[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 131747
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
105 PM EST WED DEC 13 2006

TROPICAL WEATHER DISCUSSION FOR NORTH AMERICA...
CENTRAL AMERICA...THE GULF OF MEXICO...THE CARIBBEAN SEA...
NORTHEASTERN SECTIONS OF SOUTH AMERICA...AND THE 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...
6N9W 4N20W 4N30W 3N40W 3N44W INTO NORTHEASTERN BRAZIL NEAR
2N52W. SCATTERED MODERATE SHOWERS TO ISOLATED STRONG
THUNDERSTORMS IN CLUSTERS FROM 4N TO 5N BETWEEN 15W AND 18W...
FROM 2N TO 3N BETWEEN 24W AND 26W...AND FROM 4N TO 5N BETWEEN
26W AND 28W. ISOLATED MODERATE SHOWERS TO LOCALLY STRONG
THUNDERSTORMS ARE ELSEWHERE FROM THE EQUATOR TO 7N BETWEEN
THE PRIME MERIDIAN AND 43W. ISOLATED MODERATE SHOWERS TO
LOCALLY STRONG THUNDERSTORMS ARE FROM BRAZIL TO FRENCH GUIANA
FROM 1S TO 5N BETWEEN 50W AND 53W.

...DISCUSSION...
THE GULF OF MEXICO...
UPPER LEVEL SOUTHWESTERLY FLOW MOVES FROM THE EASTERN PACIFIC
OCEAN ACROSS MEXICO NORTH OF 20N. THE FLOW OVER MEXICO SOUTH
OF 20N IS NOT CONTINUOUS OR UNIFORM. THE DEEP LAYER TROUGH
FROM THE CENTRAL U.S.A. TO THE GULF WATERS FROM 24 HOURS AGO
HAS WEAKENED. DRY AIR COVERS THE MIDDLE TO UPPER LEVELS ACROSS
THE OPEN GULF WATERS. THE GREATEST AMOUNT OF MOISTURE IS NORTH
OF 25N EAST OF 90W CROSSING FLORIDA ROUGHLY NORTH OF LAKE
OKEECHOBEE. SHOWERS ARE INLAND OVER FLORIDA FROM 27N TO 29N.
A SURFACE TROUGH RUNS FROM THE HONDURAS COAST NEAR 16N86W TO
THE NORTHEASTERN YUCATAN PENINSULA COAST TO 24N87W IN THE GULF
OF MEXICO. ISOLATED TO WIDELY SCATTERED MODERATE SHOWERS AND
THUNDERSTORMS ARE SOUTH OF 25N BETWEEN 83W AND 87W. OTHER
BROKEN TO OVERCAST MULTILAYERED CLOUDS AND POSSIBLE PRECIPITATION
ARE IN THE GULF WATERS SOUTH OF 28N EAST OF 89W. A STATIONARY
FRONT EXTENDS THROUGH EAST CENTRAL LOUISIANA TO THE NORTHWESTERN
GULF WATERS IS 250 NM EAST OF THE STATIONARY FRONT IN AN AREA OF
A WEAK PRESSURE GRADIENT AND COMPARATIVELY LOWER SURFACE
PRESSURES. AN UPPER LEVEL RIDGE STRETCHES FROM THE NORTHWESTERN
CARIBBEAN SEA...TO SOUTH FLORIDA...BEYOND 31N74W IN THE ATLANTIC
OCEAN.

