000 AXNT20 KNHC 111805 TWDAT TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 205 PM EDT WED SEP 11 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 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 1715 UTC. ...SPECIAL FEATURES... TROPICAL STORM GABRIELLE IS CENTERED NEAR 32.5N 65.9W AT 11/1500 UTC OR ABOUT 564 NM SSE OF NANTUCKET MASSACHUSETTS. THE SYSTEM IS NOW MOVING WEST AT 3 KT AND HAS AN ESTIMATED MINIMUM CENTRAL PRESSURE IS 1009 MB. MAXIMUM SUSTAINED WIND SPEED IS 40 KT WITH GUSTS TO 50 KT. SCATTERED SMALL CLUSTERS OF MODERATE CONVECTION ARE WELL E OF THE LOW CENTER FROM 29N-34N BETWEEN 61W-66W. SEE LATEST NHC INTERMEDIATE PUBLIC ADVISORY UNDER AWIPS/WMO HEADERS MIATCPAT2/WTNT32 KNHC AND THE FULL FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS MIATCMAT2/WTNT22 KNHC FOR MORE DETAILS. HURRICANE HUMBERTO IS CENTERED NEAR 16.7N 29.1W AT 11/1500 UTC OR ABOUT 297 NM W OF THE CAPE VERDE ISLANDS AND IS MOVING N AT 8 KT. ESTIMATED MINIMUM CENTRAL PRESSURE IS 989 MB. MAXIMUM SUSTAINED WIND SPEED IS 70 KT WITH GUSTS TO 85 KT. NUMEROUS MODERATE/ISOLATED STRONG CONVECTION IS FROM 14N-18N BETWEEN 26W- 31W. SCATTERED MODERATE CONVECTION IS ELSEWHERE FROM 10N-23N BETWEEN 22W-35W. 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. A BROAD AREA OF LOW PRESSURE OVER THE NW CARIBBEAN IS PRODUCING A LARGE AREA OF RAINSHOWERS AND THUNDERSTORMS. A SURFACE TROUGH EXTENDS FROM 22N87W TO THE EASTERN YUCATAN PENINSULA AND BELIZE TO THE W COAST OF HONDURAS NEAR 14N88W. THE SURFACE TROUGH SHOULD CONTINUE MOVING ACROSS THE YUCATAN TODAY AND ENTER THE BAY OF CAMPECHE ON THU WHEN SOME DEVELOPMENT IS POSSIBLE. THE SHOWER ACTIVITY ASSOCIATED WITH THIS LOW SHOWS SIGNS OF ORGANIZATION. CURRENTLY...NUMEROUS MODERATE CONVECTION AND ISOLATED TSTMS ARE FROM 16N-21N BETWEEN 85W-90W WITH SCATTERED MODERATE CONVECTION AND ISOLATED TSTMS BEING ELSEWHERE FROM 17N- 23N BETWEEN 79W-85W. THIS SYSTEM HAS A MEDIUM CHANCE...40 PERCENT...OF BECOMING A TROPICAL CYCLONE DURING THE NEXT 48 HOURS. LOCALLY HEAVY RAINS AND GUSTY WINDS ARE EXPECTED OVER BELIZE... GUATEMALA...AND THE YUCATAN PENINSULA DURING THE NEXT DAY OR TWO. ...TROPICAL WAVES... NONE. ...THE ITCZ/THE MONSOON TROUGH... THE MONSOON TROUGH CONTINUES TO BE DISRUPTED BY HURRICANE HUMBERTO. IT AXIS EXTENDS ACROSS AFRICA FROM MALI NEAR 21N02W TO MAURITANIA NEAR 17N11W...THEN RESUMES SW OF HURRICANE HUMBERTO FROM 08N37W TO 08N49W. THE ITCZ AXIS BEGINS NEAR 06N54W TO GUYANA NEAR 06N58W. SCATTERED MODERATE CONVECTION IS FROM 03N- 10N BETWEEN 12W-18W. SCATTERED SHOWERS TRAILING HURRICANE HUMBERTO ARE FROM 05N-10N BETWEEN 24W-45W. ...DISCUSSION... GULF OF MEXICO... AN ELONGATED UPPER-LEVEL LOW...INVERTED TROUGH IN THE MIDDLE- LEVEL OVER THE WESTERN GULF W OF 91W SUPPORTS A SURFACE TROUGH COLLOCATED WITHIN A REGION OF HIGH MOISTURE. THE AXIS OF THE TROUGH IS OFFSHORE EASTERN MEXICO ALONG 25N97W TO 18N94W. RAINSHOWERS AND ISOLATED TSTMS ARE S OF 26N W OF 92W. A MIDDLE TO UPPER LEVEL LOW CENTERED OVER CENTRAL FLORIDA IS SUPPORTING SHOWERS AND ISOLATED TSTMS ACROSS SOUTHERN FLORIDA WHICH EXTEND TO THE SE GULF FROM 25N-26N E OF 85W. SURFACE RIDGING DOMINATES