000 AXNT20 KNHC 181803 TWDAT TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 205 PM EDT FRI SEP 18 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 1745 UTC. ...SPECIAL FEATURES... TROPICAL DEPRESSION NINE IS CENTERED NEAR 17.7N 47.1W AT 18/1500 UTC OR ABOUT 828 NM ENE OF THE LESSER ANTILLES MOVING W-NW AT 7 KT. ESTIMATED MINIMUM CENTRAL PRESSURE IS 1007 MB. MAXIMUM SUSTAINED WIND SPEED IS 25 KT WITH GUSTS TO 35 KT. CONVECTION HAS SIGNIFICANTLY REDUCED AS THE DEPRESSION WEAKENED...ONLY ISOLATED MODERATE CONVECTION IS OBSERVED IN THE NE QUADRANT. FURTHER WEAKENING IS FORECAST...AND THE DEPRESSION IS EXPECTED TO BECOME A REMNANT LOW TONIGHT. PLEASE SEE THE LATEST NHC FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS MIATCMAT4/WTNT24 KNHC FOR MORE DETAILS. TROPICAL DEPRESSION TEN FORMED OVER THE EASTERN ATLC AT 1500 UTC. THE DEPRESSION CENTER IS NEAR 13.1N 36.7W OR ABOUT 758 NM WSW OF THE CAPE VERDE ISLANDS MOVING WNW AT 8 KT. ESTIMATED MINIMUM CENTRAL PRESSURE IS 1009 MB. MAXIMUM SUSTAINED WIND SPEED IS 25 KT WITH GUSTS TO 35 KT. SCATTERED MODERATE CONVECTION IS FROM 06N TO 20N BETWEEN 26W AND 43W. PLEASE SEE THE LATEST NHC FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS MIATCMAT5/WTNT24 KNHC FOR MORE DETAILS. ...TROPICAL WAVES... A TROPICAL WAVE IS IN THE FAR WEST CARIBBEAN EXTENDING ACROSS CENTRAL AMERICA INTO THE EPAC WATERS. ITS AXIS IS NEAR 87W ...MOVING WEST AT 20 KT OVER THE PAST 24 HOURS. CIRA LAYER PRECIPITABLE WATER IMAGERY INDICATE THE WAVE IS ASSOCIATED WITH SHALLOW MOISTURE THAT ENHANCES SCATTERED SHOWERS AND TSTMS S OF 20N W OF 83W. ...ITCZ/MONSOON TROUGH... THE MONSOON TROUGH EXTENDS ACROSS AFRICA INTO THE E TROPICAL ATLC NEAR 07N12W ALONG 06N20W TO 10N26W. THE ITCZ REMAINS UNDISCERNIBLE. SCATTERED MODERATE CONVECTION IS FROM 06N TO 09N E OF 16W. THE REMAINDER OF THE CONVECTION IS ASSOCIATED WITH T.D. NINE AND T.D. TEN IN THE SPECIAL FEATURES. ...DISCUSSION... GULF OF MEXICO... A NARROW UPPER TROUGH EXTENDS ACROSS GEORGIA SW INTO THE E GULF TO A BASE OVER EASTERN BAY OF CAMPECHE. THIS FEATURE ALOFT CONTINUES TO INFLUENCE A 1009 MB LOW OVER THE SE BASIN NEAR 25N82W FROM WHICH A SURFACE TROUGH EXTENDS SW TO 21N86W. NEXT TO THE UPPER TROUGH...A RIDGE OVER THE SW N ATLC GENERATES DIFFLUENCE ALOFT TO SUPPORT A CLUSTER OF MODERATE CONVECTION AND SCATTERED TSTMS FROM 23N TO 27N E OF 83W AND ISOLATED SHOWERS