000 AXNT20 KNHC 291142 TWDAT TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 805 AM EDT SAT SEP 29 2012 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 1045 UTC. ...SPECIAL FEATURES... NADINE WAS DOWNGRADED TO TROPICAL STORM STATUS THIS MORNING AT 0900 UTC...CENTERED NEAR 31.9N 35.9W OR ABOUT 569 NM SW OF THE AZORES MOVING N-NW AT 10 KT. ESTIMATED MINIMUM CENTRAL PRESSURE IS 992 MB. MAXIMUM SUSTAINED WIND SPEED IS 60 KT WITH GUSTS TO 75 KT. SCATTERED MODERATE CONVECTION IS FROM 30N-33N BETWEEN 32W-38W. SEE LATEST NHC FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS MIATCMAT4/WTNT24 KNHC FOR MORE DETAILS. ...TROPICAL WAVES... TROPICAL WAVE IS E OF CAPE VERDE ISLANDS EXTENDING FROM 17N20W TO 10N20W MOVING W AT 5 KT. WAVE REMAINS EMBEDDED WITHIN A MONSOONAL GYRE OFF THE COAST OF AFRICA...WHICH SEEMS TO SLOW DOWN THE WAVE. SCATTERED MODERATE CONVECTION IS FROM 7N-15N E OF 27W. TROPICAL WAVE MOVES ACROSS THE CENTRAL TROPICAL ATLC EXTENDING FROM 17N33W TO 10N39W MOVING W AT ABOUT 10 KT. TOTAL PRECIPITABLE WATER IMAGERY INDICATES THE WAVE LIES WITHIN A DEEP LAYER MOISTURE MAXIMUM. HOWEVER...ONLY ONE CLUSTER OF WEAK CONVECTION IS NOTED IN THE NE VICINITY OF THE WAVE AXIS FROM 14N-17N BETWEEN 30W-34W. TROPICAL WAVE MOVES ACROSS THE WRN CARIBBEAN EXTENDING ALONG 82W FROM 11N TO 20N MOVING WNW AT 5-10 KT. THE WAVE CURRENTLY MOVES UNDER A SHARP MIDDLE TO UPPER TROUGH DISCUSSED IN THE CARIBBEAN AND ATLC SECTIONS. THIS UPPER FEATURE WILL PLAY A ROLE ON THE FUTURE TRACK OF THE WAVE...AS SOME OF THE ENERGY FROM THE WAVE IS BEING DRAWN NNE INTO THE UPPER TROUGH. SCATTERED MODERATE CONVECTION FROM 13N-21N BETWEEN 74W-82W. ...ITCZ/MONSOON TROUGH... THE MONSOON TROUGH EXTENDS FROM THE AFRICAN COAST NEAR 12N16W ALONG 8N23W TO 9N32W...WHERE THE ITCZ CONTINUES TO 10N36W AND REDEVELOPS W OF THE CENTRAL ATLC TROPICAL WAVE NEAR 10N40W TO 8N50W. A SURFACE TROUGH IS ANALYZED FROM 15N50W TO 9N52W AT THE WESTERN EXTENT OF THE ITCZ AXIS. A BROAD CLUSTER OF SCATTERED MODERATE CONVECTION IS FROM 8N-15N BETWEEN 42W-50W...AND IS LIKELY ENHANCED DUE TO AN UPPER LEVEL TROUGH NOTED ALONG 50W OVER THE TROPICAL ATLC. SIMILAR CONVECTION IS FROM 7N-15N E OF 27W...AND FROM 3N-8N BETWEEN 26W-33W. ...DISCUSSION... GULF OF MEXICO... A BROAD/STRONG UPPER RIDGE IS CENTERED OVER MEXICO SENDING A STRONG NORTHERLY FLOW ALOFT ON WATER VAPOR IMAGERY. AN AREA OF LOWER PRESSURES AND SCATTERED MODERATE TO STRONG CONVECTION IS INLAND OVER S-CENTRAL TEXAS. THE ACTIVITY IS ASSOCIATED TO A FRONTAL BOUNDARY EXTENDING ACROSS CENTRAL TEXAS. MIDDLE TO UPPER MOISTURE AND CIRRUS FLOWS AROUND THE UPPER RIDGING CIRCULATION COVERING A GREAT PORTION OF THE NW GULF WATERS ON INFRA-RED SATELLITE IMAGERY. WITHIN THIS REGION...MOSAIC