000 AXNT20 KNHC 102339 TWDAT TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 805 PM EDT THU OCT 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... A 1008 MB LOW IS CENTERED NEAR 10N33W AND REMAINS EMBEDDED WITHIN THE MONSOON TROUGH. THE LOW IS THE FOCAL POINT OF A BROADER MONSOONAL GYRE WITH INFLUENCE FROM 08N-15N BETWEEN 29W- 43W. THE GYRE CONTINUES TO LIE BENEATH THE WESTERN PERIPHERY OF AN UPPER LEVEL ANTICYCLONIC CIRCULATION CENTERED NEAR 12N25W PROVIDING AMPLE UPPER LEVEL DIFFLUENCE FOR WIDELY SCATTERED MODERATE CONVECTION FROM 09N-14N BETWEEN 29W-41W...AND ISOLATED MODERATE CONVECTION ELSEWHERE FROM 06N-16N BETWEEN 28W-41W. ...TROPICAL WAVES... TROPICAL WAVE EXTENDS FROM 12N53W TO 21N49W MOVING W AT 10-15 KT. THE WAVE REMAINS WITHIN WEAK SURFACE TO 700 MB TROUGHING BETWEEN 47W-56W WHILE AT THE SAME TIME INTERACTING WITH AN UPPER LEVEL TROUGH AXIS EXTENDING FROM 24N41W TO 11N55W. ISOLATED MODERATE CONVECTION IS WITHIN 90 NM EITHER SIDE OF A LINE FROM 12N43W TO 19N48W. TROPICAL WAVE EXTENDS FROM 10N77W TO 19N77W MOVING W AT 10 KT. THE WAVE LIES WITHIN BROAD SURFACE TO 700 MB TROUGHING OVER THE WESTERN CARIBBEAN SEA AND FALLS BENEATH THE BASE OF AN UPPER LEVEL TROUGH AXIS NEAR 17N81W. LOW-LEVEL MOISTURE CONVERGENCE ALONG WITH MAXIMUM UPPER LEVEL DIFFLUENCE IS GENERATING SCATTERED MODERATE AND ISOLATED STRONG CONVECTION FROM 07N-12N BETWEEN 75W-80W. SCATTERED MODERATE CONVECTION IS FROM 12N-19N BETWEEN 76W-84W. ...ITCZ/MONSOON TROUGH... THE MONSOON TROUGH EXTENDS FROM THE AFRICAN COAST NEAR 11N15W TO 06N20W TO 11N29W TO 09N42W. THE INTERTROPICAL CONVERGENCE ZONE AXIS EXTENDS FROM 09N42W TO 11N52W TO 09N60W. ASIDE FROM THE CONVECTION ASSOCIATED WITH THE SPECIAL FEATURES LOW AND TROPICAL WAVE...ISOLATED MODERATE CONVECTION IS FROM 02N-09N BETWEEN 17W- 29W. ...DISCUSSION... GULF OF MEXICO... THE GULF BASIN IS PRIMARILY UNDER THE INFLUENCE OF A MIDDLE TO UPPER LEVEL ANTICYCLONIC CIRCULATION CENTERED OVER EAST-CENTRAL MEXICO NEAR 21N97W THAT EXTENDS A RIDGE AXIS NORTH-NORTHEASTWARD OVER THE LOWER AND MIDDLE MISSISSIPPI RIVER VALLEY THIS EVENING. WATER VAPOR IMAGERY INDICATES A VERY DRY AND STABLE ATMOSPHERE AS THE RESULT OF WEST TO NORTHWESTERLY FLOW ALOFT. PROJECTING THESE CONDITIONS TO THE SURFACE...A SURFACE RIDGE ANCHORED OVER THE SE CONUS STRETCHES SOUTHWARD OVER MUCH OF THE BASIN PROVIDING LIGHT ANTICYCLONIC WINDS...MOSTLY CLEAR SKIES...AND FAIR CONDITIONS. AN EXITING AND DISSIPATING COLD FRONT LINGERS ACROSS THE FLORIDA STRAITS GENERATING A FEW ISOLATED SHOWERS AND TSTMS S OF 24N E OF 83W. ALSO...W OF 90W...EAST-SOUTHEASTERLY WINDS IN THE RANGE OF 10-15 KT ARE EXPECTED TO GRADUALLY VEER MORE SOUTHEASTERLY BY FRIDAY MORNING WITH MOIST LOW-LEVEL RETURN FLOW GENERATING ISOLATED SHOWERS S OF 26N W OF 92W THROUGH THE OVERNIGHT PERIOD. CARIBBEAN SEA... THE BASE OF AN UPPER LEVEL TROUGH IS NOTED ON WATER VAPOR IMAGERY OVER A PORTION OF THE NW CARIBBEAN PROVIDING MUCH OF THE WESTERN CARIBBEAN IN A FAVORABLE UPPER LEVEL DIFFLUENT FLOW PATTERN THIS EVENING. THIS UPPER LEVEL