000 AXNT20 KNHC 130000 TWDAT TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 805 PM EDT SUN SEP 12 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 2315 UTC. ...SPECIAL FEATURES... HURRICANE IGOR IS CENTERED NEAR 17.7N 46.9W AT 12/2100 UTC OR ABOUT 925 NM E OF THE NRN LEEWARD ISLANDS MOVING W AT 12 KT. ESTIMATED MINIMUM CENTRAL PRESSURE IS 942 MB. MAXIMUM SUSTAINED WIND SPEED IS 120 KT WITH GUSTS TO 145 KT. IGOR HAS REACHED CATEGORY FOUR STATUS ON THE SAFFIR-SIMPSON SCALE AND SOME FURTHER STRENGTHENING IS EXPECTED. IGOR HAS A WELL-DEFINED EYE AND SYMMETRICALLY ORIENTED CONVECTION. NUMEROUS STRONG CONVECTION IS WITHIN 100 NM OF THE CENTER LOCATION. NUMEROUS MODERATE CONVECTION EXTENDS BETWEEN 100NM AND 150NM OF THE STORM CENTER. SEE LATEST NHC FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS MIATCMAT1/WTNT21 KNHC FOR MORE DETAILS. TROPICAL DEPRESSION TWELVE IS CENTERED NEAR 13.3N 23.0W AT 13/0000 UTC OR ABOUT 120 NM SE OF THE SOUTHERNMOST CAPE VERDE ISLANDS MOVING W NEAR 10 KT. ESTIMATED MINIMUM CENTRAL PRESSURE IS 1006 MB. MAXIMUM SUSTAINED WIND SPEED IS 30 KT WITH GUSTS TO 40 KT. SOME STRENGTHENING IS EXPECTED OVER THE NEXT COUPLE OF DAYS. NUMEROUS STRONG CONVECTION IS MAINLY NW OF THE CENTER ALREADY APPROACHING THE SRN CAPE VERDE ISLANDS FROM 12N-16N BETWEEN 23W-25W. PLEASE READ THE LATEST NHC INTERMEDIATE PUBLIC ADVISORY UNDER AWIPS/WMO HEADERS MIATCPAT2/ WTNT32 KNHC AND THE FULL FORECAST AND ADVISORY UNDER AWIPS/WMO HEADERS MIATCMAT2/WTNT22 KNHC FOR MORE DETAILS. BROAD LOW PRESSURE AROUND A 1007 MB SURFACE LOW S OF HAITI NEAR 16N72W COVERS MUCH OF THE CENTRAL CARIBBEAN MOVING W NEAR 10 KT. UPPER LEVEL ANTI-CYCLONIC FLOW IS CENTERED N OF THE MONA PASSAGE NEAR 20N68W PROVIDING DIFFLUENCE ALOFT NEAR THE SURFACE LOW CENTER HELPING ENHANCE SCATTERED MODERATE/STRONG CONVECTION CONVECTION FROM 16N-18N BETWEEN 72W-78W...FROM 17N-21N BETWEEN 66W-72W. ISOLATED MODERATE/STRONG CONVECTION IS ALSO FROM 11N-16N BETWEEN 72W-80W. WITH THE MOUNTAINOUS TERRAIN ACROSS THE NRN CARIBBEAN ISLANDS...FLASH FLOODING AND MUD SLIDES ARE POSSIBLE. WHILE NO WELL-DEFINED CENTER EXISTS AT THIS TIME ENVIRONMENTAL CONDITIONS ARE SOMEWHAT FAVORABLE FOR DEVELOPMENT...AND A TROPICAL CYCLONE COULD FORM OVER THE NEXT FEW DAYS. ...ITCZ... ITCZ AXIS IS CENTERED ALONG 7N19W 6N27W 12N37W RESUMING NEAR 11N45W 10N54W 14N61W. SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS FROM 3N-6N BETWEEN 12W-21W. SIMILAR ACTIVITY IS FROM 5N-8N BETWEEN 21W-33W. ...DISCUSSION... GULF OF MEXICO... WEAK SURFACE RIDGING COVERS THE MAJORITY OF THE GULF OF MEXICO ANCHORED BY A 1018 MB HIGH IN THE CENTRAL GULF NEAR 27N88W MAINTAINING FAIR CONDITIONS ACROSS MUCH OF THE AREA. THE SURFACE RIDGE IS SUPPORTED BY AN UPPER LEVEL RIDGE CENTERED OVER ERN TEXAS MAINTAINING NE-E FLOW ALOFT ACROSS THE BASIN ACCOMPANIED BY DRY AIR. HOWEVER...A FRONTAL BOUNDARY ACROSS