DOPPLER RADAR INDICATES SCATTERED SHOWERS ENTERING THE NW GULF BASIN ACROSS THE COASTAL WATERS OF TEXAS AND LOUISIANA N OF 26N W OF 91W. THE OVERALL ACTIVITY IS EXPECTED TO EXPEND OVER THE NW AND DRIFT ENE LATER TODAY AS AN UPPER LEVEL SHORTWAVE MOVING ACROSS NRN MEXICO BEGINS TO PUSH THE CONVECTION EASTWARD. SHORT RANGE COMPUTER MODELS SUGGEST A LOW PRESSURE SYSTEM WILL DEVELOP OVER S-CENTRAL TEXAS AND INTRODUCE A COLD FRONT TO THE NW GULF WITHIN THE NEXT 12 HOURS. OTHERWISE...WEAK SURFACE RIDGING DOMINATES THE REMAINDER OF THE GULF ANCHORED BY A WEAK 1016 MB HIGH NEAR FLORIDA BIG BEND GENERATING LIGHT TO GENTLE ANTI CYCLONIC FLOW ACROSS THE AREA. CARIBBEAN SEA... THE BASE OF AN UPPER LEVEL TROUGH AXIS EXTENDING ACROSS THE FAR WRN ATLC REACHES THE NW CARIBBEAN PROVIDING SCATTERED SHOWERS AND TSTMS OVER A GREAT PORTION OF THE BASIN BETWEEN 73W-84W INCLUDING THE WINDWARD PASSAGE AND INLAND PORTIONS OF HAITI... JAMAICA...AND CUBA. A TROPICAL WAVE ALONG 82W AND THE SW BASIN MONSOON TROUGH ARE ANALYZED WITHIN THIS REGION OF CONVECTION PROVIDING FURTHER ATMOSPHERIC INSTABILITY TO THE ENVIRONMENT IN THIS AREA. THE CONVECTION IN THIS REGION IS EXPECTED TO LINGER DURING THE NEXT 24 HOURS. OTHERWISE...A DRY AND SUBSIDENT AIRMASS ALOFT COVERS THE REMAINDER OF THE CENTRAL AND ERN CARIBBEAN E OF 73W... PROVIDING OVERALL STABLE CONDITIONS ACROSS THE AREA WITH A FEW ISOLATED LOW-TOP SHOWERS NOTED OVER THE NE CARIBBEAN AND PUERTO RICO THIS MORNING. 5-15 KT TRADE WIND FLOW WILL PERSIST ACROSS THE AREA E OF 77W DURING THE FORECAST PERIOD. ATLANTIC OCEAN... AN UPPER LEVEL TROUGH AXIS EXTENDS S ACROSS THE FAR WRN ATLC ADVECTING MIDDLE TO UPPER LEVEL MOISTURE ACROSS MUCH OF THIS AREA W OF 63W. WATER VAPOR AND SATELLITE WINDS INDICATE THE SHARPEST CYCLONIC TURNING AROUND THE UPPER TROUGH IS ACROSS THE NW BAHAMAS INTO THE NW CARIBBEAN PROVIDING A STRONG UPPER DIFFLUENT PATTERN WELL TO THE E OF IT GENERATING SCATTERED MODERATE TO ISOLATED STRONG CONVECTION S OF 26N W OF 72W. WITHIN THIS AREA OF MID-UPPER MOISTURE...A SURFACE TROUGH IS ANALYZED FROM 31N71W TO 24N72W. WEAK LOW-LEVEL CONVERGENCE AROUND THIS FEATURE IS ENOUGH TO GENERATE ISOLATED SHOWERS AND TSTMS WITHIN 200 NM E OF THE TROUGH AXIS. A SECOND SURFACE TROUGH IS ANALYZED NE OF PUERTO RICO GENERATING SIMILAR CONVECTION WITHIN 160 NM W OF THE TROUGH AXIS. EXCEPT FOR T.S. NADINE...THE REMINDER OF THE ATLC BASIN IS INFLUENCED BY SURFACE RIDGING AROUND A 1030 MB HIGH LOCATED OVER THE AZORES. NADINE IS EXPECTED TO EXPERIENCE SOME UPPER LEVEL WIND SHEAR DURING THE NEXT 24 HOURS AS IT BEGINS TO INTERACT WITH AN UPPER LEVEL CYCLONIC CIRCULATION CENTERED NEAR 34N45W. FOR ADDITIONAL INFORMATION PLEASE VISIT HTTP://WWW.HURRICANES.GOV/MARINE $$ GARCIA