[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 211204
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
705 AM EST WED NOV 21 2012

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 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY
THROUGH 1115 UTC.

...THE ITCZ/THE MONSOON TROUGH...

THE MONSOON TROUGH PASSES THROUGH COASTAL SIERRA LEONE NEAR
9N13W 6N19W. THE ITCZ CONTINUES FROM 6N19W TO 5N27W 5N35W
6N43W...5N52W IN THE FRENCH GUIANA COASTAL WATERS. A SURFACE
TROUGH IS ALONG 42W/43W FROM 2N TO 10N. THE TROUGH SHOWS UP
WELL IN THE SHORTWAVE INFRARED SATELLITE IMAGERY AND THE LATEST
SCATTEROMETER WIND DATA. CONVECTIVE PRECIPITATION...WIDELY
SCATTERED TO SCATTERED MODERATE TO ISOLATED STRONG TO THE NORTH
AND NORTHEAST OF 3N5W 3N12W 8N20W 10N20W...TO THE AFRICA COAST
ALONG 10N...SCATTERED MODERATE TO ISOLATED STRONG FROM 4N TO 6N
BETWEEN 34W AND 39W AND FROM 8N TO 10N BETWEEN 33W AND 37W...
ISOLATED MODERATE ELSEWHERE FROM 3N TO 10N TO THE EAST OF 40W.
ISOLATED MODERATE CONVECTIVE PRECIPITATION IS FROM 5N TO 10N
BETWEEN 41W AND 46W WITH THE 42W/43W SURFACE TROUGH.

...DISCUSSION...

THE GULF OF MEXICO...

A DEEP LAYER TROUGH IS MOVING THROUGH THE U.S.A....BETWEEN THE
EAST COAST AND 100W. A SURFACE TROUGH IS STILL WELL TO THE NORTH
OF THE U.S.A. GULF COAST STATES. THE TROUGH STRETCHES FROM
KENTUCKY AND TENNESSEE...TO ARKANSAS AND NORTHEASTERN TEXAS.

THE 99W UPPER LEVEL RIDGE FROM 20/1100 UTC HAS FLATTENED OUT
CONSIDERABLY. MIDDLE LEVEL TO UPPER LEVEL WESTERLY WIND FLOW
COVERS THE GULF OF MEXICO. AN UPPER LEVEL RIDGE THAT IS IN
MEXICO HAS MUCH MORE OF A WELL-DEFINED NORTHWESTERLY-TO-
SOUTHEASTERLY ANGLE TO IT.

A SURFACE TROUGH IS ALONG 24N95W 20N94W 19N91W. BROKEN TO
OVERCAST LOW TO MIDDLE LEVEL CLOUDS AND POSSIBLE PRECIPITATION
ARE TO THE SOUTH OF 25N TO THE WEST OF 90W.

A SURFACE RIDGE CURVES THROUGH LOUISIANA TO THE DEEP SOUTH OF
TEXAS...TO A COASTAL MEXICO NEAR 22N99W...INTO THE ISTHMUS OF
TEHUANTEPEC OF SOUTHERN MEXICO...ACROSS GUATEMALA AND
HONDURAS...INTO SOUTH CENTRAL NICARAGUA.

A SURGE OF NORTHERLY WIND FLOW...FROM THE SURFACE TO THE LOW
LEVELS...IS MARKED BY LOW CLOUDS THAT ARE MOVING FROM THE
EASTERN GULF OF MEXICO INTO THE NORTHWESTERN CARIBBEAN SEA.
A WEAKENING FRONTAL BOUNDARY WAS ANALYZED ON THE SURFACE MAP
ANALYSIS 24 HOURS AGO. THE CLOUDS COVER THE WESTERN ATLANTIC
OCEAN...THE GULF OF MEXICO...AND THE NORTHWESTERN CARIBBEAN SEA
TO THE NORTH OF 18N BETWEEN 78W AND 87W.

GALE-FORCE WINDS ARE BLOWING IN THE GULF OF TEHUANTEPEC.
PLEASE READ THE EASTERN PACIFIC OCEAN HIGH SEAS
FORECAST...MIAHSFEP2...FOR MORE DETAILS.

THE CARIBBEAN SEA...

BROAD UPPER LEVEL SOUTHWESTERLY WIND FLOW COVERS THE AREA THAT
IS TO THE EAST OF THE LINE THAT RUNS FROM CUBA NEAR 21N79W TO
THE COAST OF EASTERN HONDURAS NEAR 16N85W. BROAD MIDDLE LEVEL
TO UPPER LEVEL ANTICYCLONIC WIND FLOW COVERS THE REST OF THE
CARIBBEAN SEA...TO THE NORTHWEST OF THE 21N79W 16N85W LINE.

BROAD MIDDLE LEVEL TO UPPER LEVEL ANTICYCLONIC WIND FLOW
COVERS THE CARIBBEAN SEA THAT IS TO THE EAST OF 70W.

