000 AXNT20 KNHC 122331 TWDAT TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 805 PM EDT SAT SEP 12 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 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 2330 UTC. ...TROPICAL WAVES... A TROPICAL WAVE OVER THE EASTERN ATLANTIC HAS AN AXIS THAT EXTENDS FROM 16N26W TO 09N29W...MOVING W AT 05-10 KT. SSMI TPW SHOWS HIGH MOISTURE IN THE VICINITY OF THIS WAVE. A TILTED 700 MB TROUGH EXTENDS FROM W OF THE CAPE VERDE ISLANDS TO NEAR 09N31W WHICH INCLUDES THE ENVIRONMENT OF THE WAVE. SCATTERED MODERATE CONVECTION IS S OF 12N BETWEEN 22W-31W. A TROPICAL WAVE IS OVER THE CENTRAL ATLANTIC WITH AXIS THAT EXTENDS FROM 16N49W TO 09N51W...MOVING W AT 15-20 KT. A BROAD 700 MB TROUGH IS EVIDENT BETWEEN 42W AND 55W. HIGH MOISTURE IS EVIDENT IN TPW IMAGERY IN THE ENVIRONMENT OF THIS WAVE. SCATTERED MODERATE CONVECTION IS FROM 10N-15N BETWEEN 47W-55W. A TROPICAL WAVE IS OVER THE CENTRAL CARIBBEAN WITH AXIS THAT EXTENDS FROM 19N70W TO 12N70W...MOVING W AT AROUND 15 KT. THIS POSITION WAS CALCULATED AFTER ANALYZING THE LATEST SCATTEROMETER DATA AND SURFACE OBSERVATIONS. A SHARP 700 MB TROUGH IS EVIDENT BETWEEN 65W-73W. TPW IMAGERY DEPICTS MODERATE MOISTURE SURROUNDING THIS WAVE. SCATTERED MODERATE CONVECTION PREVAILS E OF THE WAVE AXIS AFFECTING PUERTO RICO...THE MONA PASSAGE AND PORTIONS OF DOMINICAN REPUBLIC AS WELL AS THEIR ADJACENT NE CARIBBEAN WATERS N OF 16N AND E OF 70W. THIS CONVECTION IS BEEN ENHANCED BY AN UPPER-LEVEL TROUGH LOCATED OVER HISPANIOLA AND EXTENDS ACROSS THE NE CARIBBEAN. A TROPICAL WAVE IS OVER CENTRAL AMERICA AND E PACIFIC WITH AXIS THAT EXTENDS FROM 14N84W TO 07N85W...MOVING W AT 15-20 KT. A SUBTLE 700 MB TROUGH IS EVIDENT BETWEEN 80W-89W. NUMEROUS SHOWERS AND THUNDERSTORMS ARE OBSERVED ACROSS NICARAGUA...HONDURAS AND THE SW CARIBBEAN WATERS S OF 16N AND W OF 80W. ...ITCZ/MONSOON TROUGH... THE MONSOON TROUGH EXTENDS FROM THE AFRICAN COAST NEAR 16N17W TO 09N33W TO 11N49W. THE INTERTROPICAL CONVERGENCE ZONE AXIS EXTENDS FROM 10N51W TO 10N60W. ASIDE FROM THE CONVECTION GENERATED BY THE TROPICAL WAVES...SCATTERED MODERATE CONVECTION IS FROM 07N-12N BETWEEN 31W-43W. ISOLATED CONVECTION IS WITHIN 200 NM N OF THE ITCZ AXIS. ...DISCUSSION... GULF OF MEXICO... A BROAD UPPER-LEVEL TROUGH EXTENDS FROM THE OHIO VALLEY SW TO THE NW AND N CENTRAL GULF SUPPORTING A COLD FRONT THAT EXTENDS ACROSS THE NORTHERN GULF WATERS FROM 27N97W TO 28N90W TO 30N86W. A LARGE PRE-FRONTAL SURFACE TROUGH EXTENDS ACROSS THE CENTRAL GULF FROM 22N96W TO 29N83W. NUMEROUS