[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 312356
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
705 PM EST SAT DEC 31 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 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
2315 UTC.

...ITCZ/MONSOON TROUGH...

THE ITCZ EXTENDS FROM LIBERIA NEAR 5N10W TO 1N40W TO BRAZIL NEAR
1N46W. ISOLATED MODERATE CONVECTION IS FROM 4N-9N BETWEEN
15W-20W...AND FROM 3N-6N BETWEEN 30W-47W.

...DISCUSSION...

GULF OF MEXICO...
A 1023 MB HIGH IS CENTERED OVER THE NE GULF OF MEXICO NEAR
27N88W PRODUCING FAIR WEATHER. 5-10 KT ANTICYCLONIC WINDS ARE
GOING AROUND THE HIGH. A SURFACE TROUGH IS OVER THE BAY OF
CAMPECHE ALONG 21N95W 17N93W PRODUCING ONLY A WIND SHIFT IN A 10
KT WIND FIELD. IN THE UPPER LEVELS...ZONAL FLOW PREVAILS.
CONSIDERABLE UPPER LEVEL MOISTURE AND HIGH CLOUDS ARE OVER
MEXICO AND THE W GULF W OF 90W FROM 20N-28N. STRONG SUBSIDENCE
IS OVER THE E GULF. EXPECT IN 24 HOURS FOR...A STRONG COLD FRONT
TO EXTEND FROM THE FLORIDA PANHANDLE TO S OF MATAMOROS MEXICO
ALONG 31N86W 24N98W WITH CONVECTION AND MOVING SE. ALSO EXPECT
20-25 KT WINDS BEHIND THE FRONT WITH A GOOD AMOUNT OF COLD AIR
ADVECTION. EXPECT 10-15 KT EASTERLY SURFACE WINDS AND FAIR
WEATHER OVER THE REMAINDER OF THE GULF.

CARIBBEAN SEA...
15-30 KT TRADEWINDS ARE OVER THE CARIBBEAN SEA AND CENTRAL
AMERICA WITH STRONGEST WINDS ALONG THE COAST OF N COLOMBIA AND
LIGHTEST WINDS OVER THE YUCATAN CHANNEL. SCATTERED MODERATE
CONVECTION IS NOTED ALONG THE COAST OF THE YUCATAN PENINSULA
FROM 17N-20N BETWEEN 87W-90W. ISOLATED SHOWERS DOTS THE
CARIBBEAN SEA NAMELY OVER THE W CARIBBEAN...NICARAGUA...AND
HONDURAS FROM 12N-18N BETWEEN 76W-86W...AND OVER THE E CARIBBEAN
E OF 70W. IN THE UPPER LEVELS...AN UPPER LEVEL RIDGE IS OVER THE
CARIBBEAN WITH AXIS ALONG 70W. UPPER LEVEL SUBSIDENCE COVERS THE
CARIBBEAN EXCEPT OVER THE COAST OF THE YUCATAN PENINSULA. EXPECT
OVER THE NEXT 24 HOURS FOR INCREASED CONVECTION TO BE OVER THE W
CARIBBEAN AND CENTRAL AMERICA W OF 82W.

ATLANTIC OCEAN...
A SURFACE TROUGH IS OVER THE SOUTHERN BAHAMAS ALONG 25N72W
20N74W. BROKEN LOW CLOUDS AND SCATTERED SHOWERS ARE WITHIN 30 NM
OF THE TROUGH. A 1035 MB HIGH IS CENTERED W OF THE MADEIRA
ISLANDS NEAR 35N23W. A SURFACE RIDGE AXIS EXTENDS SW FROM THE
HIGH TO 30N60W THUS THE EASTERN AND CENTRAL ATLANTIC HAS
EASTERLY FLOW FROM 10N-30N BETWEEN W AFRICA AND 60W. A TIGHT
SURFACE PRESSURE GRADIENT IS ALSO OVER THE EASTERN AND CENTRAL
ATLANTIC PRODUCING 25-30 KT WINDS FROM 15N-25N E OF 60W.
IN THE UPPER LEVELS...AN UPPER LEVEL LOW IS CENTERED OVER THE
TROPICAL CENTRAL ATLANTIC NEAR 17N36W. UPPER LEVEL DIFFLUENCE E
OF THE LOW IS PRODUCING WIDELY SCATTERED MODERATE CONVECTION
FROM 10N-17N BETWEEN 20W-35W. EXPECT IN 24 HOURS FOR THE TAIL
END OF A COLD FRONT TO BE OVER THE CENTRAL AND WESTERN ATLANTIC
FROM 30N66W TO THE CENTRAL BAHAMAS NEAR 25N75W WITH RAIN AND
SHOWERS.

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

$$
FORMOSA






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