000
AXNT20 KNHC 280536
TWDAT 

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
105 AM EST WED JAN 28 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 
0515 UTC.

...THE ITCZ...
ITCZ AXIS IS CENTERED ALONG 8N13W 4N17W 1N25W CROSSING THE 
EQUATOR NEAR 43W TO 1S48W. SCATTERED MODERATE CONVECTION IS 
WITHIN 90 NM N OF THE AXIS BETWEEN 19W-31W AND FROM 2N-5N 
BETWEEN 41W-45W. 
 
...DISCUSSION...

GULF OF MEXICO...
SLY LOW-LEVEL FLOW AND DRY AIR IN THE MID AND UPPER LEVELS ARE 
PROVIDING FAIR AND MILD WEATHER ACROSS MUCH OF THE GULF TONIGHT. 
VISIBILITIES MAY BE REDUCED AT TIMES OVER THE N CENTRAL AND NE 
WATERS IN FOG. HOWEVER...A SIGNIFICANT CHANGE IS UNDERWAY AS A 
COLD FRONT HAS JUST MOVED THROUGH THE TEXAS COASTAL STATIONS 
MARKED BY A NARROW LINE OF SHOWERS. STRONG N WINDS ARE FOLLOWING 
THE FRONT USHERING IN MUCH COOLER AIR. THE FRONT WILL BECOME 
REINFORCED BY A DEEPER UPPER TROUGH...EXPECTED TO SET UP GALE 
CONDITIONS IN THE ENHANCED FUNNELING ZONE OVER THE FAR SW BAY OF 
CAMPECHE ON FRI. THE FRONT IS EXPECTED TO CLEAR THE ENTIRE ZONE 
LATE FRI.

CARIBBEAN SEA...
SFC OBS AND QSCAT DATA REVEAL STRONG ELY TRADES ACROSS THE  
CARIBBEAN WITH SPEEDS MAINLY IN THE 20-25 KT RANGE...EXCEPT TO 
GALE FORCE NEAR THE COAST OF COLOMBIA ENHANCED BY CLIMATOLOGICAL 
LOW PRES OVER SOUTH AMERICA AND HIGH TERRAIN. THIS STRONG FLOW 
IS GENERATING ENOUGH INSTABILITY TO PRODUCE PATCHES OF LOW-LEVEL 
CLOUDS WITH EMBEDDED SHOWERS. CLOUDINESS APPEARS MOST ORGANIZED 
OVER THE E CARIBBEAN CLOSER TO A COUPLE OF WEAK PERTURBATIONS IN 
THE TROPICAL ATLC. HOWEVER...ALL OF THIS MOISTURE IS SHALLOW IN 
NATURE CAPPED BY ABUNDANT DRY STABLE AIR ALOFT IN A GENERAL 
CONFLUENT AREA BETWEEN AN UPPER LOW OVER HAITI AND AN UPPER HIGH 
OVER THE TROPICAL EPAC. TRADE WINDS ARE ANTICIPATED TO SLACKEN 
OVER THE W CARIBBEAN LATER TODAY IN RESPONSE TO A FRONTAL 
BOUNDARY...EXPECTED TO ENTER THE NW CARIB ON FRI.
  
ATLANTIC OCEAN...
NOT MUCH TO DISCUSS ACROSS THE ATLC BASIN WITH ONLY A WEAK 
TROUGH ANALYZED IN THE SUBTROPICS FROM 31N42W TO 28N48W. THIS 
BOUNDARY MAINLY REPRESENTS A WIND SHIFT AS SAT IMAGERY ONLY 
SHOWS A NARROW LINE OF BROKEN CLOUDS ALONG IT. THERE ARE A 
COUPLE OF WEAK FRONTS JUST N OF THE ZONE...BUT THESE ARE NOT 
PRODUCING ANY SENSIBLE WEATHER IN THE DISCUSSION ZONE. TRADE 
WINDS REMAIN 20-25 KT ACROSS A LARGE PORTION OF THE AREA... 
GENERALLY S OF 24N E OF THE BAHAMAS SUPPORTED BY AN E-W HIGH 
PRES RIDGE ALONG 32N/33N. THE UPPER PATTERN IS RATHER 
FLAT...WHICH IS NOT SURPRISING GIVEN THE ABSENCE OF SFC 
FEATURES. MOST OF THE AREA LIES UNDER A SUBSIDENT ENVIRONMENT 
PROMOTING FAIR WEATHER. HOWEVER...AN UPPER DIFFLUENT PATTERN 
OVER THE DEEP TROPICS IS AIDING IN THE DEVELOPMENT OF CONVECTION 
WITHIN THE ITCZ W OF 40W.

$$
CANGIALOSI