000 AXNT20 KNHC 121118 TWDAT TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 805 AM EDT SAT OCT 12 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 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 1015 UTC. ...SPECIAL FEATURES... A 1006 MB LOW IS CENTERED NEAR 11N41W AND REMAINS EMBEDDED WITHIN THE MONSOON TROUGH AXIS. BROAD LOW-LEVEL CYCLONIC FLOW SURROUNDS THE LOW FROM 08N-16N BETWEEN 28W-46W WITH A RELATIVE VORTICITY MAXIMUM INDICATED ON THE GLOBAL MODEL 700 MB LEVEL NEAR 12N40W. SCATTERED MODERATE CONVECTION IS FROM 09N-14N BETWEEN 35W-47W. THE LOW PRESSURE AREA REMAINS IN A FAVORABLE AREA OF TROPICAL CYCLONE FORMATION...HOWEVER WITHIN THE NEXT 24 TO 36 HOURS SOUTHWESTERLY UPPER LEVEL WIND SHEAR WILL INCREASE OVER THE LOW AS IT MOVES W-NW AT 10 KT. ...TROPICAL WAVES... TROPICAL WAVE EXTENDS FROM 14N62W TO 21N62W MOVING W AT 10-15 KT. THE WAVE LIES BENEATH THE WESTERN PERIPHERY OF AN UPPER LEVEL LOW CENTERED TO THE EAST NEAR 16N56W. WATER VAPOR IMAGERY INDICATES VERY DRY AIR ALOFT ON THE WESTERN SIDE OF THIS UPPER LOW RESULTING IN AN OVERALL LACK OF SIGNIFICANT DEEP CONVECTION IN THE VICINITY OF THE WAVE AXIS. ISOLATED MODERATE CONVECTION IS HOWEVER OCCURRING FROM 17N-21N BETWEEN 56W-60W AND IS LIKELY MORE ASSOCIATED WITH THE UPPER LEVEL LOW DYNAMICS. ...ITCZ/MONSOON TROUGH... THE MONSOON TROUGH EXTENDS FROM THE AFRICAN COAST NEAR 18N16W TO 08N25W TO 06N30W TO 11N41W TO 08N48W. THE INTERTROPICAL CONVERGENCE ZONE AXIS EXTENDS FROM 08N48W TO 07N58W. ASIDE FROM CONVECTION ASSOCIATED WITH THE SPECIAL FEATURES LOW...SCATTERED MODERATE CONVECTION IS FROM 08N-12N BETWEEN 22W-28W...AND ISOLATED MODERATE CONVECTION IS FROM 03N-08N BETWEEN 23W-31W. ...DISCUSSION... GULF OF MEXICO... A MIDDLE TO UPPER LEVEL ANTICYCLONIC CIRCULATION IS CENTERED OVER CENTRAL MEXICO NEAR 20N100W THAT IS PROVIDING THE GULF BASIN WITH NORTHWEST TO NORTHERLY FLOW ALOFT THIS MORNING. WATER VAPOR IMAGERY INDICATES THE FLOW IS MOSTLY DRY AIR AND VERY STABLE RESULTING IN MOSTLY CLEAR SKIES AND FAIR CONDITIONS AT THE SURFACE. A 1018 MB HIGH CENTERED ALONG THE FLORIDA PANHANDLE COAST NEAR 30N87W FURTHER PROMOTES THE FAIR CONDITIONS WITH ONLY A FEW ISOLATED SHOWERS OCCURRING ACROSS THE NW GULF FROM 26N-28N BETWEEN 91W-96W AS SOUTHEASTERLY RETURN FLOW CONTINUES TO CONVERGE ACROSS THIS AREA. SURFACE RIDGING IS EXPECTED TO REMAIN ACROSS THE GULF THROUGH LATE WEDNESDAY WHEN THE NEXT FRONTAL BOUNDARY IS FORECAST TO EMERGE OFF THE TEXAS GULF COAST. CARIBBEAN SEA... AN UPPER LEVEL LOW IS CENTERED NEAR 18N79W AND EXTENDS A TROUGH AXIS SOUTHWARD ALONG 80W TO A BASE OVER THE SW CARIBBEAN NEAR 11N81W. WEST OF THE TROUGH AXIS...WATER VAPOR IMAGERY INDICATES VERY DRY AND STABLE AIR WITHIN NORTHERLY FLOW PROVIDING FOR RELATIVELY QUIET