000
AXNT20 KNHC 192359
TWDAT 

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL  
705 PM EST SAT DEC 19 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 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
2315 UTC.

...ITCZ...

THE ITCZ AXIS IS CENTERED ALONG 10N16W 3N30W 1N48W. ISOLATED 
MODERATE CONVECTION IS EMBEDDED IN THE ITCZ FROM 24W-30W. 
SIMILAR CONVECTION IS WITHIN 180 NM NORTH OF THE AXIS BETWEEN 
40W-51W.

...DISCUSSION...

GULF OF MEXICO...
HIGH LEVEL CLOUDS ARE NOTICED FROM SATELLITE IMAGERY DUE TO SW 
FLOW ALOFT BRINGING MID LEVEL MOISTURE TO THE REGION. 
NEVERTHELESS...THERE IS NO LOW LEVEL SUPPORT TO INITIATE 
CONVENTION DUE TO SURFACE HIGH PRESSURE OVER THE NW BASIN 
CONTINUES TO BRING A DRIER AIR MASS TO THE ENTIRE BASIN. 
CLEARING OF CLOUDS IS BEST SEEN OVER THE NW BASIN WHERE SURFACE 
HIGH PRESSURE IS THE STRONGEST. SURFACE NORTHERLY WINDS ARE 
NOTED ON SHIP AND BUOY OBSERVATIONS ACROSS THE GULF THIS EVENING 
AS SURFACE HIGH PRESSURE IS FORECAST TO BUILD IN ACROSS THE 
NORTHERN GULF COAST THROUGH MONDAY. 

CARIBBEAN SEA...
A COLD FRONT EXTENDS FROM THE SW NORTH ATLC ACROSS EASTERN CUBA 
AND INTO THE NW CARIBBEAN. THIS FRONT IS SUPPORTED ALOFT BY A 
VIGOROUS UPPER LEVEL TROUGH LOCATED OFF THE NORTH CAROLINA ATLC 
COAST. HOWEVER...THE SOUTHERN TIP OF THIS FRONT IS QUICKLY 
WEAKENING AS IT MOVES THROUGH EASTERN CUBA AND CENTRAL JAMAICA. 
ISOLATED SHOWERS ARE OCCURRING WITHIN 30 NM E OF THE FRONTAL  
BOUNDARY. MIDDLE TO UPPER LEVEL MOISTURE FROM THE EASTERN 
PACIFIC IS BEING ADVECTED ACROSS THE NW BASIN...PROVIDING 
MOISTURE TO THE FRONTAL BOUNDARY. THE REMAINDER OF THE 
CARIBBEAN...EAST OF 73W...IS UNDER THE INFLUENCE OF A BROAD 
UPPER LEVEL RIDGE. THEREFORE...MAINLY DRY AIR AND STRONG 
SUBSIDENCE IS NOTED IN THE UPPER LEVELS ON WATER VAPOR 
IMAGERY...ONLY ISOLATED SHOWERS ARE SEEN ON THE RADAR. EASTERLY 
TRADE WINDS UP TO 20 KT CONTINUE AND GENERALLY FAIR SKIES 
PREVAIL IN THIS REGION. 

ATLANTIC OCEAN...
A 984 MB LOW IS CENTERED AROUND 36N72W WITH A COLD FRONT 
EXTENDING SOUTH INTO THE DISCUSSION AREA NEAR 30N64W. THIS COLD 
FRONT CONTINUES TO EXTEND SW ALONG 26N68W TO EASTERN CUBA NEAR 
21N76W. A SECONDARY WEAKER COLD FRONT IS ANALYZED 100 NM BEHIND 
THE MAIN FRONT. SCATTERED SHOWERS AND ISOLATED THUNDERSTORMS ARE 
OCCURRING WITHIN 50 NM EAST OF THE MAIN FRONT. FARTHER EAST 
ACROSS THE CENTRAL ATLC...ANOTHER COLD FRONT ENTERS THE REGION 
NEAR 30N25W AND EXTENDS SW ALONG 25N30W TO 21N38W...WHERE IT 
CONTINUES AS A STATIONARY FRONT TO NEAR 23N58W. SCATTERED 
SHOWERS AND THUNDERSTORMS ARE OCCURRING WITHIN 150 NM EAST OF 
THE FRONT NORTH OF 22N...WHILE ISOLATED SHOWERS LINGER WITHIN 
100 NM EITHER SIDE OF THE COLD AND STATIONARY FRONT. THIS 
FRONTAL SYSTEM IS SUPPORTED BY AN UPPER LEVEL TROUGH OVER THE 
NORTH CENTRAL ATLC. THE EASTERN ATLC IS UNDER THE INFLUENCE OF A 
1016 MB HIGH CENTERED NEAR 23N20W.

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

$$

GARCIA