000
WTPZ45 KNHC 100239
TCDEP5
HURRICANE NORBERT DISCUSSION NUMBER  25
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   EP152008
800 PM PDT THU OCT 09 2008
 
OVER THE PAST FEW HOURS...THE EYE OF NORBERT HAS BECOME BETTER-
DEFINED AND A LITTLE SMALLER. IN ADDITION THE HURRICANE HAS
MAINTAINED A RATHER SYMMETRIC AND WELL-DEFINED OUTFLOW PATTERN. THE
INITIAL INTENSITY WILL REMAIN 80 KT...THOUGH THE ESTIMATE COULD BE
A LITTLE ON THE HIGH SIDE AS NORBERT IS CLEARLY STILL GOING THROUGH
AN EYEWALL REPLACEMENT. THE INTENSITY FORECAST IS DIFFICULT BECAUSE
IT IS IMPOSSIBLE TO TELL IF AND WHEN NORBERT WILL COMPLETE ITS
EYEWALL REPLACEMENT. IF IT DOES FINISH THE CYCLE...THE SHEAR AND
WATER CONDITIONS MIGHT BE FAVORABLE ENOUGH TO ALLOW FOR THE SYSTEM
TO INTENSIFY A LITTLE...LIKE THE GFDL/HWRF SHOW. ON THE OTHER
HAND...THE STATISTICAL MODELS ARE SHOWING A SIGNIFICANT WEAKENING
AND WERE CERTAINLY MORE ACCURATE THAN THE GFDL/HWRF YESTERDAY. THIS
WEAKENING COULD BE OVERDONE SINCE THE GFS VORTEX TENDENCY TERM IS
CONTRIBUTING STRONGLY TO THE DECREASING FORECAST IN SHIPS...AND THE
GFS MODEL IS WEAKENING THE HURRICANE FASTER THAN ANY OTHER
GUIDANCE. FOR NOW...A SLOW WEAKENING OF NORBERT IS FORECAST...AND
THE NHC FORECAST IS A BLEND OF THE PREVIOUS FORECAST AND THE
INTENSITY CONSENSUS...SHOWING THE SYSTEM NEAR HURRICANE STRENGTH AS
IT APPROACHES BAJA CALIFORNIA. THERE LIKELY WON'T BE MUCH LEFT OF
THE TROPICAL CYCLONE BY THE END OF THE WEEKEND...BUT HEAVY RAINFALL
COULD BE A CONCERN OVER PORTIONS OF THE SOUTHWESTERN UNITED STATES
DUE TO MOISTURE FROM THIS SYSTEM.
 
AFTER A BRIEF SLOWDOWN THIS AFTERNOON...THE TROPICAL CYCLONE HAS
MADE A TURN TOWARD THE NORTH-NORTHWEST AND APPEARS TO BE MOVING AT
ABOUT 6 KT.  COMPUTER GUIDANCE IS IN PRETTY GOOD AGREEMENT...SAVE
THE PESKY GFS MODEL...ON A TRACK TOWARDS THE NORTH AND NORTHEAST BY
THE WEEKEND TOWARD BAJA CALIFORNIA DUE TO AN APPROACHING DEEP-
LAYERED TROUGH.  THE SPEED DIFFERENCES BETWEEN THE MODELS ARE NOW
LESS NOTICEABLE AND GUIDANCE HAS GENERALLY BECOME MORE CLUSTERED
SINCE YESTERDAY.  THE OFFICIAL FORECAST IS BASICALLY AN UPDATE OF
THE PREVIOUS FORECAST AND IS NEAR OR SLIGHTLY FASTER THAN THE
DYNAMICAL MODEL CONSENSUS.
 
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      10/0300Z 18.9N 113.2W    80 KT
 12HR VT     10/1200Z 19.9N 113.6W    75 KT
 24HR VT     11/0000Z 21.6N 113.5W    70 KT
 36HR VT     11/1200Z 23.4N 112.6W    65 KT
 48HR VT     12/0000Z 25.4N 110.9W    50 KT
 72HR VT     13/0000Z 30.0N 107.0W    20 KT...INLAND REMNANT LOW
 96HR VT     14/0000Z...DISSIPATED
 
$$
FORECASTER BLAKE/BEVEN