NORA #18 - DISCUSSION

[AussieMark]

000
WTPZ44 KNHC 060239
TCDEP4
HURRICANE NORA DISCUSSION NUMBER 18
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
8 PM PDT SUN OCT 05 2003

NORA CONTINUES TO BECOME MORE DISORGANIZED. DEEP CONVECTION IS NO
LONGER PERSISTENT AND THE SYSTEM IS STRUGGLING UNDER SOUTHEASTERLY
SHEAR ASSOCIATED WITH THE OUTFLOW FROM OLAF. DVORAK DATA T NUMBERS
ARE FALLING...AND CURRENT INTENSITY ESTIMATES ARE 90 KT FROM TAFB
AND 77 KT FROM SAB AND AFWA. THE ADVISORY INTENSITY IS REDUCED
SLIGHTLY TO 75 KT.

THE MOTION DURING THE LAST SEVERAL HOURS IS 325/5...ALTHOUGH MORE
RECENT SATELLITE IMAGES SUGGEST A SLIGHTLY MORE NORTHERLY
COMPONENT. WATER VAPOR IMAGERY INDICATES A DEVELOPING
MID/UPPER-LEVEL TROUGH JUST WEST OF CALIFORNIA...WHICH DYNAMICAL
MODELS FORECAST TO AMPLIFY SOUTHWARD. SOME OF THE TRACK
GUIDANCE...IN PARTICULAR THE NOGAPS AND GFDL...RESPOND BY TAKING
NORA ON A FAST NORTHERLY TRACK. HOWEVER...INTERACTION WITH OLAF
WILL LIKELY RESULT IN NORA MOVING MORE SLOWLY DURING THE FIRST 36
HOURS...AND MORE NORTHEASTERLY THEREAFTER. THIS SOLUTION IS SIMILAR
TO THE UKMET AND THE PREVIOUS ADVISORY...BUT A LITTLE TO THE LEFT.

NORA IS LIKELY TO ENCOUNTER STEADILY INCREASING SHEAR THROUGHOUT THE
FORECAST PERIOD...DUE TO SOME COMBINATION OF THE TROUGH APPROACHING
FROM THE NORTH AND TO THE OUTFLOW FROM OLAF. MEANWHILE THE CYCLONE
IS FORECAST TO MOVE OVER MARGINALLY WARM 26C SEA SURFACE
TEMPERATURES. AS A RESULT...THE INTENSITY FORECAST IS FOR GRADUAL
WEAKENING...SIMILAR TO THE SHIPS GUIDANCE.

FORECASTER KNABB/JARVINEN

FORECAST POSITIONS AND MAX WINDS

INITIAL 06/0300Z 20.0N 114.0W 75 KT
12HR VT 06/1200Z 20.5N 114.2W 70 KT
24HR VT 07/0000Z 21.0N 114.0W 65 KT
36HR VT 07/1200Z 21.5N 113.4W 55 KT
48HR VT 08/0000Z 22.1N 112.6W 50 KT
72HR VT 09/0000Z 23.5N 111.0W 40 KT
96HR VT 10/0000Z 26.0N 109.0W 30 KT...INLAND
120HR VT 11/0000Z 30.0N 108.0W 20 KT...INLAND DISSIPATING