[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 161136
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
705 AM EST WED DEC 16 2009

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 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
1045 UTC.

...ITCZ...

THE ITCZ AXIS IS CENTERED ALONG 7N10W 5N24W 6N39W EQ52W.
SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS WITHIN 90 NM N
AND 60 NM S OF THE AXIS BETWEEN 22W-30W. SCATTERED MODERATE
CONVECTION IS WITHIN 150 NM N OF THE AXIS BETWEEN 32W-37W.

...DISCUSSION...

GULF OF MEXICO...
AS OF 0900 UTC...AN UPPER LEVEL TROUGH EXTENDS FROM THE OHIO
VALLEY TO THE SOUTHERN PLAINS INTO NW MEXICO SUPPORTING A 1018
MB LOW OFF THE NE MEXICO COASTLINE NEAR 24N95W. A COLD FRONT
EXTENDS S FROM THE LOW TO VERACRUZ MEXICO CONTINUING INLAND. A
PRE-FRONTAL TROUGH IS AHEAD OF THE FRONT ALONG 21N94W 18N95W. A
STATIONARY FRONT EXTENDS N OF THE LOW CENTER PARALLELING THE
GULF COASTLINE ALONG 27N92W TO 29N87W WHERE IS BECOMES COLD TO
THEN OF TAMPA ACROSS NRN FLORIDA TO SAINT AUGUSTINE. SURFACE
CONVERGENCE NEAR THE LOW CENTER AND FRONTAL BOUNDARIES ALONG
WITH DIFFLUENT FLOW ALOFT TO THE E SIDE OF THE UPPER TROUGH ARE
SUPPORTING NUMEROUS SHOWERS/ISOLATED THUNDERSTORMS ACROSS THE NW
GULF FROM 20N-29N W OF 90W. ISOLATED SHOWERS ARE POSSIBLE WITHIN
100 NM OF THE BOUNDARY ELSEWHERE. A SURFACE TROUGH IS ANALYZED
ACROSS S FLORIDA FROM MIAMI TO S OF KEY WEST TO W CUBA. ISOLATED
SHOWERS ARE ALONG THE TROUGH AXIS.  N-NE GALE FORCE WINDS UP TO
35 KT ARE CURRENTLY BEHIND THE FRONT IN THE NW GULF S OF 28N W
OF 90W. EXPECT THE COLD FRONT ACROSS THE NE GULF AND NRN FLORIDA
TO DIP SWD AS THE LOW IN THE NW GULF REMAINS RELATIVELY
STATIONARY UNTIL THURSDAY WHEN IT IS FORECAST TO DEEPEN AND MOVE
NE-E ACROSS THE GULF.

CARIBBEAN SEA...
STRONG ELY TRADEWINDS CONTINUE ACROSS THE CARIBBEAN AS A
RESULT OF A STRONG PRESSURE GRADIENT BETWEEN HIGH PRESSURE OVER
THE W ATLC AND LOW PRESSURE OVER NRN COLOMBIA. THE STRONGEST
WINDS...UP TO 30 KT...ARE OFF THE COAST OF COLOMBIA. STRONG
SUBSIDENCE AND DRY AIR AROUND AN UPPER LEVEL RIDGE WITH AXIS
ALONG 70W DOMINATE THE BASIN SUPPORTING GENERALLY FAIR WEATHER
ACROSS THE AREA. HOWEVER...A LINE OF ISOLATED LOW-LEVEL SHOWERS
EMBEDDED IN THE ELY SURFACE FLOW ARE MOVING QUICKLY FROM THE
LEEWARD ISLANDS TO JAMAICA AND S OF W CUBA. A FEW ISOLATED
SHOWERS ARE ALSO NOTED OFF THE YUCATAN PENINSULA IN THE FAR NW
CARIBBEAN. EXPECT TRADE WINDS TO DIMINISH SLIGHTLY DUE TO LOW
PRESSURE IN THE GULF OF MEXICO MOVING EWD WEAKENING THE PRESSURE
GRADIENT ACROSS THE CARIBBEAN.

ATLANTIC OCEAN...
AS OF 0900 UTC...A COLD FRONT ENTERS THE DISCUSSION AREA NEAR
32N74W TO NEAR SAINT AUGUSTINE FLORIDA CONTINUING INTO THE NE
GULF OF MEXICO. ISOLATED SHOWERS ARE POSSIBLE ALONG THE FRONT
AXIS. THE SYSTEM IS SUPPORTED BY AN UPPER LEVEL TROUGH EXTENDING
OVER THE NE CONUS. A SURFACE TROUGH IS ANALYZED S OF THE FRONT
FROM N OF FREEPORT BAHAMAS NEAR 28N77W TO MIAMI FLORIDA.
ISOLATED SHOWERS ARE ALONG THE TROUGH AXIS INDICATED BY RADAR
IMAGERY. AN UPPER LEVEL RIDGE EXTENDING FROM THE CARIBBEAN
SUPPORTS A SURFACE RIDGE COVERING THE W ATLC ANCHORED BY A 1020
MB HIGH NEAR 25N66W. A SHORTWAVE UPPER LEVEL TROUGH OVER THE
CENTRAL ATLC SUPPORTS A 1009 MB LOW NEAR 28N44W. A COLD FRONT
EXTENDS FROM THE LOW CENTER ALONG 25N50W 29N61W. ISOLATED
SHOWERS ARE POSSIBLE ALONG THE FRONT AXIS. SCATTERED SHOWERS ARE
ALSO E OF THE LOW CENTER N OF 25N BETWEEN 33W-40W. FARTHER E...A
DEEP LAYER TROUGH SUPPORTS A DYING STATIONARY FRONT EXTENDING
FROM THE CANARY ISLANDS TO NW OF THE CAPE VERDE ISLANDS NEAR
21N32W. ISOLATED SHOWERS ARE POSSIBLE ALONG THE FRONT AXIS. THE
UPPER LEVEL TROUGH IS ALSO ENHANCING CONVECTION ALONG THE
CENTRAL PORTION OF THE ATLC ITCZ.

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

$$
WALTON





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