000 AXNT20 KNHC 180005 TWDAT TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 805 PM EDT FRI SEP 17 2010 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...METEOROLOGICAL ANALYSIS...WEATHER OBSERVATIONS...AND RADAR. BASED ON 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 2345 UTC. ...SPECIAL FEATURES... HURRICANE KARL IS NOW DOWNGRADED TO TROPICAL STORM. THIS SYSTEM IS INLAND OVER MEXICO CENTERED NEAR 18.8N 97.1W AT 18/0000 UTC OR ABOUT 75 MI..115 KM E OF PUEBLA MEXICO MOVING WSW AT 8 KT. ESTIMATED MINIMUM CENTRAL PRESSURE IS 995 MB. MAXIMUM SUSTAINED WIND SPEED IS 60 KT WITH GUSTS TO 80 KT. SEE LATEST NHC INTERMEDIATE PUBLIC ADVISORY UNDER AWIPS/WMO HEADERS MIATCPAT3/WTNT33 AND THE FULL FORECAST/ ADVISORY UNDER AWIPS/WMO HEADERS MIATCMAT3/WTNT23 KNHC FOR MORE DETAILS. THIS SYSTEM CONTINUES TO PRODUCE NUMEROUS STRONG CONVECTION OVER THE MEXICO REGION CAUSING LIFE THREATENING FLASH FLOODS AND MUD SLIDES...ESPECIALLY IN AREAS OF MOUNTAINOUS TERRAIN. THE OUTER BANDS OF MODERATE TO STRONG CONVECTION COVER THE REMAINDER OF THE AREA INCLUDING THE WESTERN HALF OF THE GULF OF MEXICO W OF 88W. HURRICANE IGOR IS CENTERED NEAR 24.2N 61.3W AT 18/0000 UTC OR ABOUT 600 MI SSE OF BERMUDA MOVING NW AT 9 KT. ESTIMATED MINIMUM CENTRAL PRESSURE IS 947 MB. MAXIMUM SUSTAINED WIND SPEED IS 89 KT WITH GUSTS TO 120 KT. IGOR CONTINUES TO POSE A THREAT TO BERMUDA. SEE LATEST NHC FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS MIATCMAT1/WTNT21 KNHC FOR MORE DETAILS. NUMEROUS STRONG CONVECTION IS FROM 23N-26N BETWEEN 60W-63W. SCATTERED MODERATE CONVECTION COVERS THE REMAINDER OF THE AREA FROM 21N-28N BETWEEN 58W-64W. HURRICANE JULIA IS CENTERED NEAR 25.2N 48.2W AT 17/2100 UTC OR ABOUT 1525 MI WSW OF THE AZORES MOVING WNW AT 16 KT. ESTIMATED MINIMUM CENTRAL PRESSURE IS 987 MB. MAXIMUM SUSTAINED WIND SPEED IS 65 KT WITH GUSTS TO 80 KT. SATELLITE IMAGERY SHOWS THE UPPER OUTFLOW OF IGOR IS SHEARING JULIA AND THEREFORE THIS SYSTEM IS EXPECTED TO CONTINUE TO WEAKEN OVER THE NEXT 24 HOURS. SEE LATEST NHC FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS MIATCMAT2/WTNT22 KNHC FOR MORE DETAILS. SCATTERED MODERATE TO STRONG CONVECTION IS FROM 22N-26N BETWEEN 45W-50W. ...TROPICAL WAVES... A TROPICAL WAVE IS ALONG 23W S OF 19N MOVING W AT 10 KT. SATELLITE IMAGERY AND DERIVED WINDS SHOW CYCLONIC TURNING IN THE VICINITY OF THE WAVE N OF 12N. AN EMBEDDED LOW IS ON THE WAVE AXIS NEAR 12N23W. A DEEP LAYERED MOISTURE SURROUNDS THE WAVE NOTED ON TOTAL PRECIPITABLE WATER IMAGERY. SCATTERED MODERATE TO ISOLATED STRONG CONVECTION IS FROM 7N-14N BETWEEN 22W AND 32W. HOWEVER...THE CONVECTION ASSOCIATED WITH THE WAVE IS ALSO EMBEDDED IN THE MONSOONAL TROUGH COVERING A LARGER AREA IN THE TROPICAL ATLC. ...ITCZ... THE THE