000 AXNT20 KNHC 282338 TWDAT TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 805 PM EDT THU MAY 28 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 2315 UTC. ...SPECIAL FEATURE... TROPICAL DEPRESSION ONE IS CENTERED NEAR 37.7N 69.4W AT 28/2100 UTC OR ABOUT 265 NM SOUTH-SOUTHEAST OF PROVIDENCE RHODE ISLAND AND ABOUT 490 NM SOUTHWEST OF HALIFAX NOVA SCOTIA MOVING NE AT 14 KT. ESTIMATED MINIMUM CENTRAL PRESSURE IS 1006 MB. MAXIMUM SUSTAINED WIND SPEED IS 30 KT WITH GUSTS TO 40 KT. SCATTERED MODERATE CONVECTION IS WITHIN 90 NM OF THE CENTER IN THE E SEMICIRCLE. PLEASE SEE LATEST NHC FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS MIATCMAT1/WTNT21 KNHC FOR MORE DETAILS. THE DEPRESSION COULD BECOME A TROPICAL STORM TONIGHT OR FRIDAY...BUT THEN IS EXPECTED TO WEAKEN OR DISSIPATE OVER COLDER WATERS BY SATURDAY. ...TROPICAL WAVES... A TROPICAL WAVE IS ALONG 42W S OF 7N MOVING W NEAR 15 KT. TOTAL PRECIPITABLE WATER PRODUCT FROM CIMSS INDICATES THAT THIS WAVE COINCIDES WITH A MAXIMUM IN DEEP LAYER MOISTURE. ALSO...CIMSS WAVETRAK PRODUCT INDICATES A MAXIMUM IN LOW LEVEL CYCLONIC CIRCULATION AROUND THE WAVE. SCATTERED MODERATE CONVECTION IS WITHIN 60 NM EITHER SIDE OF THE WAVE AXIS FROM 1N-4N. ...THE ITCZ... THE ITCZ AXIS IS CENTERED ALONG 9N13W 4N22W 1N31W CROSSING THE EQUATOR NEAR 47W EXTENDING INTO NE BRAZIL NEAR 1S49W. NUMEROUS MODERATE AND STRONG CONVECTION IS MOVING OFF THE W COAST OF AFRICA FROM 4N-10N...AFFECTING LOCATIONS WITHIN 90 NM OF THE COASTLINE. SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS FROM 4N-7N BETWEEN 12W-15W. SCATTERED MODERATE CONVECTION IS FROM 1N-6N BETWEEN 21W-27W. SIMILAR CONVECTION IS S OF 5N BETWEEN 33W-40W AND S OF 3N BETWEEN 44W-46W. ...DISCUSSION... GULF OF MEXICO... AN UPPER LEVEL TROUGH IS ACROSS THE N GULF...WITH AN ASSOCIATED COLD FRONT EXTENDING FROM S MISSISSIPPI NEAR 30N89W TO 28N91W TO 26N93W WITH A DISSIPATING STATIONARY FRONT CONTINUING SOUTHWESTWARD TO 24N96W TO 22N97W. ALSO...A SURFACE TROUGH EXTENDS FROM 28N90W TO 26N91W TO 24N93W. LOW LEVEL CONVERGENCE NEAR THE SURFACE FRONTS AND TROUGH...AS WELL AS ATMOSPHERIC INSTABILITY ASSOCIATED WITH THE UPPER LEVEL TROUGH...ARE RESULTING IN SCATTERED SHOWERS AND THUNDERSTORMS FROM 22N-28N BETWEEN 86W-90W...AS WELL AS NUMEROUS SHOWERS AND THUNDERSTORMS S OF 23N W OF 93W. ALL OF THIS CONVECTIVE ACTIVITY IS ALSO BEING ENHANCED BY UPPER LEVEL DIFFLUENCE BETWEEN AN UPPER LEVEL TROUGH ACROSS THE N GULF AND AN UPPER LEVEL RIDGE ACROSS THE SW GULF. ADDITIONALLY...ATMOSPHERIC INSTABILITY ASSOCIATED WITH THE UPPER LEVEL TROUGH IS SUPPORTING SCATTERED SHOWERS FROM 26N-29N E OF 84W...AS WELL AS ADJACENT INLAND LOCATIONS ALONG THE GULF COAST. ACROSS THE NW GULF TO THE W OF THE FRONTS...GENERALLY FAIR WEATHER IS OCCURRING WHERE STABLE ATMOSPHERIC CONDITIONS ARE PRESENT. CARIBBEAN SEA... DEEP