000 AXNT20 KNHC 140003 TWDAT TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 805 PM EDT MON SEP 13 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 IGOR IS CENTERED NEAR 17.7N 50.5W AT 13/2100 UTC OR ABOUT 830 NM E OF THE NORTHERN LEEWARD ISLANDS MOVING W AT 9 KT. ESTIMATED MINIMUM CENTRAL PRESSURE IS 933 MB. MAXIMUM SUSTAINED WIND SPEED IS 130 KT WITH GUSTS TO 160 KT. NUMEROUS STRONG CONVECTION IS WITHIN 90 NM OF THE CENTER WHILE NUMEROUS MODERATE AND SCATTERED STRONG CONVECTION IS ELSEWHERE FROM 13N-21N BETWEEN 47W-54W. SEE LATEST NHC FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS MIATCMAT1/WTNT21 KNHC FOR MORE DETAILS. TROPICAL STORM JULIA IS CENTERED NEAR 15.3N 27.7W AT 14/0000 UTC OR ABOUT 225 NM W OF THE SOUTHERNMOST CAPE VERDE ISLANDS MOVING WNW AT 10 KT. ESTIMATED MINIMUM CENTRAL PRESSURE IS 1000 MB. MAXIMUM SUSTAINED WIND SPEED IS 45 KT WITH GUSTS TO 55 KT. GRADUAL STRENGTHENING IS FORECAST OVER THE NEXT COUPLE OF DAYS DUE TO A FAVORABLE UPPER LEVEL DIFFLUENT ENVIRONMENT. NUMEROUS MODERATE AND SCATTERED STRONG CONVECTION IS FROM 12N-18N BETWEEN 25W-31W. SEE LATEST NHC INTERMEDIATE PUBLIC ADVISORY UNDER AWIPS/WMO HEADERS MIATCPAT2/WTNT32 KNHC AND THE FULL FORECAST/ ADVISORY UNDER AWIPS/WMO HEADERS MIATCMAT2/WTNT22 KNHC FOR MORE DETAILS. A BROAD LOW PRESSURE AREA IS LOCATED IN THE WESTERN CARIBBEAN SEA FOCUSED ON A 1006 MB LOW CENTERED NEAR 16N79W. A SURFACE TROUGH EXTENDS FROM NEAR 22N74W THROUGH THE LOW CENTER TO 9N81W MOVING WNW NEAR 10 KT. SCATTERED MODERATE TO STRONG CONVECTION IS OCCURRING FROM 15N-23N BETWEEN 71W-82W. ISOLATED MODERATE TO STRONG CONVECTION IS ALSO FROM 8N-15N BETWEEN 77W-84W. WHILE CONVECTION ALONG THE SURFACE TROUGH AND NEAR THE LOW CENTERED REMAIN LARGELY UNORGANIZED...ENVIRONMENTAL CONDITIONS ARE FAVORABLE FOR DEVELOPMENT OF A TROPICAL CYCLONE BEFORE IT MOVES INLAND OVER THE YUCATAN PENINSULA BY WEDNESDAY EVENING. REGARDLESS OF DEVELOPMENT...LOCALLY HEAVY RAINFALL IS POSSIBLE OVER PORTIONS OF HISPANIOLA...JAMAICA...CUBA...THE CAYMAN ISLANDS...AND THE YUCATAN PENINSULA DURING THE NEXT DAY OR TWO. THESE RAINS COULD CAUSE LIFE-THREATENING FLASH FLOODS AND MUD SLIDES...ESPECIALLY IN AREAS OF MOUNTAINOUS TERRAIN. ...ITCZ... ITCZ AXIS IS CENTERED ALONG 8N28W 9N34W 11N40W RESUMING NEAR 30N56W 11N63W 11N71W. SCATTERED WEAK CONVECTION IS WITHIN 130 NM EITHER SIDE OF THE AXIS BETWEEN 28W AND 40W. ...DISCUSSION... GULF OF MEXICO... A BROAD UPPER LEVEL RIDGE OF HIGH PRESSURE COVERS