000 AXNT20 KNHC 231144 TWDAT TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 805 AM EDT SAT MAY 23 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 1015 UTC. ...SPECIAL FEATURE... A 1004 MB SURFACE LOW IS LOCATED NEAR 30N89W...OR ABOUT 75 NM SOUTH OF MOBILE ALABAMA. A SURFACE TROUGH EXTENDS FROM THE SURFACE LOW TO THE NW YUCATAN PENINSULA NEAR 21N90W. LOW LEVEL CONVERGENCE NEAR THE SURFACE LOW...ALONG WITH DIFFLUENCE ASSOCIATED WITH A MIDDLE TO UPPER LEVEL TROUGH AXIS ACROSS THE CENTRAL GULF ARE SUPPORTING NUMEROUS SHOWERS AND SCATTERED TSTMS ACROSS THE GULF N OF 26N E OF 90W....INCLUDING THE NE GULF COAST. THE SURFACE LOW IS FORECAST TO MOVE N-NW DURING THE NEXT 24 HOURS AND LOCATE INLAND OVER SWRN MISSISSIPPI. HOWEVER... ADDITIONAL DEVELOPMENT OF THIS SYSTEM IS POSSIBLE...AND A TROPICAL DEPRESSION COULD FORM BEFORE THE LOW MOVES INLAND OVER THE NRN GULF COAST LATER TODAY. REGARDLESS OF DEVELOPMENT... HEAVY RAINS AND OCCASIONALLY GUSTY WINDS ARE EXPECTED ALONG PORTIONS OF THE NRN GULF COAST THROUGH THE REMAINDER OF SATURDAY. INTERESTS IN THIS AREA SHOULD MONITOR THE PROGRESS OF THE SYSTEM. ...TROPICAL WAVES... A TROPICAL WAVE IS ALONG 42W S OF 7N MOVING W NEAR 15 KT. THIS WAVE IS ASSOCIATED WITH A MAXIMUM IN DEEP LAYER MOISTURE BASED ON THE TOTAL PRECIPITABLE WATER PRODUCT FROM CIMSS WITH SATELLITE IMAGERY INDICATING INVERTED-V SIGNATURE AND WEAK CYCLONIC CURVATURE NEAR THE WAVE AXIS IN THE LOW LEVEL CLOUDS. DEEP CONVECTION REMAINS EMBEDDED WITHIN PROXIMITY OF THE ITCZ NEAR THE SRN EXTENT OF THE WAVE. SCATTERED MODERATE TO STRONG CONVECTION IS S OF 3N BETWEEN 40W-50W. A TROPICAL WAVE IS ALONG 85W S OF 12N MOVING W NEAR 15 KT. THIS WAVE HAS LARGELY ENTERED THE E PACIFIC REGION AND MORE INFORMATION CAN BE FOUND IN THE E PACIFIC TROPICAL WEATHER DISCUSSION...TWDEP...OR WMO HEADER AXPZ20 KNHC. ...THE ITCZ... THE ITCZ AXIS IS CENTERED ALONG 8N12W 3N22W CROSSING THE EQUATOR NEAR 32W AND EXTENDING INTO NE BRAZIL NEAR 2S45W. CLUSTERS OF SCATTERED MODERATE CONVECTION ARE S OF 5N BETWEEN 7W-20W. SCATTERED MODERATE TO STRONG CONVECTION IS S OF 3N BETWEEN 40W-50W. ...DISCUSSION... GULF OF MEXICO... A DEEP LAYER TROUGH IS PRESENT ACROSS THE GULF WITH THE UPPER LEVEL TROUGH AXIS EXTENDING FROM TEXAS TO THE FLORIDA KEYS. THE ASSOCIATED SURFACE FEATURE...A 1004 MB LOW NEAR 29N89W IS GENERATING NUMEROUS SHOWERS AND TSTMS...AS WELL AS STRONGER WINDS...AS THIS LOW PRESSURE AREA PUSHES UP AGAINST A HIGH PRESSURE RIDGE ACROSS THE SE CONUS. FOR MORE DETAILS ON THIS SYSTEM SEE THE SPECIAL FEATURE SECTION ABOVE. ACROSS THE W GULF...SUBSIDENCE ASSOCIATED