MODERATE CONVECTION PREVAILS ACROSS MOST OF THE BASIN N OF 19N. SCATTEROMETER DATA DEPICTS GENTLE TO MODERATE N TO NE WINDS N OF THE COLD FRONT WHILE MODERATE TO FRESH WINDS ARE PREVAILING BETWEEN THE FRONT AND THE TROUGH FROM 25N-27N BETWEEN 89W-92W. GENTLE SW TO SE WINDS ARE S OF THE TROUGH. OVER THE NEXT 24 HOURS...EXPECT FOR THE COLD FRONT AND TROUGH WILL MOVE OVER THE CENTRAL AND SOUTHERN GULF WITH CONVECTION AFFECTING THE WHOLE BASIN. CARIBBEAN SEA... AN UPPER-LEVEL TROUGH OVER HISPANIOLA AND THE EASTERN CARIBBEAN IS INTERACTING WITH A TROPICAL WAVE TO PRODUCE SCATTERED MODERATE CONVECTION OVER THE NE CARIBBEAN...INCLUDING PUERTO RICO AND DOMINICAN REPUBLIC. SCATTERED MODERATE CONVECTION IS OBSERVED OVER THE SW CARIBBEAN ARE ASSOCIATED WITH ANOTHER TROPICAL WAVE. PLEASE REFER TO THE TROPICAL WAVES SECTION FOR MORE DETAILS. GENTLE TO MODERATE TRADE WINDS COVER THE MAJORITY OF THE CARIBBEAN...EXCEPT FOR A SMALL AREA OF MODERATE TO FRESH TRADE WINDS N OF 16N WITHIN 150 NM OF THE AXIS OF THE TROPICAL WAVE OVER THE CENTRAL CARIBBEAN. OVER THE NEXT 24 HOURS...EXPECT GUSTY WINDS AND CONVECTION TO SPREAD W ACROSS PUERTO RICO...HISPANIOLA...AND CARIBBEAN WATERS AS THE TROPICAL WAVE CONTINUES MOVING W. ...HISPANIOLA... MOISTURE WILL CONTINUE ON THE INCREASE AS A TROPICAL WAVE CONTINUES MOVING W AND INTERACTS WITH AN UPPER-LEVEL TROUGH GENERATING SCATTERED MODERATE CONVECTION AFFECTING THE ISLAND. THIS ACTIVITY IS EXPECTED TO CONTINUE OVER THE NEXT 24 HOURS WITH THE RISK OF HEAVY RAINFALL...FLASH FLOODING...AND MUD SLIDES. ATLANTIC OCEAN... AN UPPER-LEVEL TROUGH OVER THE OHIO VALLEY IS PRODUCING SW FLOW ALOFT OVER THE SW N ATLC W OF 75W. ASCENT ASSOCIATED WITH THIS FLOW ALOFT SUPPORTS SCATTERED MODERATE CONVECTION N OF 27N W OF 74W. TO THE E...AN UPPER-LEVEL LOW CENTERED NEAR 28N56W IS REFLECTED AT THE SURFACE AS A TROUGH THAT EXTENDS FROM 31N53W TO 27N53W. ISOLATED CONVECTION IS OBSERVED ALONG THIS BOUNDARY. A 1016 MB SURFACE LOW CENTERED NEAR 28N42W HAS A SURFACE TROUGH THAT EXTENDS FROM THE LOW CENTER TO 30N40W. ISOLATED CONVECTION IS FROM 28N-32N BETWEEN 40W-44W. THE REMAINDER OF THE BASIN IS UNDER THE INFLUENCE OF A SURFACE RIDGE ANCHORED N OF OUR AREA. TWO TROPICAL WAVES ARE OVER THE TROPICAL ATLANTIC. PLEASE REFER TO THE TROPICAL WAVES SECTION FOR MORE DETAILS. OVER THE NEXT 24 HOURS...CONVECTION WILL INCREASE E OF FL AS THE UPPER-LEVEL TROUGH OVER THE OHIO VALLEY MOVES E AND A COLD FRONT APPROACHES THE W ATLANTIC. FOR ADDITIONAL INFORMATION PLEASE VISIT HTTP://WWW.HURRICANES.GOV/MARINE $$ ERA