000
AXNT20 KNHC 031015
TWDAT 

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
805 AM EDT SUN MAY 03 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
0800 UTC.

...THE ITCZ...

THE ITCZ AXIS EXTENDS FROM OFF THE COAST OF W AFRICA NEAR 04N01W 
TO 03N10W TO THE EQUATOR AT 23W TO NE BRAZIL NEAR 04S38W. 
SCATTERED MODERATE TO ISOLATED STRONG CONVECTION CAN BE FOUND 
NEAR THE COAST OF AFRICA FROM 01N TO 05N E OF 05W AND ALONG THE 
COAST OF BRAZIL FROM 06S TO 01S W OF 30W.

...DISCUSSION...

GULF OF MEXICO...
HIGH CLOUDS ON THE ON THE LEADING EDGE OF THE DEEP LAYER TROUGH 
MOVING THROUGH TEXAS HAVE PUSHED SOUTHEASTWARD INTO THE NW AND N 
CENTRAL GULF OF MEXICO. ELSEWHERE...FAIR WEATHER AND SUBSIDENT 
CONDITIONS PREVAIL OVER THE REGION. THE ASCAT PASS FROM 0318 
UTC SHOWS SE WINDS ACROSS THE WESTERN GULF TO 25 KT. THIS STRONG 
SOUTHEASTERLY FLOW IS THE RESULT OF THE TIGHT PRESSURE GRADIENT 
BETWEEN THE WESTERN EDGE OF THE ATLC RIDGE WHICH EXTENDS INTO 
THE EASTERN GULF AND THE TROUGHING OVER THE SOUTHERN PLAINS. AS 
THIS TROUGH MOVES EASTWARD THROUGH THE SOUTHEASTERN U.S. OVER 
THE NEXT DAY OR TWO...LOOK FOR THE RIDGE AXIS TO RETREAT TO THE 
E SOMEWHAT...WEAKENING THE PRESSURE GRADIENT AND RESULTING WINDS 
OVER THE W GULF.  

CARIBBEAN SEA...
UPPER LEVEL SOUTHWESTERLY FLOW ON THE WESTERN SIDE OF THE UPPER 
RIDGE OVER THE WESTERN AND CENTRAL CARIBBEAN IS TRANSPORTING 
UPPER LEVEL MOISTURE FROM THE EASTERN PACIFIC THROUGH CENTRAL 
AMERICA INTO THE WESTERN CARIBBEAN...WITH MULTILAYERED 
CLOUDINESS AND SOME ISOLATED SHOWERS FOUND OVER THE GULF OF 
HONDURAS AND MUCH OF THE SW CARIBBEAN WITH SCATTERED MODERATE 
CONVECTION DEVELOPING OVER THE LAST FEW HOURS WITHIN 30 NM OF 
THE COAST OF COLOMBIA AND PANAMA FROM 76W TO 78W. THE 2312 
QUIKSCAT PASS REVEALED WINDS TO 25 KT OVER MUCH OF THE CENTRAL 
CARIBBEAN...WITH EVEN STRONGER WINDS IN THE ATLC PASSAGES. THESE 
STRONG WINDS ARE THE RESULT OF THE TIGHT PRESSURE GRADIENT 
BETWEEN THE RIDGE AXIS CENTERED FROM BERMUDA THROUGH CENTRAL 
FLORIDA AND TROUGHING BOTH TO THE SOUTH AND THE EAST.  THE 
TROUGHING TO THE SOUTH IS ASSOCIATED WITH CLIMATOLOGICAL LOW 
PRESSURE CENTERED NEAR THE COAST OF COLOMBIA WHILE THE TROUGHING 
TO THE EAST IS ATTRIBUTED TO THE DEEP LAYER TROUGH BEGINNING TO 
BREAK DOWN OVER THE NORTHERN LESSER ANTILLES. MIMIC-TPW IMAGERY 
SHOWS LOW TO MID LEVEL MOISTURE CONVERGENCE OVER THE LESSER 
ANTILLES DUE TO THE TROUGH. MOSTLY ISOLATED SHOWERS CAN BE SEEN 
ON THE GUADALOUPE RADAR...WITH A MORE ORGANIZED BAND TO THE SE 
OF BARBADOS EXTENDING EASTWARD INTO THE ATLC. THE LOW LEVEL 
TROUGH IS EXPECTED TO CONTINUE MOVING NORTHWESTWARD INTO THE 
GREATER ANTILLES OVER THE NEXT DAY OR TWO...SHIFTING THE 
MOISTURE POOL AND THE GREATEST CHANCE FOR SHOWER ACTIVITY 
WESTWARD WITH IT.

