000 AXNT20 KNHC 242335 TWDAT TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 805 PM EDT SUN MAY 24 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 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 2245 UTC. ...TROPICAL WAVES... A TROPICAL WAVE IS ALONG 53W/54W S OF 17N MOVING W 15-20 KT. RECENT SURFACE OBSERVATIONS SHOW WELL-DEFINED CYCLONIC CURVATURE IN THE LOW LEVEL WINDS AROUND THIS WAVE. THIS WAVE IS ASSOCIATED WITH A MAXIMUM IN DEEP LAYER MOISTURE BASED ON TOTAL PRECIPITABLE WATER PRODUCT FROM CIMSS. SOUTHEASTERLY LOW LEVEL FLOW BETWEEN THE TROPICAL WAVE AND A SURFACE TROUGH FARTHER NORTH APPEAR TO BE ADVECTING CYCLONIC VORTICITY ASSOCIATED WITH THIS WAVE NORTHWARD. AS A RESULT...THE WAVE HAS BEEN EXTENDED NORTHWARD TO 17N...CONSISTENT WITH THE NORTHWARD EXTENSION IN DEEP LAYER MOISTURE. SCATTERED MODERATE CONVECTION IS OCCURRING WITHIN 180 NM EITHER SIDE OF THE WAVE AXIS S OF 6N...INCLUDING PORTIONS OF SURINAME...FRENCH GUIANA...AND NE BRAZIL. FARTHER TO THE NORTH...DEEP CONVECTION IN THE VICINITY OF THIS WAVE IS BEING SUPPRESSED BY SUBSIDENCE ASSOCIATED WITH A SURFACE RIDGE OVER THE E ATLC. HOWEVER...SCATTERED SHOWERS ARE OCCURRING WITHIN 90 NM EITHER SIDE OF THE WAVE AXIS FROM 6N-17N. ADDITIONALLY...TOTAL PRECIPITABLE WATER PRODUCT FROM CIMSS INDICATES THAT A NORTH-SOUTH ELONGATED DEEP LAYER MOISTURE MAXIMUM IS ALONG 25W S OF 6N MOVING W NEAR 15 KT. ALSO...COMPUTER MODEL GUIDANCE INDICATES CYCLONIC CURVATURE IN THE LOW LEVEL FLOW NEAR THIS FEATURE. THIS FEATURE IS ASSOCIATED WITH SCATTERED MODERATE CONVECTION FROM 3N-5N BETWEEN 19W-24W...WHICH IS ALSO BEING SUPPORTED BY LOW LEVEL CONVERGENCE NEAR THE ITCZ. HOWEVER...RECENT SURFACE OBSERVATIONS AND SCATTEROMETER DATA DO NOT YET CONFIRM THE PRESENCE OF A LOW AMPLITUDE TROPICAL WAVE AT THE SURFACE NEAR THIS FEATURE. HOWEVER...A TROPICAL WAVE IS SUSPECTED TO BE PRESENT HERE...WHICH WILL CONTINUE TO BE MONITORED. ...THE ITCZ... THE ITCZ AXIS IS CENTERED ALONG 8N13W 4N21W 1N29W CROSSING THE EQUATOR NEAR 33W EXTENDING TO 1S41W AND INTO NE BRAZIL NEAR 1S48W. SCATTERED MODERATE CONVECTION IS FROM 1N-3N BETWEEN 1W-6W...S OF 3N BETWEEN 9W-18W...FROM 3N-5N BETWEEN 19W-24W...AND S OF 3N BETWEEN 40W-48W. ...DISCUSSION... GULF OF MEXICO... AN UPPER LEVEL TROUGH IS PRESENT ACROSS THE GULF WITH AN AXIS EXTENDING FROM 25N79W TO 27N85W TO 30N89W TO NW OF THE DISCUSSION AREA. ALSO...SURFACE TROUGHS EXTEND FROM S LOUISIANA NEAR 29N91W TO 32N91W TO N OF THE DISCUSSION AREA...AND FROM S TEXAS NEAR 26N97W TO 30N94W TO 31N93W. LOW LEVEL CONVERGENCE NEAR THE SURFACE TROUGHS...AS WELL AS INSTABILITY ASSOCIATED WITH THE UPPER LEVEL TROUGH...ARE SUPPORTING SCATTERED SHOWERS AND THUNDERSTORMS ACROSS THE GULF N OF 23N E OF 89W...N OF 27N W OF 