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Tropical Storm NORMAN

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TROPICAL STORM NORMAN DISCUSSION NUMBER   5
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   EP152006
800 PM PDT MON OCT 09 2006
 
NORMAN HAS BEEN EXHIBITING A BURSTING TYPE CONVECTIVE PATTERN DURING
THE LAST 6-12 HOURS.  THE ADVISORY INTENSITY IS RAISED TO 45 KT
BASED ON A BLEND OF THE LASTEST SUBJECTIVE DVORAK INTENSITY
ESTIMATES OF 55 KT AND 45 KT FROM TAFB AND SAB RESPECTIVELY ALONG
WITH AN EXPERIMENTAL OBJECTIVE ESTIMATE OF 45 KT FROM UW-CIMSS.  IT
SHOULD BE NOTED THAT THERE IS SOME UNCERTAINTY IN THE INTENSITY
ESTIMATE DUE TO THE CURRENT LACK OF A WELL-DEFINED CLOUD PATTERN.
NORMAN HAS BEEN EXPERIENCING SOME WESTERLY VERTICAL SHEAR ASSOCIATED
WITH A LARGE TROUGH OVER THE WESTERN UNITED STATES.  HOWEVER...
WATER VAPOR IMAGERY SHOWS THAT A SHORTWAVE DISTURBANCE EMBEDDED
WITHIN THE LARGER-SCALE PATTERN IS LIFTING QUICKLY
NORTHEASTWARD...AND THIS EVOLUTION IS EXPECTED TO RESULT IN A
TEMPORARY WEAKENING OF THE SHEAR. THUS...THE OFFICIAL FORECAST
ALLOWS FOR SOME STRENGTHENING OVER THE NEXT DAY OR SO. 
THEREAFTER...THE SHEAR IS EXPECTED TO INCREASE AGAIN AND NORMAN IS
FORECAST TO BE MOVING OVER SLIGHTLY COOLER WATERS.  THIS SEEMINGLY
UNFAVORABLE ENVIRONMENT SHOULD RESULT IN WEAKENING WITH NORMAN
EXPECTED TO BECOME A DISSIPATING REMNANT LOW NEAR THE END OF THE
FORECAST PERIOD.
 
NORMAN IS CURRENTLY MOVING AROUND THE WESTERN PERIPHERY OF A WEAK
MID-LEVEL RIDGE CENTERED OVER SOUTHERN MEXICO...RESULTING IN A
GENERAL NORTHWARD MOTION OR 360/05.  THE CYCLONE SHOULD TURN MORE
TOWARDS THE NORTHEAST AND ACCELERATE A LITTLE AS IT REACHES THE
NORTHERN PORTION OF THE RIDGE DURING THE NEXT DAY OR SO.  WHILE THE
SYNOPTIC SCALE STEERING APPEARS RELATIVELY STRAIGHTFORWARD...TRACK
GUIDANCE CONTINUES TO BE SPREAD A BIT MOST LIKELY DUE TO VARYING
FORECAST STRENGTH AND DEPTH OF THE CYCLONE.  THE NOGAPS...
UKMET...CANADIAN AND GFDN MODELS ALL WEAKEN THE CYCLONE QUICKLY
RESULTING IN A TURN TOWARD THE SOUTHEAST BEYOND 36 HOURS.
CONVERSELY... THE ECMWF...GFDL...GFS...AND GFS ENSEMBLE MEAN
MAINTAIN A MORE VERTICALLY COHERENT VORTEX AND SHOW THE CYCLONE
CONTINUING NORTHEASTWARD TOWARD BAJA.  THE OFFICIAL FORECAST
ASSUMES NORMAN WILL REMAIN DEEP ENOUGH FOR THE NEXT COUPLE OF DAYS
AND GAIN ENOUGH LATITUDE TO BE CAUGHT IN THE DEEP-LAYERED WESTERLY
FLOW FORECAST TO DEVELOP TO ITS NORTH. 

FORECAST POSITIONS AND MAX WINDS
 
INITIAL      10/0300Z 16.9N 117.8W    45 KT
 12HR VT     10/1200Z 17.6N 117.8W    50 KT
 24HR VT     11/0000Z 18.6N 117.3W    50 KT
 36HR VT     11/1200Z 19.9N 116.3W    45 KT
 48HR VT     12/0000Z 20.8N 115.3W    40 KT
 72HR VT     13/0000Z 22.5N 113.0W    25 KT
 96HR VT     14/0000Z 25.0N 110.5W    20 KT...REMNANT LOW
120HR VT     15/0000Z...DISSIPATED
 
$$
FORECASTER RHOME/PASCH
 
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