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#38681 (Received by flhurricane at: 4:37 AM 10.Aug.2005) TCDAT4 TROPICAL DEPRESSION IRENE DISCUSSION NUMBER 23 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 5 AM EDT WED AUG 10 2005 THERE IS LITTLE OR NO EVIDENCE THAT IRENE STILL HAS A CLOSED CIRCULATION. AS NOTED IN THE PREVIOUS DISCUSSION...LAST NIGHT'S QUIKSCAT AMBIGUITIES COULD NOT DEFINE A CENTER...AND THE LOW CLOUD LINES IN THE NIGHT-VIS IMAGERY ALSO SUGGEST THAT IRENE IS ELONGATING AND LIKELY HAS DEGENERATED INTO AN OPEN TROUGH. IF THERE IS A CENTER...IT IS PROBABLY SOUTH OF THE CURRENT ADVISORY POSITION IN THE DEEP CONVECTION SOUTH OF 22N. GIVEN THE UNCERTAINTIES HOWEVER...IT IS PRUDENT TO WAIT FOR VISIBLE IMAGERY BEFORE DISSIPATING OR RELOCATING THE CYCLONE. THE INITIAL INTENSITY IS LOWERED TO 25 KT BASED ON THE MOST RECENT QUIKSCAT DATA AND THE PRESENT LACK OF ORGANIZATION OF THE SYSTEM. IF IRENE SURVIVES...THE UPPER-LEVEL FLOW PATTERN IS STILL EXPECTED TO BECOME GRADUALLY MORE FAVORABLE FOR DEVELOPMENT...AND THE SHIPS GUIDANCE CONTINUES TO FORECAST STRENGTHENING. THE OFFICIAL FORECAST...A BLEND OF THE SHIPS AND GFDL GUIDANCE...CALLS FOR LESS DEVELOPMENT THAN THE PREVIOUS ADVISORY. THE INITIAL MOTION OF THIS DISORGANIZED SYSTEM IS HARD TO DETERMINE BUT MY BEST ESTIMATE IS 270/10. A MID-LEVEL HIGH IS CENTERED NEAR BERMUDA TO THE NORTHWEST OF IRENE. THE GFDL...GFS...UKMET AND NOGAPS MODELS CONTINUE TO WANT TO TAKE IRENE TO THE WEST-NORTHWEST AND THEN NORTHWEST LATE IN THE FORECAST PERIOD AS THEY SLIDE THIS HIGH EASTWARD. THE SIMPLER BAM MODELS DO NOT HAVE THE NORTHWEST TURN. OVER THE PAST FEW DAYS...THE GLOBAL MODELS HAVE HAD A SIGNIFICANT RIGHT BIAS WHILE THE BAMS HAVE PERFORMED RELATIVELY WELL. GIVEN THE PRESENT WESTWARD MOTION AND THESE BIASES...THE OFFICIAL FORECAST HAS BEEN SHIFTED A LITTLE WESTWARD...AND IS A COMPROMISE BETWEEN THE FSU SUPERENSEMBLE AND THE MEDIUM BAM. BOTH THE TRACK AND INTENSITY FORECASTS ARE VERY LOW CONFIDENCE. FORECASTER FRANKLIN FORECAST POSITIONS AND MAX WINDS INITIAL 10/0900Z 22.4N 57.3W 25 KT 12HR VT 10/1800Z 22.9N 59.0W 25 KT 24HR VT 11/0600Z 23.7N 61.1W 30 KT 36HR VT 11/1800Z 24.6N 63.4W 35 KT 48HR VT 12/0600Z 25.7N 65.5W 40 KT 72HR VT 13/0600Z 27.0N 68.0W 40 KT 96HR VT 14/0600Z 28.5N 70.5W 45 KT 120HR VT 15/0600Z 30.0N 73.0W 50 KT |