89W...AS WELL AS ADJACENT INLAND LOCATIONS ALONG THE GULF COAST. ACROSS THE SW GULF...DEEP LAYER DRY AIR AND SUBSIDENCE ASSOCIATED WITH WEST-NORTHWESTERLY FLOW ALOFT ARE SUPPORTING GENERALLY FAIR WEATHER CONDITIONS. A WEAK SURFACE PRESSURE GRADIENT IS MAINTAINING LIGHT WINDS ACROSS MUCH OF THE GULF. HOWEVER...SOUTHERLY RETURN FLOW IS FORECAST TO INCREASE OVER THE FAR WESTERN GULF BEGINNING LATE MONDAY. CARIBBEAN SEA... SCATTERED SHOWERS AND THUNDERSTORMS ARE OCCURRING ACROSS THE CARIBBEAN N OF 15N BETWEEN 73W-81W. THIS ACTIVITY IS BEING SUPPORTED BY UPPER LEVEL DIFFLUENCE IN MOIST WEST-NORTHWESTERLY FLOW ALOFT BETWEEN AN UPPER LEVEL TROUGH OVER THE GULF OF MEXICO...AND AN UPPER LEVEL RIDGE ACROSS THE W CARIBBEAN. ADDITIONALLY...ATMOSPHERIC INSTABILITY OVER HIGHER TERRAIN IS RESULTING IN SCATTERED SHOWERS AND THUNDERSTORMS AFFECTING CUBA...HISPANIOLA...PUERTO RICO...PANAMA...COSTA RICA...AND NEARBY COASTAL WATERS. UPPER LEVEL MOISTURE AND HIGH LEVEL CLOUDS ARE STREAMING GENERALLY EASTWARD ACROSS THE CARIBBEAN. MEANWHILE...THE PRESSURE GRADIENT S OF SURFACE HIGH PRESSURE NEAR BERMUDA IS MAINTAINING E TO SE WINDS UP TO 20 KT ACROSS PORTIONS OF THE E CARIBBEAN. ATLANTIC OCEAN... SCATTERED SHOWERS AND THUNDERSTORMS ARE OCCURRING FROM 24N-30N W OF 74W INCLUDING THE NW BAHAMAS AND ADJACENT INLAND LOCATIONS OF FLORIDA...AS WELL AS S OF 24N BETWEEN 68W-80W INCLUDING PORTIONS OF CUBA...HISPANIOLA...PUERTO RICO...AND THE SE BAHAMAS. THIS ACTIVITY IS BEING SUPPORTED BY UPPER LEVEL DIFFLUENCE IN MOIST SOUTHWESTERLY FLOW ALOFT BETWEEN AN UPPER LEVEL TROUGH OVER THE GULF OF MEXICO AND AN UPPER LEVEL RIDGE ACROSS THE SW NORTH ATLC. FARTHER TO THE E...AN UPPER LEVEL TROUGH IS PRESENT WITH AN AXIS EXTENDING FROM AN UPPER LEVEL LOW NEAR 33N44W TO 29N50W TO 25N55W. THIS UPPER LEVEL LOW AND TROUGH ARE ASSOCIATED WITH A SURFACE TROUGH EXTENDING FROM A 1018 MB SURFACE LOW NEAR 32N48W TO 32N44W TO 24N51W TO 21N67W. ATMOSPHERIC INSTABILITY NEAR THE UPPER LEVEL LOW AND TROUGH...UPPER LEVEL DIFFLUENCE IN MOIST SOUTHWESTERLY FLOW ALOFT E OF THE UPPER LEVEL LOW AND TROUGH...AND LOW LEVEL CONVERGENCE NEAR THE SURFACE LOW AND TROUGH ARE SUPPORTING SCATTERED SHOWERS AND ISOLATED THUNDERSTORMS N OF 25N BETWEEN 39W-48W AND FROM 19N-25N BETWEEN 45W-68W. DURING THE NEXT DAY...THE 1018 MB SURFACE LOW IS FORECAST TO REMAIN STATIONARY. ACROSS THE E ATLC...A SURFACE RIDGE IS PRESENT WHERE MAINLY ZONAL FLOW ALOFT IS OCCURRING AND FAIR WEATHER CONDITIONS PERSIST. ACROSS THE TROPICAL ATLC...UPPER LEVEL RIDGES ARE PRESENT FROM 1N-7N E OF 13W AND S OF 5N BETWEEN 23W-48W. UPPER LEVEL DIVERGENCE ASSOCIATED WITH THE UPPER LEVEL RIDGES IS ENHANCING THE CONVECTION ASSOCIATED WITH THE ITCZ AND THE TROPICAL WAVE ALONG 53W/54W S OF 17N. $$ COHEN