ZCZC MIATCDAT5 ALL TTAA00 KNHC DDHHMM TROPICAL STORM NATE DISCUSSION NUMBER 11 NWS NATIONAL HURRICANE CENTER MIAMI FL AL152011 400 AM CDT SAT SEP 10 2011 AN AIR FORCE RECONNAISSANCE PLANE INVESTIGATING NATE THIS MORNING FOUND A MAXIMUM FLIGHT-LEVEL WIND OF 49 KT AND SURFACE WINDS NEAR 40 KT. DROPSONDE DATA ALSO SUGGEST THAT THE MINIMUM PRESSURE IS UP A LITTLE TO 1000 MB. THESE DATA SUGGEST THAT NATE MAY HAVE WEAKENED SLIGHTLY...BUT SINCE THE PLANE WAS UNABLE TO SAMPLE THE SOUTHEASTERN SIDE OF THE TROPICAL STORM...I PREFER TO HOLD THE INITIAL WIND SPEED AT 45 KT. SATELLITE AND AIRCRAFT FIXES SUGGEST THAT NATE IS NOW ON A MORE STEADY WESTWARD PATH...WITH THE LATEST INITIAL MOTION ESTIMATE OF 270/4. A BUILDING LOW- TO MID-LEVEL RIDGE TO THE NORTH OF THE STORM SHOULD STEER NATE WESTWARD OR WEST-SOUTHWESTWARD WITH A SLIGHT INCREASE IN FORWARD SPEED THROUGH LANDFALL OVER SOUTHERN MEXICO...WHICH IS NOW FORECAST TO OCCUR IN ABOUT 36 HOURS. THE OFFICIAL TRACK FORECAST IS FASTER AND A LITTLE TO THE SOUTH OF THE PREVIOUS ONE...AND IS NEAR THE MIDDLE OF THE GUIDANCE ENVELOPE. AS MENTIONED IN THE PREVIOUS ADVISORY...THE WEAKENING OR LACK OF STRENGTHENING OF NATE DURING THE PAST 24 HOURS...DESPITE A VERY FAVORABLE ENVIRONMENT...WAS NOT WELL FORECAST BY THE NHC OR THE MODELS. THIS COULD BE THE RESULT OF COOL WATER UPWELLING DUE TO THE VERY SLOW MOTION OF THIS TROPICAL CYCLONE. NOW THAT NATE APPEARS TO BE MOVING AND REMAINS IN A FAVORABLE ENVIRONMENT FOR STRENGTHENING...SOME INTENSIFICATION APPEARS LIKELY. THE OFFICIAL FORECAST SHOWS STEADY STRENGTHENING UNTIL LANDFALL AND IS CLOSE TO THE SHIPS MODEL. NATE IS FORECAST TO DISSIPATE OVER THE SIERRA MADRE MOUNTAINS BY 72 HOURS. FORECAST POSITIONS AND MAX WINDS INIT 10/0900Z 20.0N 93.7W 45 KT 50 MPH 12H 10/1800Z 20.0N 94.3W 50 KT 60 MPH 24H 11/0600Z 19.9N 95.4W 55 KT 65 MPH 36H 11/1800Z 19.8N 96.6W 60 KT 70 MPH...INLAND 48H 12/0600Z 19.7N 97.7W 30 KT 35 MPH...INLAND 72H 13/0600Z...DISSIPATED $$ FORECASTER CANGIALOSI/AVILA NNNN
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Page last modified: Tuesday, 17-Jul-2012 13:44:01 UTC