000
AXNT20 KNHC 190538
TWDAT 

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
105 AM EST MON JAN 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 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
0445 UTC.

...THE ITCZ...
THE ITCZ AXIS IS CENTERED ALONG 7N9W ALONG THE EQUATOR BETWEEN 
22W TO 37W THEN S OF THE EQUATOR INTO SOUTH AMERICA NEAR 2S46W. 
SCATTERED MODERATE/STRONG CONVECTION IS FROM 3N TO S OF THE 
EQUATOR BETWEEN 27W-38W. CLUSTERS OF SIMILAR CONVECTION ARE FROM 
2N-5N E OF 13W TO ACROSS THE PRIME MERIDIAN. SCATTERED MODERATE/ 
ISOLATED STRONG CONVECTION IS WITHIN 60 NM ON EITHER SIDE OF THE 
ITCZ FROM 18W-24W. CLUSTERS OF SIMILAR CONVECTION ARE FROM 8N TO 
THE EQUATOR BETWEEN 38W-52W. 

...DISCUSSION...

GULF OF MEXICO...
A DEEP LAYERED TROUGH IS ACROSS THE E US AND SUPPORTS A COLD 
FRONT THAT ENTERS THE GULF E OF TALLAHASSEE FLORIDA EXTENDING SW 
ALONG 28N87W TO OFF THE MEXICO COAST NEAR 24N96W. SCATTERED 
SHOWERS WITH EMBEDDED ISOLATED THUNDERSTORMS WITHIN 120 NM SE 
OF THE FRONT. A WEAK RIDGE OF HIGH PRESSURE EXTENDS FROM THE W 
ATLC THROUGH THE FLORIDA STRAITS OVER THE S GULF ALONG 23N. 
ALOFT...NORTHWESTERLY FLOW DOMINATES THE GULF WITH A JET STREAM 
OF WINDS FROM 80 TO 130 KT EXTENDING N OF LINE FROM NEAR 
BROWNSVILLE TEXAS TO THE YUCATAN CHANNEL. BAND OF MODERATE 
SUBSIDENCE AND DRIER STABLE AIR IS N OF THE FRONT EXTENDING 
WITHIN 120 NM OF LINE FROM TEXAS S OF GALVESTON TO NEAR 27N87W 
LEAVING MOST OF THE N GULF CLEAR TONIGHT. 

CARIBBEAN SEA...
BROAD UPPER TROUGH THAT COVERS THE GULF OF MEXICO DIPS S OVER 
THE NW CARIBBEAN COUPLED WITH THE UPPER RIDGE ANCHORED OVER 
SOUTH AMERICA IS GIVING THE CARIBBEAN MOSTLY SW TO W UPPER FLOW. 
MODERATE/STRONG SUBSIDENCE DOMINATES THE ENTIRE AREA. A SURFACE 
TROUGH EXTENDS FROM THE W ATLC ACROSS HISPANIOLA TO NEAR 12N75W. 
SCATTERED SHOWERS ARE ACROSS HISPANIOLA AND WITHIN 90 NM OF A 
LINE FROM 18N72W TO 10N80W. NE SURFACE FLOW IS BANKING LOW 
CLOUDS WITH SCATTERED SHOWERS ALONG THE MOUNTAINS OF W PANAMA 
AND COSTA RICA AS WELL AS WITHIN 90 NM ALONG THE COASTLINE. THE 
REMAINDER OF THE CARIBBEAN IS TRANQUIL TONIGHT.

ATLANTIC OCEAN...
BROAD UPPER LEVEL TROUGH THAT COVERS THE GULF OF MEXICO AND THE 
NW CARIBBEAN COVERS THE W ATLC W OF 60W. THIS UPPER TROUGH IS 
SUPPORTING A STATIONARY FRONT THAT ENTERS THE REGION NEAR 32N59W 
EXTENDING SW ALONG 27N64W TO JUST N OF HISPANIOLA NEAR 21N71W 
WHERE IT CONTINUES INTO THE CARIBBEAN AS A SURFACE TROUGH. 
SCATTERED SHOWERS AND POSSIBLE ISOLATED THUNDERSTORMS ARE WITHIN 
120 NM ON EITHER SIDE OF THE FRONT N OF 25N. A JET STREAM WITH 
WINDS OF 80 TO 120 KT EXTENDS FROM ACROSS THE GULF MEXICO WITHIN 
120/150 NM OF LINE FROM 24N80W ALONG 24N75W WEAKENING TO 80 TO 
100 KT NE TO BEYOND BERMUDA. THE REMAINDER OF THE ATLC IS 
DOMINATED BY BENIGN UPPER FEATURES AND A BROAD SURFACE RIDGE 
THAT COVERS THE AREA N OF 10N E OF 60W ANCHORED BY A 1035 MB 
HIGH NEAR 32N33W GIVING THE AREA FAIR WEATHER CLOUDS TONIGHT. 

$$
WALLACE