000 AXNT20 KNHC 072344 TWDAT TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 805 PM EDT SAT SEP 07 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 WAVE EXTENDS FROM 10N17W TO 19N16W MOVING W AT 10 KT. A 1006 MB LOW IS CENTERED A LONG THE WAVE AXIS NEAR 13N17W AND REMAINS THE FOCUS FOR LOW-LEVEL CYCLONIC MOTION ON SATELLITE IMAGERY AND CONVECTION AS THE WAVE EMERGES OFF THE COAST OF WEST AFRICA THIS EVENING. SCATTERED MODERATE AND ISOLATED STRONG CONVECTION IS FROM 13N-15N BETWEEN 17W-19W WITH ISOLATED MODERATE CONVECTION ELSEWHERE FROM 10N-18N BETWEEN 12W-20W. ...TROPICAL WAVES... TROPICAL WAVE EXTENDS FROM 12N34W TO 21N35W MOVING W AT 5-10 KT. A 1008 MB LOW IS CENTERED ALONG THE WAVE AXIS NEAR 15N35W AND REMAINS THE FOCUS OF A BROAD MONSOONAL GYRE EMBEDDED WITHIN THE MONSOON TROUGH FROM 10N-20N BETWEEN 27W-44W. WATER VAPOR IMAGERY INDICATES THE WAVE IS LOCATED ON THE WESTERN PERIPHERY OF AN UPPER LEVEL ANTICYCLONE CENTERED NEAR 17N26W AND THIS PLACES THE WAVE BENEATH A FAVORABLE UPPER LEVEL DIFFLUENT ENVIRONMENT. AS A RESULT...WIDELY SCATTERED MODERATE CONVECTION IS FROM 14N-20N BETWEEN 28W-37W. TROPICAL WAVE EXTENDS FROM 10N83W TO 19N82W MOVING W AT 5-10 KT. THE WAVE REMAINS WITHIN BROAD LOW-LEVEL CYCLONIC FLOW ACROSS THE WESTERN CARIBBEAN SEA BETWEEN 76W-87W AND WITHIN VERY BROAD MIDDLE TO UPPER LEVEL TROUGHING WHICH DIPS SOUTHWARD TO 18N FROM THE GULF OF MEXICO. WITH AMPLE LIFTING MECHANISMS IN PLACE ACROSS THE WESTERN CARIBBEAN SEA...SCATTERED MODERATE CONVECTION IS OCCURRING FROM 10N-16N BETWEEN 77W-85W. TROPICAL WAVE EXTENDS FROM 15N89W TO 20N88W MOVING W AT 5-10 KT. THE WAVE IS BECOMING DIFFICULT TO DISCERN ON SATELLITE IMAGERY AND GLOBAL MODEL DATA INDICATES THAT ENERGY ASSOCIATED WITH THE WAVE HAS BECOME DISPERSED ACROSS PORTIONS OF THE NW CARIBBEAN SEA...YUCATAN PENINSULA...AND SW GULF OF MEXICO. THE WAVE IS FORECAST TO DISSIPATE OVER THE NEXT 6 TO 12 HOURS. SCATTERED MODERATE CONVECTION IS FROM 16N-20N BETWEEN 87W-91W. ...ITCZ/MONSOON TROUGH... THE MONSOON TROUGH EXTENDS FROM THE AFRICAN COAST NEAR 14N17W TO 12N20W TO 15N32W TO 07N49W. THE INTERTROPICAL CONVERGENCE ZONE AXIS EXTENDS FROM 07N49W TO 06N56W. ASIDE FROM CONVECTION ASSOCIATED WITH THE TROPICAL WAVES DISCUSSED ABOVE...WIDELY SCATTERED MODERATE CONVECTION IS FROM 07N-14N BETWEEN 20W-27W. ISOLATED MODERATE CONVECTION IS FROM 06N-09N BETWEEN 