000
AXNT20 KNHC 281749
TWDAT 

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
205 PM EDT WED MAR 28 2007

TROPICAL WEATHER DISCUSSION FOR NORTH AMERICA...CENTRAL 
AMERICA...THE GULF OF MEXICO...THE CARIBBEAN SEA...NORTHEASTERN 
SECTIONS OF SOUTH AMERICA...AND THE 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.

...ITCZ...

AS IS USUAL FOR THIS TIME OF THE YEAR THE ITCZ AXIS IS N OF THE 
EQUATOR. IT IS CENTERED ALONG 5N10W 2N25W 2N35W CROSSING THE 
EQUATOR AT 48W INTO NE BRAZIL. CLUSTERS OF SCATTERED MODERATE TO 
ISOLATED STRONG CONVECTION ARE WITHIN 100-120 NM N OF THE AXIS W 
OF 20W. SIMILAR CONVECTION IS NEAR 3N12W. 

...DISCUSSION...

GULF OF MEXICO...
A BROAD UPPER RIDGE THAT IS ANCHORED IN THE EPAC JUST SOUTH OF 
COSTA RICA COVERS THE YUCATAN PENINSULA AND THE ENTIRE GULF. 
STRONG SUBSIDENCE AND DRY AIR CONTINUE TO DOMINATE MOST OF THE 
REGION AND THE FLORIDA PENINSULA LIMITING ANY SHOWER ACTIVITY. 
SOME UPPER LEVEL MOISTURE IS BEING TRANSPORTED FROM THE EPAC 
INTO SOUTH-CENTRAL MEXICO AND THE BAY OF CAMPECHE BY STRONG SW 
UPPER FLOW. A 1023 MB WRN ATLANTIC SURFACE HIGH IS PRODUCING 
10-15 E TO SE WINDS OVER MOST OF THE GULF. THE SE RETURN FLOW 
WILL SLIGHTLY INCREASE TONIGHT OVER THE NW CORNER OF THE GULF AS 
SURFACE LOW PRES DEEPENS OVER NE MEXICO. WINDS HAVE ALREADY 
DIMINISHED OVER THE STRAITS OF FLORIDA. 

CARIBBEAN...
UPPER HIGH IN THE E PACIFIC ALSO COVERS THE W CARIBBEAN W OF 75W 
AS THE UPPER LOW SHIFTS FURTHER E TO JUST N OF THE LEEWARD 
ISLANDS WITH THE UPPER TROUGH CONTINUING MAINLY S TO NEAR 
13N66W. STRONG SUBSIDENCE AND DRY AIR DOMINATES MOST OF THE 
BASIN. A SURFACE REFLECTION IN THE FORM OF A SURFACE TROUGH 
EXTENDS FROM NEAR 22N65W ACROSS THE MONA PASSAGE TO NEAR 15N70W. 
THIS SURFACE TROUGH HAS BEEN REPOSITIONED BASED ON SURFACE DATA 
AND EARLIER QUIKSCAT PASS. THIS FEATURE IS STILL GENERATING  
SCATTERED SHOWERS/ISOLATED THUNDERSTORMS OVER PUERTO RICO...THE 
VIRGIN ISLANDS AND THE REGIONAL COASTAL WATERS. THE SE CARIBBEAN 
IS UNDER THE INFLUENCE OF A STRONG UPPER RIDGE THAT IS ANCHORED 
IN THE TROPICAL ATLC NEAR 6N36W GIVING THE AREA SW UPPER FLOW. 
THESE WINDS ARE ADVECTING TROPICAL MOISTURE FROM NORTH SOUTH 
AMERICA INTO THE SE CARIBBEAN AND THE TROPICAL N ATLANTIC.  
MODERATE TO STRONG EASTERLY WINDS ARE OVER THE W CARIBBEAN W OF 
75W WHILE THE REMAINDER OF THE CARIBBEAN IS UNDER LIGHT/MODERATE 
SURFACE WINDS. 

ATLANTIC...
AN UPPER LEVEL TROUGH DOMINATES THE FLOW NORTH OF 20N WEST OF 
60W...WITH A SHORT WAVE TROUGH MOVING E ACROSS THE CENTRAL 
BAHAMAS AND ANOTHER UPPER LEVEL TROUGH EXTENDING ACROSS THE 
VIRGIN ISLES TO THE EASTERN CARIBBEAN. A SURFACE REFLECTION IN 
THE FORM OF A SURFACE TROUGH LIES ACROSS THE MONA PASSAGE. AN 
AREA OF SCATTERED MODERATE CONVECTION IS FOUND E OF THE TROUGH  
FROM 20N-28N BETWEEN 45W-65W. A DIFFLUENT PATTERN ALOFT BETWEEN 
THE UPPER TROUGH AND STRONG UPPER RIDGE THAT DOMINATES THE 
EAST-CENTRAL ATLC IS ENHANCING THIS CONVECTIVE ACTIVITY. LATEST 
SAT VIS IMAGERY SHOWS A SWIRL OF LOW CLOUDS FORMING NEAR 21N67W. 
MODEL GUIDANCE CONTINUE TO DEVELOP A WEAK SFC LOW PROBABLY NE OF 
PUERTO RICO AND MOVE IT ENE ALONG REMNANTS OF A FRONT BOUNDARY 
THAT EXTENDS FROM 23N57W NE TO BEYOND 32N38W. A BAND OF MOISTURE 
IS FORECAST TO PERSIST OVER THE NE CARIBBEAN DURING THE NEXT FEW 
DAYS KEEPING THE CHANCES OF RAINFALL OVER THE AREA. BROAD 
SURFACE RIDGE REMAINS OVER THE E ATLC E OF THE COLD FRONT 
ANCHORED BY A 1030 MB HIGH SE OF THE AZORES. THIS AREA REMAINS 
RATHER TRANQUIL WITH ONLY SCATTERED FRAGMENTS OF LOW LEVEL 
CLOUDS.  
       
$$
GR