000
AXNT20 KNHC 281044
TWDAT 

TROPICAL WEATHER DISCUSSION 
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
805 AM EDT TUE APR 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 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
1115 UTC.

...THE ITCZ...
THE ITCZ AXIS IS CENTERED ALONG 04N09W TO 02N22W TO 02S43W. 
SCATTERED MODERATE TO ISOLATED STRONG CONVECTION WITHIN 90 NM OF 
AXIS E OF 13W TO THE AFRICAN COAST. 

...DISCUSSION...

GULF OF MEXICO...
A WEAKENING BAND OF SHOWERS AND TSTMS IS MOVING THROUGH THE 
LOWER MISSISSIPPI VALLEY AND ADJACENT GULF WATERS THIS EVENING. 
THIS ACTIVITY IS ASSOCIATED WITH A SHORT WAVE TROUGH MOVING 
THROUGH SOUTHERN PLAINS. OTHERWISE...SURFACE FLOW IS MAINLY 15 
TO 20 KT ACROSS THE GULF ON THE SE FRINGE OF 1031 MB SURFACE 
HIGH PRES CENTERED OFF THE CAROLINA COAST. BROKEN TO OVERCAST 
SKIES COVER THE NW GULF ASSOCIATED WITH THE NEARBY 
CONVECTION...WITH GENERALLY SCATTERED SKIES ELSEWHERE. THE HIGH 
PRES OFF THE CAROLINAS IS EXPECTED TO WEAKEN LATER IN THE WEEK 
ALLOWING THE E TO SE WINDS ACROSS THE GULF TO DIMINISH. 

CARIBBEAN SEA...
HIGH PRES LOCATED N OF AREA MAINTAINS FRESH TO STRONG SURFACE 
WIND ACROSS MUCH OF THE BASIN WITH THE STRONGEST WINDS IN THE 
TYPICAL AREA NEAR THE COAST OF COLOMBIA. THIS WEATHER PATTERN 
WILL PERSIST DURING THE NEXT 24 HOURS. THE HIGH IS FORECAST TO 
GRADUALLY WEAKEN TUE THROUGH FRI. AS A RESULT...THE TRADE WINDS 
ARE EXPECTED TO DIMINISH DURING THIS TIME-FRAME. A BROAD UPPER 
LEVEL RIDGE COVERS MOST OF THE CARIBBEAN...WITH MOSTLY SW TO W 
UPPER LEVEL WINDS. THESE WINDS ARE TRANSPORTING ABUNDANT 
MID/UPPER LEVEL MOISTURE FROM THE EPAC REGION ACROSS N CENTRAL 
AMERICA INTO THE CARIBBEAN SEA...THEN OVER E CUBA...JAMAICA AND 
HISPANIOLA. TRADE WINDS CONVERGENCE IS AIDING LOW-TOPPED TRADE 
WIND SHOWERS ACROSS THE REGION...MORE CONCENTRATED OVER THE 
EASTERN CARIBBEAN AND JAMAICA. PATCHES OF LOW-LEVEL MOISTURE 
WILL CONTINUE TO PROPAGATE ACROSS THE CARIBBEAN SEA PRODUCING 
ISOLATED TO SCATTERED PASSING SHOWERS. 

ATLANTIC OCEAN...
A 1031 MB HIGH PRES AREA OFF THE CAROLINA COAST CONTINUES TO 
DOMINATE THE PATTERN IN THE WESTERN ATLC. SCATTEROMETER AND BUOY 
DATA SHOW A BROAD AREA OF 20 TO 25 KT TRADE WINDS PERSISTING 
SOUTH OF THE SURFACE HIGH...MAINLY W OF 60W. SIMILARLY FRESH TO 
STRONG NE TO E WINDS ARE NOTED OVER THE EASTERN ATLC BETWEEN A 
1030 MB HIGH PRES AREA NEAR THE AZORES AND LOW PRES OVER W 
AFRICA. A COLD FRONT EXTENDS FROM NE TO SW IN BETWEEN THE HIGH 
PRES CELLS...AND IS ANALYZED AS A SURFACE TROUGH S OF 32N ALONG 
ROUGHLY 45W. ALOFT...A REX BLOCK PATTERN CONTINUES OVER THE FAR 
WESTERN ATLC...WITH AN UPPER LOW ALONG 30N BETWEEN N FLORIDA AND 
BERMUDA SOUTH OF AN UPPER RIDGE OFF NEW ENGLAND. UPPER ENERGY 
DIGGING INTO THE BASE OF A MID/UPPER TROUGH ON THE EASTERN SIDE 
OF THE BLOCKING PATTERN EAST OF 60W IS FOSTERING A REINFORCING 
COLD FRONT OVER THE CENTRAL ATLC WATERS N OF 32N. THIS STALLS 
JUST TO THE NORTH OF THE AREA THROUGH WED AS THE BULK OF THE 
ENERGY LIFTS NE. MEANWHILE THE BLOCKING PATTERN BREAKS DOWN...AS 
THE UPPER LOW OFF N FLORIDA SHIFTS SE. THIS IN TURN ALLOWS THE 
SURFACE HIGH PRES OFF THE SE U.S. COAST TO WEAKEN...AND TRADES 
WINDS TO DIMINISH SLIGHTLY THROUGH THE BAHAMAS. EXPECT 
INCREASING DEEP LAYER MOISTURE NE OF THE LEEWARDS...AND SE OF 
THE UPPER TROUGH STARTING TODAY. MEANWHILE LITTLE CHANGE 
EXPECTED OVER THE EASTERN ATLC AS SURFACE HIGH PRES REMAINS IN 
PLACE ALONG 30N.

$$
CHRISTENSEN