000 AXNT20 KNHC 112353 TWDAT TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 805 PM EDT THU OCT 11 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 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 2315 UTC. ...SPECIAL FEATURES... TROPICAL DEPRESSION SIXTEEN IS UPGRADED TO TROPICAL STORM PATTY AT 11/2100 UTC. AT THIS TIME...IT IS CENTERED NEAR 25.8N 72.5W OR ABOUT ABOUT 255 MI...415 KM NE OF THE CENTRAL BAHAMAS. PRESENT MOVEMENT IS STATIONARY. ESTIMATED MINIMUM CENTRAL PRESSURE IS 1007 MB. MAXIMUM SUSTAINED WIND SPEED IS 35 KT WITH GUSTS TO 45 KT. SEE LATEST NHC FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS MIATCMAT1/WTNT21 KNHC. PATTY IS EXPECTED TO BE SHORT LIVED TROPICAL CYCLONE DUE TO A COUPLE OF FACTORS. ONE IS INCREASING SOUTHWESTERLY SHEAR DURING THE NEXT DAY OR SO. SECOND IS THE PRESENCE OF A COLD FRONT IN THE WESTERN PORTION OF THE CIRCULATION PLUS SOME DRIER AND MORE STABLE AIR THAT WILL LIKELY ENTRAIN INTO THE CENTER. THESE ENVIRONMENTAL CONDITIONS SHOULD CAUSE THE CYCLONE TO WEAKEN BY TOMORROW AS IT MOVES SLOWLY TO THE SW AROUND A BUILDING HIGH PRESSURE INTO THE WESTERN ATLANTIC OCEAN. NUMEROUS MODERATE TO STRONG CONVECTION IS FROM 24N TO 28N BETWEEN 70W AND 72.5W. SCATTERED MODERATE TO STRONG CONVECTION IS ELSEWHERE FROM 27N TO 31N BETWEEN 65W AND 72W. A BROAD AREA OF LOW PRESSURE ASSOCIATED WITH A TROPICAL WAVE IS LOCATED NEAR 12N59W OR ABOUT 75 MILES EAST-SOUTHEAST OF BARBADOS. SHOWER AND THUNDERSTORM ACTIVITY CONTINUES TO SHOW SOME SIGNS OF ORGANIZATION...AND ENVIRONMENTAL CONDITIONS APPEAR CONDUCIVE FOR GRADUAL DEVELOPMENT OVER THE NEXT COUPLE OF DAYS. THIS SYSTEM HAS A HIGH CHANCE OF BECOMING A TROPICAL CYCLONE DURING THE NEXT 48 HOURS AS IT MOVES NORTHWESTWARD AT 10 TO 15 MPH. REGARDLESS OF DEVELOPMENT...STRONG GUSTY WINDS AND HEAVY RAINFALL ARE POSSIBLE ACROSS PORTIONS OF THE LESSER ANTILLES DURING THE NEXT COUPLE OF DAYS. A DIFFLUENT PATTERN ALOFT IS OBSERVED OVER THIS SYSTEM...AND IS HELPING TO SUPPORT THE CONVECTION ASSOCIATED WITH IT. THUNDERSTORM ACTIVITY HAS ALSO INCREASED NEAR THE CIRCULATION CENTER. A CLUSTER OF NUMEROUS MODERATE TO ISOLATED STRONG CONVECTION IS NOTED WITHIN 110 NM NE QUADRANT OF LOW CENTER. SCATTERED MODERATE ISOLATED STRONG CONVECTION IS ELSEWHERE FROM 9N TO 16N BETWEEN 50W AND 57W. BUOY 41101 LOCATED NEAR 14.5N56W IS REPORTING SUSTAINED WINDS OF 25 KT AND SEAS TO 11 FT. THE LOW PRES IS FORECAST TO REACH A POSITION NEAR 15N62W IN ABOUT 24 HOURS. ...THE ITCZ/THE MONSOON TROUGH... THE MONSOON TROUGH EXTENDS FROM NEAR THE SENEGAL/GUINEA BISSAU BORDER TO 5N25W...THEN THE ITCZ CONTINUES TO 5N40W TO 9N54W. ISOLATED MODERATE CONVECTION IS NOTED FROM 4N TO 10N BETWEEN 22N AND 30N. SIMILAR CONVECTION IS NEAR 10.5N31.5W AND NEAR 8.5N37W. ...DISCUSSION... GULF OF MEXICO... A RIDGE/TROUGH PATTERN DOMINATES THE GULF REGION ALOFT. THE RIDGE EXTENDS FROM AN ANTICYCLONIC CIRCULATION LOCATED OVER CENTRAL MEXICO NEAR 20N100W TO THE N INTO TEXAS COVERING