Tropical Storm LOWELL

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TROPICAL STORM LOWELL DISCUSSION NUMBER  10
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   EP132008
200 AM PDT TUE SEP 09 2008
 
THE CLOUD PATTERN OF LOWELL REMAINS THAT OF A SHEARED TROPICAL
CYCLONE.  A SERIES OF MICROWAVE IMAGES BETWEEN 0100 AND 0600 UTC
CONFIRMS THAT THE CENTER OF LOWELL IS ALONG THE EASTERN EDGE
OF THE CONVECTION.  A QUIKSCAT PASS FROM 0120 UTC REVEALED A
COUPLE OF BELIEVABLE 40-45 KT WIND VECTORS.  BASED ON THE QUIKSCAT
DATA AND DVORAK INTENSITY ESTIMATES OF T3.0...THE INITIAL INTENSITY
IS LOWERED TO 45 KT.  THIS COULD BE A LITTLE GENEROUS SINCE THE
CLOUD TOPS HAVE WARMED AND THE OVERALL CLOUD PATTERN HAS DEGRADED
SINCE THE CLASSIFICATIONS WERE PERFORMED.

THE MICROWAVE IMAGERY SHOWS THAT LOWELL CONTINUES MOVING
NORTHWESTWARD...BUT AT A LITTLE SLOWER FORWARD SPEED.  A MID- TO
UPPER-LEVEL TROUGH SEEN IN WATER VAPOR IMAGERY APPROACHING THE
WEST COAST OF THE UNITED STATES IS FORECAST TO TURN LOWELL TO THE 
NORTH...THEN NORTHEAST DURING THE NEXT COUPLE OF DAYS.  THE TRACK
GUIDANCE IS IN GOOD AGREEMENT ON THIS SOLUTION.  HOWEVER...THE MAIN
QUESTION IS HOW DEEP OF A TROPICAL CYCLONE LOWELL WILL REMAIN
DURING THIS TIME.   THE DYNAMICAL MODELS ALL KEEP LOWELL A DEEP
ENOUGH SYSTEM THAT IT ACCELERATES NORTHEASTWARD ACROSS THE BAJA
PENINSULA AND INTO NORTHWEST MEXICO IN 2-3 DAYS.  HOWEVER...IT IS
POSSIBLE THAT LOWELL WILL WEAKEN MORE QUICKLY...AND NOT FEEL AS MUCH
INFLUENCE FROM THE TROUGH.  FOR NOW THE OFFICIAL FORECAST IS
SOMEWHAT BETWEEN THESE SOLUTIONS.  THE NEW NHC FORECAST IS A LITTLE
FASTER THAN THE PREVIOUS ADVISORY...BUT REMAINS SLOWER THAN THE
MODEL CONSENSUS AT 48 HOURS AND BEYOND.

THE NEW INTENSITY FORECAST SHOWS GRADUALLY WEAKENING OF LOWELL
DURING THE NEXT FEW DAYS.  THE FORECAST IS IN EXCELLENT AGREEMENT
WITH THE INTENSITY GUIDANCE WHICH PREDICTS THE CYCLONE TO WEAKEN AS
THE RESULT OF CONTINUED SHEAR...A MORE STABLE ENVIRONMENT...AND
SLIGHTLY COOLER SSTS ALONG THE PATH OF THE STORM.  
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      09/0900Z 20.7N 112.9W    45 KT
 12HR VT     09/1800Z 21.4N 113.3W    45 KT
 24HR VT     10/0600Z 22.4N 113.3W    40 KT
 36HR VT     10/1800Z 23.3N 112.8W    40 KT
 48HR VT     11/0600Z 24.4N 112.1W    35 KT
 72HR VT     12/0600Z 26.5N 111.0W    25 KT
 96HR VT     13/0600Z 28.5N 110.0W    20 KT...INLAND
120HR VT     14/0600Z...DISSIPATED
 
$$
FORECASTER BROWN
 
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