ZCZC MIATCDEP2 ALL TTAA00 KNHC DDHHMM TROPICAL DEPRESSION NORA DISCUSSION NUMBER 9 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL EP172009 800 PM PDT THU SEP 24 2009 THE LOW-LEVEL CENTER OF NORA IS NOW COMPLETELY EXPOSED DUE TO STRONG WESTERLY SHEAR...AND THE LAST LITTLE BIT OF DEEP CONVECTION DISSIPATED BETWEEN 2300 AND 0000 UTC. DVORAK FINAL-T NUMBERS HAVE DECREASED TO T1.5 AND T2.0 FROM TAFB AND SAB...RESPECTIVELY...AND THE LATEST 3-HOUR AVERAGE FINAL T-NUMBER FROM UW-CIMSS IS T2.0. NORA IS THEREFORE DOWNGRADED TO A 30-KT DEPRESSION ON THIS ADVISORY. ADDITIONAL WEAKENING IS EXPECTED OVER THE NEXT COUPLE OF DAYS DUE TO CONTINUED STRONG WESTERLY SHEAR. OCCASIONAL BURSTS OF DEEP CONVECTION COULD STILL OCCUR SINCE NORA IS EXPECTED TO REMAIN OVER WATERS WARMER THAN 26.5C FOR SEVERAL DAYS...BUT IT SHOULD NOT BE ENOUGH TO MAINTAIN IT AS A TROPICAL CYCLONE. THE NEW FORECAST CALLS FOR NORA TO BECOME A REMNANT LOW SOON AND DISSIPATE BY DAY 4...BUT SOME OF THE GLOBAL MODELS SUGGEST THIS COULD OCCUR SOONER. THE INITIAL MOTION IS 265 DEGREES AT 7 KT. EXCEPT FOR THE GFS...WHICH IS A SIGNIFICANT SOUTHERN OUTLIER...THE DYNAMICAL MODELS ARE IN GOOD AGREEMENT THROUGH 72 HOURS. THE NHC TRACK FORECAST IS JUST A LITTLE SOUTH OF THE PREVIOUS FORECAST AND VERY CLOSE TO THE MODEL CONSENSUS. NORA IS EXPECTED TO MOVE JUST SOUTH OF DUE WEST DURING THE NEXT 24-36 HOURS AND THEN TURN TOWARD THE WEST-NORTHWEST ON DAY 3 DUE TO A WEAKNESS IN THE LOW-LEVEL RIDGE CAUSED BY A COLD FRONT WEST OF CALIFORNIA. FORECAST POSITIONS AND MAX WINDS INITIAL 25/0300Z 17.4N 121.6W 30 KT 12HR VT 25/1200Z 17.3N 122.6W 25 KT 24HR VT 26/0000Z 17.2N 124.0W 25 KT...REMNANT LOW 36HR VT 26/1200Z 17.2N 125.6W 20 KT...REMNANT LOW 48HR VT 27/0000Z 17.5N 127.3W 20 KT...REMNANT LOW 72HR VT 28/0000Z 18.5N 130.0W 20 KT...REMNANT LOW 96HR VT 29/0000Z...DISSIPATED $$ FORECASTER BERG NNNN
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Page last modified: Thursday, 31-Dec-2009 12:09:28 UTC