ZCZC MIATCDEP5 ALL TTAA00 KNHC DDHHMM HURRICANE OTIS DISCUSSION NUMBER 15 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 2 PM PDT SAT OCT 01 2005 THE CONVECTIVE CLOUD TOPS HAVE CONTINUED TO WARM... WITH ONLY A LIMITED AREA COLDER THAN -50C. SUBJECTIVE AND OBJECTIVE DVORAK CI NUMBERS AT 18Z WERE ALL NEAR 5.0/90 KT BUT WITH T NUMBERS 4.0/65 KT. AN AMSU OVERPASS AT 1357Z YIELDED INTENSITY ESTIMATES OF 73-76 KT FROM CIMSS AND CIRA... AND A SSMIS OVERPASS AT 1608Z REVEALS ONLY HALF OF AN EYEWALL REMAINING. BASED ON A BLEND OF THE VARIOUS DVORAK T AND CI NUMBERS... THE AMSU ESTIMATES... AND THE OVERALL DETERIORATING STRUCTURE... THE ADVISORY INTENSITY IS REDUCED TO 75 KT. SHIPS FORECASTS OTIS TO REMAIN A HURRICANE FOR ONLY ANOTHER 12 HOURS OR SO... WHILE THE GFDL DOES SO THROUGH 24 HOURS. THE EFFECTS OF OCEAN UPWELLING DUE TO THE SLOW FORWARD SPEED OF THE HURRICANE COULD LEAD TO A FAIRLY RAPID DECLINE IN THE INTENSITY. ON THE OTHER HAND... IF OTIS GETS MOVING AS INDICATED IN THE OFFICIAL FORECAST... IT COULD STILL HOLD ON TO HURRICANE INTENSITY UNTIL MAKING LANDFALL SOMEWHERE ALONG THE PACIFIC COAST OF THE BAJA CALIFORNIA PENINSULA. THEREFORE... IT IS PRUDENT TO MAINTAIN THE HURRICANE WATCHES AND WARNINGS ALREADY IN PLACE. OTIS IS FORECAST TO WEAKEN SUBSTANTIALLY AFTER PASSING OVER THE RUGGED TERRAIN OF THE CENTRAL BAJA CALIFORNIA PENINSULA... AND AS THE SOUTHWESTERLY WIND SHEAR INCREASES. OTIS BECAME ESSENTIALLY STATIONARY DURING THE MORNING HOURS... BUT IT APPEARS TO HAVE RECENTLY RESUMED A SLOW MOTION... ABOUT 350/3. THE WEAK STEERING RESULTS FROM OTIS BEING CAUGHT BETWEEN A MID TO UPPER LEVEL TROUGH JUST WEST OF THE NORTHERN BAJA CALIFORNIA PENINSULA AND A WEAK RIDGE OVER THE NORTHERN GULF OF MEXICO. THE VARIOUS DYNAMICAL MODELS ARE IN RATHER POOR AGREEMENT ON HOW FAST THIS PATTERN WILL MOVE OTIS... BUT AT LEAST THEY AGREE ON THE GENERAL NORTHWARD DIRECTION. THE NEW OFFICIAL TRACK FORECAST IS SLOWER THAN THE PREVIOUS ADVISORY... TO ACCOUNT FOR THE STALL EARLIER TODAY AND TO LEAN CLOSER TO THE MODEL CONSENSUS... BUT IS ESSENTIALLY ALONG THE SAME NORTHWARD PATH. OTIS IS EXPECTED TO DISSIPATE IN ABOUT FOUR DAYS AS IT REACHES MAINLAND NORTHWESTERN MEXICO. FORECASTER KNABB FORECAST POSITIONS AND MAX WINDS INITIAL 01/2100Z 22.0N 111.9W 75 KT 12HR VT 02/0600Z 22.5N 112.2W 65 KT 24HR VT 02/1800Z 23.6N 112.7W 60 KT 36HR VT 03/0600Z 25.2N 113.1W 60 KT 48HR VT 03/1800Z 26.9N 113.4W 50 KT...INLAND 72HR VT 04/1800Z 29.5N 113.5W 30 KT...OVER WATER 96HR VT 05/1800Z 31.5N 113.5W 25 KT...DISSIPATING INLAND 120HR VT 06/1800Z...DISSIPATED $$ NNNN
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Page last modified: Saturday, 01-Oct-2005 20:55:24 UTC