000 AXNT20 KNHC 150554 TWDAT TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 205 AM EDT TUE OCT 15 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 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 0515 UTC. ...TROPICAL WAVES... TROPICAL WAVE EXTENDS FROM 06N46W TO 15N40W MOVING W AT 10-15 KT. THE WAVE COINCIDES WITH SURFACE TO 700 MB TROUGHING WITH LOW- LEVEL MOISTURE CONVERGENCE IN THE VICINITY OF THE WAVE AXIS. IN ADDITION...MOIST SOUTHWESTERLY DIFFLUENT UPPER LEVEL FLOW IS HELPING TO SUSTAIN SCATTERED MODERATE CONVECTION FROM 07N-11N BETWEEN 42W-47W. TROPICAL WAVE EXTENDS FROM 10N82W TO 20N80W MOVING W AT 15 KT. THE WAVE LIES BENEATH AN UPPER LEVEL ANTICYCLONIC CIRCULATION CENTERED OVER THE WESTERN CARIBBEAN NEAR 15N82W PROVIDING AN OVERALL DIFFLUENT ENVIRONMENT. WIDELY SCATTERED MODERATE CONVECTION IS FROM 09N-17N BETWEEN 74W-84W. ...ITCZ/MONSOON TROUGH... THE MONSOON TROUGH EXTENDS FROM THE AFRICAN COAST NEAR 12N17W TO 11N18W. THE INTERTROPICAL CONVERGENCE ZONE AXIS EXTENDS FROM 11N18W TO 06N30W TO 08N36W. WIDELY SCATTERED MODERATE CONVECTION IS FROM 03N-09N BETWEEN 20W-36W. ...DISCUSSION... GULF OF MEXICO... A MIDDLE TO UPPER LEVEL ANTICYCLONIC CIRCULATION IS CENTERED OVER NE MEXICO NEAR 24N98W THAT IS PROVIDING THE GULF BASIN WITH GENERALLY DRY AND STABLE FLOW ALOFT THIS EVENING. THIS STABILITY REFLECTS TO THE SURFACE AS A RIDGE REMAINS IN PLACE EXTENDING SW FROM THE SE CONUS WITH LIGHT ANTICYCLONIC WINDS IN THE RANGE OF 5 TO 15 KT ACROSS THE BASIN THROUGH THE OVERNIGHT HOURS INTO TUESDAY. THE SURFACE RIDGING IS EXPECTED TO REMAIN ACROSS THE GULF THROUGH WEDNESDAY WHEN THE NEXT FRONTAL BOUNDARY IS FORECAST TO EMERGE OFF THE TEXAS GULF COAST LATE WEDNESDAY. CARIBBEAN SEA... MUCH OF THE WESTERN CARIBBEAN IS UNDER THE INFLUENCE OF UPPER LEVEL DIFFLUENCE IN ASSOCIATION WITH AN UPPER LEVEL RIDGE EXTENDING FROM 19N86W TO 09N74W. PLENTY OF MOISTURE AND INSTABILITY...ALONG WITH LOW-LEVEL MOISTURE CONVERGENCE IN THE VICINITY OF A TROPICAL WAVE ALONG 81W IS GENERATING WIDELY SCATTERED SHOWERS AND TSTMS THIS EVENING FROM 09N-17N BETWEEN 74W-84W. A FEW ISOLATED SHOWERS ARE ALSO NOTED ACROSS WESTERN CUBA AS WELL BUT CONTINUE TO DIMINISH. FARTHER EAST...AN UPPER LEVEL TROUGH IS NOTED ON WATER VAPOR IMAGERY OVER THE SW NORTH ATLC AND DIPS TROUGHING SOUTHWARD TO 16N BETWEEN 68W-80W. EAST OF THE TROUGH AXIS MIDDLE TO UPPER LEVEL DIFFLUENT IS MAXIMIZED GENERATING SCATTERED SHOWERS AND ISOLATED TSTMS FROM 14N-20N BETWEEN 66W-72W...INCLUDING PORTIONS OF EASTERN HISPANIOLA AND THE MONA PASSAGE. OTHERWISE...NORTHERLY FLOW ALOFT DOMINATES E OF 66W AND IS PROVIDING AN OVERALL STABLE ENVIRONMENT ALOFT THIS EVENING FOR THE LESSER