711 
WTPZ41 KNHC 210820
TCDEP1
HURRICANE NORA DISCUSSION NUMBER  20
NATIONAL WEATHER SERVICE MIAMI FL
2 AM PDT SUN SEP 21 1997
 
THE INITIAL MOTION ESTIMATE IS 315/06.  THE 00Z AVIATION MODEL
SHOWS A WEAKNESS DEVELOPING IN THE RIDGE TO THE NORTH OF THE
HURRICANE DUE TO A SLOW MOVING CUT OFF LOW OVER THE SOUTHWESTERN
UNITED STATES.  MOST OF THE MODELS SHOW A TURN TOWARD THE NORTH AND
SLIGHTLY FASTER MOVEMENT.  THE NOGAPS IS FURTHEST EAST WHILE THE
UKMET IS FURTHER WEST AND MUCH SLOWER. THE REST OF THE MODELS ARE
CLUSTERD NEAR THE SOUTHERN GULF OF CALIFORNIA IN 72 HOURS.  THE
OFFICIAL TRACK FORECAST IS IN THE MIDDLE OF THIS CLUSTER IN CLOSE
AGREEMENT WITH THE GFLD AND QUITE SIMILAR TO THE PREVIOUS ADVISORY.
 
THERE HAS BEEN A VERY LARGE INCREASE IN DEEP CONVECTION SURROUNDING
A LARGE EYE OVER THE PAST 6 HOURS.  OBJECTIVE T NUMBERS ARE NEAR 7.0
WHILE TAFB AND SAB INTENSITIES ARE A CONSERVATIVE 5.0.  THE WIND
SPEED IS INCREASED TO 90 KNOTS AND IT COULD GO HIGHER WITH THIS
IMPRESSIVE CLOUD PATTERN....VERY WARM SSTS...AND MINIMAL SHEAR FOR
THE NEXT 3 DAYS.
 
NORA IS FORECAST TO PASS CLOSE TO SOCORRO ISLAND IN ABOUT 36 HOURS
AND THE GOVERNMENT OF MEXICO HAS ISSUED A HURRICANE WATCH FOR THE
REVILLAGIGEDO ISLANDS.
 
LAWRENCE
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL     21/0900Z 16.4N 107.1W    90 KTS
12HR VT     21/1800Z 17.1N 107.8W   100 KTS
24HR VT     22/0600Z 18.1N 108.9W   100 KTS
36HR VT     22/1800Z 19.5N 110.0W   100 KTS
48HR VT     23/0600Z 21.2N 110.0W   100 KTS
72HR VT     24/0600Z 24.5N 110.0W    80 KTS