000 AXNT20 KNHC 102345 TWDAT TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 805 PM EDT TUE SEP 10 2013 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 2315 UTC. ...SPECIAL FEATURES... TROPICAL STORM HUMBERTO IS CENTERED NEAR 15.0N 28.1W AT 10/2100 UTC OR 210 NM W OF THE SOUTHERNMOST CAPE VERDE ISLANDS MOVING NW AT 7 KT. ESTIMATED MINIMUM CENTRAL PRESSURE IS 993 MB. MAXIMUM SUSTAINED WIND SPEED IS 60 KT WITH GUSTS TO 75 KT. SCATTERED MODERATE CONVECTION IS FROM 11N-16N BETWEEN 24W-33W. SEE LATEST NHC FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS MIATCMAT4/WTNT24 KNHC FOR MORE DETAILS. TROPICAL STORM GABRIELLE IS CENTERED NEAR 31.9N 64.9W AT 11/0000 UTC OR 25 NM SSW OF BERMUDA MOVING N AT 9 KT. ESTIMATED MINIMUM CENTRAL PRESSURE IS 1004 MB. MAXIMUM SUSTAINED WIND SPEED IS 50 KT WITH GUSTS TO 60 KT. SCATTERED MODERATE CONVECTION IS FROM 29N-34N BETWEEN 57W-65W. SEE LATEST NHC INTERMEDIATE PUBLIC FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS MIATCPAT2/WTNT32 KNHC AND THE FULL FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS MIATCMAT2/WTNT22 KNHC FOR MORE DETAILS. ...TROPICAL WAVES... TROPICAL WAVE EXTENDS FROM 18N47W TO 22N50W MOVING W AT 10-15 KT. A 1012 MB LOW IS CENTERED AT THE SOUTHERN EXTENT OF THE WAVE NEAR 18N47W WITH AN ISOLATED MODERATE CONVECTIVE BURST IN THE VICINITY OF 18N46W. TO THE NW OF THE LOW CENTER...WIDELY SCATTERED MODERATE CONVECTION IS OCCURRING FROM 18N-21N BETWEEN 49W-54W. THE WAVE CONTINUES TO REMAINS WEAK WITH GLOBAL MODELS INDICATING A WEAK TROUGH WILL IMPACT THE LESSER ANTILLES OVER THE UPCOMING WEEKEND BRINGING INCREASED SHOWER AND TSTM ACTIVITY TO THE EASTERN CARIBBEAN SATURDAY AND SUNDAY. ...ITCZ/MONSOON TROUGH... THE INTERTROPICAL CONVERGENCE ZONE AXIS EXTENDS FROM 09N41W TO 09N54W. ISOLATED MODERATE CONVECTION IS FROM 06N-09N BETWEEN 46W- 53W. ...DISCUSSION... GULF OF MEXICO... AN UPPER LEVEL TROUGH AXIS EXTENDS FROM OVER EASTERN TEXAS NEAR 31N96W S-SE TO A BASE OVER THE WESTERN GULF NEAR 23N93W. WATER VAPOR IMAGERY INDICATES AN AREA OF MAXIMUM MIDDLE TO UPPER LEVEL DIFFLUENCE LIES EAST OF THE TROUGH AXIS AND IS GENERATING WIDELY SCATTERED SHOWERS AND ISOLATED TSTMS ACROSS MUCH OF THE WESTERN GULF W OF 89W THIS EVENING. A WEAK SURFACE TROUGH IS ALSO ANALYZED NEARLY PARALLEL TO THE MEXICO COAST FROM 20N95W TO 24N98W PROVIDING LOW-LEVEL MOISTURE CONVERGENCE AND INCREASED AREAL COVERAGE OF SCATTERED SHOWERS AND TSTMS FROM 20N-26N BETWEEN 96W-99W. FARTHER EAST...A MIDDLE TO UPPER LEVEL LOW IS CENTERED OVER THE SW NORTH ATLC NEAR 29N79W AND CONTINUES TO PROVIDE OVERALL DRY AND STABLE CONDITIONS ALOFT ON ITS WESTERN PERIPHERY OVER A LARGE PORTION OF THE EASTERN GULF. A FEW ISOLATED SHOWERS AND TSTMS ARE HOWEVER OCCURRING ACROSS THE FAR SW FLORIDA PENINSULA AND ADJACENT COASTAL WATERS FROM 25N-26N EAST OF 83W. LOOKING AHEAD...A SURFACE TROUGH...CURRENTLY