000 AXNT20 KNHC 232328 TWDAT TROPICAL WEATHER DISCUSSION... NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 805 PM EDT WED APR 23 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 6N8W 2N16W 1N30W CROSSING THE EQUATOR NEAR 43W TO 1S50W. CLUSTERS OF SCATTERED MODERATE/STRONG CONVECTION ARE FROM 3N-6N E OF 13W ACROSS THE PRIME MERIDIAN AND INLAND OVER SW AFRICA. CLUSTERS OF SCATTERED MODERATE CONVECTION ARE FROM 1N-5N BETWEEN 35W-52W. ...DISCUSSION... GULF OF MEXICO... A BROAD UPPER RIDGE DOMINATES THE W GULF ANCHORED IN THE E PACIFIC REGION WITH THE AXIS EXTENDING ACROSS MEXICO AND INTO THE CENTRAL PLAIN STATES. A SURFACE RIDGE EXTENDS FROM OVER THE SE US WITH A WEAK 1019 MB HIGH REMAINING IN THE N GULF NEAR 28N89W. A BROAD UPPER TROUGH COVERS THE REMAINDER OF THE GULF E OF 88W ACROSS FLORIDA AND INTO THE W ATLC WHERE AN UPPER LOW IS NE OF THE BAHAMAS. THE GULF REMAINS RATHER QUIET THIS EVENING. THE SURFACE RIDGE WILL BEGIN TO SHIFT EASTWARD LATE THU WITH RETURN FLOW EXPECTED OVER THE W GULF AND THE NEXT FRONT IS EXPECTED TO ENTER THE GULF LATE IN THE WEEKEND. CARIBBEAN SEA... THE UPPER TROUGH OVER THE E GULF EXTENDS INTO THE NW CARIBBEAN N OF THE CAYMAN ISLANDS E OF THE WINDWARD PASSAGE. THE REMAINDER OF THE CARIBBEAN IS DOMINATED BY UPPER WESTERLY FLOW GENERATED BY THE E/W UPPER RIDGE THAT EXTENDS FROM THE TROPICS ACROSS SOUTH AMERICA SPREADING THIN HIGH CLOUDS MAINLY OVER THE FAR S CARIBBEAN S OF 13N E OF 80W. MODERATE EASTERLY TRADE WINDS COVER THE AREA RESULTING FROM THE WEAK PRESSURE GRADIENT OVER THE ATLC WATERS. AFTERNOON SHOWERS/ISOLATED THUNDERSTORMS HAVE GENERATED OVER PORTIONS OF HISPANIOLA AND ARE DRIFTING N INTO THE W ATLC COASTAL WATERS. HOWEVER WITH THE STRONG SUBSIDENCE AND DRY AIR THAT DOMINATES THE CARIBBEAN...THIS ACTIVITY WILL DIMINISH LATER TONIGHT. OTHERWISE THE CARIBBEAN REMAINS RATHER QUIET THIS EVENING. ATLANTIC OCEAN... BROAD UPPER TROUGH THAT COVERS THE E GULF OF MEXICO EXTENDS OVER THE W ATLC INTO THE CENTRAL ATLC WITH AN UPPER LOW NEAR 28N72W AND A 1010 MB SURFACE LOW NEAR 29N73W. A SURFACE TROUGH EXTENDS S TO OVER THE BAHAMA ISLANDS NEAR 22N75W WITH SCATTERED SHOWERS/ISOLATED THUNDERSTORMS TO THE E WITHIN 45/60 NM OF LINE FROM 23N73W TO 27N69W. A SECOND SURFACE 1010 MB LOW IS TO THE E NEAR 28N69W WITH A SURFACE TROUGH EXTENDING ALONG 27N66W TO NEAR 23N68W. SCATTERED SHOWERS/THUNDERSTORMS ARE FROM 28N-31N BETWEEN 67W-72W WITH SCATTERED SHOWERS AND POSSIBLE ISOLATED THUNDERSTORMS WELL TO THE E OF THIS SURFACE TROUGH WITHIN 75 NM OF LINE FROM 23N64W TO 28N58W. AFTERNOON SHOWERS/ISOLATED THUNDERSTORMS HAVE GENERATED INLAND OVER PORTIONS OF HISPANIOLA AND ARE DRIFTING N OVER THE IMMEDIATE COASTAL WATERS. A STRONG UPPER LOW IS OVER THE N/CENTRAL ATLC WITH AN ASSOCIATED COLD FRONT APPROACHING THE REGION AND A SURFACE TROUGH EXTENDING INTO THE REGION NEAR 32N44W TO 25N50W. ISOLATED SHOWERS ARE WITHIN 150 NM E OF THIS TROUGH. A LARGE UPPER RIDGE IS OVER THE REMAINDER OF THE CENTRAL ATLC INTO THE E ATLC EXTENDING FROM AN UPPER HIGH NEAR 11N43W NE TO BEYOND 32N21W. A LARGE SURFACE RIDGE DOMINATES THE E ATLC N OF 20N E OF 45W ANCHORED BY A 1027 MB HIGH N OF THE MADEIRA ISLANDS. THUS FAIR WEATHER SKIES COVER THE E ATLC. THE TYPICAL E/W UPPER RIDGE AXIS EXTENDS ACROSS THE TROPICS AND SOUTH AMERICA. $$ WALLACE