[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 222346
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
705 PM EST MON DEC 22 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 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
2315 UTC.

...THE ITCZ...
ITCZ IS CENTERED ALONG 6N10W 3N20W 2N40W 2N51W. A SURFACE TROUGH
IS EMBEDDED WITHIN THE ITCZ ALONG 37W FROM 5N-13N. ISOLATED
SHOWERS ARE ASSOCIATED WITH THE TROUGH BETWEEN 34W-40W. ISOLATED
MODERATE CONVECTION IS FROM 1N-6N BETWEEN 17W-22W. ELSEWHERE...
SCATTERED MODERATE CONVECTION IS WITHIN 150 NM OF THE SOUTH
AMERICAN COAST BETWEEN 48W-61W.

...DISCUSSION...

GULF OF MEXICO...
AS OF 2100 UTC...A COLD FRONT EXTENDS FROM THE W ATLC THROUGH
THE STRAITS OF FLORIDA TO 22N87W THEN CONTINUING STATIONARY INTO
A 1019 MB SURFACE LOW LOCATED NEAR 24N96W. WITH A SURFACE RIDGE
OF HIGH PRESSURE EXTENDING FROM SRN TEXAS SWD ALONG THE ERN
COAST OF MEXICO...A STATIONARY FRONTAL BOUNDARY CONTINUES SWD
FROM THE LOW INTO THE WRN BAY OF CAMPECHE AND INLAND ACROSS ERN
MEXICO NEAR VERACRUZ. BROKEN/OVERCAST STRATOCUMULUS LOW CLOUDS
WITH ISOLATED SHOWERS ARE N OF THE FRONT AND W OF 86W. A SURFACE
TROUGH ALSO EXTENDS N-NW FROM THE SURFACE LOW ALONG THE TEXAS
GULF COAST FROM BROWNSVILLE TO GALVESTON. SE OF THE FRONT...
OVERCAST LOW TO MIDDLE LEVEL CLOUDINESS WITH EMBEDDED SHOWERS
COVER THE BAY OF CAMPECHE S OF 21N. A DEEP LAYERED TROUGH OVER
THE ERN CONUS AND N/CENTRAL GULF SUPPORTS THE AFOREMENTIONED
FRONTAL BOUNDARY. MODERATE TO STRONG SUBSIDENCE AND DRY STABLE
AIR ARE NOTED ACROSS SRN FLORIDA AND THE SRN GULF WATERS...
MAINLY S OF THE SURFACE FRONTAL BOUNDARY.

CARIBBEAN SEA...
THE CARIBBEAN SEA REMAINS UNDER THE INFLUENCE OF A BROAD UPPER
HIGH CENTERED NEAR 14N69W AND ENCOMPASSES THE ENTIRE CARIBBEAN
BASIN WITH STRONG SUBSIDENCE IN DRY AIR. THIS UPPER-LEVEL
FEATURE ALSO ENVELOPS CENTRAL AMERICA AND THE NW PORTION OF
SOUTH AMERICA. HOWEVER...AREAS OF SHALLOW LOW-LEVEL MOISTURE
STREAM ACROSS THE BASIN USHERED IN ON NE-E TRADE WIND FLOW.
ISOLATED TO SCATTERED SHOWERS ARE NOTED MOVING ACROSS THE NRN
LEEWARD ISLANDS N OF 15N...ALSO FROM 16N-19N BETWEEN 69W-76W IN
THE N/CENTRAL CARIBBEAN...AND S OF 18N W OF 80W IN THE WRN
CARIBBEAN. LOOKING AHEAD...STRONG HIGH PRESSURE IS FORECAST TO
BUILD N OF AREA WITH INCREASING TRADE WINDS EXPECTED OVER THE
TROPICAL N ATLC AND MUCH OF THE CARIBBEAN SEA WED THROUGH FRI.

ATLANTIC OCEAN...
A COLD FRONT ENTERS THE W ATLC NEAR 32N67W AND EXTENDS ACROSS
THE NW BAHAMAS AND STRAITS OF FLORIDA INTO THE GULF OF MEXICO.
BROKEN/OVERCAST STRATOCUMULUS LOW CLOUDS WITH ISOLATED SHOWERS
ARE BEHIND THE FRONT. A BROAD UPPER LEVEL RIDGE EXTENDS FROM THE
CARIBBEAN SEA WITH AXIS FROM THE MONA PASSAGE NE TO BEYOND
32N48W. MOSTLY FAIR WEATHER CONDITIONS ARE OBSERVED E OF THE
COLD FRONT TO 50W. A SURFACE TROUGH IS IN THE CENTRAL ATLC AND
EXTENDS FROM 28N42W TO 19N42W. POSSIBLE ISOLATED SHOWERS ARE
WITHIN 150 NM W OF THE TROUGH WHICH IS SUPPORTED BY UPPER LEVEL
TROUGHING OVER THE E/CENTRAL ATLC. THE AXIS ENTERS THE AREA NEAR
32N21W THEN CONTINUES SW INTO THE TROPICS TO NEAR 15N40W AND
THEN WWD TO NEAR 15N55W. UPPER DIFFLUENCE E OF THIS UPPER TROUGH
ALONG WITH AN UPPER RIDGE AMPLIFIED ALONG THE W AFRICAN COAST IS
ENHANCING SCATTERED SHOWERS AND ISOLATED TSTMS WITHIN 200 NM ON
EITHER SIDE OF A LINE FROM 28N10W TO 14N33W. NE TO E WINDS ARE
EXPECTED TO INCREASE ACROSS THE TROPICS LATE MONDAY TO AT LEAST
MIDWEEK AS STRONG HIGH PRESSURE BUILDS N OF AREA.

$$
HUFFMAN





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