Tropical Storm NORMA

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TROPICAL STORM NORMA DISCUSSION NUMBER   4
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
2 PM PDT FRI SEP 23 2005

THE CENTER CONTINUES NEAR THE EASTERN EDGE OF THE DEEP CONVECTION...
BUT DVORAK CLASSIFICATIONS SUGGEST SOME STRENGTHENING.  MAXIMUM
WINDS ARE ESTIMATED TO BE 45 KT FOR THIS ADVISORY.  DYNAMICAL
GUIDANCE SUGGESTS THAT SOME EASTERLY SHEARING IS LIKELY TO PREVAIL
OVER NORMA THROUGH THE FORECAST PERIOD...BUT THIS SHEAR IS NOT
EXPECTED TO BE HIGH ENOUGH TO PREVENT AT LEAST A LITTLE
STRENGTHENING.  THE OFFICIAL FORECAST IS SIMILAR TO THE SHIPS
GUIDANCE...BUT A LITTLE HIGHER IN THE LATTER PART OF THE FORECAST
PERIOD.

INITIAL MOTION IS ABOUT 300/4.  CURRENTLY THERE IS A WEAK MID-LEVEL
RIDGE TO THE NORTH OF NORMA.  A LARGE 500 MB TROUGH IS PREDICTED TO
APPROACH THE CALIFORNIA COAST IN 2-3 DAYS...AND ERODE THE WESTERN
EXTENSION OF THIS RIDGE.  TRACK GUIDANCE IS DIVERGENT BETWEEN A
NORTHERLY TRACK AND A MORE CLIMATOLOGICAL WEST-NORTHWESTWARD TO
WESTWARD COURSE.  AS A COMPROMISE I HAVE ADJUSTED THE FORECAST BACK
TO THE LEFT SOMEWHAT...SHOWING A GENERALLY NORTHWESTWARD TRACK
THROUGH THE PERIOD.  THIS IS IN BEST AGREEMENT WITH THE LATEST U.K.
MET. OFFICE GLOBAL MODEL OUTPUT.

FORECASTER PASCH
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      23/2100Z 15.3N 110.2W    45 KT
 12HR VT     24/0600Z 15.8N 110.6W    45 KT
 24HR VT     24/1800Z 16.3N 111.2W    50 KT
 36HR VT     25/0600Z 16.9N 111.9W    55 KT
 48HR VT     25/1800Z 17.5N 112.8W    55 KT
 72HR VT     26/1800Z 18.5N 114.5W    55 KT
 96HR VT     27/1800Z 19.5N 116.0W    50 KT
120HR VT     28/1800Z 20.5N 117.5W    40 KT
 
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