000 AXNT20 KNHC 091736 TWDAT TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 205 PM EDT WED SEP 09 2015 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...WEATHER OBSERVATIONS...RADAR...AND METEOROLOGICAL ANALYSIS. BASED ON 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 1715 UTC. ...SPECIAL FEATURES... TROPICAL DEPRESSION GRACE HAS DISSIPATED INTO AN OPEN WAVE OVER THE CENTRAL ATLC. THE FINAL ADVISORY POSITION AS OF 09/1500 UTC IS 14.5N 49.0W. ISOLATED MODERATE CONVECTION IS WITHIN 75 NM OF THE DISSIPATED CENTER. ADDITIONAL INFORMATION ON THIS SYSTEM CAN BE FOUND IN HIGH SEAS FORECASTS ISSUED BY THE NATIONAL WEATHER SERVICE...UNDER AWIPS HEADER NFDHSFAT1 AND WMO HEADER FZNT01 KWBC TROPICAL DEPRESSION EIGHT AT 09/1500 UTC IS NEAR 30.7N 60.8W...MOVING EAST-SOUTHEAST AT 3 KT. THE ESTIMATED CENTRAL PRESSURE IS 1011 MB. THE MAXIMUM SUSTAINED WINDS ARE 30 KT WITH GUSTS TO 40 KT. SCATTERED TO NUMEROUS MODERATE CONVECTION IS FROM 28N TO 34N BETWEEN 56W AND 61W. PUBLIC ADVISORIES ABOUT TROPICAL DEPRESSION EIGHT ARE BEING ISSUED UNDER THE AWIPS/WMO HEADER MIATCPAT3/WTNT33 KNHC. ...TROPICAL WAVES... AN EASTERN ATLC TROPICAL WAVE HAS AN AXIS THAT EXTENDS FROM NEAR 20N26W TO 09N26W...MOVING W AT AROUND 10 KT. A BROAD SURGE OF MOISTURE IS NOTED IN THE ENVIRONMENT OF THE WAVE...EXTENDING AS FAR N AS 23N OVER THE EASTERN ATLC. AN INVERTED TROUGH AT 700 MB IS INDICATED IN MODEL FIELDS BETWEEN 24W AND 28W. ISOLATED MODERATE CONVECTION IS FROM 08N TO 15N BETWEEN 25W AND 34W. A CENTRAL ATLC TROPICAL WAVE IS APPROACHING THE LESSER ANTILLES WITH AN AXIS EXTENDING FROM NEAR 16N58W TO 09N60W...MOVING W AT 15 TO 20 KT OVER THE PAST 24 HOURS. SSMI TPW INDICATES MODERATE MOISTURE S OF 15N IN THE WAVE ENVIRONMENT. UPPER LEVEL DIFFLUENCE OVER THE WAVE IS HELPING TO ENHANCE OUTFLOW OVER THE CONVECTION ASSOCIATED WITH THE WAVE. SCATTERED MODERATE CONVECTION IS FROM 09N TO 16N BETWEEN 56W AND 64W. A CENTRAL CARIBBEAN TROPICAL WAVE HAS AN AXIS EXTENDING FROM NEAR 17N71W TO 10N72W...MOVING W AT 15 TO 20 KT OVER THE PAST 24 HOURS. A SHALLOW POLEWARD MOISTURE SURGE IS NOTED IN SSMI TPW WITH A 700 MB INVERTED TROUGH INDICATED IN MODEL FIELDS BETWEEN 70W AND 77W. NO DEEP CONVECTION IS OCCURRING WITH THE WAVE AT THIS TIME. A WESTERN CARIBBEAN TROPICAL WAVE HAS NOW COMPLETELY MOVED INLAND OVER CENTRAL AMERICA AND EXTENDS S OVER THE E PACIFIC. PLEASE REFER TO THE E PACIFIC TROPICAL WEATHER DISCUSSION UNDER AWIPS HEADER MIATWDEP FOR MORE DETAILS. ...ITCZ/MONSOON TROUGH... THE MONSOON TROUGH EXTENDS ACROSS COASTAL AFRICA NEAR 14N17W TO 10N30W TO 11N41W. OTHER THAN CONVECTION ASSOCIATED WITH THE TROPICAL WAVE OVER THE