PATTERN ALONG WITH THE PRESENCE OF A TROPICAL WAVE ALONG 78W IS GENERATING A LARGE AREA OF SCATTERED SHOWERS AND TSTMS...SOME STRONG...S OF 20N W OF 76W. THE STRONG CONVECTION IS CURRENTLY OCCURRING ACROSS NORTHERN COLOMBIA AND EASTERN PANAMA AND LIKELY ENHANCED DUE TO THE CLOSE PROXIMITY OF THE MONSOON TROUGH AXIS EXTENDING ALONG 09N/10N BETWEEN 75W-86W. FARTHER EAST...THE OVERALL UPPER LEVEL DIFFLUENT REGIME CONTINUES TO PROVIDE INCREASED CLOUDINESS AND PRECIPITATION FOR THE EASTERN CARIBBEAN N OF 16N. WHILE DAYTIME HEATING AND INSTABILITY HAS INITIATED SCATTERED SHOWERS AND TSTMS ACROSS HISPANIOLA AND PUERTO RICO...ISOLATED SHOWERS AND TSTMS STRETCH WELL NORTHWARD INTO THE SW NORTH ATLC AHEAD OF A COLD FRONT CURRENTLY EXTENDING FROM OFFSHORE OF THE CAROLINAS TO THE BAHAMAS AND FLORIDA STRAITS. A VERY BROAD AND WEAK SURFACE PRESSURE GRADIENT EXISTS BETWEEN 60W-80W AND LENDS ITSELF ALONG WITH THE UPPER LEVEL DIFFLUENCE TO OVERALL LIFT...CLOUDINESS... AND WIDELY SCATTERED SHOWER ACTIVITY. FINALLY...E-SE TRADES CONTINUE TO USHER IN LOW-LEVEL MOISTURE AND ISOLATED SHOWER ACTIVITY E OF 70W WITH THE HIGHEST CONCENTRATION IN THE VICINITY OF 14N65W. HISPANIOLA... CURRENTLY MIDDLE TO LOW-LEVEL MOISTURE...PEAK HEATING...AND INSTABILITY ARE GENERATING SCATTERED SHOWERS AND TSTMS ACROSS HISPANIOLA IN AN AREA OF OVERALL DIFFLUENCE ALOFT OVER THE REGION SPANNING THE EASTERN CARIBBEAN AND THE SW NORTH ATLC. THIS MOISTURE STRETCHES EASTWARD TO 60W AND IS EXPECTED TO REMAIN IN PLACE OVER THE NEXT FEW DAYS WITH MAXIMUM AREAL COVERAGE OF CONVECTIVE ACTIVITY OCCURRING DURING THE AFTERNOON AND EVENING HOURS. ATLANTIC OCEAN... A MIDDLE TO UPPER LEVEL LOW IS NOTED ON WATER VAPOR IMAGERY CENTERED OVER THE MID-ATLC STATES NEAR 39N78W. THE TROUGH SUPPORTS A 1007 MB LOW CENTERED NEAR 36N75W WITH A COLD FRONT EXTENDING SE FROM THE LOW TO 32N72W THEN SOUTH-SOUTHWEST TO 28N74W TO 24N80W. ASIDE FROM THE LOW AND FRONTAL BOUNDARY...MUCH OF THE SW NORTH ATLC FALLS UNDER A VERY WEAK SURFACE PRESSURE GRADIENT WITH LOWER PRESSURE GENERALLY BETWEEN 60W-80W. WIDELY SCATTERED SHOWERS AND ISOLATED TSTMS ARE OCCURRING WITHIN 150 NM EITHER SIDE OF THE FRONT...BUT ARE ALSO OCCURRING FROM 18N-32N BETWEEN 58W-80W DUE TO THE OVERALL BROAD SURFACE TROUGHING AND DIFFLUENCE ALOFT. EVENTUALLY BY EARLY SATURDAY MOST OF THE SURFACE TROUGHING SHIFTS NORTH OF THE DISCUSSION AREA WITH HIGH PRESSURE RIDGING BUILDING IN FROM BOTH THE EAST ACROSS THE CENTRAL ATLC AND THE WEST FROM THE NE GULF OF MEXICO. UNTIL THEN...CONDITIONS ARE EXPECTED TO REMAIN RATHER UNSETTLED WITH SHOWER AND TSTM ACTIVITY. FARTHER EAST...A SURFACE RIDGE INFLUENCES THE CENTRAL ATLC N OF 23N BETWEEN 30W-60W ANCHORED BY A 1021 MB HIGH CENTERED NEAR 31N48W. THE SURFACE RIDGING STRETCHES ACROSS THE EASTERN ATLC...HOWEVER IS SLIGHTLY WEAKER DUE TO A DISSIPATING COLD FRONTAL BOUNDARY EXTENDING FROM 32N25W TO 28N29W. NO SIGNIFICANT PRECIPITATION IS OCCURRING ALONG THE FRONT AT THIS TIME. FOR ADDITIONAL INFORMATION PLEASE VISIT HTTP://WWW.HURRICANES.GOV/MARINE $$ HUFFMAN