[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 091759
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
105 PM EDT WED NOV 09 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
1715 UTC.

...SPECIAL FEATURES...

TROPICAL STORM SEAN IS CENTERED NEAR 28.3N 70.6W AT 09/1800 UTC
OR 390 NM SW OF BERMUDA MOVING N-NW AT 4 KT. ESTIMATED MINIMUM
CENTRAL PRESSURE IS 994 MB. MAXIMUM SUSTAINED WIND SPEED IS 50
KT WITH GUSTS TO 60 KT. SCATTERED MODERATE CONVECTION IS FROM
26N-30N BETWEEN 67W-72W. SEE LATEST NHC INTERMEDIATE PUBLIC
ADVISORY UNDER AWIPS/WMO HEADERS MIATCPAT4/WTNT34 KNHC AND THE
FULL FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS MIATCMAT4/WTNT24
KNHC FOR MORE DETAILS.

...ITCZ/MONSOON TROUGH...

THE MONSOON TROUGH EXTENDS FROM 10N14W TO 09N16W. THE
INTERTROPICAL CONVERGENCE ZONE AXIS EXTENDS FROM 09N16W TO
06N30W TO 06N53W. WIDELY SCATTERED MODERATE CONVECTION IS FROM
05N-10N BETWEEN 10W-18W. SCATTERED MODERATE AND ISOLATED STRONG
CONVECTION IS FROM 04N-10N BETWEEN 21W-37W. WIDELY SCATTERED
MODERATE CONVECTION IS FROM 05N-09N BETWEEN 37W-55W.

...DISCUSSION...

GULF OF MEXICO...
A SHORTWAVE UPPER LEVEL TROUGH IS NOTED ON WATER VAPOR IMAGERY
MOVING ACROSS THE GREAT LAKES REGION THAT SUPPORTS A COLD FRONT
EXTENDING FROM THE SE CONUS ACROSS THE NW GULF WATERS FROM
30N91W TO 26N94W TO THE NE MEXICO COAST NEAR 25N98W. WHILE MOST
OF THE ENERGY ASSOCIATED WITH THE UPPER LEVEL TROUGH IS LOCATED
NORTH OF THE BASIN...THE FRONT LACKS ANY SIGNIFICANT DEEP
CONVECTION...HOWEVER...WIDELY SCATTERED SHOWERS ARE OCCURRING
WITHIN 120 NM EITHER SIDE OF THE COLD FRONT. A SURFACE TROUGH IS
ANALYZED FROM THE COLD FRONT NEAR 26N93W TO SOUTHERN MEXICO NEAR
19N94W. RECENT SHIP...BUOY...AND OFFSHORE OIL RIG OBSERVATIONS
NW OF THE COLD FRONT INDICATE STRONG N TO NE WINDS TO 30 KT.
ELSEWHERE...THE EASTERN GULF WATERS ARE UNDER THE INFLUENCE OF A
WEAKENING SURFACE RIDGE AXIS EXTENDING FROM NORTHERN FLORIDA
NEAR 30N84W TO NORTH OF THE YUCATAN PENINSULA NEAR 23N90W. THE
RIDGE IS EXPECTED TO DISSIPATE AS THE FRONT MOVES EASTWARD INTO
THE SW NORTH ATLC THROUGH EARLY FRIDAY. BEHIND THE FRONT A RIDGE
IS FORECAST TO INFLUENCE THE GULF OVER THE WEEKEND WITH STRONG
N-NE WINDS GRADUALLY DIMINISHING BY SATURDAY.

