000 AXNT20 KNHC 201155 TWDAT TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 805 AM EDT MON SEP 20 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 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 1015 UTC. ...SPECIAL FEATURES... HURRICANE IGOR IS CENTERED NEAR 35.2N 64.0W AT 20/1200 UTC OR ABOUT 174 NM N OF BERMUDA MOVING NNE AT 17 KT. ESTIMATED MINIMUM CENTRAL PRESSURE IS 957 MB. MAXIMUM SUSTAINED WIND SPEED IS 65 KT WITH GUSTS TO 80 KT. IGOR REMAINS A LARGE SYSTEM AND BERMUDA IS STILL REPORTING TROPICAL STORM CONDITIONS. SEE LATEST NHC INTERMEDIATE PUBLIC ADVISORY UNDER AWIPS/WMO HEADERS MIATCPAT1/WTNT31 AND THE FULL FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS MIATCMAT1/WTNT21 KNHC FOR MORE DETAILS. MOST OF THE SHOWER ACTIVITY IS N OF THE CENTER. NUMEROUS MODERATE/SCATTERED STRONG CONVECTION IS FROM 34N-43N BETWEEN 59W-70W. TROPICAL STORM JULIA IS CENTERED NEAR 35.5N 47.9W AT 20/0900 UTC OR ABOUT 1010 NM W OF THE AZORES MOVING ENE AT 8 KT. ESTIMATED MINIMUM CENTRAL PRESSURE IS 998 MB. MAXIMUM SUSTAINED WIND SPEED IS 40 KT WITH GUSTS TO 50 KT. WEAKENING IS EXPECTED AS JULIA MOVES OVER COOLER WATERS AND CONTINUES TO EXPERIENCE WIND SHEAR FROM THE OUTFLOW OF HURRICANE IGOR. SEE LATEST NHC FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS MIATCMAT2/WTNT22 KNHC FOR MORE DETAILS. NUMEROUS MODERATE/SCATTERED STRONG CONVECTION IS FROM 33N-38N BETWEEN 37W-46W. AN AREA OF LOW PRESSURE IS LOCATED W OF THE CAPE VERDE ISLANDS CONCENTRATED NEAR A 1007 MB LOW NEAR 16N32W MOVING NW NEAR 5-10 KT. CONVECTION NEAR THE CENTER HAS INCREASED. NUMEROUS STRONG CONVECTION IS NOW FROM 15N-17N BETWEEN 30W-33W...WITH SCATTERED MODERATE/ISOLATED STRONG CONVECTION FROM 15N-20N BETWEEN 28W-33W. ENVIRONMENTAL CONDITIONS ARE FAVORABLE FOR FURTHER DEVELOPMENT INTO A TROPICAL CYCLONE DURING THE NEXT 48 HRS. ...TROPICAL WAVES... A TROPICAL WAVE IS APPROACHING THE W AFRICAN COAST ALONG 19N15W TO 10N19W MOVING W NEAR 10 KT. SATELLITE IMAGERY INDICATES BROAD CYCLONIC FLOW AROUND THE WAVE AXIS WITH A SURGE OF DEEP LAYER MOISTURE JUST OFF THE COAST EVIDENT IN TOTAL PRECIPITABLE WATER IMAGERY. SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS FROM 9N-16N BETWEEN 15W-20W. ...ITCZ... A MONSOONAL TROUGH IS ANALYZED FROM LOW PRESSURE SYSTEM NEAR 16N32W TO 10N45W INDICATING AN AREA WHERE THE WINDS S OF THE AXIS ARE MAINLY SWLY AS OPPOSED TO TYPICAL ITCZ CONVERGENCE OF SE-NE WINDS. THE TRADITIONAL ITCZ AXIS PICKS UP NEAR 10N46W TO 11N54W.SCATTERED MODERATE/STRONG CONVECTION IS FROM 7N-13N BETWEEN 32W-43W. AN EMBEDDED SURFACE TROUGH EXTENDS TO THE W ALONG 15N57W TO 9N54W ENHANCING SCATTERED MODERATE/STRONG CONVECTION FROM 9N-17N BETWEEN 51W-59W. ...DISCUSSION... GULF OF MEXICO... ENHANCED MOISTURE REMAINS ACROSS THE FAR NW GULF WHERE A SURFACE TROUGH IS ANALYZED ALONG THE TEXAS/MEXICO COASTLINE FROM 30N93W 27N96W TO 24N95W. SURFACE CONVERGENCE NEAR THE