING
MOSTLY FAIR WEATHER ACROSS THE WRN ATLC. THE RIDGE IS SUPPORTED
BY AN UPPER LEVEL RIDGE WITH AXIS ALONG 74W. AN UPPER LEVEL
TROUGH TO THE E ALONG 40W CONTINUES TO SUPPORT A FRONTAL
BOUNDARY IN THE CENTRAL ATLC. THE NRN PORTION OF THE FRONT HAS
REMAINED STATIONARY ALONG 32N38W TO 29N40W BECOMING COLD ALONG
23N45W 21N50W DISSIPATING TO 19N55W. SCATTERED SHOWERS ARE
MAINLY E OF THE FRONT N OF 25N BETWEEN 35W-40W. ISOLATED SHOWERS
ARE ALONG THE FRONT ELSEWHERE. FARTHER S...AN AREA OF ACTIVE
WEATHER IS JUST E OF THE SRN WINDWARD ISLANDS FROM 10N-12N
BETWEEN 53W-62W DUE TO WIND SPEED CONVERGENCE. THE REMAINDER OF
THE BASIN IS INFLUENCED BY SURFACE RIDGING AROUND A 1036 MB HIGH
NE OF THE AZORES ISLANDS NEAR 43N13W PROVIDING GENERALLY FAIR
WEATHER ACROSS THE ERN ATLC. ALOFT...AN UPPER LEVEL RIDGE
CENTERED NEAR 44N15W IS SUPPORTING THE SURFACE RIDGE. AN
ELONGATED UPPER TROUGH IS THE S BETWEEN THE CAPE VERDE AND
CANARY ISLANDS CAUSING NO SIGNIFICANT WEATHER.

FOR ADDITIONAL INFORMATION PLEASE VISIT
HTTP://WWW.HURRICANES.GOV/MARINE

$$
WALTON




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