ITCZ/MONSOONAL HAS BROKEN DOWN OVER THE PAST SEVERAL DAYS DUE TO THE LARGE SCALE WIND FIELD FROM HURRICANES IGOR AND JULIA. RESIDUAL WIDELY SCATTERED MODERATE CONVECTION IS HOWEVER FROM 7N TO 14N BETWEEN 22W AND 40W. A SURGE OF SCATTERED MODERATE TO STRONG CONVECTION WILL MOVE OFF THE COAST OF WEST AFRICA FROM 5N TO 14N OVER THE NEXT FEW HOURS. ...DISCUSSION... GULF OF MEXICO... ALTHOUGH HURRICANE KARL IS INLAND OVER MEXICO...REMNANT OUTER BANDS FROM THIS SYSTEM CONTINUE TO SPREAD ACROSS MOST OF THE CENTRAL AND WESTERN GULF PRODUCING SCATTERED HEAVY SHOWERS AND THUNDERSTORMS W OF 88W. THIS AREA OF CONVECTION IS EXPECTED TO CONTINUE TO MOVE WESTWARD ACROSS THE WESTERN HALF OF THE GULF OVER THE NEXT 24 HOURS. FAIR WEATHER CONDITIONS ARE PRESENT ACROSS THE REMAINDER OF THE GULF WITH A FEW ISOLATED SHOWERS EMBEDDED IN THE EASTERLY 5-15 KT FLOW. THE UPPER LEVEL RIDGE OF HIGH PRESSURE OVER THE SE CONUS WEAKENED IN RESPONSE OF THE PASSAGE OF KARL OVER THE GULF THESE PAST SEVERAL DAYS. HOWEVER...COMPUTER MODELS SUGGEST THIS UPPER LEVEL FEATURE WILL REBUILD OVER THE SE CONUS AND PROMOTE FAIR WEATHER TO THE EAST AND CENTRAL GULF WHILE SOME REMNANT CONVECTION ASSOCIATED WITH KARL WILL CONTINUE OVER THE FAR WEST BASIN THROUGH EARLY NEXT WEEK. CARIBBEAN SEA... FAIR WEATHER CONDITIONS WITH A FEW ISOLATED SHOWERS ARE OBSERVED ACROSS MOST OF THE BASIN...DUE TO DRY STABLE AIR ALOFT CAPTURED ON WATER VAPOR IMAGERY...SHOWING THE STRONGEST AREA OF SUBSIDENCE BETWEEN 74W AND 84W N OF 12N. MONSOONAL TROUGHINESS IS NOTED OVER NORTHERN SOUTH AMERICA GENERATING SCATTERED SHOWERS AND THUNDERSTORMS TO THE FAR SW CARIBBEAN S OF 12N W OF 76W...AND ALSO ALONG THE COASTAL WATERS OF VENEZUELA AND COLOMBIA TO 20 NM OFFSHORE. CYCLONIC 10-15 KT SURFACE FLOW IS OVER THE EASTERN BASIN E OF 70W DUE TO THE LARGE SCALE WIND FIELD FROM HURRICANE IGOR. COMPUTER MODELS INDICATE THIS LARGE SCALE WIND FIELD WILL DRAG CONSIDERABLE MOISTURE ACROSS THE ESE CARIBBEAN GENERATING SCATTERED MODERATE TO STRONG CONVECTION OVER THIS REGION IN THE NEXT 12 TO 24 HOURS. ATLANTIC OCEAN... HURRICANES IGOR AND JULIA TOGETHER WITH A TROPICAL WAVE OVER THE EAST TROPICAL ATLC ARE THE PRIMARY SURFACE FEATURES OVER THE ATLANTIC. IGOR CONTINUES TO POSE A THREAT TO BERMUDA. SATELLITE IMAGERY SHOWS THE UPPER OUTFLOW OF IGOR IS STARTING TO SHEAR JULIA. A LARGE AREA OF AFRICAN DUST FROM THE SAHARA REGION IS NOTED ON SATELLITE IMAGERY...COVERING MOST OF THE EASTERN ATLC FROM 14N TO 28N BETWEEN THE COAST OF AFRICA AND 41W. THIS SAHARAN AIR LAYER...ALONG WITH THE EAST ATLC UPPER LEVEL RIDGE SUPPORTING THE SUB-TROPICAL 1027 MB HIGH LOCATED NEAR 40N38W...ARE KEEPING FAIR WEATHER CONDITIONS IN THIS REGION. FOR ADDITIONAL INFORMATION PLEASE VISIT HTTP://WWW.HURRICANES.GOV/MARINE $$ GARCIA