LAYER DRY AIR AND SUBSIDENCE IN NORTHWESTERLY FLOW ALOFT...ALONG WITH MID-LEVEL DRY SAHARAN AIR...ARE RESULTING IN GENERALLY FAIR WEATHER CONDITIONS ACROSS MUCH OF THE CARIBBEAN. HOWEVER...ATMOSPHERIC INSTABILITY OVER HIGHER TERRAIN IS RESULTING IN SCATTERED SHOWERS AND THUNDERSTORMS AFFECTING CUBA...NICARAGUA...HONDURAS...COSTA RICA...AND PANAMA...AND NEARBY COASTAL WATERS. SURFACE HIGH PRESSURE ACROSS THE CENTRAL ATLANTIC IS MAINTAINING FRESH TO STRONG TRADE WINDS ACROSS THE CENTRAL CARIBBEAN. THE STRONGEST OF THESE WINDS IS FOUND NEAR THE COAST OF COLOMBIA...WHERE E WINDS OF 25 TO 30 KT ARE OCCURRING. THE TRADE WINDS ARE ADVECTING POCKETS OF LOW LEVEL MOISTURE AND ISOLATED SHOWERS WESTWARD ACROSS THE CARIBBEAN. THE GREATEST CONCENTRATION OF THESE SHOWERS IS FROM 15N-17N BETWEEN 72W-76W. ATLANTIC OCEAN... UPPER LEVEL DIVERGENCE AND DEEP LAYER MOISTURE W OF AN UPPER LEVEL HIGH CENTERED NEAR 25N60W IS RESULTING IN SCATTERED SHOWERS AND THUNDERSTORMS N OF 23N BETWEEN 68W-74W...FROM 19N-21N BETWEEN 62W-65W...AND N OF 29N BETWEEN 55W-61W. THE SHOWER AND THUNDERSTORM ACTIVITY N OF 23N BETWEEN 68W-74W IS ALSO BEING SUPPORTED BY LOW LEVEL CONVERGENCE NEAR A SURFACE TROUGH EXTENDING FROM 31N65W TO 32N65W TO N OF THE DISCUSSION AREA. ALSO...UPPER LEVEL DIVERGENCE ASSOCIATED WITH AN UPPER LEVEL RIDGE WITH AN AXIS EXTENDING FROM 30N79W TO 27N81W IS SUPPORTING SCATTERED SHOWERS AND THUNDERSTORMS S OF 29N BETWEEN 75W-80W INCLUDING THE NW BAHAMAS...CUBA...AND ADJACENT INLAND LOCATIONS OF FLORIDA. FARTHER TO THE E...AN UPPER LEVEL TROUGH N OF THE DISCUSSION AREA IS ASSOCIATED WITH A COLD FRONT EXTENDING FROM NE OF THE DISCUSSION AREA TO 32N34W TO 30N39W TO 29N42W CONTINUING WESTWARD AS A STATIONARY FRONT TO 30N49W. ALSO...A SURFACE TROUGH EXTENDS FROM 27N48W TO 22N51W. LOW LEVEL CONVERGENCE IS SUPPORTING SCATTERED SHOWERS WITHIN 60 NM EITHER SIDE OF THE COLD AND STATIONARY FRONTS AND SURFACE TROUGH. BEHIND THE FRONTS...A 1027 MB SURFACE HIGH IS LOCATED NEAR 35N46W AND IS FORECAST TO MOVE SOUTHWARD AND BE LOCATED NEAR 32N47W AS A 1024 MB SURFACE HIGH AT 29/1800 UTC. SUBSIDENCE ASSOCIATED WITH THIS SURFACE HIGH IS RESULTING IN GENERALLY FAIR WEATHER CONDITIONS TO THE N OF THE COLD AND STATIONARY FRONTS. ACROSS THE E ATLC...A SURFACE RIDGE IS PRESENT WHERE MAINLY ZONAL FLOW ALOFT IS OCCURRING AND FAIR WEATHER CONDITIONS PERSIST. THE SURFACE RIDGE IS ASSOCIATED WITH A 1022 MB HIGH NEAR 27N39W. THIS HIGH IS FORECAST TO DISSIPATE DURING THE NEXT DAY. ACROSS THE TROPICAL ATLC...AN UPPER LEVEL RIDGE IS PRESENT S OF 14N E OF 53W WITH AN UPPER LEVEL HIGH NEAR 10N18W. UPPER LEVEL DIVERGENCE ASSOCIATED WITH THE UPPER LEVEL HIGH AND RIDGE IS ENHANCING THE CONVECTION ASSOCIATED WITH THE ITCZ AND THE TROPICAL WAVE ALONG 42W S OF 7N...AS WELL AS NUMEROUS SHOWERS AND THUNDERSTORMS FROM 1N-4N BETWEEN 7W-13W. $$ COHEN