ANTILLES. HISPANIOLA... CURRENTLY THE ISLAND FALLS WITHIN MAXIMUM UPPER LEVEL DIFFLUENCE ALOFT BETWEEN UPPER LEVEL TROUGHING TO THE NORTH OVER THE SW NORTH ATLC REGION AND AN UPPER LEVEL ANTICYCLONIC CIRCULATION ANCHORED OVER THE WESTERN AND CENTRAL CARIBBEAN SEA THIS EVENING. MOISTURE IN PLACE OVER THE REGION CONTINUES TO LIFT GENERATING CLOUDINESS AND WIDELY SCATTERED SHOWERS AND ISOLATED TSTMS ACROSS EASTERN PORTIONS OF THE ISLAND AND THE ADJACENT COASTAL WATERS FROM 16N-21N BETWEEN 67W-72W. THE UPPER LEVEL TROUGHING IS EXPECTED TO CONTINUE DIGGING SOUTHWARD AND REMAIN OVER THE ISLAND THROUGH EARLY WEDNESDAY PROVIDING THE INCREASED PROBABILITY OF SHOWER AND TSTM ACTIVITY THROUGH MID-WEEK. ATLANTIC OCEAN... A MIDDLE TO UPPER LEVEL LOW IS NOTED ON WATER VAPOR IMAGERY CENTERED NEAR 33N72W THAT EXTENDS TROUGHING SOUTHWARD TO A BASE NEAR 20N73W OVER THE SW NORTH ATLC. THIS IS SUPPORTING AN OVERALL WEAK PRESSURE GRADIENT AND LOWER PRESSURE W OF 60W. A 1013 MB IS CENTERED NEAR 32N72W AND EXTENDS SURFACE TROUGHING NORTHWARD ALONG 72W TO 39N73W. SCATTERED SHOWERS AND ISOLATED TSTMS ARE OCCURRING PRIMARILY N OF 31N BETWEEN 65W-76W WITH THIS FEATURE. A WEAK CIRCULATION IS NOTED ALONG A SURFACE TROUGH AXIS EXTENDING FROM 28N80W TO 31N80W AND IS PRODUCING ISOLATED SHOWERS N OF 28N W OF 77W THIS EVENING. THIS FEATURE CONTINUES TO WEAKEN AND WILL EVENTUALLY DISSIPATE DUE TO A LACK OF FAVORABLE UPPER LEVEL SUPPORT. LASTLY FOR THE REGION...A SURFACE TROUGH IS ANALYZED FROM THE SE BAHAMAS NEAR 22N74W TO 26N70W AND REMAINS THE PRIMARY FOCUS FOR SCATTERED SHOWERS AND TSTMS ASSOCIATED WITH FAVORABLE DYNAMICS EAST OF THE UPPER LEVEL TROUGH AXIS. LOW-LEVEL MOISTURE CONVERGENCE OCCURRING IN THE VICINITY OF THE SURFACE TROUGH ALONG WITH MAXIMUM UPPER LEVEL DIFFLUENCE IS GENERATING A LARGE AREA OF SCATTERED SHOWERS AND ISOLATED TSTMS FROM 18N-31N BETWEEN 60W-78W. THE UPPER LEVEL TROUGHING IS FORECAST TO GRADUALLY DRIFT EASTWARD THROUGH WEDNESDAY WITH MOST OF THE ACTIVE WEATHER ASSOCIATED WITH THE TROUGHING OCCURRING E OF 70W FOR THE LATTER PART OF THE WEEK. FARTHER EAST...WATER VAPOR IMAGERY INDICATES AN UPPER LEVEL TROUGH AXIS EXTENDS FROM 35N38W TO 33N51W THAT SUPPORTS A COLD FRONT ANALYZED FROM THE AZORES NEAR 38N26W SW TO 30N41W TO 26N60W. ISOLATED SHOWERS AND TSTMS ARE OCCURRING WITHIN 120 NM EITHER SIDE OF THE BOUNDARY AS IT SLOWLY MOVES EASTWARD. FINALLY...THE REMAINDER OF THE CENTRAL AND EASTERN ATLC ARE UNDER THE INFLUENCE OF A SURFACE RIDGE ANCHORED BY A 1024 MB HIGH CENTERED NEAR THE MADEIRA ISLANDS NEAR 33N16W. THE RIDGE AXIS EXTENDS FROM THE HIGH SOUTHWESTWARD TO 23N50W. FOR ADDITIONAL INFORMATION PLEASE VISIT HTTP://WWW.HURRICANES.GOV/MARINE $$ HUFFMAN