A SURFACE TROUGH IS ALONG 19N65W...JUST TO THE EAST OF PUERTO
RICO...15N67W...TO COASTAL VENEZUELA NEAR 11N69W. ISOLATED
MODERATE TO LOCALLY STRONG CONVECTIVE PRECIPITATION IS WITHIN
60 NM ON EITHER SIDE OF 13N70W 15N67W 19N63W.

THE MONSOON TROUGH IS ALONG 8N74W IN COLOMBIA...PASSING THROUGH
7N81W IN PANAMA...BEYOND SOUTHERN COSTA RICA...INTO THE EASTERN
PACIFIC OCEAN. CONVECTIVE PRECIPITATION...SCATTERED MODERATE TO
STRONG FROM 11N TO 14N BETWEEN 80W AND 84W IN THE WATERS TO THE
EAST OF NICARAGUA...NUMEROUS STRONG IN THE EASTERN PACIFIC OCEAN
FROM 5N TO 10N BETWEEN 76W IN COLOMBIA AND 85W IN COSTA RICA AND
ITS COASTAL WATERS IN THE EASTERN PACIFIC OCEAN. THE UPPER LEVEL
SOUTHWESTERLY WIND FLOW THAT IS IN THE AREA IS SHEARING THE
CLOUD TOPS OF THIS AREA OF PRECIPITATION. BROKEN TO OVERCAST
MIDDLE LEVEL AND HIGH LEVEL CLOUDS ARE ELSEWHERE TO THE SOUTH OF
18N BETWEEN 71W AND 84W.

PLEASE READ THE OFFSHORE FORECAST...MIAHSFAT2...AND THE
OFFSHORE FORECAST...MIAOFFNT3...FOR MORE DETAILS ABOUT
THE 20 TO 25 KNOT WINDS AND 8 FOOT SEA HEIGHTS FROM
11N TO 15N TO THE WEST OF 81W.

THE REST OF THE ATLANTIC OCEAN...

A MIDDLE LEVEL TO UPPER LEVEL TROUGH PASSES THROUGH 32N58W
TO 27N54W. THE TROUGH DISAPPEARS SOMEWHAT IN THE MIDDLE LEVEL
TO UPPER LEVEL WESTERLY-TO-SOUTHWESTERLY WIND FLOW THAT COVERS
THE ATLANTIC OCEAN TO THE WEST OF THE TROUGH...BASICALLY
EVERYWHERE TO THE NORTH OF 20N TO THE WEST OF 60W. THE TROUGH
SUPPORTS A COLD FRONT THAT PASSES THROUGH 32N56W TO 29N60W
AND 21N68W. ONE SURFACE TROUGH IS ALONG 24N62W 20N66W.
A SECOND SURFACE TROUGH IS ALONG 29N66W 27N72W 28N76W.
A DISSIPATING COLD FRONT PASSES THROUGH 32N61W 30N71W 30N76W.
ISOLATED MODERATE CONVECTIVE PRECIPITATION IS WITHIN 60 TO 90 NM
ON EITHER SIDE OF 20N63W 24N59W 28N55W. WIDELY SCATTERED MODERATE
TO ISOLATED STRONG CONVECTIVE PRECIPITATION IS TO THE NORTH
OF 27N BETWEEN 40W AND 52W. RAINSHOWERS ARE POSSIBLE ELSEWHERE
TO THE NORTH OF 21N TO THE WEST OF 64W.

A MIDDLE LEVEL TO UPPER LEVEL TROUGH EXTENDS FROM A CYCLONIC
CIRCULATION CENTER THAT IS NEAR 18N39W TO 9N48W AND 6N50W
A SURFACE TROUGH IS ALONG 50W/51W FROM 13N TO 22N. THE TROUGH
IS BECOMING WEAKER WITH TIME GRADUALLY. BROKEN TO OVERCAST
MULTILAYERED CONVECTIVE DEBRIS CLOUDS AND POSSIBLE REMAINING
PRECIPITATION FROM 10N TO 20N BETWEEN 30W AND 40W.

A DEEP LAYER EASTERN ATLANTIC OCEAN TROUGH SUPPORTS A COLD
FRONT THAT PASSES THROUGH 32N15W TO 31N17W. A DISSIPATING
COLD FRONT IS ALONG 31N17W 28N30W 31N39W.

A 1021 MB HIGH PRESSURE CENTER IS NEAR 26N25W. BROAD SURFACE
ANTICYCLONIC WIND FLOW COVERS THE AREA FROM 9N TO THE DISSIPATING
31N17W 28N30W 31N39W COLD FRONT...BETWEEN AFRICA AND 45W.

PLEASE READ THE HIGH SEAS FORECAST...MIAHSFAT2...FOR MORE
DETAILS ABOUT 20 TO 25 KNOT WINDS AND 8 TO 12 FOOT SEAS WITH
THE 31N57W 23N67W COLD FRONT...20 KNOT WINDS AND 8 TO 12 FOOT
SEA HEIGHTS TO THE NORTH OF THE LINE FROM 27N50W TO 24N42W
23N38W 27N35W...20 TO 25 KNOT WINDS AND 12 FOOT SEA HEIGHTS
WITH A DEVELOPING COLD FRONT FROM 31N65W TO 31N77W.

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

$$
MT





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