000 AXNT20 KNHC 082352 TWDAT TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 805 PM EDT SUN SEP 08 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 DEPRESSION NINE IS CENTERED NEAR 13.1N 21.4W AT 09/0000 UTC OR 165 NM SE OF PRAIA CAPE VERDE ISLANDS MOVING W AT 10 KT. ESTIMATED MINIMUM CENTRAL PRESSURE IS 1007 MB. MAXIMUM SUSTAINED WIND SPEED IS 25 KT WITH GUSTS TO 35 KT. NUMEROUS MODERATE AND SCATTERED STRONG CONVECTION IS FROM 10N-17N BETWEEN 20W-26W WITH SCATTERED MODERATE AND ISOLATED STRONG CONVECTION ELSEWHERE FROM 10N-17N BETWEEN 17W-27W. SEE LATEST NHC INTERMEDIATE PUBLIC ADVISORY UNDER AWIPS/WMO HEADERS MIATCPAT4/WTNT34 KNHC AND THE FULL FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS MIATCMAT4/WTNT24 KNHC FOR MORE DETAILS. ...TROPICAL WAVES... TROPICAL WAVE EXTENDS FROM 14N38W TO 21N38W MOVING W AT 10-15 KT. A 1010 MB LOW IS CENTERED ALONG THE WAVE AXIS NEAR 18N AND THIS REMAINS THE FOCUS FOR WIDELY SCATTERED MODERATE CONVECTION OCCURRING FROM 18N-23N BETWEEN 34W-42W. GLOBAL MODELS SUGGEST THE WAVE WILL CONTINUE TO DRIFT WESTWARD DURING THE NEXT FEW DAYS WEAKENING SOMEWHAT AS IT APPROACHES W OF 45W AS A MID- LATITUDE UPPER LEVEL TROUGH DIGS SOUTHWARD AND BEGINS TO PROVIDE AN INCREASED SHEAR ENVIRONMENT ACROSS THE CENTRAL TROPICAL ATLC. TROPICAL WAVE EXTENDS FROM 13N87W TO 22N87W MOVING W AT 10-15 KT. THE WAVE COINCIDES WITH BROAD AND WEAK SURFACE TO 700 MB TROUGHING OVER THE NW CARIBBEAN SEA...THE YUCATAN PENINSULA... AND PORTIONS OF THE SW GULF OF MEXICO. SCATTERED MODERATE CONVECTION IS FROM 13N-22N BETWEEN 84W-93W...AND IT IS LIKELY ENHANCED BY BROAD UPPER LEVEL TROUGHING TO THE NORTH OVER THE GULF OF MEXICO PROVIDING A DIFFLUENT ENVIRONMENT FOR SUSTAINING CONVECTION. ANY CONVECTION OCCURRING ACROSS INTERIOR PORTIONS OF CENTRAL AMERICA THIS EVENING FACE THE INCREASED LIKELIHOOD OF LOCALIZED FLASH FLOODING AND MUD SLIDES. ...ITCZ/MONSOON TROUGH... THE MONSOON TROUGH EXTENDS FROM THE AFRICAN COAST NEAR 15N17W TO 12N25W TO 18N38W TO 13N44W. THE INTERTROPICAL CONVERGENCE ZONE AXIS EXTENDS FROM 13N44W TO 09N50W TO 08N55W. ASIDE FROM CONVECTION ASSOCIATED WITH TROPICAL DEPRESSION NINE AND THE TROPICAL WAVE ALONG 38W...ISOLATED MODERATE CONVECTION IS FROM 05N-13N BETWEEN 22W-32W...AND FROM 08N-12N BETWEEN 43W-47W. ...DISCUSSION... GULF OF MEXICO... AN UPPER LEVEL TROUGH AXIS EXTENDS FROM OVER THE SW NORTH ATLC NEAR 29N81W OVER THE FLORIDA PENINSULA AND OVER THE NE GULF WATERS TO 29N91W. THIS UPPER LEVEL PATTERN IS RESULTING IN MOST OF THE GULF BASIN UNDER THE INFLUENCE OF WEST-NORTHWESTERLY FLOW ALOFT. OVER WESTERN PORTIONS OF THE BASIN STRETCHING INLAND OVER EASTERN MEXICO...ANOTHER UPPER LEVEL TROUGH EXTENDS FROM AN UPPER LEVEL LOW CENTERED OVER WEST TEXAS NEAR 30N101W SE TO 22N95W. THIS TROUGHING SUPPORTS A SURFACE TROUGH ANALYZED FROM 24N96W TO 18N93W WITH SCATTERED SHOWERS AND ISOLATED TSTMS OCCURRING OVER A LARGE PORTION OF THE WESTERN GULF W OF 89W. THE APPROACH OF A TROPICAL WAVE ALONG 87W IS ALSO GENERATING SCATTERED SHOWERS AND STRONG TSTMS ACROSS THE YUCATAN PENINSULA THIS EVENING. E-SE WINDS IN THE RANGE OF 5-15 KT WILL PERSIST THROUGH THE OVERNIGHT HOURS INTO MONDAY AS SURFACE RIDGING REMAINS ANCHORED OVER THE SE CONUS. EASTERLY WINDS WILL GRADUALLY INCREASE TO 10-20 KT TUESDAY INTO WEDNESDAY AS THE PRESSURE GRADIENT BETWEEN