000 AXNT20 KNHC 091752 TWDAT TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 205 PM EDT WED APR 09 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 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 1445 UTC. ...ITCZ... ITCZ AXIS IS CENTERED ALONG 4N10W 2N25W 1S30W EQ45W INTO NE BRAZIL. SCATTERED MODERATE CONVECTION IS WITHIN 130 NM N OF AXIS BETWEEN 20W AND 28W. SCATTERED SHOWERS AND ISOLATED TSTMS ARE ELSEWHERE. ...DISCUSSION... GULF OF MEXICO... BROAD UPPER RIDGE ANCHORED IN THE E PACIFIC NEAR ACAPULCO MEXICO COVERS THE ENTIRE GULF WITH MODERATE TO STRONG SUBSIDENCE. ONLY FRAGMENTS OF LOW LEVEL CLOUDS ARE SEEN ON SATELLITE IMAGERY... PARTICULARLY NEAR THE TEXAS COAST DUE TO THE MOIST ONSHORE FLOW AND OVER THE NE GULF. THE RIDGE AXIS EXTENDS NE FROM THE ISTHMUS OF TEHUANTEPEC TO THE FLORIDA PANHANDLE. THE MID/UPPER LEVEL SHORTWAVE TROUGH THAT MOVED ACROSS THE GULF DURING THE LAST COUPLE OF DAYS HAS FINALLY LEFT THE REGION AND NOW EXTENDS FROM THE NW BAHAMAS TO HONDURAS. AT THE SURFACE...A TROUGH LIES ACROSS THE FLORIDA STRAITS AND THE SE PORTION OF THE GULF GENERATING ISOLATED TO SCATTERED SHOWERS. A SFC RIDGE ACROSS THE EASTERN SEABOARD ENVELOPS THE NE CORNER OF THE GULF AND THE FLORIDA PENINSULA WITH MOSTLY FAIR WEATHER. LIGHT TO MODERATE SE WINDS DOMINATES THE ENTIRE GULF. HOWEVER...RETURN SLY FLOW IS FORECAST TO INCREASE TONIGHT INTO THU AHEAD OF THE NEXT COLD FRONT WHICH IS FORECAST TO MOVE INTO NW GULF WATERS FRI. THE FRONT WILL EXTEND FROM THE FLORIDA BIG BEND TO BAY OF CAMPECHE SAT AND MOVE SE OF AREA SUN. STRONG N WINDS WILL FOLLOW THE FRONTAL BOUNDARY. CARIBBEAN SEA... AS PREVIOUSLY MENTIONED...THE SHORTWAVE TROUGH STRETCHES ACROSS THE NW CARIBBEAN BETWEEN CENTRAL CUBA AND HONDURAS. WATER VAPOR IMAGERY AND CLOUD-TRACKED WINDS INDICATE A WEAK CYCLONIC CIRCULATION IN THE BASE OF THE TROUGH JUST W OF COSTA RICA. BROAD UPPER RIDGE COVERS THE REMAINDER OF THE CARIBBEAN WITH A SWLY UPPER LEVEL FLOW. THESE WINDS ARE TRANSPORTING A PLUME OF UPPER LEVEL MOISTURE THROUGH THE CENTRAL CARIBBEAN FROM THE CONVECTION OVER PANAMA AND COSTA RICA. THIS SHOWER AND TSTM ACTIVITY IS ASSOCIATED WITH THE CLOSE PROXIMITY OF THE EPAC ITCZ AND A DIFFLUENT PATTERN ALOFT BETWEEN THE SHORTWAVE TROUGH AND THE RIDGE. BRISK EASTERLY TRADES DOMINATE THE BASIN AND WILL RELAX OVER THE CENTRAL AND EASTERN WATERS AS THE ATLC RIDGE LOCATED N OF AREA WEAKENS AND SHIFTS MAINLY E. POCKETS OF LOW LEVEL MOISTURE ARE ENTERING THE E CARIBBEAN THROUGH THE LESSER ANTILLES PRODUCING ISOLATED TO SCATTERED PASSING SHOWERS. THE REMAINDER OF THE CARIBBEAN IS PRETTY QUIET. ATLANTIC OCEAN... THE AFOREMENTIONED SHORTWAVE TROUGH SUPPORTS A WEAK FRONTAL SYSTEM WITH SEVERAL LOWS THAT EXTENDS ALONG 30N/31N BETWEEN 50W AND 70W THEN CONTINUES SW ACROSS THE W ATLC INTO THE CENTRAL BAHAMAS. A SFC TROUGH EXTENDS FROM THE CENTRAL BAHAMAS ACROSS THE STRAIT OF FLORIDA INTO THE SE GULF OF MEXICO NEAR 24N85W. SCATTERED SHOWERS AND ISOLATED THUNDERSTORMS ARE FOUND WITHIN 125 NM E OF THE FRONT N OF 27N. BROAD UPPER RIDGE COVERS THE REMAINDER OF THE WEST-CENTRAL ATLC WITH THE MEAN AXIS ALONG 55W AND A WEAK 1019 MB SFC HIGH NEAR 25N60W. BROAD UPPER TROUGH REMAINS OVER THE E ATLC. THE ATTENDANT COLD FRONT ENTERS THE DISCUSSION AREA NEAR 31N17W THEN CONTINUES SW AND W TO 28N36W. AT THIS POINT...A SFC TROUGH EXTENDS NW ACROSS THE CENTRAL ATLC. AN ASCAT PASS FROM AROUND 1130 UTC REVEALS MODERATE TO STRONG SWLY WINDS BETWEEN THE MADEIRA/CANARY ISLANDS. A NARROW E/W UPPER RIDGE COVERS THE TROPICS. $$ GR