[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 301750
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
105 PM EST TUE DEC 30 2008

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...METEOROLOGICAL ANALYSIS...WEATHER
OBSERVATIONS...AND RADAR.

BASED ON 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY
THROUGH 1715 UTC.

...THE ITCZ...

FROM SIERRA LEONE NEAR 7N12W TO 4N20W TO 3N30W TO 2N40W TO
THE EQUATOR NEAR 51W IN EXTREME NORTHEASTERN BRAZIL. SCATTERED
STRONG SHOWERS AND THUNDERSTORMS FROM 24.5N TO 25N BETWEEN 24W
AND 26W...AND FROM 1N TO 4N BETWEEN 30W AND 33W ALONG THE COAST
OF EXTREME NORTHEASTERN BRAZIL. ISOLATED MODERATE SHOWERS TO
LOCALLY STRONG THUNDERSTORMS FROM 5N TO 7N BETWEEN 14W AND 18W...
FROM 10N TO 11N BETWEEN 42W AND 44W...IN THE COASTAL WATERS
FROM FRENCH GUIANA TO GUYANA.

...DISCUSSION...

THE GULF OF MEXICO...
THE BASE OF A MIDDLE TO UPPER LEVEL TROUGH IS ALONG THE LINE
FROM 26N81W BEYOND BERMUDA. MIDDLE TO UPPER LEVEL DRY AIR IN
SUBSIDENCE COVERS THE NORTHEASTERN CORNER AND SOUTH OF 26N.
UPPER LEVEL ANTICYCLONIC FLOW IS MOVING ACROSS THE ENTIRE AREA.
UPPER LEVEL MOISTURE MOVES FROM THE RIO GRANDE VALLEY ACROSS
COASTAL TEXAS AND SOUTH TEXAS...TOWARD EAST TEXAS. THE TAIL END
OF A COLD FRONT PASSES THROUGH THE ATLANTIC OCEAN AND REACHES
FLORIDA ON THE SOUTHERN SHORES OF LAKE OKEECHOBEE. A DISSIPATING
COLD FRONT CONTINUES FROM THE LAKE TO 26N85W. A DISSIPATING
STATIONARY FRONT CONTINUES FROM 26N85W TO 26N94W...CURVING TO
24N97W TO 19N96W. A LOOSELY-CONNECTED CLOUD BAND WITH POSSIBLE
SHOWERS MARKS WHAT WE ARE CALLING THE CURRENT POSITION OF THE
FRONT.

THE CARIBBEAN SEA...
UPPER LEVEL ANTICYCLONIC FLOW COVERS THE NORTHWESTERN CORNER OF
THE AREA...NORTH OF 14N IN HONDURAS TO 24N IN THE SOUTH CENTRAL
GULF OF MEXICO...BETWEEN 80W AND 100W. SHOWERS ARE POSSIBLE IN
CLUSTERS OF LOW CLOUDS...SOME IN LINES OF SURFACE-TO-LOW LEVEL
CONFLUENT WIND FLOW...THAT ARE SPREAD ACROSS THE AREA. MODERATE
TO STRONG TRADEWINDS CONTINUE ONLY IN THE SOUTHWESTERN CORNER OF
OF THE AREA.

THE ATLANTIC OCEAN...
THE BASE OF A MIDDLE TO UPPER LEVEL TROUGH IS ALONG THE LINE
FROM 26N81W BEYOND BERMUDA. BROAD CYCLONIC FLOW IS WEST OF 60W.
A LONGWAVE UPPER LEVEL RIDGE EXTENDS FROM 23N51W BEYOND 32N50W.
A BROAD LONGWAVE MIDDLE TO UPPER LEVEL TROUGH PASSES THROUGH
32N20W TO 26N25W TO 21N36W. THE TROUGH WEAKENS AND REALLY HAS
DISAPPEARED POSSIBLY ALONG WHAT MAY BE A LINE FROM 21N36W TO TO
17N46W. THIS TROUGH SUPPORTS ONE COLD FRONT THAT PASSES THROUGH
32N20W TO 23N25W. SHOWERS ARE POSSIBLE FROM THE CANARY ISLANDS
BEYOND 32N BETWEEN 12W AND 20W. BROAD CYCLONIC FLOW COVERS THE
EASTERN ATLANTIC OCEAN NORTH OF 20N EAST OF 38W. ISOLATED
MODERATE SHOWERS TO LOCALLY STRONG THUNDERSTORMS FROM 10N TO 11N
BETWEEN 42W AND 44W...UNDER THE UPPER LEVEL SOUTHWESTERLY WIND
FLOW THAT IS SOUTH OF 15N60W 15N50W 21N30W BEYOND 31N10W.

$$
MT





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