ANALYZED OFF THE COAST OF THE YUCATAN PENINSULA IN THE NW CARIBBEAN SEA...IS EXPECTED TO CONTINUE DRIFTING WESTWARD AND INTO THE SW GULF BY LATE WEDNESDAY INTO THURSDAY. THIS SURFACE TROUGHING IS FORECAST TO DEVELOP INTO A LOW PRESSURE AREA OVER THE SW GULF AND INCREASE SE WINDS ON ITS EASTERN PERIPHERY GENERALLY W OF 90W OVER THE UPCOMING WEEKEND INTO MONDAY. CARIBBEAN SEA... AN UPPER LEVEL ANTICYCLONE IS CENTERED OVER THE NW CARIBBEAN AND IS PROVIDING FOR AN OVERALL DIFFLUENT ENVIRONMENT FOR MUCH OF THE WESTERN CARIBBEAN THIS EVENING. AS A RESULT...SCATTERED SHOWERS AND TSTMS COVER A LARGE PORTION OF THE BASIN W OF 75W. ONE CONCENTRATED AREA OF STRONG CONVECTION IS OCCURRING ACROSS JAMAICA AND IN THE ADJACENT COASTAL WATERS FROM 13N-21N BETWEEN 76W-81W. FARTHER WEST...A SURFACE TROUGH IS ANALYZED FROM COASTAL HONDURAS NEAR 15N87W TO 21N86W AND CONTINUES TO PROVIDE FOCUS FOR SCATTERED MODERATE TO STRONG TSTMS FROM 14N-22N BETWEEN 84W-92W...INCLUDING INTERIOR PORTIONS OF CENTRAL AMERICA GENERALLY NW OF NICARAGUA. FINALLY...OVER THE EASTERN CARIBBEAN...AN UPPER LEVEL LOW IS CENTERED NEAR 13N65W AND CONTINUES TO MOVE WESTWARD. WATER VAPOR IMAGERY INDICATES THAT MAINLY DRY AIR ALOFT ACCOMPANIES THIS FEATURE...HOWEVER A SMALL AMOUNT OF MOISTURE IS ADVECTING NORTHWARD ON THE EASTERN PERIPHERY OF THE UPPER LEVEL LOW. INCREASED CLOUDINESS IS NOTED ON SATELLITE IMAGERY E OF 65W WITH POSSIBLE ISOLATED LOW-TOPPED SHOWERS OCCURRING ACROSS THE LESSER ANTILLES THIS EVENING. HISPANIOLA... CURRENTLY A FEW ISOLATED SHOWERS AND TSTMS ARE OCCURRING OVER WESTERN PORTIONS OF THE ISLAND...HOWEVER THE OVERALL SYNOPTIC PATTERN IS DOMINATED BY AN UPPER LEVEL LOW AND ASSOCIATED UPPER LEVEL TROUGH AXIS APPROACHING FROM THE EAST WITH THE LOW CENTERED NEAR 13N65W. WATER VAPOR IMAGERY INDICATES MODERATE TO STRONG DRY AND STABLE AIR MOVING OVERHEAD WHICH WILL PROVIDE FOR FAIRLY TRANQUIL CONDITIONS OVERNIGHT INTO WEDNESDAY. ONCE THE UPPER LEVEL TROUGH AXIS PASSES TO THE WEST OF HISPANIOLA LATE WEDNESDAY INTO THURSDAY...CLOUDINESS WILL GRADUALLY INCREASE WITH LOW-TOPPED SHOWERS AND THE POTENTIAL ONCE AGAIN FOR AFTERNOON AND EVENING TSTMS TO OCCUR. ATLANTIC OCEAN... A MIDDLE TO UPPER LEVEL LOW IS CENTERED OVER THE SW NORTH ATLC NEAR 29N79W. WHILE THE UPPER LEVEL FEATURE DOES NOT SUPPORT ANY SURFACE FRONTAL BOUNDARY...MIDDLE TO UPPER LEVEL DYNAMICS ARE SUPPORTING ENHANCED CLOUDINESS AND WIDELY SCATTERED SHOWERS AND ISOLATED TSTMS OCCURRING FROM 21N-32N BETWEEN 70W-81W... INCLUDING THE BAHAMAS AND THE NORTHERN ADJACENT COASTAL WATERS OF CUBA THIS EVENING. FARTHER EAST...GABRIELLE CONTINUES TO TRACK NORTHWARD BETWEEN 60W-70W. THE REMAINDER OF THE CENTRAL AND EASTERN ATLC IS UNDER THE INFLUENCE OF A SURFACE RIDGE ANCHORED BY A 1035 MB HIGH CENTERED NW OF THE AZORES NEAR 42N33W. FOR ADDITIONAL INFORMATION PLEASE VISIT HTTP://WWW.HURRICANES.GOV/MARINE $$ HUFFMAN