AND TSTMS WITHIN 60 NM EITHER SIDE OF THE SURFACE TROUGH. STRONG SUBSIDENCE AND DRY STABLE AIR WITH CLEAR SKIES COVERS THE W GULF W OF 90W. SURFACE TROUGH/LOW WILL MOVE NE ACROSS FLORIDA TONIGHT AND SAT. WEAK SURFACE RIDGE WILL PERSIST OVER THE N/CENTRAL GULF THIS WEEKEND. CARIBBEAN SEA... A TROPICAL WAVE IS MOVING ACROSS THE FAR W CARIBBEAN...ACROSS CENTRAL AMERICA TO EPAC WATERS. SHALLOW MOISTURE ENHANCES SCATTERED SHOWERS AND TSTMS S OF 20N W OF 83W. OVER THE SW BASIN...THE MONSOON TROUGH MOVES ACROSS PANAMA TO COLOMBIA ADJACENT WATERS NEAR 11N73W AND SUPPORT SCATTERED MODERATE CONVECTION SW OF A LINE FROM 15N83W TO 11N77W. MIDDLE LEVEL DIFFLUENCE OVER THE S-SE CARIBBEAN SUPPORT SIMILAR CONVECTION S OF 13N BETWEEN 60W AND 72W. UPPER DIFFLUENCE REGIONS AND SHALLOW MOISTURE SUPPORT ISOLATED SHOWERS AND TSTMS OVER THE GREATER ANTILLES...CUBA...HISPANIOLA AND PUERTO RICO. DRY AIR SUBSIDENCE AND STRONG DEEP LAYER WIND SHEAR FAVOR FAIR WEATHER AND CLEAR SKIES ELSEWHERE. THE TROPICAL WAVE WILL MOVE COMPLETELY INTO EPAC WATERS TONIGHT. ...HISPANIOLA... AN UPPER RIDGE CENTERED OVER THE SW N ATLC AND A LOW CENTERED S OF THE HISPANIOLA GENERATES A DIFFLUENT ENVIRONMENT ALOFT THAT ALONG SHALLOW MOISTURE ACROSS THE ISLAND SUPPORT CLOUDINESS AND ISOLATED SHOWERS AND TSTMS. MOISTURE AND SHOWER/THUNDERSTORM ACTIVITY WILL PERSIST THROUGH EARLY SAT WITH SOME CLEARING SAT NIGHT AND SUN. ATLANTIC OCEAN... THE MAIN FEATURES IN THE BASIN ARE TROPICAL DEPRESSION NINE AND RECENTLY FORMED TROPICAL DEPRESSION TEN ALREADY DISCUSSED IN THE SPECIAL FEATURES SECTION. THE UPPER TROUGH MENTIONED IN THE GULF OF MEXICO SECTION ALONG WITH A RIDGE OVER THE SW N ATLC CENTERED NEAR 24N69W CONTINUE TO GENERATE DIFFLUENCE ALOFT...THUS SUPPORTING ISOLATED SHOWERS AND TSTMS ALSO LINKED TO A 1009 MB LOW NEAR 29N79W. FARTHER EAST...UPPER DIFFLUENCE ALSO SUPPORTS AN AREA OF SCATTERED MODERATE TO ISOLATED STRONG CONVECTION N OF 25N BETWEEN 66W AND 75W. OVER THE NORTH CENTRAL ATLC...A SHORT- WAVE TROUGH WITH EMBEDDED LOW SUPPORT A 1015 MB LOW NEAR 27N53W WITH TROUGH EXTENDING FROM 29N53W TO THE LOW TO 26N56W. SCATTERED MODERATE CONVECTION AND TSTMS ASSOCIATED WITH THIS LOW ARE N OF 23N BETWEEN 44W AND 56W. THE REMAINDER ATLC BASIN IS BEING DOMINATED BY SURFACE RIDGING ANCHORED BY A 1021 MB HIGH NEAR 28N35W. FOR ADDITIONAL INFORMATION PLEASE VISIT HTTP://WWW.HURRICANES.GOV/MARINE $$ NR