000
AXNT20 KNHC 161723
TWDAT 

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

...ITCZ...

THE ITCZ AXIS IS CENTERED ALONG 7N10W 5N20W 6N40W 1N50W. WIDELY 
SCATTERED MODERATE CONVECTION IS FROM 5N-9N BETWEEN 
25W-30W...AND FROM 7N-9N BETWEEN 34W-37W. 

...DISCUSSION...

GULF OF MEXICO...
AS OF 1500 UTC...A 1032 MB HIGH IS CENTERED OVER N MEXICO NEAR 
27N101W. NOT FAR AWAY A 1016 MB LOW IS OVER THE NW GULF OF 
MEXICO NEAR 25N95W. NEEDLESS TO SAY A VERY TIGHT PRESSURE 
GRADIENT IS OVER THE NW GULF OF MEXICO. GALE FORCE WINDS ARE S 
OF 28N AND W OF 95W. A COLD FRONT EXTENDS E FROM THE LOW CENTER 
TO SOUTH FLORIDA ALONG 26N86W 27N80W. A COLD FRONT ALSO EXTENDS 
S FROM THE LOW CENTER TO THE BAY OF CAMPECHE AND SOUTH MEXICO 
ALONG 18N95W 18N97W 20N100W. RADAR SHOWS RAIN AND SHOWERS OVER 
THE NW GULF AND OVER S TEXAS FROM 24N-29N BETWEEN 95W-100W. 
SCATTERED SHOWERS ARE ALSO WITHIN 60 NM OF THE REMAINDER OF THE 
FRONTS. ELSEWHERE...WINDS N OF THE FRONT OVER THE NE GULF ARE 
PREDOMINATELY NE 15-20 KT. IN THE UPPER LEVELS...THE BACK SIDE 
OF AN UPPER LEVEL RIDGE IS PRODUCING SW FLOW OVER THE ENTIRE 
GULF OF MEXICO. SIGNIFICANT UPPER LEVEL MOISTURE IS OVER THE 
GULF EXCEPT THE SE GULF WHERE STRONG SUBSIDENCE PERSISTS. 
EXPECT...THE SURFACE LOW AND RELATED COLD FRONTS TO DRIFT NE TO 
THE LOUISIANA COAST IN 24 HOURS WITH CONVECTION.

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. STRONGEST WINDS OF 
25-30 KT REMAIN NEAR THE COASTS OF COLOMBIA AND VENEZUELA. 
PATCHES OF BROKEN LOW CLOUDS WITH ISOLATED SHOWERS DOTS THE 
CARIBBEAN NAMELY OVER THE CENTRAL AND EASTERN CARIBBEAN E OF 
78W FROM 13N-20N...AND THE W CARIBBEAN AND CENTRAL AMERICA W OF 
82W FROM 8N-20N. IN THE UPPER LEVELS...AN UPPER LEVEL RIDGE IS 
OVER THE CARIBBEAN WITH AXIS ALONG 73W. VERY STRONG SUBSIDENCE 
IS ACROSS THE BASIN SUPPRESSING DEEP CONVECTION. 
EXPECT...CONVECTION OVER THE NW CARIBBEAN OVER THE NEXT 24 
HOURS. ALSO EXPECT THE TRADEWINDS AND SHOWERS TO PERSIST WITH 
LITTLE CHANGE.   

ATLANTIC OCEAN...
A COLD FRONT IS OVER THE NW ATLANTIC FROM 32N67W TO S FLORIDA 
NEAR 27N80W. SCATTERED SHOWERS ARE 120 NM N OF THE FRONT. A 1020 
MB HIGH IS OVER THE W ATLANTIC NEAR 25N69W. A 1008 MB LOW IS 
CENTERED OVER THE CENTRAL ATLANTIC NEAR 27N39W. A SURFACE TROUGH 
EXTENDS NE TO 28N34W 30N29W. SCATTERED MODERATE CONVECTION IS 
FROM 25N-30N BETWEEN 32W-36W.  ISOLATED MODERATE CONVECTION IS 
ALSO SW OF THE CANARY ISLANDS FROM 24N-27N BETWEEN 21W-24W.      
IN THE UPPER LEVELS...AN UPPER LEVEL RIDGE IS OVER THE W 
ATLANTIC W OF 50W. A BROAD UPPER LEVEL TROUGH IS OVER THE E 
ATLANTIC N OF 20N E OF 50W. ZONAL FLOW IS OVER THE REMAINDER OF 
THE AREA. EXPECT... A THE COLD FRONT OVER THE W ATLANTIC TO MOVE 
SE TO THE CENTRAL ATLANTIC OVER THE NEXT 24 HOURS WITH SHOWERS 
AND CONVECTION. 

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

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FORMOSA