000 AXNT20 KNHC 161200 TWDAT TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 805 AM EDT SUN SEP 16 2012 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 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 1115 UTC. ...SPECIAL FEATURES... HURRICANE NADINE IS CENTERED NEAR 30.5N 44.7W 16/0900 UTC OR ABOUT 1035 NM E OF BERMUDA...AND ABOUT 985 NM WSW OF THE AZORES. NADINE IS MOVING E AT 15 KT. ESTIMATED MINIMUM CENTRAL PRESSURE IS 983 MB. MAXIMUM SUSTAINED WIND SPEED IS 70 KT WITH GUSTS TO 85 KT. SEE LATEST NHC FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS MIATCMAT4/WTNT24 KNHC FOR MORE DETAILS. A CLUSTER OF STRONG CONVECTION HAS FORMED FROM 30N-31N BETWEEN 43W-45W. SCATTERED MODERATE CONVECTION IS ELSEWHERE FROM 28N-34N BETWEEN 38W-47W. ...TROPICAL WAVES... TROPICAL WAVE EXTENDS JUST WEST OF THE CAPE VERDE ISLANDS FROM 18N27W TO 11N26W MOVING W AT 10-15 KT. THIS WAVE IS NOT AS ROBUST AS SOME OF THE STRONGER WAVES THAT HAVE EMERGED OFF AFRICA...BUT IT STILL ALIGNS WITH A SMALL SURGE OF DEEP LAYER MOISTURE PRESENT IN TOTAL PRECIPITABLE WATER IMAGERY. NO DEEP CONVECTION IS CURRENTLY ASSOCIATED WITH THE WAVE. TROPICAL WAVE APPROACHES THE LESSER ANTILLES ALONG 18N56W TO 11N54W MOVING W AT 10-15 KT. A 1010 MB SURFACE LOW IS ANALYZED ALONG THE WAVE AT 13N55W. THE WAVE LIES WITHIN AN AREA OF MAXIMUM MOISTURE EVIDENT IN TOTAL PRECIPITABLE WATER IMAGERY. SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS FROM 13N-18N BETWEEN 56W-60W. THIS ACTIVITY MAY BEGIN TO IMPACT THE LESSER ANTILLES SHORTLY. LOCALLY HEAVY RAINS AND SQUALLS COULD AFFECT PORTIONS OF THE LESSER ANTILLES TODAY THROUGH AND MONDAY. ...ITCZ/MONSOON TROUGH... THE MONSOON TROUGH EXTENDS ACROSS W AFRICA TO THE COAST OF MAURITANIA AT 18N16W CONTINUING OVER ATLC WATERS ALONG 10N26W 9N41W. SCATTERED MODERATE/STRONG CONVECTION IS FROM 5N-10N BETWEEN 30W-46W. ...DISCUSSION... GULF OF MEXICO... PATCHES OF SHOWERS/THUNDERSTORMS CONTINUE OVER SEVERAL AREAS OF THE GULF OF MEXICO. ISOLATED SHOWERS/THUNDERSTORMS REMAIN OVER THE SE GULF NEAR THE WEST COAST OF FLORIDA AND ACROSS SOUTH FLORIDA AND THE FLORIDA STRAITS. THIS ACTIVITY IS LINKED TO DIFFLUENCE ALOFT AROUND THE E SIDE OF AN UPPER LEVEL TROUGH ALONG 85W. A SURFACE TROUGH IN THE WESTERN CARIBBEAN ALONG 27N96W TO 23N93W IS ALSO SUPPORTING A FEW SHOWERS/THUNDERSTORMS NEAR THE AXIS. A FEW PATCHES ARE ALSO ALONG THE MEXICAN AND SE TEXAS