000
AXNT20 KNHC 271746
TWDAT 

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
105 PM EST TUE JAN 27 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.

...THE ITCZ...
ITCZ AXIS IS CENTERED ALONG 6N9W 3N17W 2N30W 1N47W CROSSING THE 
ITCZ NEAR 50W. CLUSTERS OF SCATTERED MODERATE/ISOLATED STRONG 
CONVECTION ARE WITHIN 120 NM N OF THE ITCZ FROM 34W-46W AND 
WITHIN 90 NM S OF THE ITCZ FROM 33W-38W. SCATTERED MODERATE 
CONVECTION IS S OF 6N W OF 47W TO INLAND OVER SOUTH AMERICA. 
 
...DISCUSSION...

GULF OF MEXICO...
BROAD UPPER RIDGE CONTINUES TO DOMINATE THE GULF ANCHORED IN THE 
E PACIFIC REGION GIVING THE ENTIRE GULF WESTERLY UPPER FLOW. A 
SURFACE RIDGE ANCHORED IN THE W ATLC EXTENDS W ACROSS MUCH OF 
THE GULF GIVING THE ENTIRE GULF SOUTHERLY SURFACE FLOW. THIS 
COMBINED IS PRODUCING FAIR AND MILD CONDITIONS ACROSS THE AREA. 
SCATTERED SHOWERS OVER THE FLORIDA STRAITS AND FAR SE WATERS 
INCLUDING THE FLORIDA KEYS ASSOCIATED WITH WEAK TROUGH IN THE W 
ATLC. THIS RATHER TRANQUIL PATTERN IS EXPECTED TO CONTINUE UNTIL 
THE NEXT FRONT ENTERS THE NW WATERS LATE TONIGHT CROSSING THE 
GULF BY FRI AS A SURFACE RIDGE BUILDS OVER THE PLAIN STATES. 

CARIBBEAN SEA...
AN UPPER LOW IS OVER THE WINDWARD PASSAGE EXTENDING AN UPPER 
TROUGH SW TO THE TIP ON NICARAGUA/HONDURAS. HOWEVER...STRONG 
SUBSIDENCE AND DRY STABLE AIR ALOFT IS LIMITING ANY DEEP 
SHOWERS/CONVECTION. A TIGHT SURFACE PRESSURE GRADIENT BETWEEN 
THE RIDGE OVER THE ATLC AND LOWER PRESSURE OVER THE TROPICS IS 
PRODUCING STRONG EASTERLY TRADE WINDS ACROSS THE CARIBBEAN WITH 
GALE FORCE WINDS ALONG THE COAST OF COLOMBIA. THESE WINDS WILL 
DIMINISH BY WED AS THE ATLC RIDGE BEGINS TO WEAKEN THROUGH FRI. 
THESE WINDS ARE ALSO USHERING IN LOW LEVEL CLOUDS WITH ISOLATED 
FAST MOVING SHOWERS ACROSS THE ENTIRE CARIBBEAN. A COLD FRONT 
WILL MOVE INTO THE REGION OVER THE YUCATAN CHANNEL LATE FRI AND 
WILL CONTINUE EASTWARD EXTENDING FROM CENTRAL CUBA TO THE GULF 
OF HONDURAS FRI NIGHT AND HAITI TO EASTERN HONDURAS SAT NIGHT. 
 
ATLANTIC OCEAN...
RELATIVELY TRANQUIL WEATHER CONTINUES ACROSS THE ATLC TODAY AS 
THE ATLC HIGH PRESSURE RIDGE COVERS MUCH OF THE BASIN. NEAR 
ZONAL WESTERLY UPPER FLOW DOMINATES THE ATLC W OF 30W WITH AN 
UPPER TROUGH OVER THE REMAINDER OF THE FAR E ATLC. AT THE 
SURFACE IS A WEAK COLD FRONT THAT EXTENDS FROM THE N/CENTRAL 
ATLC THROUGH BERMUDA TO 31N70W. A SECOND COLD FRONT IS TO THE E 
EXTENDING THROUGH 32N41W TO 31N44W CONTINUING AS A SURFACE 
TROUGH TO 28N51W. ISOLATED SHOWERS ARE WITHIN 60 NM EITHER SIDE 
OF THE FRONT/TROUGH. A REMNANT SURFACE TROUGH IS OVER THE SW 
ATLC EXTENDING FROM 27N61W TO 22N69W GENERATING ISOLATED SHOWERS 
WITHIN 180 NM W OF THE TROUGH. STRONG SUBSIDENCE AND DRY STABLE 
AIR ALOFT IS LIMITING ANY DEEP SHOWERS/CONVECTION ACROSS THE 
ENTIRE BASIN. THE SURFACE RIDGE THAT DOMINATES MUCH OF THE ATLC 
EXTENDS FROM A 1029 MB HIGH JUST W OF THE MADEIRA ISLANDS SW 
THROUGH 32N22W ALONG 27N30W THEN W TO A 1028 MB HIGH IN THE W 
ATLC NEAR 30N75W AND CONTINUES TO OVER THE GULF OF MEXICO AND 
THE FAR SE US WITH A WEAKNESS IN THE VICINITY OF THE SURFACE 
TROUGHS MENTIONED ABOVE. 
 
$$
WALLACE