000
AXNT20 KNHC 181749
TWDAT 

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL  
105 PM EST FRI DEC 18 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 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
1715 UTC.

...ITCZ...

THE ITCZ AXIS IS CENTERED ALONG 8N12W 5N20W 6N30W 5N40W 2N52W. 
WIDELY SCATTERED MODERATE CONVECTION IS FROM 3N-6N BETWEEN 
14W-23W.

...DISCUSSION...

GULF OF MEXICO...
AS OF 1500 UTC...A 1022 MB HIGH IS CENTERED OVER N MEXICO NEAR 
26N103W. A 1001 MB LOW IS OVER THE FLORIDA PANHANDLE NEAR 
30N86W. A TIGHT SURFACE PRESSURE GRADIENT IS OVER THE NE GULF OF 
MEXICO PRODUCING 25-30 KT WINDS. A COLD FRONT EXTENDS S FROM THE 
LOW CENTER TO THE SE CARIBBEAN ALONG 25N84W 20N85W. WIDELY  
SCATTERED MODERATE CONVECTION IS E OF THE COLD FRONT OVER THE E 
GULF OF MEXICO AND FLORIDA FROM 20N-32N E OF 84W. RADAR ALSO 
SHOWS SOME EMBEDDED SEVERE THUNDERSTORM CELLS OVER S FLORIDA. IN 
THE UPPER LEVELS...THE LEADING EDGE OF AN UPPER LEVEL TROUGH IS 
OVER THE W GULF W OF 90W WHILE THE BACK SIDE OF AN UPPER LEVEL 
RIDGE IS OVER THE E GULF. THESE FEATURES ARE PRODUCING SOUTHERLY 
UPPER LEVEL FLOW OVER THE ENTIRE GULF. SIGNIFICANT UPPER LEVEL 
MOISTURE IS OVER THE BAY OF CAMPECHE...AND OVER FLORIDA. STRONG 
SUBSIDENCE IS OVER THE REMAINDER OF THE GULF ESPECIALLY OVER THE 
NW GULF AND S TEXAS. EXPECT...THE LOW TO DEEPEN AND RACE TO THE 
NORTH CAROLINA COAST IN 24 HOURS WITH A TRAILING COLD FRONT TO 
THE NORTHERN BAHAMAS. ALSO EXPECT IN 24 HOURS NORTHERLY SURFACE 
FLOW WITH COLD AIR ADVECTION TO DOMINATE THE ENTIRE GULF OF 
MEXICO AND FLORIDA.  

CARIBBEAN SEA...
AS OF 1500 UTC...A COLD FRONT IS OVER THE NW CARIBBEAN EXTENDING 
FROM W CUBA TO N HONDURAS ALONG 22N84W 16N86W. SCATTERED 
MODERATE CONVECTION IS E OF THE FRONT OVER W CUBA AND THE NW 
CARIBBEAN FROM 20N-23N BETWEEN 81W-84W. STRONG ELY TRADEWINDS 
CONTINUE ACROSS THE REMAINDER OF THE CARIBBEAN. STRONGEST WINDS 
REMAIN NEAR THE COASTS OF COLOMBIA AND VENEZUELA. PATCHES OF 
BROKEN LOW CLOUDS WITH ISOLATED SHOWERS ARE OVER THE LEEWARD 
ISLANDS...AND OVER THE W CARIBBEAN AND CENTRAL AMERICA W OF 80W. 
IN THE UPPER LEVELS...MOSTLY ZONAL FLOW IS OVER THE CARIBBEAN. 
OUTSIDE OF THE NW CARIBBEAN...VERY STRONG SUBSIDENCE IS ACROSS 
THE BASIN SUPPRESSING DEEP CONVECTION. EXPECT... THE COLD FRONT 
TO EXTEND FROM E CUBA TO E HONDURAS IN 24 HOURS WITH CONVECTION. 
ALSO EXPECT THE TRADEWINDS AND SHOWERS TO PERSIST OVER THE 
LEEWARD ISLANDS AND PUERTO RICO OVER THE NEXT 24 HOURS.  

ATLANTIC OCEAN...
A COLD FRONT IS OVER CENTRAL AND WESTERN ATLANTIC FROM 32N38W TO 
28N42W 22N60W. A STATIONARY FRONT CONTINUES TO THE NORTHERN 
BAHAMAS ALONG 23N70W 27N79W. SCATTERED MODERATE CONVECTION IS 
OVER THE CENTRAL ATLANTIC E OF THE COLD FRONT FROM 26N-32N 
BETWEEN 35W-41W. SCATTERED SHOWERS ARE WITHIN 30 NM OF THE 
REMAINDER OF THE FRONTS. A 1018 MB HIGH IS OVER THE E ATLANTIC 
NEAR 23N29W. A COLD FRONT IS FURTHER E ALONG 32N7W 25N15W 
17N25W. SCATTERED SHOWERS ARE WITHIN 30 NM OF THE FRONT. IN THE 
UPPER LEVELS...AN UPPER LEVEL RIDGE IS OVER THE W ATLANTIC W OF 
60W. ZONAL FLOW IS OVER THE REMAINDER OF THE ATLANTIC. EXPECT... 
THE COLD FRONT PRESENTLY IN THE GULF OF MEXICO TO BE OVER THE W 
ATLANTIC FROM 32N74W TO E CUBA IN 24 HOURS WITH CONVECTION. ALSO 
EXPECT THE FRONT OVER THE CENTRAL ATLANTIC TO MOVE E WITH 
SHOWERS. 

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

$$
FORMOSA