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Hurricane NORA


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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
 
 
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