000 AXNT20 KNHC 300543 TWDAT TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 205 AM EDT THU APR 30 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 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 0515 UTC. ...THE ITCZ... THE ITCZ AXIS EXTENDS FROM W AFRICA AT 07N11W TO THE EQUATOR AT 25W THEN CONTINUES S OF THE EQUATOR TO NE BRAZIL NEAR 03S40W. SCATTERED MODERATE CONVECTION IS OBSERVED WITHIN 90 NM N OF AXIS BETWEEN 18W AND 21W...WITHIN 90 NM S OF AXIS BETWEEN 29W AND 33W...AND WITHIN 60 NM OF AXIS W OF 36W. ...DISCUSSION... GULF OF MEXICO... A SURFACE RIDGE EXTENDS FROM HIGH PRES NEAR BERMUDA THROUGH NORTH FLORIDA AND ACROSS THE NORTHERN GULF WATERS. THE SURFACE RIDGE HAS BECAME DOMINANT OVER THE GULF ON WED AS AN UPPER TROUGH EXITED TO THE SE OVER FLORIDA AND CUBA...WEAKENING AN ASSOCIATED SURFACE TROUGH THROUGH THE YUCATAN PENINSULA. BUOYS AND SCATTEROMETER SHOW SE RETURN FLOW OVER THE NW GULF REACHING 15 TO 20 KT...BETWEEN THE HIGH PRES RIDGE AND DEVELOPING LOW PRES OVER THE SOUTHERN PLAINS AND NORTHERN MEXICAN PLATEAU. STRONG CONVECTION IS FLARING OVER WEST AND CENTRAL TEXAS...BUT THIS WILL NOT IMPACT GULF WATERS. CMAN SITES IN THE FLORIDA KEYS ALSO HINT AT 20 KT EASTERLY FLOW PERSISTING THROUGH THE STRAITS OF FLORIDA AND INTO THE SE GULF WATERS N OF THE WESTERN CUBAN COAST. A 00Z SCATTEROMETER PASS ALSO SHOWED 20 KT FLOW OFF THE NORTHERN AND WESTERN COASTS OF THE YUCATAN PENINSULA. LOOKING AHEAD FOR THE NEXT COUPLE OF DAYS...THE SURFACE RIDGE HOLDS AND LITTLE CHANGE IS EXPECTED. CARIBBEAN SEA... SURFACE HIGH PRES NEAR BERMUDA IS MAINTAINING GENERALLY 15 KT TRADE WIND FLOW ACROSS THE NORTHERN CARIBBEAN WITH SLIGHTLY HIGHER 15 TO 20 KT EAST FLOW S OF 15N. THE IS EXCEPT IS THE COLOMBIAN COAST WHERE 20 TO 25 KT WINDS WERE NOTED ON A 23Z QUIKSCAT PASS. SCATTERED MODERATE SHOWERS IN THE TRADE WIND FLOW PERSIST...MAINLY OVER THE NE CARIBBEAN...BUT THIS ACTIVITY SEEMS A LITTLE DIMINISHED FROM THE PAST COUPLE OF DAYS. LITTLE CHANGE IS EXPECTED OVER THE NEXT COUPLE OF DAYS. ATLANTIC OCEAN... W OF 50W...AN UPPER TROUGH IS PUSHING THROUGH THE BAHAMAS AND COMING IN PHASE WITH AN UPPER LOW SLIDING EAST ACROSS BERMUDA...AHEAD OF A SHORT WAVE TROUGH DIGGING THROUGH THE CAROLINAS. FOR THE SURFACE...1027 MB HIGH PRES NEAR BERMUDA IS SHIFTING EAST...AHEAD OF A WEAK COLD FRONT STALLING N OF THE AREA ASSOCIATED WITH THE SHORT WAVE TROUGH. THIS IN TURN MEANS THAT THE TRADE WIND FLOW FROM N OF THE LEEWARDS THROUGH THE SOUTHERN BAHAMAS IS WEAKENING SLIGHTLY. RECENT BUOY REPORTS ONLY SHOWING AROUND 15 KT IN THIS AREA...ALTHOUGH A 23Z QUIKSCAT PASS HINTED OF PATCH OF 20 KT FLOW AS WELL. WESTWARD MOVING SHOWERS PERSIST IN THE TRADE WIND FLOW...BUT SOMEWHAT DIMINISHED FROM EARLIER WITH THE WEAKER FLOW. QUIKSCAT...ASCAT AND A SHIP OBSERVATION ALL SHOW WEAK CYCLONIC TURNING NE OF THE LEEWARDS...ON THE FAVORABLE SE SIDE OF THE UPPER TROUGH. E OF 50W...SURFACE RIDGE EXTENDS FROM A 1030 MB HIGH PRES CELL NEAR 31N29W TO A 1027 MB HIGH NEAR 30N45W. 20 TO 25 KT NE FLOW IS NOTED ON SCATTEROMETER OFF THE NW AFRICAN COAST BETWEEN THE HIGH PRES AND LOW PRES OVER WEST AFRICA. THIS FLOW WILL DIMINISH SLIGHTLY INTO THU AS AN UPPER TROUGH AMPLIFIES OVER THE CENTRAL ATLC...INDUCING THE SURFACE HIGH PRES TO WEAKEN AND SHIFT NE. $$ CHRISTENSEN