THE NRN GULF EXTENDING FROM THE NRN FLORIDA PANHANDLE TO ACROSS SRN LOUISIANA IS SUPPORTING SCATTERED SHOWERS/THUNDERSTORMS S OF THE FRONT TO 29N E OF 96W. A FEW ISOLATED STRONG STORMS ARE ALSO ACROSS THE FLORIDA PENINSULA DUE TO SEABREEZE CONVERGENCE. A WEAK SURFACE TROUGH IS IN THE SRN BAY OF CAMPECHE ALONG 21N95W TO 16N94W SUPPORTING A FEW ISOLATED SHOWERS/THUNDERSTORMS ACROSS SRN MEXICO. AN AREA OF ENHANCED MOISTURE PREVIOUSLY ASSOCIATED WITH A SURFACE TROUGH IN THE WRN CARIBBEAN HAS MOVED ACROSS THE YUCATAN PENINSULA AND S OF GUATEMALA IN THE E PACIFIC HELPING TO GENERATE SCATTERED SHOWERS/THUNDERSTORMS ACROSS THE YUCATAN PENINSULA. DAYTIME HEATING AND INSTABILITY ARE ALSO SUPPORTING SCATTERED SHOWERS/THUNDERSTORMS ACROSS WRN CUBA AND TO THE N OVER THE SE GULF OF MEXICO. EXPECT SHOWERS/THUNDERSTORMS TO CONTINUE ACROSS THE NRN GULF AS THE FRONTAL BOUNDARY DRIFTS SWD. CARIBBEAN SEA... DAYTIME HEATING AND INSTABILITY ARE SUPPORTING SCATTERED SHOWERS/THUNDERSTORMS ACROSS WRN CUBA AND THE IMMEDIATE COASTAL WATERS. THE REMAINDER OF THE NW CARIBBEAN IS UNDER THE INFLUENCE OF DRY AIR ALOFT KEEPING CONDITIONS FAIR. A BROAD AREA OF LOW PRESSURE CENTERED AROUND A 1007 MB LOW S OF HAITI NEAR 16N72W IS IMPACTING MUCH OF THE CENTRAL CARIBBEAN. SEE SPECIAL FEATURES ABOVE FOR MORE DETAILS. THE FAR ERN CARIBBEAN IS ALSO UNDER THE INFLUENCE OF DRY AIR ALOFT AROUND AN UPPER LEVEL RIDGE CENTERED OVER HISPANIOLA MAINTAINING FAIR CONDITIONS. EXPECT CONTINUED SHOWER/THUNDERSTORM ACTIVITY ACROSS THE CENTRAL CARIBBEAN AND INTO THE WRN CARIBBEAN AS THE LOW PRESSURE SYSTEM MOVES WWD. ATLANTIC OCEAN... A DEEP LAYER TROUGH EXTENDS DOWN THE ERN UNITED STATES SEABOARD SUPPORTING A FRONTAL BOUNDARY THAT EXTENDS ACROSS NRN FLORIDA AND ALONG THE NRN GULF OF MEXICO. SCATTERED SHOWERS/THUNDERSTORMS ARE S OF THE FRONT FROM 29N-31N W OF 76W. A SECOND DEEP LAYER TROUGH IS TO THE E ALONG 55W SUPPORTING A SECOND FRONTAL BOUNDARY ENTERING THE DISCUSSION AREA NEAR 32N55W TO 28N67W. ISOLATED SHOWERS/THUNDERSTORMS ARE WITHIN 45 NM EITHER SIDE OF THE FRONT. SHOWERS/THUNDERSTORMS ARE ALSO N OF HISPANIOLA APPROACHING TURKS AND CAICOS ASSOCIATED WITH THE BROAD AREA OF LOW PRESSURE IN THE CENTRAL CARIBBEAN. THE REMAINDER OF THE SW ATLC IS UNDER THE INFLUENCE OF DRY AIR AROUND AN UPPER LEVEL RIDGE CENTERED NEAR 27N71W. FARTHER E...A WEAK SURFACE TROUGH EXTENDS FROM 22N57W TO 18N56W SUPPORTING A FEW ISOLATED SHOWERS/THUNDERSTORMS WITHIN 90 NM W OF THE AXIS. MAJOR HURRICANE IGOR IS DUE E. SEE SPECIAL FEATURES ABOVE. THE REMAINDER OF THE ERN ATLC IS DOMINATED BY SURFACE RIDGING ANCHORED BY A 1033 MB HIGH CENTERED N OF THE AZORES ISLANDS. ALOFT...AN UPPER LEVEL RIDGE IS N OF IGOR WITH AN UPPER LEVEL TROUGH COVERING THE ERN ATLC CENTERED BETWEEN THE AZORES ISLANDS AND THE CANARY ISLANDS. FOR ADDITIONAL INFORMATION PLEASE VISIT HTTP://WWW.HURRICANES.GOV/MARINE $$ WALTON