000
AXNT20 KNHC 180505
TWDAT 

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
105 AM EST SUN 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 
0430 UTC.

...THE ITCZ...
THE ITCZ AXIS IS CENTERED ALONG 6N10W 1N20W ALONG THE EQUATOR 
FROM 22W-42W AND INTO NE BRAZIL NEAR 1S46W. SCATTERED MODERATE 
CONVECTION IS WITHIN 150 NM ON EITHER SIDE OF THE AXIS BETWEEN 
19W-29W. SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS FROM 
3S-2N BETWEEN 32W-39W.

...DISCUSSION...

GULF OF MEXICO...
A SURFACE RIDGE EXTENDS FROM A 1029 MB HIGH CENTERED OVER 
GEORGIA SW ACROSS THE FLORIDA BIG BEND TO THE BAY OF CAMPECHE.   
E TO SE WINDS 10-15 KT IN THE SW GULF WILL SHIFT SOUTHERLY AND 
DIMINISH AS THE RIDGE WEAKENS AND DRIFTS SOUTHEAST. N OF 
25N...SOUTHERLY RETURN FLOW TO 15 KT IS EXPECTED TO SHIFT SW AND 
INCREASE TO 15-20 KT AS A COLD FRONT APPROACHES FROM THE NORTH. 
THIS FRONT IS EXPECTED TO ENTER THE NW GULF LATER TODAY. 
ISOLATED SHOWERS ARE OBSERVED ON DOPPLER RADAR IN THE FLORIDA 
STRAIGHTS. ELSEWHERE...MODERATE TO STRONG SUBSIDENCE ALOFT IS 
PREVENTING THE FORMATION OF SIGNIFICANT CONVECTION.

CARIBBEAN SEA...
PATCHY CLOUDS AND ISOLATED SHOWERS...ASSOCIATED WITH A FORMER 
FRONTAL BOUNDARY...REMAIN IN THE NW CARIBBEAN. NE WINDS 20-25 KT 
IN THE REGION ARE EXPECTED TO WEAKEN TO NE-E 15-20 KT. BROAD 
CIRCULATION IS EVIDENT ON SATELLITE IMAGERY SURROUNDING A SFC 
TROUGH IN THE E CARIBBEAN. THIS TROUGH ENTERS THE REGION FROM 
THE W ATLC THROUGH THE MONA PASSAGE AND EXTENDS TO CURACAO IN 
THE NETHERLANDS ANTILLES. SCATTERED SHOWERS MOVING OVER THE MONA 
PASSAGE...PUERTO RICO AND ERN HISPANIOLA ARE OBSERVED ON SAN 
JUAN DOPPLER RADAR. ADDITIONAL SHOWERS ARE W OF THE TROUGH AXIS 
N OF 13N AND E OF 75W. THIS TROUGH IS EXPECTED TO MOVE WESTWARD 
AND BECOME DIFFUSE NEAR 76W ON MON. MODERATE TRADE WINDS PERSIST 
ACROSS THE CARIBBEAN W OF THE TROUGH. ALOFT...AN UPPER LEVEL 
TROUGH IS ACROSS THE NW CARIBBEAN WHILE AN UPPER LEVEL RIDGE IS 
ACROSS THE CENTRAL AND ERN CARIBBEAN WITH STRONG SUBSIDENCE AND 
DRY AIR OBSERVED E OF 71W.

ATLANTIC OCEAN...
SFC HIGH PRESSURE OVER SOUTHEAST GEORGIA IS MAINTAINING FAIR 
CONDITIONS ACROSS THE W ATLC...HOWEVER...A COLD FRONT IS 
EXPECTED TO MOVE OFF THE SE US COAST LATE TONIGHT AS THE HIGH 
WEAKENS AND SHIFTS TO THE SOUTHEAST. SCATTERED SHOWERS EXTEND 60 
NM AHEAD OF A COLD FRONT THAT ENTERS THE DISCUSSION AREA NEAR 
31N57W AND EXTENDS TO 26N63W WHERE IT WEAKENS AND CONTINUES AS A 
SFC TROUGH TO THE WINDWARD PASSAGE. FARTHER SOUTH...ANOTHER SFC 
TROUGH EXTENDS FROM 21N67W THROUGH THE MONA PASSAGE AND INTO THE 
E CARIBBEAN. SCATTERED SHOWERS ASSOCIATED WITH THE TROUGH ARE S 
OF 22N BETWEEN 65W-70W. A STRONG SURFACE RIDGE ANCHORED ON A 
1036 MB HIGH NEAR 32N33W COVERS THE REMAINDER OF THE ATLC. 
ALOFT...A DIFFLUENT PATTERN IN THE TROPICS IS ENHANCING 
CONVECTION ALONG THE ITCZ.

$$
WADDINGTON