000 AXNT20 KNHC 280600 TWDAT TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 205 AM EDT SUN AUG 28 2011 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 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 0415 UTC. ...SPECIAL FEATURE... HURRICANE IRENE IS CENTERED NEAR 38.1N 75.0W AT 28/0600 UTC OR ABOUT 13 NM SSE OF OCEAN CITY MARYLAND AND ABOUT 170 NM SSW OF NEW YORK CITY MOVING N-NE AT 15 KT. THE LATEST MINIMUM CENTRAL PRESSURE REPORTED BY THE HURRICANE HUNTER AIRCRAFT WAS 958 MB. MAXIMUM SUSTAINED WIND SPEED IS 70 KT WITH GUSTS TO 85 KT. PLEASE SEE THE LATEST INTERMEDIATE PUBLIC ADVISORY UNDER AWIPS/WMO HEADER MIATCPAT4/WTNT34 KNHC AND THE FULL FORECAST/ ADVISORY UNDER AWIPS/WMO HEADER MIATCMAT4/WTNT24 KNHC FOR MORE DETAILS. SCATTERED TO HEAVY SHOWERS WITH ISOLATED/SCATTERED THUNDERSTORMS COVER A LARGE AREA INLAND OVER THE NE CONUS AND WITHIN 150 NM ALONG THE COAST FROM N OF CAPE HATTERAS NORTH CAROLINA BORDER TO CENTRAL MAINE. A 1012 MB LOW IS OFF THE COAST OF AFRICA NEAR 10N19W. CLUSTERS OF SCATTERED/NUMEROUS STRONG CONVECTION ARE WITHIN 60 NM OF LINE FROM DAKAR SENEGAL W OF THE LOW TO 10N22W. ENVIRONMENTAL CONDITIONS APPEAR CONDUCIVE FOR DEVELOPMENT OF THIS WAVE DURING THE NEXT COUPLE OF DAYS AS IT MOVES WESTWARD AT 9 KT. THIS SYSTEM HAS A MEDIUM CHANCE OF BECOMING A TROPICAL CYCLONE DURING THE NEXT 48 HOURS. ...THE ITCZ/THE MONSOON TROUGH... THE MONSOON TROUGH IS ANALYZED ACROSS AFRICA ENTERING THE E TROPICAL ATLC NEAR 12N15W TO 10N18W THEN RESUMES NEAR 14N37W TO 10N48W. THE ITCZ AXIS CONTINUES FROM 10N48W ALONG 9N54W TO SOUTH AMERICA NEAR 8N59W. SCATTERED MODERATE/STRONG CONVECTION IS WITHIN 90 NM OF LINE FROM 5N20W 7N24W TO 11N23W. CLUSTERS OF SCATTERED MODERATE CONVECTION ARE FROM 5N-8N BETWEEN 10W-15W... WITHIN 150 NM S OF THE MONSOON TROUGH BETWEEN 37W-43W...AND WITHIN 180 NM N OF THE ITCZ BETWEEN 54W-58W. ...DISCUSSION... GULF OF MEXICO... AN UPPER TROUGH OVER THE E CONUS DIPS S OVER THE N GULF TO 27N SUPPORTING A COLD FRONT THAT AT 28/0300 UTC EXTENDS FROM SW GEORGIA ACROSS NE FLORIDA INTO THE GULF NEAR 30N83W ALONG 29N88W TO 29N92W WHERE IT BECOMES STATIONARY TO INLAND OVER E TEXAS NEAR THE LOUISIANA BORDER. SCATTERED SHOWERS/THUNDERSTORMS ARE FROM 27N-29N E OF 90W TO JUST INLAND OVER FLORIDA NEAR TAMPA. AN UPPER RIDGE ANCHORED OVER THE NW CARIBBEAN IS GIVING THE REMAINDER OF THE GULF WESTERLY FLOW ALOFT LEAVING THE REMAINDER OF THE GULF WATERS ARE UNDER CLEAR SKIES TONIGHT. THE COLD FRONT WILL DISSIPATE THROUGH LATE MON. LOW PRESSURE IS EXPECTED TO DEVELOP IN THE SW GULF WED AND THU. ATLC SURFACE RIDGE WILL BUILD WESTWARD ALONG THE FAR N GULF COAST TUE THROUGH THU. CARIBBEAN SEA... AN UPPER RIDGE COVERS THE W