000 AXNT20 KNHC 111738 TWDAT TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 205 PM EDT FRI SEP 11 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 STORM HENRI IS CENTERED NEAR 38.0N 59.4W AT 11/1500 UTC OR ABOUT 590 SSW OF CAPE RACE NEWFOUNDLAND MOVING N AT 17 KT. ESTIMATED MINIMUM CENTRAL PRESSURE IS 1008 MB. MAXIMUM SUSTAINED WIND SPEED IS 35 KT WITH GUSTS TO 40 KT. NUMEROUS MODERATE CONVECTION IS FROM 38N TO 42N BETWEEN 56W AND 61W. SEE LATEST NHC FORECAST/ADVISORY UNDER AWIPS/ WMO HEADERS MIATCMAT3/WTNT23 KNHC FOR MORE DETAILS. ...TROPICAL WAVES... A TROPICAL WAVE EXTENDS FROM 17N20W TO 08N22W MOVING W AT 15 KT. THE WAVE COINCIDES WITH LOW AMPLITUDE 700 MB TROUGHING S OF 13N BETWEEN 15W AND 27W. SSMI TPW INDICATES THE WAVE IS EMBEDDED IN A ENVIRONMENT OF MODERATE TO HIGH MOISTURE. ISOLATED MODERATE CONVECTION IS FROM 06N TO 12N BETWEEN 17W AND 24W. A TROPICAL WAVE EXTENDS FROM 18N37W TO 09N39W MOVING W AT 15 KT. THE WAVE COINCIDES WITH A 700 MB TROUGH BETWEEN 35W AND 45W. THIS WAVE IS ALSO EMBEDDED IN AN ENVIRONMENT OF MODERATE TO HIGH MOISTURE. ISOLATED MODERATE CONVECTION IS FROM 07N TO 16N BETWEEN 37W AND 42W. A TROPICAL WAVE...INCLUDING THE REMNANTS OF GRACE...EXTENDS FROM 20N62W TO 12N62W MOVING W AT 15 TO 20 KT. THE WAVE COINCIDES WITH A 700 MB TROUGH BETWEEN 60W AND 65W...AND A 850 MB RELATIVE VORTICITY MAXIMUM NEAR 17N63W. SCATTERED MODERATE CONVECTION IS FROM 14N TO 22N BETWEEN 57W AND 64W. A TROPICAL WAVE EXTENDS FROM 17N73W TO 08N75W MOVING W AT 15 TO 20 KT. THE WAVE COINCIDES WITH SUBTLE 700 MB TROUGHING BETWEEN 70W AND 76W. SCATTERED MODERATE CONVECTION IS FROM 08N TO 16N BETWEEN 73W AND 84W. SOME OF THIS CONVECTION IS ALSO ASSOCIATED WITH THE EASTERN PACIFIC MONSOON TROUGH. ...ITCZ/MONSOON TROUGH... THE MONSOON TROUGH EXTENDS FROM THE AFRICAN COAST NEAR 11N15W TO 07N25W TO 09N37W. THE ITCZ BEGINS WEST OF A TROPICAL WAVE NEAR 10N41W AND CONTINUES TO 07N58W. OTHER THAN CONVECTION ASSOCIATED WITH THE TROPICAL WAVES...ISOLATED MODERATE CONVECTION IS WITHIN 125 NM OF THE MONSOON TROUGH AXIS. SCATTERED MODERATE CONVECTION IS FROM 06N TO 13N BETWEEN 41W AND 56W. ...DISCUSSION... GULF OF MEXICO... A BROAD UPPER LEVEL TROUGH EXTENDS FORM THE CENTRAL AND EASTERN US TO THE N GULF COAST AND FL. SHORTWAVE ENERGY ALOFT MOVING AROUND THE BASE OF THIS TROUGH IS SUPPORTING CLUSTERS OF MODERATE TO STRONG CONVECTION OVER THE NW GULF FROM 26N TO 30N BETWEEN 88W AND 97W. A DIURNAL SURFACE TROUGH EXTENDS OVER THE SW GULF FROM 22N95W TO 18N95W. ISOLATED THUNDERSTORMS ARE WITHIN 30 NM OF THE TROUGH AXIS. A 