THE RIDGE AND LOWER PRESSURE OVER SOUTHERN MEXICO STRENGTHENS. CARIBBEAN SEA... AN NARROW UPPER LEVEL RIDGE AXIS EXTENDS FROM OVER HISPANIOLA NEAR 18N72W TO OVER EASTERN HONDURAS NEAR 15N84W. NORTH OF THIS RIDGE AXIS...BROAD UPPER LEVEL TROUGHING AND A DIFFLUENT ENVIRONMENT REMAINS AS A LIFTING MECHANISM GENERATING SCATTERED SHOWERS AND TSTMS N OF 17N BETWEEN 74W-91W. THE PRESENCE OF A TROPICAL WAVE ALONG 87W IS ALSO ADDING INCREASED LOW-LEVEL MOISTURE CONVERGENCE ACROSS FAR WESTERN PORTIONS OF THE NW CARIBBEAN...CENTRAL AMERICA...AND YUCATAN PENINSULA...COINCIDING WITH THE STRONGEST ONGOING CONVECTION AT THIS TIME. SOUTH OF THE RIDGE AXIS...CONDITIONS REMAINS GENERALLY FAIR WITH ONLY SCATTERED SHOWERS AND ISOLATED TSTMS OCCURRING WITHIN 90 NM EITHER SIDE OF THE MONSOON TROUGH AXIS ANALYZED FROM NORTHERN COLOMBIA NEAR 09N76W TO 09N79W TO THE BASE OF THE TROPICAL WAVE NEAR 13N87W. FINALLY...SURFACE TROUGHING EXTENDS SOUTHWESTWARD FROM THE REMNANT LOW OF GABRIELLE CENTERED IN THE SW NORTH ATLC NEAR 25N69W TO THE NORTHERN COAST OF HISPANIOLA NEAR 20N72W. LOW- LEVEL MOISTURE CONVERGENCE E OF 74W AND A FAVORABLE UPPER LEVEL DIFFLUENT ENVIRONMENT IN THE VICINITY OF HISPANIOLA IS GENERATING SCATTERED SHOWERS AND TSTMS N OF 14N BETWEEN 67W-74W. OTHERWISE...THE LESSER ANTILLES REMAIN UNDER FAIR SKIES AND TRANQUIL CONDITIONS THIS EVENING DUE TO SURFACE RIDGING EXTENDING SOUTHWESTWARD FROM THE CENTRAL ATLC. HISPANIOLA... CURRENTLY SURFACE TROUGHING EXTENDS FROM THE REMNANT LOW OF GABRIELLE NEAR 25N69W TO THE NORTHERN COAST OF THE ISLAND NEAR 20N72W. LOW-LEVEL MOISTURE CONVERGENCE EAST OF THIS TROUGHING AND A FAVORABLE UPPER LEVEL DIFFLUENT PATTERN OVER THE ISLAND CONTINUE TO SUPPORT SCATTERED SHOWERS AND TSTMS AT THIS TIME. WITH THE SURFACE TROUGHING SLOWLY DRIFTING NORTHEAST OVER THE NEXT 24 TO 48 HOURS...CONDITIONS ARE EXPECTED TO GRADUALLY IMPROVE BY LATE TUESDAY AS THE MORE USUAL TRADE WIND REGIME RE- ESTABLISHES ITSELF. AS ALWAYS...WITH PEAK DAYTIME HEATING AND INSTABILITY...AFTERNOON AND EARLY EVENING CONVECTION IS POSSIBLE OVER THE NEXT FEW DAYS. ATLANTIC OCEAN... A MIDDLE TO UPPER LEVEL TROUGH AXIS EXTENDS INTO THE DISCUSSION AREA NEAR 32N74W TO OVER THE FLORIDA PENINSULA NEAR 28N81W AND WESTWARD OVER PORTIONS OF THE NE GULF OF MEXICO. THIS TROUGHING SUPPORTS A STATIONARY FRONT TO THE NORTH...HOWEVER A HIGH PRESSURE RIDGE ANCHORED BY A 1017 MB HIGH CENTERED ACROSS ALABAMA CONTINUES TO DOMINATE ACROSS MUCH OF THE SW NORTH ATLC W OF 70W. WITH THE MID-LEVEL LIFT IN PLACE WIDELY SCATTERED SHOWERS AND ISOLATED TSTMS ARE OCCURRING OVER THE SOUTHERN FLORIDA PENINSULA AND ADJACENT COASTAL WATERS FROM 25N-27N BETWEEN 76W-82W WITH ISOLATED SHOWERS ELSEWHERE N OF 24N BETWEEN 72W-77W. FARTHER EAST...THE REMNANT 1008 MB LOW OF GABRIELLE IS CENTERED NEAR 25N69W WITH A SURFACE TROUGH AXIS EXTENDING N-NE TO BEYOND BERMUDA NEAR 32N65W AND S-SW FROM THE LOW CENTER TO THE NORTHERN COAST OF HISPANIOLA NEAR 20N72W. SCATTERED SHOWERS AND ISOLATED TSTMS ARE OCCURRING PRIMARILY EAST OF THE SURFACE TROUGHING W OF A LINE FROM 32N56W TO 18N66W. EAST OF THIS CONVECTION...A SURFACE RIDGE ANCHORED BY A 1032 MB HIGH CENTERED S OF THE AZORES NEAR 37N29W DOMINATES THE REMAINDER OF THE CENTRAL AND EASTERN ATLC. FOR ADDITIONAL INFORMATION PLEASE VISIT HTTP://WWW.HURRICANES.GOV/MARINE $$ HUFFMAN