EASTERN ATLC...ISOLATED MODERATE CONVECTION IS WITHIN 125 NM OF THE MONSOON TROUGH AXIS W OF 34W. ...DISCUSSION... GULF OF MEXICO... A SHARP UPPER TROUGH IS OVER THE GULF...EXTENDING FROM THE N CENTRAL GULF NEAR THE MS COAST...TO BAY OF CAMPECHE. ASCENT ASSOCIATED WITH THE TROUGH SUPPORTS SCATTERED THUNDERSTORMS FROM 26N TO 30N W OF 90W. A DIURNAL SURFACE TROUGH IS OVER THE SW GULF...EXTENDING FROM 23N92W TO 18N93W. NO CONVECTION IS NOTED WITH THIS TROUGH. A SURFACE RIDGE AXIS EXTENDS FROM HIGH PRESSURE OVER THE SW N ATLC TO THE N GULF COAST. THIS RIDGE AXIS SUPPORTS GENERALLY LIGHT S TO SE WINDS ACROSS THE ENTIRE GULF BASIN THIS AFTERNOON. OVER THE NEXT 24 HOURS CONVECTION IS FORECAST TO CONTINUE OVER THE NW GULF. CARIBBEAN SEA... UPPER LEVEL RIDGING DOMINATES THE CARIBBEAN THIS AFTERNOON. MOST OF THE CARIBBEAN IS VOID OF CONVECTION DUE TO DRY AIR AND SUBSIDENCE. HOWEVER...TWO AREAS OF CONVECTION ARE NOTED. THE NEARBY E PACIFIC MONSOON TROUGH SUPPORTS ISOLATED MODERATE CONVECTION S OF 12N W OF 81W. SCATTERED MODERATE CONVECTION IS SPREADING ACROSS THE LESSER ANTILLES ASSOCIATED WITH A TROPICAL WAVE. PLEASE REFER TO THE TROPICAL WAVES SECTION FOR MORE DETAILS. GENTLE TO MODERATE TRADE WINDS COVER THE MAJORITY OF THE CARIBBEAN WITH AN AREA OF MODERATE TO FRESH TRADE WINDS OVER THE CENTRAL CARIBBEAN S OF 17N. EXPECT CONVECTION TO CONTINUE OVER THE SW CARIBBEAN OVER THE NEXT 24 HOURS. CONVECTION WILL ALSO CONTINUE OVER THE S LEEWARD ISLANDS THROUGH TONIGHT AND WILL SPREAD W OVER THE SE CARIBBEAN THROUGH THURSDAY WITH THE TROPICAL WAVE. ...HISPANIOLA... ISOLATED SHOWERS AND THUNDERSTORMS WILL DEVELOP OVER THE ISLAND IN AFTERNOON HEATING...DIMINISHING LATE THIS EVENING. A SIMILAR PATTERN IS EXPECTED ACROSS HISPANIOLA ON THURSDAY. ATLANTIC OCEAN... AN UPPER RIDGE EXTENDS FROM NEAR CUBA TO THE W ATLC OFFSHORE OF FL. UPPER LEVEL DIFFLUENCE ASSOCIATED WITH THIS RIDGE SUPPORTS SCATTERED THUNDERSTORMS WITHIN 50 NM OF A LINE FROM MIAMI TO 31N79W. A SURFACE RIDGE IS ANCHORED BY A 1018 MB HIGH NEAR 29N74W. TROPICAL DEPRESSION EIGHT IS CENTERED NEAR 31N61W. PLEASE REFER TO THE SPECIAL FEATURES SECTION FOR MORE DETAILS. A 1019 MB HIGH IS CENTERED OVER THE EASTERN ATLC NEAR 27N30W. TWO TROPICAL WAVES ARE OVER THE TROPICAL ATLC. PLEASE REFER TO THE TROPICAL WAVES SECTION FOR MORE DETAILS. THE REMNANTS OF TROPICAL DEPRESSION GRACE ARE OVER THE CENTRAL TROPICAL ATLC. PLEASE REFER TO THE SPECIAL FEATURES SECTION FOR MORE DETAILS. OVER THE NEXT 24 HOURS EXPECT CONVECTION TO CONTINUE FROM THE N BAHAMAS TO 31N W OF 70W OVER THE W ATLC. FOR ADDITIONAL INFORMATION PLEASE VISIT HTTP://WWW.HURRICANES.GOV/MARINE $$ LATTO