WITH W-NW FLOW ALOFT IS SUPPORTING GENERALLY FAIR WEATHER CONDITIONS...WITH UPPER LEVEL MOISTURE AND HIGH LEVEL DEBRIS CLOUDS FROM SCATTERED SHOWERS ACROSS CENTRAL MEXICO STREAMING EWD. GENERALLY LIGHT NLY WINDS ARE OBSERVED ACROSS PORTIONS OF THE WRN GULF W OF 90W. CARIBBEAN SEA... SCATTERED SHOWERS AND ISOLATED TSTMS PERSIST ACROSS THE ERN CARIBBEAN N OF 13N E OF 71W. THIS ACTIVITY IS BEING DRIVEN BY UPPER LEVEL DIVERGENCE IN MOIST SWLY FLOW ALOFT BETWEEN AN UPPER LEVEL TROUGH OVER THE WRN CARIBBEAN...AND AN UPPER LEVEL RIDGE ACROSS THE SE CARIBBEAN. THIS ACTIVITY IS EXPECTED TO CONTINUE OVER THE NEXT COUPLE OF DAYS ACROSS THE NRN CARIBBEAN AS THE UPPER SHORTWAVE TROUGH SHIFTS EWD ACROSS THE GREATER ANTILLES BRINGING INCREASED CHANCES FOR SCATTERED SHOWERS. CLOSER TO THE UPPER LEVEL TROUGH AXIS ACROSS THE WRN CARIBBEAN...ISOLATED SHOWERS ARE OBSERVED OVER ERN CUBA...JAMAICA...HISPANIOLA AND NEARBY N/CENTRAL CARIBBEAN WATERS FROM 15N-21N BETWEEN 72W-81W. MEANWHILE...THE SURFACE PRESSURE GRADIENT SW OF A SURFACE RIDGE OVER THE CENTRAL ATLC IS MAINTAINING ELY WINDS UP TO 20 KT ACROSS PORTIONS OF THE ERN CARIBBEAN. ATLANTIC OCEAN... SCATTERED SHOWERS AND ISOLATED TSTMS ARE OCCURRING S OF 32N W OF 73W INCLUDING THE BAHAMAS AND THE NEARBY W ATLC WATERS ALONG THE COAST OF FLORIDA. THIS ACTIVITY IS BEING SUPPORTED BY UPPER LEVEL DIFFLUENCE IN MOIST SWLY FLOW ALOFT BETWEEN AN UPPER LEVEL TROUGH OVER THE GULF OF MEXICO AND WRN CARIBBEAN...AND AN UPPER LEVEL RIDGE ACROSS THE SW NORTH ATLC. THE MOST CONCENTRATED AREA OF CONVECTION IS LOCATED OVER THE ERN STRAITS OF FLORIDA AND ANDROS ISLAND IN THE BAHAMAS FROM 22N-25N BETWEEN 76W-79W. FARTHER TO THE E...AN UPPER LEVEL TROUGH IS PRESENT WITH AN AXIS EXTENDING FROM AN UPPER LEVEL LOW NEAR 30N54W TO 27N60W TO 26N70W. ATMOSPHERIC INSTABILITY NEAR THE UPPER LEVEL LOW AND TROUGH...AS WELL AS UPPER LEVEL DIFFLUENCE IN MOIST SWLY FLOW ALOFT...ARE SUPPORTING SCATTERED SHOWERS AND ISOLATED TSTMS WITHIN 200 NM EITHER SIDE OF A LINE FROM 32N44W 26N46W 22N62W SWD TO OVER THE NE CARIBBEAN SEA. THIS ACTIVITY IS ALSO BEING SUPPORTED BY LOW LEVEL CONVERGENCE NEAR A SURFACE TROUGH EXTENDING FROM 32N51W TO 20N62W. ACROSS THE E ATLC...A SURFACE RIDGE IS PRESENT WHERE MAINLY ZONAL FLOW ALOFT IS OCCURRING AND FAIR WEATHER CONDITIONS PERSIST UNDER N TO NE SURFACE FLOW. ACROSS THE TROPICAL ATLC...AN UPPER LEVEL RIDGE IS S OF 14N E OF 40W WITH AN UPPER LEVEL HIGH NEAR 7N29W. UPPER LEVEL DIVERGENCE ASSOCIATED WITH THE UPPER LEVEL HIGH AND UPPER LEVEL RIDGE IS ENHANCING THE CONVECTION ASSOCIATED WITH THE ITCZ. $$ HUFFMAN