ZCZC MIATCDEP5 ALL TTAA00 KNHC DDHHMM HURRICANE OTIS DISCUSSION NUMBER 10 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 8 AM PDT FRI SEP 30 2005 THE EYE HAS BECOME CLOUD-COVERED IN VISIBLE IMAGERY... BUT THE EYE STRUCTURE HAS CONTINUED TO IMPROVE BASED ON RECENT MICROWAVE SATELLITE IMAGERY AND RADAR DATA FROM CABO SAN LUCAS MEXICO. THE INITIAL INTENSITY OF 70 KT IS BASED ON A BLEND OF SATELLITE INTENSITY ESTIMATES OF 77 KT FROM TAFB...65 KT FROM SAB... 65 KT FROM AFWA... AND AN AVERAGE ODT VALUE OF T4.5/77 KT OVER THE PAST 1.5 HOURS. THE CONVECTIVE BANDING CONTINUES TO IMPROVE AND OUTFLOW IS GOOD TO EXCELLENT IN ALL QUADRANTS. THE INITIAL MOTION ESTIMATE IS 325/07. OTIS MADE A SLIGHT WESTWARD JOG DURING THE PAST 6 HOURS... BUT THIS IS BELIEVED TO BE A TEMPORARY MOTION AND WAS LIKELY DUE TO THE RE-ALIGNMENT OF THE MID- AND LOW-LEVEL CIRCULATION CENTERS. A 30/0532Z TRMM OVERPASS INDICATED THE MID-LEVEL EYE FEATURE WAS TILTED ABOUT 20 NMI TO THE EAST OF THE LOW-LEVEL EYE... BUT RADAR DATA AND A 30/1205Z AMSU OVERPASS SUGGEST THAT THE TWO CIRCULATIONS ARE NOW VERTICALLY STACKED. THE OFFICIAL FORECAST TRACK AND REASONING REMAINS ESSENTIALLY UNCHANGED. OTIS IS EXPECTED TO CONTINUE TO MOVE NORTHWESTWARD AROUND THE WEAKENING WESTERN PORTION OF A LARGE SUBTROPICAL RIDGE LOCATED OVER NORTHERN MEXICO FOR THE NEXT 48 HOURS. AFTER THAT... HOWEVER... THERE IS CONSIDERABLE DIVERGENCE IN THE MODEL GUIDANCE ON HOW THE UPPER-LOW OFF THE CALIFORNIA COAST IS HANDLED. THE GFS... NOGAPS... AND UKMET MODELS DROP THE LOW SOUTHEASTWARD TO THE WEST AND SOUTHWEST OF OTIS... WHICH RESULTS IN THE HURRICANE BEING LIFTED NORTHWARD ACROSS BAJA AND THEN NORTHEASTWARD ACROSS EXTREME NORTHWESTERN MEXICO AND THE SOUTHWESTERN UNITED STATES. IN CONTRAST... THE GFDL... CANADIAN... AND ECMWF MODELS WEAKEN THE UPPER-LOW AND BUILD THE RIDGE TO THE NORTH OF OTIS... CAUSING THE CYCLONE TO TURN SLOWLY WESTWARD AWAY FROM BAJA CALIFORNIA. THE LATEST TREND IN WATER VAPORY IMAGERY AND IN UW-CIMSS WATER VAPOR-DERIVED WINDS INDICATE THAT THE UPPER-LOW IS STRONGER... DIGGING SOUTHWARD... AND THAT MORE RIDGING IS OCCURRING TO THE NORTH AND WEST OF THE UPPER-LOW. ALSO... 500 MB HEIGHTS HAVE DECREASED MORE THAN 40 METERS DURING THE PAST 24 HOURS ALONG THE CENTRAL AND SOUTHERN CALIFORNIA COASTS AND OVER SOUTHERN BAJA. ALL OF THIS WOULD TEND TO SUPPORT THE GFS-NOGAPS-UKMET SOLUTION... AND THAT 3-MODEL CONSENSUS WAS CLOSELY FOLLOWED. SOME ADDITIONAL STRENGTHENING IS FORECAST FOR THE NEXT 24 HOURS SINCE OTIS IS EXPECTED TO REMAIN OVER 28C OR WARMER SSTS AND THE VERTICAL SHEAR IS FORECAST TO REMAIN 5 KT OR LESS. THE INTENSITY FORECAST IS CLOSE TO THE SHIPS AND GFDL MODELS THROUGH 72 HOURS. THE FORECAST TRACK AND WIND RADII KEEP THE STRONGER WINDS OFFSHORE. HOWEVER...ANY DEVIATION TO THE RIGHT COULD BRING STRONGER WINDS TO THE SOUTHWEST PORTION OF BAJA CALIFORNIA LATER TODAY OR SATURDAY. FORECASTER STEWART FORECAST POSITIONS AND MAX WINDS INITIAL 30/1500Z 21.1N 110.7W 70 KT 12HR VT 01/0000Z 21.8N 111.4W 75 KT 24HR VT 01/1200Z 22.5N 111.8W 80 KT 36HR VT 02/0000Z 23.5N 112.4W 75 KT 48HR VT 02/1200Z 24.5N 113.0W 70 KT 72HR VT 03/1200Z 26.0N 113.5W 60 KT 96HR VT 04/1200Z 28.5N 113.5W 45 KT...INLAND CENTRAL BAJA 120HR VT 05/1200Z 31.5N 112.0W 30 KT...INLAND NWRN MEXICO $$ NNNN
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Page last modified: Friday, 30-Sep-2005 15:10:21 UTC