ZCZC MIATCDAT4 ALL TTAA00 KNHC DDHHMM TROPICAL STORM NICHOLAS DISCUSSION NUMBER 11 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 5 AM EDT THU OCT 16 2003 NICHOLAS SEEMS TO BE TRANSITIONING FROM A SHEARED CONVECTIVE BLOB SYSTEM TO ONE WITH MORE CURVED BANDING FEATURES. HOWEVER...THERE STILL APPEARS TO BE SOME SOUTH-SOUTHWESTERLY MID-LEVEL FLOW UNDERCUTTING THE OUTFLOW LAYER...BUT THIS HAS BEEN WEAKENING AND MOVING AWAY FROM THE CYCLONE DURING THE PAST FEW HOURS. THE SATELLITE INTENSITY ESTIMATE IS A CONSENSUS T3.0/45 KT FROM ALL THREE AGENCIES...BUT THE CONVECTIVE PATTERN HAS IMPROVED SOME SINCE THE 06Z FIXES. ALSO...A 16/0300Z PARTIAL TRMM OVERPASS INDICATED THAT THE INNER-CORE HAS TIGHTNED UP CONSIDERABLY...SO THE INITIAL INTENSITY HAS BEEN INCREASED SLIGHTLY TO 50 KT. THE INITIAL MOTION ESTIMATE IS 310/08. THERE REMAINS UNCERTAINTY IN THE EXACT LOCATION OF THE LOW-LEVEL CENTER. THE PAST 4 MICROWAVE POSITIONS SUGGEST THAT THE LOW-LEVEL CENTER IS FARTHER SOUTH THAN THE PREVIOUS POSITION AND FORECAST TRACK. HOWEVER...IT IS POSSIBLE THAT THE LOW-LEVEL CENTER MAY BE DEVELOPING CLOSER TO THE DEEPER CONVECTION NOW...SO THE THE INITIAL POSITION AND FORECAST TRACK WAS ONLY SHIFTED SLIGHTLY TO THE LEFT. THE NHC MODEL GUIDANCE REMAINS QUITE DIVERGENT...WITH THE GFDN AND NOGAPS MODELS TAKING NICHOLAS ALMOST DUE NORTH FROM THE OUTSET. THESE ARE THE RIGHTMOST OF ALL THE MODELS AND WERE DISCOUNTED. THE GFDL..GFS...AND UKMET MODELS ARE CONSISTENT THROUGH 36 HOURS IN TAKING THE CYCLONE TOWARD THE NORTHWEST. AFTER THAT...THEY ALSO DIVERGE SIGNIFICANTLY WITH THE GFDL AND GFS FORECASTING A NORTHWARD MOTION...WHILE THE UKMET MAINTAINS A GENERAL SLOW NORTHWESTWARD MOTION. THE UKMET SOLUTION WAS CLOSELY FOLLOWED GIVEN THAT MODEL'S GOOD PERFORMANCE THE PAST 48 HOURS...AND THE FACT THAT ALL THE GLOBAL MODELS MAINTAIN SOME MID-LEVEL RIDGING TO THE NORTH OF NICHOLAS THROUGHOUT THE PERIOD. ALL OF THE GLOBAL MODELS AGREE THAT THE UPPER-LEVEL FLOW WILL BE MOST FAVORABLE DURING THE NEXT 36 HOURS OR SO FOR ANY SIGNIFICANT STRENGTHENING TO OCCUR. THE EXCEPTION IS THE UKMET WHICH KEEPS A SMALL ANTICYCLONE ABOVE NICHOLAS THROUGH 72 HOURS. THE OFFICIAL FORECAST IS A BLEND OF THE MUCH WEAKER SHIPS INTENSITY MODEL AND THE STRONGER 86-KT GFDL MODEL. IF THE UKMET TRACK AND UPPER-LEVEL FLOW PATTERN FORECASTS VERIFY...THEN NICHOLAS WILL PROBABLY BE STRONGER AT 72-96 HOURS THAN THE OFFICIAL FORECAST IS INDICATING. FORECASTER STEWART FORECAST POSITIONS AND MAX WINDS INITIAL 16/0900Z 13.3N 45.8W 50 KT 12HR VT 16/1800Z 14.1N 46.5W 55 KT 24HR VT 17/0600Z 15.3N 47.5W 60 KT 36HR VT 17/1800Z 16.3N 48.1W 65 KT 48HR VT 18/0600Z 17.3N 48.9W 65 KT 72HR VT 19/0600Z 18.0N 50.0W 65 KT 96HR VT 20/0600Z 19.0N 51.0W 65 KT 120HR VT 21/0600Z 21.0N 52.0W 65 KT NNNN
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Page last modified: Monday, 07-Feb-2005 16:50:00 UTC