1016 MB HIGH IS CENTERED NEAR 27N86W SUPPORTING MAINLY GENTLE TO MODERATE ANTICYCLONIC WINDS OVER THE GULF BASIN...WITH THE EXCEPTION OF VARIABLE AND GUSTY WINDS IN THE VICINITY OF CONVECTION OVER THE NW GULF. THE TROUGH WILL DIG SOUTH AND EAST OVER THE NEXT 24 HOURS WITH CONVECTION LIKELY ACROSS THE NORTHERN HALF OF THE GULF. CARIBBEAN SEA... AN UPPER LEVEL ANTICYCLONE IS CENTERED OVER THE NW CARIBBEAN NEAR 18N87W. AN UPPER TROUGH EXTENDS OVER THE CENTRAL AND EASTERN CARIBBEAN ALONG AN AXIS FROM PUERTO RICO TO N COLOMBIA. UPPER LEVEL DIFFLUENCE WITH THE NEARBY MONSOON TROUGH AND A TROPICAL WAVE SUPPORT CONVECTION OVER THE SW CARIBBEAN. PLEASE REFER TO THE TROPICAL WAVES SECTION FOR MORE DETAILS. ASCENT ON THE EASTERN SIDE OF THE UPPER TROUGH IS ENHANCING CONVECTION ASSOCIATED WITH A TROPICAL WAVE OVER THE EASTERN CARIBBEAN. PLEASE SEE THE TROPICAL WAVES SECTION FOR MORE DETAILS. GENTLE TO MODERATE TRADE WINDS COVER THE MAJORITY OF THE CARIBBEAN BASIN TODAY...EXCEPT A SMALL AREA OF WINDS OF 25 TO 30 KT ALONG THE NORTHERN PORTION OF THE WAVE OVER THE EASTERN CARIBBEAN. ...HISPANIOLA... ISOLATED SHOWERS AND THUNDERSTORMS WILL OCCUR THIS AFTERNOON AND EVENING IN SHALLOW MOISTURE OVER THE ISLAND. MOISTURE WILL INCREASE FROM EAST TO WEST EARLY SATURDAY AS A TROPICAL WAVE APPROACHES THE ISLAND. SHOWERS AND THUNDERSTORMS WILL BECOME LIKELY ON SATURDAY WITH LOCALLY HEAVY RAINFALL POSSIBLE. ATLANTIC OCEAN... AN UPPER LEVEL RIDGE CENTERED OVER THE NW CARIBBEAN HAS AN AXIS THAT EXTENDS NW ACROSS THE SW N ATLC. FLOW BETWEEN THIS RIDGE AND A BROAD UPPER TROUGH OVER THE EASTERN HALF OF THE US SUPPORTS SCATTERED THUNDERSTORMS N OF 24N BETWEEN 74W AND 79W. A SHARP UPPER TROUGH EXTENDS FROM 30N62W TO PUERTO RICO...SUPPORTING ISOLATED MODERATE CONVECTION WITHIN 50 NM OF A LINE FROM 23N71W TO 29N61W. A TROPICAL WAVE OVER THE EASTERN CARIBBEAN AND SW ATLC ALONG 62W SUPPORTS CONVECTION. PLEASE REFER TO THE TROPICAL WAVES SECTION FOR MORE DETAILS. AN UPPER LOW IS CENTERED NEAR 28N48W SUPPORTS ISOLATED MODERATE CONVECTION FROM 25N TO 28N BETWEEN 45W AND 52W. A SURFACE LOW NEAR 29N37W HAS A SURFACE TROUGH AXIS THAT EXTENDS FROM 30N35W THROUGH THE LOW CENTER TO 26N41W. ISOLATED MODERATE CONVECTION IS WITHIN 100 NM OF THE LOW CENTER. TWO TROPICAL WAVES ARE OVER THE CENTRAL AND EASTERN ATLC. PLEASE REFER TO THE TROPICAL WAVES SECTION FOR MORE DETAILS. TROPICAL STORM HENRI IS OVER THE WEST CENTRAL ATLC. PLEASE REFER TO THE SPECIAL FEATURES SECTION FOR MORE DETAILS. FOR ADDITIONAL INFORMATION PLEASE VISIT HTTP://WWW.HURRICANES.GOV/MARINE $$ LATTO