COAST. THE REMAINDER OF THE BASIN HAS MOSTLY CLEAR SKIES. WEAK UPPER RIDGING COVERS THE AREA TO THE WEST OF THE UPPER TROUGH ACROSS THE WESTERN GULF. THE SURFACE TROUGH IS EXPECTED TO DRIFT WEST AND WILL EVENTUALLY BE ABSORBED BY A FRONTAL BOUNDARY THAT WILL REACH THE BASIN ON MONDAY. MOIST CONDITIONS AND BROAD SURFACE TROUGHING WILL REMAIN ACROSS THE BASIN UNTIL THEN. CARIBBEAN SEA... LITTLE HAS CHANGED ACROSS THE CARIBBEAN OVER THE PAST 6 HOURS. FAIR WEATHER PREVAILS ACROSS THE BASIN RELATED TO DRY AIR ALOFT AROUND AN UPPER LEVEL RIDGE COVERING THE WESTERN CARIBBEAN...AND AN INVERTED UPPER TROUGH COVERING THE EASTERN CARIBBEAN. A FEW WIDELY ISOLATED SHOWERS/THUNDERSTORMS ARE NEAR CENTRAL CUBA AND NEAR THE HISPANIOLA COAST. A FEW CLUSTERS OF SHOWERS/THUNDERSTORMS ALSO CONTINUE OFFSHORE OF HONDURAS AND NICARAGUA...AS WELL AS OVER NORTHERN COSTA RICA. TRADEWIND FLOW OF 15-20 KT IS PRESENT ACROSS THE CENTRAL CARIBBEAN WITH LIGHTER WINDS TO EITHER SIDE. EXPECT SHOWERS/THUNDERSTORMS ACROSS THE SW CARIBBEAN AND CENTRAL AMERICA DURING THE DAYTIME HOURS WITH ACTIVITY INCREASING OVER THE EXTREME EASTERN CARIBBEAN AS A TROPICAL WAVE APPROACHES FROM THE EAST. ATLANTIC OCEAN... AN UPPER LEVEL RIDGE COVERS THE FAR WESTERN ATLC PROVIDING MOSTLY FAIR CONDITIONS AROUND SURFACE RIDGING EXTENDING FROM THE NE CONUS. AN UPPER LEVEL TROUGH IS ALONG 63W SUPPORTING A SURFACE TROUGH ALONG 31N63W 27N71W. THE UPPER TROUGH IS MOSTLY EMBEDDED WITH DRY AIR KEEPING SHOWER ACTIVITY AT A MINIMUM EXCEPT FOR A FEW SHOWERS/THUNDERSTORMS ABOUT 200 NM EAST OF THE SURFACE TROUGH AXIS NORTH OF 28N. TO THE E...HURRICANE NADINE MOVES THROUGH THE CENTRAL ATLC. SEE SPECIAL FEATURES ABOVE FOR MORE DETAILS. A WEAK 1016 MB SURFACE HIGH IS SE OF NADINE CENTERED NEAR 24N35W. THE RIDGE IS SUPPORTED BY AN UPPER LEVEL RIDGE CENTERED SOUTH OF NADINE NEAR 21N51W. THE UPPER RIDGE ALONG WITH THE SURFACE RIDGE ARE PROVIDING FAIR CONDITIONS ACROSS THE REMAINDER OF THE CENTRAL AND EASTERN ATLC. A BROAD UPPER LEVEL TROUGH COVERS THE EASTERN ATLC CENTERED NEAR THE AZORES ISLANDS...BUT IS NOT CAUSING ANY ACTIVE WEATHER IN THE DISCUSSION AREA. THE FIRST VISIBLE SATELLITE IMAGERY OF THE DAY ALONG WITH GOES-R ENHANCED IMAGERY INDICATE THAT A THIN AREA OF SAHARAN DUST EXTENDS S OF 30N FROM THE COAST OF AFRICA AROUND THE TROPICAL WAVE TO NEAR 50W. FOR ADDITIONAL INFORMATION PLEASE VISIT HTTP://WWW.HURRICANES.GOV/MARINE $$ WALTON