000
AXNT20 KNHC 222340
TWDAT 

TROPICAL WEATHER DISCUSSION...     
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
805 PM EDT TUE APR 22 2008

TROPICAL WEATHER DISCUSSION FOR NORTH AMERICA...CENTRAL 
AMERICA...THE GULF OF MEXICO...THE CARIBBEAN SEA...NORTHERN 
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 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
2215 UTC.

...THE ITCZ...

ITCZ AXIS IS CENTERED ALONG 6N9W 4N16W 2N26W 1N37W CROSSING THE 
EQUATOR NEAR 42W TO 1S50W. A SECOND ITCZ AXIS IS SOUTH OF THE 
EQUATOR WITH THE MOST CONVECTIVE ACTIVITY. SCATTERED MODERATE/ 
STRONG CONVECTION IS INLAND OVER W AFRICA MOVING OFF THE COAST 
OF LIBERIA. CLUSTERS OF SCATTERED MODERATE/ISOLATED STRONG 
CONVECTION ARE FROM 2N TO S OF THE EQUATOR BETWEEN 30W-42W. 

...DISCUSSION...

GULF OF MEXICO...
AN UPPER LOW IS IN THE W ATLC WITH THE UPPER TROUGH EXTENDING 
OVER THE FAR E GULF AND THE FLORIDA PENINSULA. A SURFACE TROUGH 
EXTENDS THROUGH THE W ATLC ALONG THE N COAST OF CUBA INTO THE 
GULF TO NEAR 24N87W WITH ISOLATED SHOWERS WITHIN 60 NM OF THE 
SURFACE TROUGH. OTHERWISE A BROAD UPPER RIDGE DOMINATES THE 
REMAINDER OF THE GULF ANCHORED IN THE E PACIFIC REGION WITH THE 
AXIS EXTENDING OVER MEXICO AND TEXAS. A WEAK 1017 MB HIGH 
REMAINS N OF THE SURFACE TROUGH NEAR 29N87W. SOME SCATTERED 
SHOWERS/ISOLATED THUNDERSTORMS ARE INLAND OVER SE LOUISIANA AND 
MAY DRIFT SE TO OVER THE MISSISSIPPI DELTA BUT OTHERWISE THE 
REMAINDER OF THE GULF IS QUIET THIS AFTERNOON. THE SURFACE RIDGE 
WILL BUILD OVER THE GULF AND REMAIN IN PLACE THROUGH FRI. 
 
CARIBBEAN SEA...
THE CARIBBEAN IS DOMINATED BY UPPER WESTERLY FLOW GENERATED BY 
THE E/W UPPER RIDGE THAT EXTENDS FROM THE TROPICS ACROSS SOUTH 
AMERICA. A WEAK SURFACE TROUGH IS ALONG THE N COAST OF CUBA WITH 
ISOLATED SHOWERS WITHIN 60 NM OF THE TROUGH. MODERATE EASTERLY 
TRADE WINDS COVER THE AREA RESULTING FROM THE WEAK PRESSURE 
GRADIENT OVER THE ATLC WATERS. AFTERNOON SHOWERS/ISOLATED 
THUNDERSTORMS HAVE GENERATED AGAIN OVER JAMAICA AND PORTIONS OF 
HISPANIOLA AND ARE DRIFTING N OVER THE IMMEDIATE COASTAL WATERS. 
HOWEVER WITH THE STRONG SUBSIDENCE AND DRY AIR THAT DOMINATES 
THE CARIBBEAN...THIS ACTIVITY WILL DIMINISH LATER THIS EVENING. 

ATLANTIC OCEAN...
BROAD UPPER TROUGH COVERS THE W INTO THE CENTRAL ATLC TO OVER 
FLORIDA WITH A NEAR VERTICALLY STACKED UPPER LOW AND 1010 MB 
SURFACE LOW NEAR 32N76W. A SURFACE TROUGH EXTENDS INTO THE 
REGION NEAR 32N74W S OVER THE CENTRAL BAHAMA ISLANDS NEAR 24N76W 
THEN ALONG THE N COAST OF CUBA AND INTO THE GULF OF MEXICO. A 
SECOND SURFACE TROUGH EXTENDS FROM THE SURFACE LOW ALONG 30N76W 
TO 29N79W. A WEAK 1012 MB LOW IS E OF THE BAHAMAS NEAR 26N70W 
WITH A SURFACE TROUGH EXTENDING ALONG 24N67W TO OVER THE TURKS 
AND CAICOS NEAR 21N73W. SCATTERED SHOWERS/THUNDERSTORMS ARE TO 
THE E OF THESE SYSTEMS WITHIN 150 NM OF LINE FROM 22N65W TO 
BEYOND 32N73W. ALSO EMBEDDED WITHIN THIS BROAD UPPER TROUGH IS A 
SECOND NEAR VERTICALLY STACKED UPPER LOW AND A 1011 MB LOW ARE 
IN THE CENTRAL ATLC NEAR 32N50W. A SURFACE TROUGH EXTENDS FROM 
THE SURFACE LOW ALONG 27N53W TO 20N57W. ISOLATED SHOWERS ARE N 
OF 26N FROM 45W-51W. AFTERNOON SHOWERS/ISOLATED THUNDERSTORMS 
HAVE GENERATED OVER PUERTO RICO AND PORTIONS OF HISPANIOLA AND 
CUBA DRIFTING N OVER THE IMMEDIATE COASTAL WATERS. A LARGE UPPER 
RIDGE IS OVER THE REMAINDER OF THE CENTRAL ATLC INTO THE E ATLC 
EXTENDING FROM AN UPPER HIGH NEAR 10N43W NE TO BEYOND 32N31W. A 
LARGE SURFACE RIDGE DOMINATES THE E ATLC N OF 16N E OF 50W 
ANCHORED BY A 1024 MB HIGH NEAR 30N28W...THUS FAIR WEATHER SKIES 
OVER THE AREA E OF 50W. THE TYPICAL E/W UPPER RIDGE AXIS EXTENDS 
ACROSS THE TROPICS AND SOUTH AMERICA. 

$$
WALLACE