TROUGH ALONG WITH UPPER DIFFLUENCE ON THE BACK SIDE OF A WEAK UPPER LEVEL WIND JET OVER LOUISIANA ARE SUPPORTING SCATTERED SHOWERS/POSSIBLE THUNDERSTORMS FROM 22N-29N W OF 93W. THIS ACTIVITY IS EXPECTED TO REMAIN OVER THE FAR WRN GULF FOR THE NEXT COUPLE OF DAYS. MOSTLY FAIR WEATHER PREVAILS ACROSS THE ERN GULF DUE TO SUBSIDENCE ALOFT AROUND THE PERIPHERY OF AN UPPER LEVEL RIDGE COVERING MUCH OF THE BASIN CENTERED OVER WRN MEXICO NEAR 23N97W. WATER VAPOR IMAGERY ALSO INDICATES DRY AIR BEING DRAWN AROUND THE ERN EDGE OF THE UPPER RIDGE ACROSS FLORIDA AND THE W ATLC. EXPECT FAIR WEATHER TO CONTINUE ACROSS THE ERN HALF OF THE BASIN. CARIBBEAN SEA... MOSTLY FAIR WEATHER COVERS MUCH OF THE CARIBBEAN UNDER THE INFLUENCE OF A DRY AND STABLE AIRMASS OVER THE WRN HALF OF THE BASIN. UPPER RIDGING COVERS THE FAR NW CARIBBEAN EXTENDING FROM THE GULF OF MEXICO WHILE UPPER LEVEL TROUGHING DIGS DOWN ACROSS THE CENTRAL CARIBBEAN FROM THE W ATLC. A FEW ISOLATED SHOWERS ARE NOTED ACROSS THE NW CARIBBEAN S OF CUBA AROUND THE WRN SIDE OF THE BASE OF THE UPPER TROUGH. ISOLATED SHOWERS/THUNDERSTORMS ARE ALSO ACROSS THE SW CARIBBEAN S OF 14N BETWEEN 75W-84W ASSOCIATED WITH AN EXTENSION OF THE E PACIFIC MONSOONAL TROUGH FROM NICARAGUA TO N OF COLOMBIA NEAR 12N72W. STRONGER SHOWERS/THUNDERSTORMS ARE N OF VENEZUELA S OF 17N BETWEEN 66W-72W IN ASSOCIATION WITH AN AREA OF ENHANCED MOISTURE THAT HAS BEEN MOVING ACROSS THE ERN CARIBBEAN IN THE WAKE OF HURRICANE IGOR NOW WELL TO THE N. LARGE SWELLS CONTINUE TO IMPACT HISPANIOLA...PUERTO RICO...THE VIRGIN ISLANDS...AND THE LEEWARD ISLANDS IN ASSOCIATION WITH IGOR...AND ARE BEGINNING TO GRADUALLY SUBSIDE. EXPECT SHOWERS/THUNDERSTORMS TO CONTINUE OVER THE ERN CARIBBEAN OVER THE NEXT 24 HRS. ATLANTIC OCEAN... THE FAR W ATLC IS EXPERIENCING MOSTLY FAIR WEATHER ASSOCIATED WITH DRY AIR SINKING DOWN INTO THE AREA AROUND AN UPPER LEVEL RIDGE COVERING THE GULF OF MEXICO AND AN UPPER LEVEL TROUGH ACROSS THE W ATLC. TO THE NE...HURRICANE IGOR CONTINUES NWD WITH TROPICAL STORM JULIA TO THE E OF IGOR. SEE SPECIAL FEATURES FOR MORE DETAILS ON BOTH OF THESE SYSTEMS. A SURFACE TROUGH IS ANALYZED S OF IGOR INDICATING WHERE THE SURFACE WINDS SHIFT FROM NW TO SW. A FEW ISOLATED SHOWERS/THUNDERSTORMS ARE N OF THE LEEWARD ISLANDS DUE TO MOISTURE FROM THE ERN CARIBBEAN BEING DRAWN NWD IN THE WAKE OF IGOR. A SURFACE TROUGH E OF THE LESSER ANTILLES IS ENHANCING SCATTERED SHOWERS/THUNDERSTORMS FROM 9N-17N BETWEEN 51W-59W. E OF JULIA...SURFACE RIDGING PREVAILS AROUND A WEAKENING 1018 MB HIGH S OF THE AZORES ISLANDS PROVIDING GENERALLY FAIR WEATHER ACROSS THE E ATLC N OF THE LOW PRESSURE SYSTEM W OF THE CAPE VERDE ISLANDS. ALOFT...AN UPPER LEVEL RIDGE COVERS THE CENTRAL ATLC CENTERED NEAR 29N52W WITH AN UPPER LEVEL TROUGH TO THE E EXTENDING FROM PORTUGAL TO THE CANARY ISLANDS. FOR ADDITIONAL INFORMATION PLEASE VISIT HTTP://WWW.HURRICANES.GOV/MARINE $$ WALTON