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#366468 (Received by flhurricane at: 8:43 PM 05.Aug.2010) TCDAT4 TROPICAL STORM COLIN SPECIAL DISCUSSION NUMBER 8 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL AL042010 730 PM AST THU AUG 05 2010 ...THIS SPECIAL ADVISORY HAS BEEN ISSUED TO PRIMARILY UPDATE THE INTENSITY AND WIND RADII FORECASTS. SHORTLY AFTER THE PREVIOUS ADVISORY HAD BEEN ISSUED...AN AIR FORCE RESERVE RECONNAISSANCE AIRCRAFT INVESTIGATING TROPICAL STORM COLIN REPORTED A 600-FT FLIGHT-LEVEL WIND OF 71 KT ABOUT 14 NMI NORTHEAST OF THE CIRCULATION CENTER. IN ADDITION...A SURFACE PRESSURE OF 1005 MB WAS ALSO OBSERVED IN THE GENERAL VICINITY. IT IS UNCERTAIN IF THESE VALUES WERE ASSOCIATED WITH A SMALL MESOVORTEX LOCATED NORTHEAST OF THE CENTER...WHICH WOULD NOT BE REPRESENTATIVE OF THE LARGER-SCALE WIND FIELD. FOR THIS REASON...THE INTENSITY WAS INITIALIZED AT 40 KT IN AGREEMENT WITH NEARBY SFMR WINDS. HOWEVER...SINCE THE TIME OF THAT RECON REPORT...DEEP CONVECTION IN THE NORTHEASTERN QUADRANT OF COLIN HAS CONTINUED TO DEVELOP CLOSER TO THE LOW-LEVEL CIRCULATION CENTER...WHICH JUSTIFIES INCREASING THE INTENSITY TO 50 KT BASED ON A BLEND OF THE FLIGHT-LEVEL WINDS AND SFMR SURFACE WINDS. SINCE A FORECAST INTENSITY OF 50 KT WAS NOT EXPECTED TO OCCUR UNTIL 48 HOURS IN THE PREVIOUS ADVISORY...A SPECIAL ADVISORY WAS REQUIRED TO INCREASE THE INTENSITY AND TO ADJUST THE INTENSITY FORECAST UPWARD DURING THE NEXT 36 HOURS. ALSO...DROPSONDE DATA INDICATES AN EXPANSION OF THE 34-KT WIND RADII IN THE SOUTHEASTERN QUADRANT WAS NECESSARY. NO SIGNIFICANT CHANGES TO THE PREVIOUS TRACK FORECAST OR REASONING WERE MADE. INTERNET PROBLEMS WILL PREVENT THE NHC WEB SITE FROM BEING UPDATED AT THIS TIME. PLEASE SEE WEATHER.GOV FOR ADVISORY TEXT PRODUCTS. FORECAST POSITIONS AND MAX WINDS INITIAL 05/2330Z 25.6N 66.3W 50 KT 12HR VT 06/0600Z 26.6N 67.1W 50 KT 24HR VT 06/1800Z 28.1N 67.3W 50 KT 36HR VT 07/0600Z 29.6N 67.3W 50 KT 48HR VT 07/1800Z 31.3N 67.1W 55 KT 72HR VT 08/1800Z 36.0N 65.0W 55 KT 96HR VT 09/1800Z 40.0N 61.5W 60 KT 120HR VT 10/1800Z 49.0N 48.0W 50 KT...POST-TROP/EXTRATROP $$ FORECASTER STEWART/BROWN |