ATLANTIC OCEAN...
A WEAK UPPER TROUGH CURRENTLY LIES FROM BERMUDA JUST NORTH OF 
THE BAHAMAS INTO FLORIDA...CORRESPONDING WITH THE SAME POSITION 
AS THE RIDGE AXIS AS THE SURFACE. MOSTLY DRY AIR ALOFT IN THIS 
REGION HAS BROUGHT FAIR WEATHER HERE. THERE IS NO NOTABLE SHOWER 
ACTIVITY ON BAHAMIAN OR U.S. RADARS IN THIS REGION AT THE 
MOMENT. THE 0136 ASCAT PASS SHOWS THE STRONGEST WINDS IN THE 
ATLC CAN BE FOUND ON THE NORTHEASTERN EDGE OF THE SURFACE TROUGH 
ALONG 62W TO 52W FROM 22N TO 27N...WITH EASTERLY WINDS TO 25 KT. 
THE PRESSURE GRADIENT IS GREATEST HERE IN THE REGION BETWEEN 
THIS TROUGH AND THE RIDGE AXIS TO ITS NORTHEAST. THE LOW LEVEL 
TROUGH IS EXPECTED TO CONTINUE WESTWARD TOWARD THE TURKS AND 
CAICOS OVER THE NEXT DAY OR TWO...TRANSPORTING LOW LEVEL 
MOISTURE AND A GREATER CHANCE FOR SHOWER ACTIVITY ALONG WITH IT.

ELSEWHERE IN THE TROPICAL ATLC...SCATTERED MODERATE WITH 
ISOLATED STRONG CONVECTION IS NEAR THE ITCZ ALONG THE COAST OF 
BRAZIL FROM 06S TO 01S W OF 30W...COINCIDING WITH A REGION OF 
MODERATE UPPER LEVEL DIFFLUENCE. SCATTERED MODERATE WITH 
ISOLATED STRONG CONVECTION CAN ALSO BE FOUND ON THE EASTERN EDGE 
OF THE ITCZ NEAR THE COAST OF WEST AFRICA FROM 01N TO 05N E OF 
05W. THIS AREA LIES UNDER A WEAK ANTICYCLONE PROVIDING UPPER 
LEVEL DIFFLUENCE TO LIFT THE MOISTURE CONVERGED ALONG THE ITCZ. 
THE 2352 AND 2112 ASCAT PASSES SHOW THE STRONGEST WINDS IN THE 
TROPICAL E ATLC NORTH OF THE CAPE VERDE ISLANDS BETWEEN 15N AND 
25N E OF 35W TO THE COAST OF AFRICA WHERE THE PRESSURE GRADIENT 
HAS BEEN TIGHTENED ON THE SOUTHERN EDGE OF THE HIGH PRESSURE 
RIDGE DUE TO A DEEP LAYER LOW CENTERED N OF THE AREA...WITH AN 
ASSOCIATED DISSIPATING STATIONARY FRONT EXTENDING FROM 31N37W TO 
23N43W. THE TROUGHING AT THE SURFACE IS EXPECTED TO WEAKEN 
HERE...ALONG WITH THE WINDS...OVER THE NEXT 24 HOURS.

$$
SCHAUER CLARK