[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 180549
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
105 AM EST TUE DEC 18 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 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY
THROUGH 0515 UTC.

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

THE MONSOON TROUGH PASSES THROUGH SIERRA LEONE AND IT REACHES
THE COAST OF GUINEA NEAR 10N14W. THE ITCZ CONTINUES FROM 10N14W
TO 10N16W 7N20W 3N30W AND 4N45W...CURVING INTO EXTREME
NORTHEASTERN BRAZIL NEAR 2N52W...JUST TO SOUTHEAST OF FRENCH
GUIANA. CONVECTIVE PRECIPITATION...NUMEROUS STRONG FROM 3N TO 4N
BETWEEN 15W AND 23W...FROM 2N TO 4N BETWEEN 28W AND 30W...
FROM 1N TO 3N BETWEEN 30W AND 32W...FROM 2N TO 6N BETWEEN 38W
AND 42W...FROM 5N TO 7N BETWEEN 42W AND 44W...AND FROM 7N TO 10N
BETWEEN 44W AND 49W...SCATTERED MODERATE TO ISOLATED STRONG FROM
FROM 1N TO 2N BETWEEN 7W AND 8W AND FROM 4N TO 6N BETWEEN 8W AND
15W.

...DISCUSSION...

THE GULF OF MEXICO...

A DEEP LAYER TROUGH IS DIGGING THROUGH THE SOUTHEASTERN
U.S.A....PASSING THROUGH CENTRAL MISSISSIPPI...INTO THE NORTH
CENTRAL GULF WATERS...TO THE MEXICO GULF COAST NEAR 22N98W.
BROKEN LOW TO MIDDLE LEVEL CLOUDS AND POSSIBLE RAINSHOWERS ARE
IN THE NORTHWESTERN CORNER OF THE CARIBBEAN SEA...MOVING THROUGH
THE YUCATAN CHANNEL...AND TO THE SOUTHEAST OF THE LINE THAT
EXTENDS FROM KEY WEST FLORIDA TO 23N90W. SIMILAR CLOUDS AND
POSSIBLE PRECIPITATION ARE IN THE SOUTHWESTERN CORNER OF THE
AREA TO THE SOUTH OF 23N TO THE WEST OF 93W. BROKEN TO OVERCAST
HIGH LEVEL CLOUDS ARE TO THE NORTH OF 23N TO THE EAST OF 93W.

A SURFACE RIDGE ORIGINATES IN THE ATLANTIC OCEAN...PASSING
THROUGH 25N72W AND ACROSS THE BAHAMAS...THROUGH THE FLORIDA
STRAITS...TO 25N90W IN THE CENTRAL GULF OF MEXICO.

THE CARIBBEAN SEA...

MIDDLE LEVEL NORTHEASTERLY WIND FLOW COVERS THE AREA TO THE EAST
OF 70W...BECOMING MIDDLE LEVEL EASTERLY WIND FLOW BETWEEN 70W
AND 80W...AND MIDDLE LEVEL SOUTHEASTERLY-TO-SOUTHERLY WIND FLOW
TO THE WEST OF 80W TO THE NORTH OF 16N.

MIDDLE LEVEL TO UPPER LEVEL SOUTHWESTERLY WIND FLOW MOVES FROM
THE EASTERN PACIFIC OCEAN...CROSSING PANAMA AND COLOMBIA...
INTO THE SOUTHWESTERN CORNER OF THE CARIBBEAN SEA. COMPARATIVELY
DRIER AIR IN SUBSIDENCE IS EVIDENT ACROSS THE ENTIRE AREA
ON WATER VAPOR SATELLITE IMAGERY.

BROKEN LOW TO MIDDLE LEVEL CLOUDS AND POSSIBLE RAINSHOWERS
ARE TO THE NORTH OF 18N TO THE WEST OF 80W IN THE NORTHWESTERN
CORNER OF THE AREA. SIMILAR CLOUDS AND PRECIPITATION ARE IN THE
EASTERN CARIBBEAN SEA...FROM 15N TO 18N BETWEEN 61W AND 65W.
THE 24-HOUR RAINFALL TOTAL FOR THE TIME PERIOD THAT ENDED AT
18/0000 UTC FOR GUADELOUPE WAS 0.57 INCHES.

THE SURFACE PRESSURE GRADIENT IS WEAK ACROSS THE AREA.

THE MONSOON TROUGH PASSES THROUGH 6N76W IN COLOMBIA...TO 8N81W
IN SOUTHERN PANAMA...TO 9N83W IN SOUTHERN COSTA RICA...BEYOND
9N86W IN THE EASTERN PACIFIC OCEAN. RAINSHOWERS ARE POSSIBLE
TO THE SOUTH OF 11N TO THE WEST OF 80W IN THE SOUTHWESTERN
CORNER OF THE CARIBBEAN SEA...BROKEN TO OVERCAST MULTILAYERED
CLOUDS AND SCATTERED MODERATE CONVECTIVE PRECIPITATION ARE TO
THE NORTH OF 3N TO THE EAST OF 90W IN THE EASTERN PACIFIC OCEAN.

THE ATLANTIC OCEAN...

A MIDDLE LEVEL TO UPPER LEVEL TROUGH PASSES THROUGH 32N36W
TO 23N44W AND 16N56W. AN UPPER LEVEL SHEAR AXIS CONTINUES FROM
16N56W TO 12N61W IN THE SOUTHEASTERN CORNER OF THE CARIBBEAN
SEA. THIS TROUGH SUPPORTS A COLD FRONT THAT PASSES THROUGH
32N39W TO 31N41W. A SURFACE TROUGH IS ABOUT 180 NM TO THE EAST
OF THE FRONT...PASSING THROUGH 32N35W 27N40W 24N45W 19N46W.
CONVECTIVE PRECIPITATION...BROKEN TO OVERCAST MULTILAYERED
CLOUDS AND ISOLATED MODERATE WITHIN 120 NM ON EITHER SIDE
OF 18N44W 22N36W BEYOND 32N31W...WIDELY SCATTERED MODERATE
TO ISOLATED STRONG FROM 7N TO 11N BETWEEN 56W AND 61W...
WIDELY SCATTERED MODERATE FROM 23N TO 27N BETWEEN 39W AND 44W...
BROKEN MULTILAYERED CLOUDS ARE FROM 11N TO 18N BETWEEN 44W
AND 60W.

A SURFACE RIDGE ORIGINATES IN THE ATLANTIC OCEAN...
FROM 33N52W TO 25N72W...BEYOND THE FLORIDA STRAITS.

AN UPPER LEVEL TROUGH PASSES THROUGH 18N16W ALONG THE COAST
OF MAURITANIA TO 10N26W. NO SIGNIFICANT CONVECTIVE
PRECIPITATION BASED SOLELY ON SATELLITE IMAGERY.

A SURFACE RIDGE PASSES OVER THE MADEIRA ARCHIPELAGO
TO 27N26W AND 19N38W.

PLEASE READ THE HIGH SEAS FORECAST...MIAHSFAT2...FOR MORE
DETAILS ABOUT...20 KNOT WINDS AND 8 TO 9 FOOT SEA HEIGHTS
TO THE EAST OF THE 31N36W 23N45W SURFACE TROUGH...AND
20 TO 25 KNOT WINDS AND SEAS LESS THAN 8 FEET TO THE NORTH
OF 30N TO THE WEST OF 76W AT THE TIME OF 12 HOURS INTO THE
FORECAST PERIOD WITH A COLD FRONT THAT WILL BE NEAR THE
FLORIDA/GEORGIA COAST.

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

$$
MT





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