CARIBBEAN SEA...
AN UPPER LEVEL ANTICYCLONIC CIRCULATION IS CENTERED OVER
GUATEMALA AND HONDURAS NEAR 15N89W THAT IS PROVIDING MUCH OF THE
CARIBBEAN BASIN WITH NW FLOW ALOFT. WATER VAPOR IMAGERY
INDICATES THAT MUCH OF THIS FLOW IS ACCOMPANIED BY STABLE DRY
AIR AND STRONG SUBSIDENCE. SATELLITE IMAGERY SHOWS THAT POSSIBLE
ISOLATED SHOWERS ARE OCCURRING WITHIN 60 NM EITHER SIDE OF A
LINE FROM 14N82W TO 18N88W. FARTHER SOUTH...A 1009 MB LOW IS
CENTERED NEAR 11N77W ALONG THE MONSOON TROUGH EXTENDING FROM THE
EAST PACIFIC REGION ALONG 10N TO 74W. ISOLATED SHOWERS AND TSTMS
ARE OCCURRING S OF 14N BETWEEN 75W-84W. THE REMAINDER OF THE
EASTERN CARIBBEAN IS UNDER THE INFLUENCE OF AN UPPER LEVEL
TROUGH EXTENDING OVER THE SW NORTH ATLC...OF WHICH TROPICAL
STORM SEAN IS EMBEDDED WITHIN...WITH AXIS FROM 27N70W TO A BASE
NEAR 14N61W. LOW-LEVEL CONVERGENCE OF SOUTHEASTERLY WINDS ACROSS
THE NE CARIBBEAN AND UPPER LEVEL DIFFLUENCE ASSOCIATED WITH THE
UPPER LEVEL TROUGH ARE GENERATING SCATTERED SHOWERS AND ISOLATED
TSTMS FROM 15N-20N BETWEEN 62W-72W.

ATLANTIC OCEAN...
THE INFLUENCE OF TROPICAL STORM SEAN ENCOMPASSES MUCH OF THE SW
NORTH ATLC N OF 20N W OF 66W...WITH ONGOING CONVECTION MENTIONED
ABOVE...A BROAD CYCLONIC 20 KT WIND FIELD...AND SEAS TO 20 FT
WITH LONG AND PERSISTENT N TO NE FETCH NORTHWEST OF THE STORM
CENTER. SWELLS GENERATED BY SEAN ARE EXPECTED TO AFFECT PORTIONS
OF THE SOUTHEASTERN U.S. COAST AND BERMUDA DURING THE NEXT
COUPLE OF DAYS...CAUSING LIFE-THREATENING SURF AND RIP CURRENTS.
EAST OF 66W...AN UPPER LEVEL LOW IS NEARLY COLLOCATED OVER SEAN
NEAR 27N71W WITH TROUGH AXIS EXTENDING SE TO 14N61W. MIDDLE TO
UPPER LEVEL DIFFLUENCE AND CONVERGENT SE LOW-LEVEL WINDS ARE
GENERATING SCATTERED SHOWERS AND TSTMS FROM 18N-33N BETWEEN
58W-66W. FARTHER EAST...OVER THE CENTRAL AND EASTERN ATLC...AN
UPPER LEVEL RIDGE AXIS EXTENDS FROM 12N54W TO 20N48W TO 29N38W.
MOST OF THE ACTIVE WEATHER IS LOCATED NORTH AND EAST OF THIS
RIDGE WITH A COLD FRONT ANALYZED INTO THE DISCUSSION AREA NEAR
32N16W TO 27N24W WHERE THE FRONT BECOMES STATIONARY ALONG 28N34W
TO 26N39W TO 27N44W. A WEAK 1015 MB LOW IS LOCATED NEAR THE TAIL
END OF THE FRONT NEAR 28N49W WITH A SURFACE TROUGH EXTENDING SW
FROM THE LOW TO 23N54W. LOW-LEVEL MOISTURE CONTINUES TO CONVERGE
AND LIFT ALONG AND NORTH OF THE FRONTAL BOUNDARY WITH SCATTERED
SHOWERS AND ISOLATED TSTMS OCCURRING WITHIN 120 NM SOUTH...AND
240 NM NORTH OF THE STATIONARY FRONT.

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

$$
HUFFMAN




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