THE GULF WITH UPPER LEVEL ANTICYCLONIC CIRCULATION CENTERED OVER THE FAR SW LOUISIANA STATE NEAR 30N93W. THIS UPPER FLOW IS PROVIDING A MODERATELY DRY AIRMASS ALOFT ACROSS MUCH OF THE GULF...NOTED ON WATER VAPOR IMAGERY...SUPPRESSING DEEP CONVECTION ACROSS THE BASIN. HOWEVER...A NEARLY STATIONARY FRONTAL BOUNDARY IS ANALYZED ACROSS THE CENTRAL FLORIDA PENINSULA FROM WEST PALM BEACH TO MARCO ISLAND...ENTERING THE EASTERN GULF AS A SURFACE TROUGH TO NEAR 24N83W. THIS FEATURE...COMBINED WITH LAND-SEA SURFACE CONVERGENCE AND DIURNAL HEATING...IS GENERATING SCATTERED SHOWERS AND ISOLATED THUNDERSTORMS ACROSS THE WESTERN COASTAL WATERS OF THE FLORIDA PENINSULA S OF 27N TO 40 NM OFFSHORE. THIS AREA OF CONVECTION IS EXPECTED TO CONTINUE TO MOVE WEST OVER THE NEXT 24 HOURS. ISOLATED SHOWERS ARE ELSEWHERE ACROSS THE GULF THIS EVENING...EMBEDDED IN THE SURFACE ENE FLOW. CARIBBEAN SEA... A BROAD AREA OF LOW PRESSURE CENTERED AROUND A 1006 MB LOW NEAR 16N79W CONTINUES TO BE THE CENTER OF ATTENTION ACROSS THE CARIBBEAN...IMPACTING MUCH OF THE CENTRAL AND SW BASIN. SEE SPECIAL FEATURES ABOVE FOR MORE DETAILS. THE REMAINDER OF THE NW AND EASTERN CARIBBEAN ARE UNDER THE INFLUENCE OF DRY AIR ALOFT KEEPING CONDITIONS FAIR WITH ISOLATED SHOWERS EMBEDDED IN THE TRADE WINDS. EXPECT CONTINUED SHOWER/THUNDERSTORM ACTIVITY ACROSS THE CENTRAL AND WESTERN CARIBBEAN AS THE LOW PRESSURE SYSTEM MOVES WWD. ATLANTIC OCEAN... A DEEP LAYER TROUGH COVERS THE WESTERN ATLC N OF THE AREA MOVING OFF THE EASTERN US SEABOARD SUPPORTING A WEAK COLD FRONT THAT EXTENDS ACROSS THE WESTERN ATLC AND INTO THE FLORIDA PENINSULA ALONG 32N70W 28N75W 26N80W...GENERATING SCATTERED SHOWERS N OF 23N W OF 70W. AN AREA OF STRONG SCATTERED CONVECTION EXTENDS N OF HISPANIOLA AND EASTERN CUBA S OF 23N W OF 70W...ASSOCIATED WITH THE BROAD AREA OF LOW PRESSURE IN THE CENTRAL CARIBBEAN DISCUSSED ABOVE IN THE SPECIAL FEATURES SECTION. AN UPPER LEVEL OCCLUDED LOW IS OVER THE N CENTRAL ATLANTIC AND SUPPORTS A SECOND DISSIPATING COLD FRONT THAT ENTERS THE DISCUSSION AREA NEAR 32N50W TO 27N66W. ISOLATED SHOWERS/THUNDERSTORMS ARE WITHIN 45 NM EITHER SIDE OF THE FRONT. ASIDE MAJOR HURRICANE IGOR AND TROPICAL STORM JULIA...THE REMAINDER OF THE ATLC N OF 22N IS UNDER THE INFLUENCE OF DRY AND STABLE AIR ALOFT AROUND AN UPPER LEVEL RIDGE SUPPORTING A 1032 MB HIGH LOCATED NORTH OF THE DISCUSSION AREA NEAR 44N25W. FOR ADDITIONAL INFORMATION PLEASE VISIT HTTP://WWW.HURRICANES.GOV/MARINE $$ GARCIA