CARIBBEAN W OF 75W ANCHORED NEAR 18N85W WHILE THE UPPER TROUGH OVER THE CENTRAL ATLC EXTENDS S OVER THE REMAINDER OF THE CARIBBEAN BASIN. DEEP LAYER MOISTURE REMAINS ACROSS THE CARIBBEAN BASIN AND COMBINED WITH THE FLOW ALOFT IS GENERATING LARGE CLUSTERS OF SCATTERED SHOWERS/ THUNDERSTORMS OVER THE CENTRAL CARIBBEAN N OF 11N BETWEEN 70W-80W TO ACROSS HISPANIOLA...E CUBA...AND JAMAICA. THE MONSOON TROUGH EXTENDS FROM COLOMBIA NEAR 8N76W ACROSS PANAMA INTO THE SW CARIBBEAN ALONG 9N81W TO OVER NICARAGUA NEAR 12N84W GENERATING SCATTERED SHOWERS/ISOLATED THUNDERSTORMS INLAND AND WITHIN 45 NM ALONG THE COAST OF PANAMA BETWEEN 80W-82W. THIS IS LEAVING MOST OF THE NW CARIBBEAN UNDER CLEAR SKIES TONIGHT EXCEPT SCATTERED SHOWERS/ISOLATED THUNDERSTORMS IN THE GULF OF HONDURAS WITHIN 60 NM ALONG THE COAST OF HONDURAS AND THE YUCATAN PENINSULA S OF 20N W OF 84W. A SURFACE RIDGE WILL BUILD WESTWARD OVER THE W ATLC MON THROUGH WED INCREASING TRADES OVER THE CENTRAL AND E CARIBBEAN. THE TRADES WILL THEN WEAKEN THU AS THE RIDGE BEGINS TO RETREAT BACK TO THE NE. ATLANTIC OCEAN... THE PRIMARY FOCUS TONIGHT IS HURRICANE IRENE MOVING ALONG THE COAST OF NEW ENGLAND...SEE SPECIAL FEATURES ABOVE. THE UPPER TROUGH THAT COVERS THE E CONUS EXTENDS INTO THE W ATLC W OF 77W WHILE THE ASSOCIATED FRONTAL BOUNDARY REMAINS INLAND AND IN THE GULF OF MEXICO. AN UPPER LOW IS IN THE W/CENTRAL ATLC NEAR 27N61W EXTENDING AN UPPER TROUGH S INTO THE E CARIBBEAN THROUGH THE MONA PASSAGE SUPPORTING A 1010 MB SURFACE LOW NEAR 29N64W. A WEAKENING SURFACE TROUGH IS TO THE E EXTENDING FROM 30N61W TO 26N58W AND A SECOND SURFACE TROUGH TO THE S EXTENDING FROM 23N56W TO 19N56W. CLUSTERS OF SCATTERED SHOWERS/ISOLATED THUNDERSTORMS COVER THE AREA FROM 21N-31N BETWEEN 52W-69W. A SURFACE RIDGE EXTENDING INTO THE REMAINDER OF THE CENTRAL ATLC THROUGH A 1022 MB HIGH NEAR 30N51W TO 25N45W AND A SECOND SURFACE RIDGE OVER THE E ATLC EXTENDS THROUGH 32N22W TO 28N31W. A 1011 MB LOW IS TO THE S CENTERED NEAR 18N35W WITH A WEAK SURFACE TROUGH ANALYZED FROM 25N30W THROUGH THE LOW TO 15N36W WITH SCATTERED SHOWERS/ISOLATED THUNDERSTORMS ARE WITHIN 120 NM EITHER SIDE OF THE SURFACE TROUGH N OF 20N. A SURFACE TROUGH IS IN THE W TROPICAL ATLC EXTENDING FROM 16N59W TO 11N58W MOVING TOWARD THE LESSER ANTILLES. LINGERING LARGE SWELLS GENERATED FROM HURRICANE IRENE WILL GRADUALLY SUBSIDE THROUGH SUN NIGHT. CENTRAL ATLC HIGH PRES WILL BUILD WESTWARD IN THE WAKE OF IRENE. HIGH PRESSURE WILL THEN SLOWLY RETREAT AS A WEAK FRONTAL TROUGH MOVES INTO THE NW PORTION MON NIGHT SLOWLY SHIFTING E AND EXTENDING FROM BERMUDA TO THE CENTRAL BAHAMAS BY THU. ADDITIONAL INFORMATION PLEASE VISIT HTTP://WWW.HURRICANES.GOV/MARINE $$ PAW