ZCZC MIATCDEP4 ALL TTAA00 KNHC DDHHMM HURRICANE NORA DISCUSSION NUMBER 17 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 2 PM PDT SUN OCT 05 2003 THE CONVECTIVE PATTERN OF NORA HAS BECOME RAGGED THIS AFTERNOON. THE HURRICANE IS STILL GENERATING CLOUD TOPS OF -80C NEAR THE CENTER...BUT THE CENTRAL DENSE OVERCAST HAS DECREASED IN SIZE AND THE OUTER BANDING HAS DIMINISHED. SATELLITE INTENSITY ESTIMATES ARE 90 KT FROM TAFB...AND 77 KT FROM SAB AND AFWA. THE INITIAL INTENSITY IS REDUCED TO 80 KT. CIRRUS OUTFLOW IS GOOD OVER THE NORTHWESTERN SEMICIRCLE...AND RESTRICTED ELSEWHERE BY THE OUTFLOW OF OLAF. THE INITIAL MOTION IS 320/5. THE TRACK FORECAST FOR NORA IS VERY COMPLICATED. WATER VAPOR IMAGERY INDICATES A DEVELOPING MID/UPPER-LEVEL TROUGH JUST WEST OF CALIFORNIA...WHICH LARGE-SCALE MODELS FORECAST TO AMPLIFY SOUTHWARD. THIS BY ITSELF WOULD CAUSE NORA TO RECURVE NORTHEASTWARD WITH TIME. HOWEVER...HURRICANE OLAF IS NOW 500 NM EAST-SOUTHEAST OF NORA...AND IT APPEARS THE TWO CYCLONES WILL COME CLOSE ENOUGH TO INTERACT. THE MOST LIKELY RESULT OF SUCH AN INTERACTION WOULD BE FOR NORA TO MOVE SLOWLY FOR THE FIRST PART OF THE FORECAST...PERHAPS STALLING...THEN SWING MORE TO THE NORTHEAST OR EAST AFTER OLAF PASSES. THIS IS THE SCENARIO OF THE UKMET AND NOGAPS...ALTHOUGH IT SHOULD BE NOTED THAT BOTH OF THESE MODELS DISSIPATE OLAF DUE TO LANDFALL NEAR CABO CORRIENTES. THE TRACK FORECAST IS CHANGED SIGNIFICANTLY FROM THE PREVIOUS PACKAGE. IT NOW CALLS FOR NORA TO MOVE MORE SLOWLY TO THE NORTH INITIALLY...THEN TURN NORTHEASTWARD BEHIND OLAF INSTEAD OF IN FRONT OF IT. THIS IS STILL A LOW-CONFIDENCE FORECAST...AND MORE ADJUSTMENTS MAY BE NEEDED LATER TONIGHT. LARGE-SCALE MODELS SUGGEST THAT NORA IS LIKELY TO ENCOUNTER SIGNIFICANT SHEAR AS IT TRIES TO RECURVE...EITHER FROM THE TROUGH TO THE NORTH OR FROM THE OUTFLOW OF OLAF. THIS SHOULD CAUSE WEAKENING EVEN THOUGH THE CYCLONE IS FORECAST TO STAY OVER 26C SEA SURFACE TEMPERATURES. ANY STRONGER INTERACTION WITH OLAF COULD ALSO CAUSE WEAKENING. THE INTENSITY FORECAST WILL THUS CALL FOR GRADUAL WEAKENING SIMILAR TO BUT SLOWER THAN THAT INDICATED BY THE GFDL AND SHIPS. FORECASTER BEVEN FORECAST POSITIONS AND MAX WINDS INITIAL 05/2100Z 19.5N 113.7W 80 KT 12HR VT 06/0600Z 20.1N 114.1W 75 KT 24HR VT 06/1800Z 20.9N 114.2W 70 KT 36HR VT 07/0600Z 21.2N 113.8W 65 KT 48HR VT 07/1800Z 21.7N 112.9W 60 KT 72HR VT 08/1800Z 22.5N 111.5W 50 KT 96HR VT 09/1800Z 24.5N 108.5W 35 KT 120HR VT 10/1800Z 28.5N 106.5W 20 KT...INLAND DISSIPATING NNNN
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Page last modified: Monday, 07-Feb-2005 16:50:00 UTC