000
WTPZ45 KNHC 090829
TCDEP5
HURRICANE NORBERT DISCUSSION NUMBER  22
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   EP152008
200 AM PDT THU OCT 09 2008
 
THE CLOUD PATTERN IS NOT AS IMPRESSIVE AS 12 TO 24 HOURS AGO. THE
EYE CONTINUES TO BE DISTINCT ON IR IMAGES BUT THE SURROUNDING RING
OF DEEP CONVECTION HAS WEAKENED. THE UPPER LEVEL OUTFLOW CONTINUES
TO BE WELL ESTABLISHED. MICROWAVE DATA ALSO SHOWS THAT EYEWALL
STRUCTURE IS LESS DEFINED THAN A FEW HOURS AGO. BOTH SUBJECTIVE AND
OBJECTIVE T-NUMBERS HAVE BEGUN TO COME DOWN. INITIAL INTENSITY IS
LOWERED TO 110 KNOTS.  DURING THE NEXT 12 TO 24 HOURS...NORBERT IS
EXPECTED TO BE OVER WARM WATERS AND WITHIN A LIGHT SHEAR
ENVIRONMENT AND SOME FLUCTUATIONS IN INTENSITY ARE LIKELY DUE TO
CHANGES IN THE EYEWALL STRUCTURE. THEREAFTER...THE SHEAR IS
FORECAST TO INCREASE AND A GRADUAL WEAKENING IS ANTICIPATED.
NEVERTHELESS...NORBERT IS FORECAST TO CROSS BAJA CALIFORNIA AS A
CATEGORY TWO HURRICANE BUT A FASTER WEAKENING SHOULD OCCUR AS THE
CYCLONE MOVES OVER MAINLAND MEXICO.
 
THERE HAS BEEN NO SIGNIFICANT CHANGE IN THE FORECAST. NORBERT IS
MOVING TOWARD THE NORTHWEST OR 310 DEGREES AT 6 KNOTS AROUND THE
WESTERN EDGE OF A RIDGE OVER NORTHERN MEXICO. THE HURRICANE SHOULD
TURN MORE TO THE NORTH AND NORTH-NORTHEAST AS IT GRADUALLY
APPROACHES A BROAD MID-LATITUDE TROUGH AND BECOMES EMBEDDED IN THE
SOUTHWESTERLY FLOW AHEAD OF THE TROUGH. THIS TRACK SHOULD BRING THE
CORE OF THE HURRICANE NEAR THE SOUTHWEST COAST OF BAJA CALIFORNIA
ON SATURDAY.  MOST OF THE DYNAMICAL MODELS ARE IN GOOD AGREEMENT
BRINGING THE CYCLONE OVER BAJA CALIFORNIA AND MAINLAND MEXICO AND
SO DOES THE OFFICIAL FORECAST. ONLY THE GFS MODEL INSISTS ON
WEAKENING THE CYCLONE WHILE KEEPING IT STATIONARY JUST TO THE
SOUTHWEST OF BAJA CALIFORNIA. THIS SOLUTION DOES NOT APPEAR TO BE
REALISTIC AT THIS TIME. 
 
A HURRICANE WATCH WILL LIKELY BE REQUIRED FOR PORTIONS OF
SOUTHWESTERN BAJA CALIFORNIA LATE TONIGHT OR EARLY FRIDAY.
  
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      09/0900Z 17.5N 112.5W   110 KT
 12HR VT     09/1800Z 18.3N 113.2W   110 KT
 24HR VT     10/0600Z 19.5N 114.0W   100 KT
 36HR VT     10/1800Z 21.5N 113.5W   100 KT
 48HR VT     11/0600Z 23.5N 112.5W    90 KT
 72HR VT     12/0600Z 28.5N 108.5W    30 KT...INLAND
 96HR VT     13/0600Z 35.0N 104.0W    20 KT...REMNANT LOW
120HR VT     14/0600Z...DISSIPATED
 
$$
FORECASTER AVILA