Tropical Storm NICHOLAS

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TROPICAL STORM NICHOLAS DISCUSSION NUMBER  27
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
5 AM EDT MON OCT 20 2003
 
IT IS ASSUMED THAT THE STORM HAS REMAINED ABOUT STATIONARY OVERNIGHT
UNDER WEAK STEERING CURRENTS.  GLOBAL MODELS ARE IN GOOD AGREEMENT
ABOUT A NORTHWEST AND THEN NORTHWARD MOTION FOR 120 HOURS AROUND
THE WESTERN PERIPHERY OF A SUBTROPICAL RIDGE WITH ONLY MODEST
ACCELERATION.  THE NOGAPS MODEL IS SOMEWHAT FASTER THAN THE OTHERS
BRINGING THE FORWARD SPEED TO ABOUT 15 KNOTS AFTER 72 HOURS AS A
TROUGH OVER THE WESTERN NORTH ATLANTIC IS REINFORCED BY ANOTHER
SHORT WAVE.  THE OFFICIAL FORECAST IS SIMILAR TO THE PREVIOUS
ADVISORY AND LEANS TOWARD THE SLOWER GUIDANCE.

ABOUT 25 KNOTS OF WESTERLY VERTICAL SHEAR CONTINUES TO AFFECT
NICHOLAS...AND THE LOW LEVEL CENTER APPEARS TO BE MOSTLY EXPOSED TO
THE WEST OF THE AREA OF DEEP CONVECTION THAT CONSTITUTES THE
CENTRAL DENSE OVERCAST.  SATELLITE INTENSITY ESTIMATES HAVE
DECREASED A LITTLE BUT STILL SUPPORT A 45-KNOT INITIAL WIND SPEED. 
THE SHIPS MODEL FORECASTS SLOW WEAKENING AS THE VERTICAL SHEAR
INCREASES TO 30 KNOTS AFTER 48 HOURS AND THE OFFICIAL FORECAST
FOLLOWS THIS GUIDANCE.    

FORECASTER LAWRENCE
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      20/0900Z 17.8N  47.6W    45 KT
 12HR VT     20/1800Z 18.0N  47.9W    45 KT
 24HR VT     21/0600Z 18.5N  48.9W    45 KT
 36HR VT     21/1800Z 19.4N  49.9W    40 KT
 48HR VT     22/0600Z 20.4N  50.9W    40 KT
 72HR VT     23/0600Z 22.0N  51.9W    35 KT
 96HR VT     24/0600Z 25.0N  52.5W    30 KT
120HR VT     25/0600Z 29.0N  53.0W    25 KT
 
 
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