34W-46W. ...DISCUSSION... GULF OF MEXICO... WEST-NORTHWESTERLY FLOW ALOFT DOMINATES ACROSS MUCH OF THE GULF BASIN THIS EVENING ON THE WESTERN PERIPHERY OF VERY BROAD TROUGHING BETWEEN 70W-100W. THE MAIN TROUGH AXIS...ORIENTED EAST- WEST REMAINS ALONG 30N BETWEEN 82W-90W...THEN W-NW TO OVER NORTH TEXAS NEAR 32N96W. PLENTY OF MOISTURE IS NOTED ON WATER VAPOR IMAGERY W OF 86W AND WHILE A WEAK SURFACE PRESSURE GRADIENT EXISTS...SCATTERED SHOWERS AND ISOLATED TSTMS ARE OCCURRING W OF 86W. SOME OF THE ACTIVITY THIS EVENING IS FOCUSED ALONG A SURFACE TROUGH ANALYZED FROM OFFSHORE OF SOUTHERN TEXAS NEAR 27N97W TO 19N95W IN THE SW GULF. FARTHER EAST...A SHORTWAVE MID- LEVEL TROUGH IS NOTED ON WATER VAPOR IMAGERY NEAR 28N82W THAT SUPPORTS A SURFACE TROUGH EXTENDING ACROSS THE SOUTHERN FLORIDA PENINSULA FROM 27N80W SW TO 25N81W AND INTO THE SE GULF NEAR 24N84W. SCATTERED SHOWERS AND TSTMS ARE OCCURRING PRIMARILY ACROSS INLAND AREAS OF THE SOUTHERN AND CENTRAL FLORIDA PENINSULA S OF 28N WITH ISOLATED SHOWERS NOTED S OF 25N E OF 84W. E-SE WINDS ARE FORECAST TO PERSIST THROUGH EARLY TUESDAY IN THE RANGE OF 5 TO 15 KT GRADUALLY INCREASING ACROSS PORTIONS OF THE NORTHERN GULF ON LATE TUESDAY INTO WEDNESDAY DUE TO A STRONGER PRESSURE GRADIENT AS STRONG HIGH PRESSURE BUILDS ACROSS THE SE CONUS. CARIBBEAN SEA... A MIDDLE TO UPPER LEVEL TROUGH AXIS DIPS SOUTH ALONG 85W OVER THE WESTERN CARIBBEAN AND THIS IS PROVIDING FOR AN OVERALL UNSTABLE ENVIRONMENT W OF 80W. IN ADDITION...AT THE SURFACE A TROPICAL WAVE IS ANALYZED ALONG 82W AND REMAINS EMBEDDED WITHIN BROAD LOW-LEVEL TROUGHING W OF 75W. GIVEN AMPLE SURFACE MOISTURE CONVERGENCE...AND AMPLE LIFTING DYNAMICS...SCATTERED SHOWERS AND WIDELY SCATTERED TSTMS ARE OCCURRING W OF 77W THIS EVENING. THE MOST INTENSE ACTIVITY IS LOCATED IN THE VICINITY OF THE TROPICAL WAVE ALONG THE COAST OF NICARAGUA AND ACROSS INLAND PORTIONS OF HONDURAS. ANOTHER AREA OF HEAVY RAINFALL AND TSTMS IS ACROSS GUATEMALA THIS EVENING. WITH THE WIDESPREAD NATURE OF THE CONVECTION ACROSS MUCH OF CENTRAL AMERICA...LOCALIZED FLASH FLOODING AND MUDSLIDES ARE POSSIBLE AS WELL THROUGH THE OVERNIGHT HOURS WITH THE MOST PERSISTENT AREAS OF CONVECTION. SCATTERED SHOWERS AND TSTMS ARE ALSO OCCURRING ACROSS CUBA... INCLUDING THE ADJACENT COASTAL WATERS WITH THIS CONVECTION MOST LIKELY DUE TO PEAK DAYTIME HEATING AND INSTABILITY. FARTHER EAST...AN UPPER LEVEL