[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 271743
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
105 PM EST SUN NOV 27 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.

...ITCZ/MONSOON TROUGH...

THE MONSOON TROUGH EXTENDS FROM THE AFRICAN COAST NEAR 10N14W TO
9N18W. THE ITCZ CONTINUES FROM 9N18W ALONG 6N28W 6N37W 5N46W.
SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS FROM 4N-7N
BETWEEN 6W-16W. ISOLATED MODERATE/STRONG CONVECTION IS FROM
3N-9N BETWEEN 22W-34W...AND FROM 2N-7N BETWEEN 34W-46W.

...DISCUSSION...

GULF OF MEXICO...
MAINLY SWLY FLOW ALOFT COVERS THE GULF OF MEXICO TODAY BETWEEN
AN UPPER LEVEL RIDGE WITH AXIS UP THE FLORIDA PENINSULA AND
INTO THE W ATLC...AND A NARROW UPPER LEVEL TROUGH EXTENDING FROM
WISCONSIN TO ACROSS TEXAS AND INTO NRN MEXICO. THIS UPPER TROUGH
OVER THE CENTRAL CONUS IS SUPPORTING A COLD FRONT THAT CURRENTLY
EXTENDS FROM THE ALABAMA/MISSISSIPPI BORDER NEAR 30N88W TO THE
BAY OF CAMPECHE ALONG 24N91W 18N95W CONTINUING INTO MEXICO. A
PRE-FRONTAL TROUGH IS AHEAD OF THE FRONT FROM 24N89W TO 19N93W
ALONG A WELL-DEFINED ROPE CLOUD SEEN IN SATELLITE IMAGERY.
SCATTERED SHOWERS/POSSIBLE THUNDERSTORMS ARE WITHIN 100 NM AHEAD
OF THE FRONT...AND WITHIN 300 NM BEHIND THE FRONT. STRONG NW
WINDS OF GALE FORCE UP TO 45 KTS ARE BEHIND THE FRONT DUE TO THE
STRONG PRESSURE GRADIENT BETWEEN LOW PRESSURES NEAR THE FRONT
AND A STRONG SURFACE HIGH BUILDING OVER WRN TEXAS. THE ERN GULF
IS STILL UNDER FAIR CONDITIONS INFLUENCED BY DRY AIR ALOFT AND
SURFACE RIDGING AROUND A 1027 MB HIGH IN THE W ATLC. THE FRONT
IS EXPECTED TO CONTINUE PUSHING EWD ACROSS THE BASIN REACHING
FLORIDA BY MONDAY.

CARIBBEAN SEA...
DRY AIR ALOFT AROUND AN UPPER LEVEL RIDGE EXTENDING UP THE
FLORIDA PENINSULA AND INTO THE W ATLC IS INFLUENCING THE WRN
CARIBBEAN NW OF A LINE FROM COSTA RICA TO HAITI PROVIDING FAIR
CONDITIONS. THIS AREA IS ALSO AROUND THE SRN PERIPHERY OF A
SURFACE RIDGE COVERING THE WRN ATLC. SCATTERED SHOWERS/ISOLATED
THUNDERSTORMS ARE IN THE SW CARIBBEAN FROM 9N-14N BETWEEN
74W-79W ASSOCIATED WITH THE MONSOON TROUGH THAT EXTENDS FROM THE
COSTA RICA/PANAMA BORDER TO THE NRN TIP OF COLOMBIA NEAR 12N73W.
THE ERN CARIBBEAN IS IMPACTED BY BROAD CYCLONIC FLOW AROUND A
SURFACE TROUGH EXTENDING FROM 18N64W TO 12N67W. ALOFT...BROAD
AND MOIST SWLY FLOW ALOFT AROUND THE BASE OF A BROAD UPPER LEVEL
TROUGH MAINLY TO THE N OVER THE CENTRAL ATLC. TOTAL PRECIPITABLE
WATER IMAGERY ALSO INDICATES HIGH DEEP LAYER MOISTURE VALUES
OVER THIS AREA. WHILE ONLY ISOLATED SHOWERS ARE WITHIN A 200 NM
RADIUS OF THE SURFACE TROUGH AXIS...STRONGER
SHOWERS/THUNDERSTORMS COVER BOTH THE WINDWARD AND LEEWARD
ISLANDS. SOME AREAS HAVE RECEIVED BETWEEN 2 AND 3 INCHES OVER
THE PAST 24 HOURS WITH THE POTENTIAL OF FLOODING. MOIST
CONDITIONS ARE EXPECTED TO REMAIN OVER THE ERN CARIBBEAN FOR THE
NEXT COUPLE OF DAYS. THE FRONT CURRENTLY IN THE GULF OF MEXICO
IS EXPECTED TO BEGIN IMPACTING THE NW CARIBBEAN WITHIN THE NEXT
24 HOURS.

ATLANTIC OCEAN...
SURFACE RIDGING AROUND A 1027 MB HIGH NEAR 34N72W IS MAINTAINING
FAIR CONDITIONS OVER THE W ATLC. AN UPPER LEVEL RIDGE EXTENDING
UP THE FLORIDA PENINSULA AND UP THE ERN SEABOARD IS SUPPORTING
THE SURFACE RIDGE. A TILTED UPPER LEVEL TROUGH TO THE E EXTENDS
FROM 33N52W TO THE SE BAHAMAS NEAR 22N72W SUPPORTING A
DISSIPATING STATIONARY FRONT ALONG 31N55W TO 26N63W. MOSTLY DRY
AIR ACCOMPANIES THE UPPER TROUGH WHICH IS INHIBITING SHOWER
ACTIVITY NEAR THE FRONT AXIS. HOWEVER...UPPER LEVEL DIFFLUENCE
FARTHER E IS SUPPORTING A SWATH OF SHOWERS/THUNDERSTORMS FROM
THE NE CARIBBEAN TO NEAR 30N49W. FARTHER E...A WEAK 1017 MB LOW
IS CENTERED NEAR 30N38W CAUSING NO ACTIVE WEATHER. THE REMAINDER
OF THE ERN ATLC IS DOMINATED BY A BROAD SURFACE RIDGE AROUND A
1031 MB HIGH NEAR 40N19W PROVIDING MOSTLY FAIR WEATHER.
ALOFT...A SURFACE RIDGE EXTENDS FROM E OF THE LESSER ANTILLES TO
NEAR 32N37W...WHILE AN UPPER LEVEL TROUGH IS ALONG 25W.

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

$$
WALTON







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