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| #16628 (Received by flhurricane at: 9:39 PM 01.Dec.2004) TCDAT1 TROPICAL STORM OTTO DISCUSSION NUMBER 6 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 10 PM EST WED DEC 01 2004 WHILE THE CONVECTIVE PATTERN IS NOT VERY IMPRESSIVE...A 01/2158Z QUIKSCAT OVERPASS INDICATED THAT OTTO HAS MAINTAINED A WELL-DEFINED LOW-LEVEL WIND FIELD CONTAINING SEVERAL 30-35 KT UN-FLAGGED WINDS. DRIFTING BUOY 44623 JUST SOUTH OF THE CENTER REPORTED A PRESSURE OF 997.5 MB AT 00Z. THE INITIAL INTENSITY IS MAINTAINED AT 35 KT FOR THIS ADVISORY BASED ON A DVORAK T-NUMBER OF T2.5...OR 35 KT...FROM TAFB AND THE 35-KT QUIKSCAT WINDS. HOWEVER...THE LOWER CENTRAL PRESSURE SUGGESTS THAT THE INTENSITY COULD BE A LITTLE STRONGER. INITIAL MOTION OVER THE PAST 12 HOURS HAS BEEN 150/06. THE LATEST NHC MODEL SUITE IS QUITE DIVERGENT. THE UKMET IS THE LEFTMOST MODEL AND TAKES OTTO DUE EAST WHILE THE NOGAPS MODEL IS THE RIGHTMOST OF ALL THE MODELS AND TAKES THE CYCLONE ALMOST DUE SOUTH. HOWEVER... ALL THE MODELS AGREE ON A SLOW FORWARD SPEED. AS THE MID-LATITUDE WESTERLIES BECOME INCREASINGLY MORE ZONAL OVER THE FORECAST PERIOD ...WEAK 500 MB RIDGING IS EXPECTED TO OCCUR NORTH OF OTTO. THIS SHOULD GRADUALLY NUDGE THE CYCLONE IN A GENERAL SOUTHEAST TO SOUTHERLY DIRECTION. THIS IS ALSO CONSISTENT WITH THE FORECAST NORTHWESTERLY COMPONENT OF THE VERTICAL SHEAR VECTOR...WHICH SHOULD HELP KEEP THE CONVECTION DISPLACED TO THE SOUTHEAST OF THE CENTER AND HELP TO DRAG IT IN A GENERAL SOUTHEASTWARD DIRECTION. THE OFFICIAL TRACK IS A LITTLE TO THE RIGHT OF THE PREVIOUS FORECAST TRACK AND CLOSE TO THE CONU CONSENSUS MODEL. THE SHIPS MODEL GRADUALLY INCREASES THE 850-200 MB SHEAR TO 35 KT BY 36H AND DISSIPATES OTTO BY 48-60H. HOWEVER...GIVEN THAT OTTO ORIGINATED FROM A COLD-CORE LOW AND LIKELY DOES NOT EXTEND TO THE 200 MB LEVEL...THE SHIPS SHEAR VALUES MAY BE EXCESSIVE..GIVEN THAT THE 300 MB WIND ACROSS OTTO IS EXPECTED TO BE ABOUT 10 KT LESS THAN AT THE 200 MB LEVEL. SINCE OTTO IS ALSO FORECAST TO MOVE OVER GRADUALLY WARMER WATER...THE INTENSITY WAS HELD HIGHER THAN THE SHIPS MODEL AND SIMILAR TO THE PREVIOUS INTENSITY FORECAST. FORECASTER STEWART FORECAST POSITIONS AND MAX WINDS INITIAL 02/0300Z 30.2N 49.7W 35 KT 12HR VT 02/1200Z 29.6N 49.4W 35 KT 24HR VT 03/0000Z 28.8N 48.7W 30 KT 36HR VT 03/1200Z 27.8N 47.8W 30 KT 48HR VT 04/0000Z 27.0N 47.0W 25 KT...DISSIPATING 72HR VT 05/0000Z 25.5N 46.0W 25 KT...DISSIPATING 96HR VT 06/0000Z 24.0N 46.0W 20 KT...REMNANT LOW 120HR VT 07/0000Z...DISSIPATED |