CONDITIONS THIS MORNING N OF 17N W OF 78W. HOWEVER S OF 17N...THE UPPER LEVEL LIFTING DYNAMICS CONTINUE TO GENERATE SCATTERED SHOWERS AND ISOLATED TSTMS OFF THE HONDURAS AND NICARAGUA COASTS FROM 13N-17N BETWEEN 82W-86W. WITH A RELATIVELY STRONG UPPER LEVEL LOW CENTERED OVER THE REMAINDER OF THE WESTERN CARIBBEAN...ISOLATED SHOWERS AND TSTMS ARE OCCURRING NEAR THE BASE OF THE UPPER LEVEL TROUGH AND IN THE AREA OF MAXIMUM MIDDLE TO UPPER LEVEL DIFFLUENCE EAST OF THE TROUGH AXIS. ISOLATED SHOWERS AND TSTMS ARE OCCURRING WITHIN 240 NM EITHER SIDE OF A LINE FROM 11N79W TO 20N74W. FINALLY...A WEAK TROPICAL WAVE IS ANALYZED ALONG 62W IMPACTING THE LESSER ANTILLES THIS MORNING WITH MUCH OF THE PRECIPITATION ASSOCIATED WITH THE WAVE REMAINING TO THE EAST-NORTHEAST OF THE LEEWARD ISLANDS AT THIS TIME. AS THE WAVE MOVES WESTWARD...INCREASED LOW- LEVEL MOISTURE...CLOUDINESS...AND PRECIPITATION IS EXPECTED FOR THE ISLANDS DURING THE NEXT 24 TO 36 HOURS. HISPANIOLA... CURRENTLY THE ISLAND FALLS WITHIN AN AREA OF MIDDLE TO UPPER LEVEL DIFFLUENCE NOTED TO THE EAST OF AN UPPER LEVEL TROUGH ALONG 80W. THE ADVECTION OF MOISTURE FROM THE EAST PACIFIC NEAR THE BASE OF THE TROUGH AND MOISTURE FROM NORTHERN SOUTH AMERICA NORTHWARD ACROSS THE CENTRAL CARIBBEAN SEA AND SW NORTH ATLC IS PROVIDING FOR ISOLATED SHOWERS AND TSTMS THIS MORNING. AS THE TROUGH ALONG 80W IS FORECAST TO EVENTUALLY MOVE SOUTHWEST BY LATE SUNDAY INTO MONDAY...UNTIL THEN HISPANIOLA WILL LIKELY REMAIN IN AN UPPER LEVEL DIFFLUENT PATTERN WITH INCREASED PROBABILITY OF ISOLATED SHOWERS AND TSTMS. OF COURSE AS ALWAYS WITH PEAK DAYTIME HEATING AND INSTABILITY...MAXIMUM AREAL COVERAGE OF CONVECTION IS LIKELY TO OCCUR IN THE AFTERNOON AND EVENING HOURS. ATLANTIC OCEAN... A MIDDLE TO UPPER LEVEL LOW IS CENTERED OVER THE MID-ATLC STATES NEAR 37N76W THAT SUPPORTS AN OCCLUDED 1011 MB LOW CENTERED OFFSHORE NEAR 38N75W. A STATIONARY FRONT EXTENDS FROM THE LOW PRESSURE SYSTEM INTO THE DISCUSSION AREA NEAR 32N69W TO 26N74W AND BECOMES SURFACE TROUGHING FROM 27N73W TO 21N74W. PLENTY OF MIDDLE TO UPPER LEVEL MOISTURE ADVECTION IS NOTED ON WATER VAPOR IMAGERY EAST OF THE UPPER LEVEL TROUGH AXIS WITH WIDELY SCATTERED SHOWERS AND ISOLATED TSTMS OCCURRING FROM 18N-32N BETWEEN 62W-77W...FOCUSED IN THE VICINITY OF THE SURFACE BOUNDARIES. FARTHER EAST...THE REMAINDER OF THE CENTRAL AND EASTERN ATLC IS UNDER THE INFLUENCE OF A SURFACE RIDGE ANCHORED BY A 1023 MB HIGH CENTERED NEAR 35N37W AND A 1020 MB HIGH CENTERED NEAR 31N18W. BRIDGING BOTH OF THESE HIGH CENTERS IS A DISSIPATING STATIONARY FRONT ANALYZED FROM 32N27W TO 29N40W. ISOLATED SHOWERS ARE OCCURRING WITHIN 90 NM EITHER SIDE OF THE FRONT. FOR ADDITIONAL INFORMATION PLEASE VISIT HTTP://WWW.HURRICANES.GOV/MARINE $$ HUFFMAN