THE CARIBBEAN SEA...
A SURFACE TROUGH RUNS FROM THE HONDURAS COAST NEAR 16N86W
TO THE NORTHEASTERN YUCATAN PENINSULA COAST TO 24N87W IN THE
GULF OF MEXICO. ISOLATED TO WIDELY SCATTERED MODERATE SHOWERS
AND THUNDERSTORMS ARE FROM 20N TO 25N BETWEEN 83W AND 87W.
A SECOND SURFACE TROUGH EXTENDS FROM 40 TO 50 NM EAST OF
EASTERN HONDURAS NEAR 16N83W...PASSING IN BETWEEN SAN ANDRES
AND PROVIDENCIA TO 13N81W...TO 10N79W ABOUT 35 NM NORTH OF
THE PANAMA COAST. STRONG SHOWERS AND THUNDERSTORMS ARE FROM
11N TO 13N BETWEEN 80W AND 82W. SCATTERED MODERATE SHOWERS TO
ISOLATED STRONG THUNDERSTORMS ARE FROM 14N TO 16N BETWEEN 80W
AND 84W. ISOLATED MODERATE SHOWERS AND POSSIBLE THUNDERSTORMS
ARE ELSEWHERE FROM 10N TO 18N BETWEEN 80W AND 84W. A FEW AREAS
OF DISORGANIZED MIDDLE TO UPPER LEVEL CYCLONIC FLOW ARE IN THE
ITCZ SOUTH AND SOUTHWEST OF PANAMA AND COSTA RICA. UPPER LEVEL
SOUTHWESTERLY FLOW IS IN THE SOUTHWESTERN CORNER OF THE
CARIBBEAN SEA AS SEEN ON WATER VAPOR IMAGERY AND 13/1500 UTC
CIMSS SATELLITE DERIVED WIND DATA. NOT WELL DEFINED MIDDLE LEVEL
CYCLONIC FLOW...FROM THE SATELLITE AND THE CIMSS DATA...IS
UNDERNEATH THE HIGHER LEVEL SOUTHWESTERLY WINDS. AN UPPER LEVEL
RIDGE IS MOVING SOUTHEASTWARD...FROM THE AREA OF THE NORTHERN
AND WESTERN BAHAMAS TO THE TURKS AND CAICOS AND THE ATLANTIC
OCEAN WATERS NORTH OF HISPANIOLA. ISOLATED MODERATE SHOWERS
FROM 20N TO 22N BETWEEN 67W AND 69W. THE REST OF THE MIDDLE
TO UPPER LEVEL FLOW EAST OF 70W IS MOVING TOWARD THE BASE
OF A MIDDLE TO UPPER LEVEL TROUGH THAT ENDS IN THE EASTERN
CARIBBEAN SEA FROM GRENADA TO ST.LUCIA.

THE ATLANTIC OCEAN...
A MIDDLE LEVEL CYCLONIC CIRCULATION CENTER IS STARTING TO FORM
NEAR 27N69W IN DRY AIR AND UNDER THE NORTHERN EXTENSION OF THE
CARIBBEAN SEA-31N74W RIDGE. A MIDDLE TO UPPER LEVEL TROUGH
PASSES THROUGH 32N43W TO 23N49W TO THE EASTERN/SOUTHEASTERN
CARIBBEAN SEA FROM GRENADA TO ST.LUCIA. WELL-DEVELOPED MIDDLE
TO UPPER LEVEL DRY AIR IS NORTH OF 20N WEST OF 40W. THIS TROUGH
SUPPORTS THE COLD FRONT THAT PASSES THROUGH 32N38W TO 24N45W
TO 20N50W. A STATIONARY FRONT CONTINUES FROM 20N50W TO 19N61W.
BROKEN MULTILAYERED CLOUDS ARE WITHIN 180 NM ON EITHER SIDE OF
17N42W 23N37W 28N37W BEYOND 32N37W. SHOWERS AND POSSIBLE
THUNDERSTORMS ARE NORTH OF 20N IN THIS CLOUDINESS. STRATIFORM
CLOUDS AND POSSIBLE PRECIPITATION ARE WEST OF 40W...MOVING
SOUTHWARD. WHATEVER REMAINS OF THE UPPER LEVEL RIDGE FROM
24 HOURS AGO CONTINUES TO BEING SQUEEZED IN BETWEEN THE
APPROACHING TROUGH AND THE CYCLONIC FLOW AROUND A MIDDLE TO
UPPER LEVEL CYCLONIC CIRCULATION CENTER NEAR 26N26W. CYCLONIC
FLOW AROUND THIS CENTER ROUGHLY COVERS THE ATLANTIC WATERS FROM
20N TO 30N BETWEEN 20W AND 30W. UPPER LEVEL ANTICYCLONIC FLOW
COVERS THE ATLANTIC WATERS NORTH OF 30N BETWEEN 16W AND 30W.
MIDDLE TO UPPER LEVEL CYCLONIC FLOW FROM A CYCLONIC CENTER IN
NORTHEASTERN ALGERIA STARTS TO IMPOSE ON THE ANTICYCLONE NORTH
OF 30N BETWEEN 16W AND 30W.

$$
MT




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