THE WESTERN PART OF THE GULF WATERS. THE UPPER-LEVEL TROUGH STRETCHES FROM THE CAROLINAS ACROSS FLORIDA AND THE SE PORTION OF THE GULF WITH THE BASE OF THE TROUGH OVER WESTERN CUBA. MODERATE TO STRONG SUBSIDENCE AND IMPLIED DRY AIR MASS IS NOTED ACROSS MOST OF THE AREA. SOME CONVECTIVE ACTIVITY HAS FLARED UP OVER EASTERN TEXAS. AT THE SURFACE...A RIDGE...ANCHORED ON A HIGH PRES OVER THE SE CONUS...DOMINATES THE GULF. PRES GRADIENT BETWEEN THE RIDGE AND TROPICAL STORM PATTY WILL BRING AN INCREASE IN WINDS ACROSS THE EASTERN GULF...INCLUDING ALSO THE STRAITS OF FLORIDA FRI THROUGH SUN. IN FACT...LATEST SCATTEROMETER DATA PROVIDED OBSERVATIONS OF 15-20 NE WINDS ACROSS THIS AREA. THE CARIBBEAN SEA... LIGHT TO MODERATE WINDS ARE OBSERVED ACROSS THE CARIBBEAN SEA DUE TO THE PRESENCE OF TROPICAL STORM PATTY N OF THE AREA. HOWEVER...EXPECT AN INCREASE IN WINDS OVER NW CARIBBEAN TONIGHT THROUGH SAT AS STRONG HIGH PRES BUILDS OVER EASTERN U.S. THE GFS COMPUTER MODELS SUGGESTS WINDS OF MAINLY 20 KT ACROSS WESTERN CUBA AND THE NW CARIBBEAN. SCATTERED MODERATE TO STRONG CONVECTION IS OVER PARTS OF COSTA RICA AND PANAMA IN ASSOCIATION WITH THE MONSOON TROUGH. IN THE UPPER LEVELS...THE ANTICYCLONIC CIRCULATION CENTERED OVER CENTRAL MEXICO EXTENDS A RIDGE ACROSS NORTH-CENTRAL AMERICA AND THE WESTERN CARIBBEAN INTO EASTERN CUBA. AN UPPER LEVEL LOW IS SPINNING OVER THE NE CARIBBEAN AN IS HELPING TO INDUCE SOME CONVECTIVE ACTIVITY ACROSS PUERTO RICO AND REGIONAL COASTAL WATERS. BETWEEN THESE TWO UPPER-LEVEL FEATURES...A NE WIND FLOW ALOFT PREVAILS. THE SAN JUAN DOPPLER RADAR IS SHOWING SCATTERED SHOWERS AND ISOLATED TSTMS ACROSS THE REGIONAL WATERS...MORE CONCENTRATED NEAR THE US/UK VIRGIN ISLANDS AND ACROSS THE CARIBBEAN WATERS. JUST E OF THE LESSER ANTILLES...THERE IS A LOW PRES SYSTEM WITH THE POTENTIAL OF BECOMING A TROPICAL CYCLONE. SEE SPECIAL FEATURES FOR MORE DETAILS. PRES GRADIENT BETWEEN HIGH PRES NEAR 34N41W AND THE AFOREMENTIONED LOW PRES IS ALREADY PRODUCING FRESH TO STRONG ELY WINDS ACROSS THE TROPICAL N ATLC FROM 13N AND 18N BETWEEN 55W AND 60W AS NOTED PER THE MOST RECENT SCATTEROMETER DATA. THE ATLANTIC OCEAN... TROPICAL STORM PATTY HAS DEVELOPED JUST E OF THE BAHAMAS. SEE SPECIAL FEATURES FOR MORE DETAILS. HIGH PRES CENTERED OVER THE SE UNITED STATES DOMINATES THE STATE OF FLORIDA AND NOW IS PRODUCING NE WINDS ACROSS SOUTH FLORIDA. THESE WINDS WILL BRING SOME PATCHES OF SHALLOW MOISTURE WITH EMBEDDED SHOWERS ACROSS EASTERN FLORIDA. A LARGE 1026 MB HIGH IS OVER THE ATLANTIC NEAR 34N41W COVERING MOST OF THE EAST AND CENTRAL ATLANTIC. IN THE UPPER LEVELS...THE TROUGH THAT WAS COVERING EASTERN NORTH AMERICA THE PAST COUPLE OF DAYS NOW IS EXITING THE EAST COAST OF THE UNITED STATES. AS PREVIOUSLY MENTIONED...THIS TROUGH EXTENDS FROM THE CAROLINAS ACROSS FLORIDA AND THE SE PORTION OF THE GULF WITH THE BASE OF THE TROUGH OVER WESTERN CUBA. FOR ADDITIONAL INFORMATION PLEASE VISIT HTTP://WWW.HURRICANES.GOV/MARINE $$ GR