ANTICYCLONE IS CENTERED SW OF HISPANIOLA NEAR 18N74W AND CONTINUES TO PROVIDE GENERALLY NORTHERLY FLOW ALOFT OVER THE EASTERN AND CENTRAL CARIBBEAN. AT THE SURFACE HOWEVER...SURFACE TROUGHING EXTENDS FROM THE REMNANTS OF GABRIELLE ACROSS HISPANIOLA TO NEAR 19N73W. LOW-LEVEL MOISTURE CONVERGENCE IS MAXIMIZED ACROSS THE EASTERN CARIBBEAN DUE TO E- SE FLOW E OF 72W WITH SCATTERED SHOWERS AND TSTMS OCCURRING FROM 13N-20N BETWEEN 67W-73W. THE MOST INTENSE CONVECTION AT THIS TIME IS ACROSS MUCH OF HISPANIOLA. AS THE LOW ASSOCIATED WITH GABRIELLE DRIFTS NE AND THE TROPICAL WAVE ALONG 83W MOVES WEST TO NEAR THE YUCATAN PENINSULA COAST OVER THE NEXT 24 HOURS...E- SE WINDS ARE EXPECTED TO GRADUALLY TAKE HOLD BY LATE SUNDAY INTO MONDAY. LOOKING BEYOND MONDAY...CONDITIONS LOOK RATHER BENIGN THROUGH THURSDAY WITH TRADES PERSISTING IN THE RANGE OF 10-20 KT. HISPANIOLA... CURRENTLY SCATTERED SHOWERS AND TSTMS ARE OCCURRING ACROSS MUCH OF THE ISLAND THIS EVENING DUE TO SURFACE TROUGHING EXTENDING S- SW FROM THE 1010 MB REMNANT LOW OF GABRIELLE CENTERED NEAR 24N69W. THIS CONVECTION IS MOST LIKELY ENHANCED BY A FAVORABLE UPPER LEVEL DIFFLUENT ENVIRONMENT ON THE NORTHERN PERIPHERY OF AN ANTICYCLONIC CIRCULATION CENTERED SW OF HISPANIOLA NEAR 18N74W AND PEAK DAYTIME HEATING AND INSTABILITY. ATLANTIC OCEAN... MID-LEVEL TROUGHING IS NOTED ON WATER VAPOR IMAGERY OVER MUCH OF THE SW NORTH ATLC W OF 60W WITH MOISTURE ADVECTING ACROSS THE FLORIDA PENINSULA AND AREAS W OF 72W THIS EVENING. MID-LEVEL DYNAMICS REMAIN STRONG ENOUGH TO SUPPORT WIDELY SCATTERED SHOWERS AND ISOLATED TSTMS FROM 25N-31N BETWEEN 72W-82W. FARTHER EAST...ALSO LOCATED WITHIN THE INFLUENCE OF THE MID-LEVEL TROUGHING IS THE REMNANT LOW OF GABRIELLE ANALYZED AT 1010 MB AND CENTERED NEAR 24N69W. A SURFACE TROUGH AXIS EXTENDS NORTH FROM THE LOW TO 32N67W AND SOUTH-SOUTHWEST FROM THE LOW TO WESTERN HISPANIOLA NEAR 19N73W. MIDDLE TO UPPER LEVEL DIFFLUENCE IS MAXIMIZED E OF 70W WITH SCATTERED SHOWERS AND WIDELY SCATTERED TSTMS OCCURRING FROM 19N-32N BETWEEN 58W-70W. OTHERWISE...THE CENTRAL ATLC IS UNDER THE INFLUENCE OF A SURFACE RIDGE ANCHORED BY A 1021 MB HIGH CENTERED NEAR 31N50W AND THE EASTERN ATLC IS UNDER THE INFLUENCE OF ANOTHER SURFACE RIDGE ANCHORED BY A STRONGER 1027 MB HIGH CENTERED ACROSS THE AZORES NEAR 39N29W. FOR ADDITIONAL INFORMATION PLEASE VISIT HTTP://WWW.HURRICANES.GOV/MARINE $$ HUFFMAN