THE NORTHERN GULF N OF 26N WHERE LOW TO MIDDLE LEVEL DRY AIR SUPPORTS FAIR WEATHER THIS AFTERNOON. THE SURFACE TROUGH IN THE SPECIAL FEATURES ABOVE IS EXPECTED TO MOVE SLOWLY W-NW ACROSS THE YUCATAN PENINSULA TODAY AND ENTER THE BAY OF CAMPECHE ON THU. A SURFACE LOW IS EXPECTED TO DEVELOP ALONG THE TROUGH OVER THE SW GULF LATER IN THE WEEK THEN INTENSIFY SLOWLY THROUGH SUN AS IT DRIFTS NW. THE LOW COULD POSSIBLY DEVELOP INTO A TROPICAL CYCLONE. CARIBBEAN SEA... A BROAD AREA OF LOW PRESSURE IS OVER THE NW CARIBBEAN COLLOCATED WITHIN A REGION OF UPPER-LEVEL DIVERGENCE AND MAXIMUM MOISTURE AS DEPICTED IN TOTAL PRECIPITABLE WATER IMAGERY. A SURFACE TROUGH EXTENDS FROM 22N87W TO THE EASTERN YUCATAN PENINSULA AND BELIZE TO THE W COAST OF HONDURAS NEAR 14N88W. NUMEROUS MODERATE CONVECTION AND ISOLATED TSTMS ARE FROM 16N-21N BETWEEN 85W-90W. SCATTERED MODERATE CONVECTION AND ISOLATED TSTMS ARE ELSEWHERE FROM 17N-23N BETWEEN 79W-85W. A HIGH MOIST ENVIRONMENT IN THE SE GULF IS COLLOCATED WITHIN AN AREA OF UPPER-LEVEL DIFFLUENCE BETWEEN THE RIDGE OVER THE WESTERN BASIN AND A LOW CENTERED S OF HISPANIOLA NEAR 16N69W. THIS AREA OF DIFFLUENCE IS SUPPORTING SHOWERS AND TSTMS S OF 13N BETWEEN 75W-80W. THE UPPER-LEVEL LOW IN THE EASTERN BASIN IS POSITIONED OVER A MODERATE MOIST ENVIRONMENT AND SUPPORTS SCATTERED SHOWERS FROM 11N-16N BETWEEN 62W-69W. DRY AIR SUBSIDENCE OVER THE REMAINDER CENTRAL CARIBBEAN SUPPORTS FAIR WEATHER. THE SURFACE TROUGH SHOULD CONTINUE MOVING ACROSS THE YUCATAN TODAY AND ENTER THE BAY OF CAMPECHE ON THU WHEN SOME DEVELOPMENT IS POSSIBLE. CLOUDINESS AND SHOWERS ASSOCIATED WITH A BROAD AREA OF LOW PRESSURE CURRENTLY CENTERED ABOUT 650 MILES EAST OF THE LEEWARD ISLANDS MAY START GENERATING SHOWERS OVER THE FAR E-NE CARIBBEAN AS SOON AS TONIGHT AS IT CONTINUES TO MOVE WESTWARD. HISPANIOLA... A DRY AIRMASS MOVES ACROSS THE ISLAND THIS AFTERNOON...THUS SUPPORTING FAIR WEATHER. THESE WEATHER CONDITIONS ARE EXPECTED TO LAST UNTIL EARLY THIS EVENING. MOISTURE WILL BE ADVECTED FROM THE EASTERN CARIBBEAN LATE TONIGHT WHICH ALONG WITH AN UPPER- LEVEL LOW MAY ENHANCE SHOWERS AND TSTMS THROUGHOUT THURSDAY. ATLANTIC OCEAN... THE PRIMARY CONCERNS FOR THE ATLC BASIN ARE TROPICAL STORM GABRIELLE IN THE W ATLC AND HURRICANE HUMBERTO IN THE E ATLC. SEE SPECIAL FEATURES ABOVE. AN UPPER-LEVEL LOW CENTERED OVER CENTRAL FLORIDA SUPPORTS A SURFACE TROUGH THAT EXTENDS FROM 30N73W TO THE BAHAMAS NEAR 24N78W. SCATTERED SHOWERS ASSOCIATED WITH THIS SURFACE AND UPPER-LEVEL FEATURES ARE FROM 26N-30N W OF 74W. AN AREA OF SIMILAR CONVECTION IS FROM 22N-24N BETWEEN 77W- 80W BEING SUPPORTED BY UPPER-LEVEL DIFFLUENCE FROM THE AFOREMENTIONED LOW AND THE RIDGE OVER THE WESTERN CARIBBEAN. A SURFACE TROUGH ABOUT 650 MILES EAST OF THE LEEWARD ISLANDS EXTENDS AN AXIS FROM 20N59W TO A 1012 MB LOW NEAR 17N50W. SCATTERED MODERATE CONVECTION IS WITHIN 150 NM SW OF THE AXIS. THE REMAINDER OF THE ATLC IS DOMINATED BY A WEAK SURFACE RIDGE ANCHORED BY A 1033 MB HIGH WELL N OF THE AZORES. A WEAK PRESSURE PATTERN WILL PREVAIL ACROSS THE MOST OF THE ATLC. FOR ADDITIONAL INFORMATION PLEASE VISIT HTTP://WWW.HURRICANES.GOV/MARINE $$ RAMOS