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Tropical Storm NICHOLAS (Text)

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TROPICAL STORM NICHOLAS DISCUSSION NUMBER  11
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
5 AM EDT THU OCT 16 2003
 
NICHOLAS SEEMS TO BE TRANSITIONING FROM A SHEARED CONVECTIVE BLOB
SYSTEM TO ONE WITH MORE CURVED BANDING FEATURES. HOWEVER...THERE
STILL APPEARS TO BE SOME SOUTH-SOUTHWESTERLY MID-LEVEL FLOW
UNDERCUTTING THE OUTFLOW LAYER...BUT THIS HAS BEEN WEAKENING AND
MOVING AWAY FROM THE CYCLONE DURING THE PAST FEW HOURS. THE
SATELLITE INTENSITY ESTIMATE IS A CONSENSUS T3.0/45 KT FROM ALL
THREE AGENCIES...BUT THE CONVECTIVE PATTERN HAS IMPROVED SOME SINCE
THE 06Z FIXES. ALSO...A 16/0300Z PARTIAL TRMM OVERPASS INDICATED
THAT THE INNER-CORE HAS TIGHTNED UP CONSIDERABLY...SO THE INITIAL
INTENSITY HAS BEEN INCREASED SLIGHTLY TO 50 KT.
 
THE INITIAL MOTION ESTIMATE IS 310/08. THERE REMAINS UNCERTAINTY IN
THE EXACT LOCATION OF THE LOW-LEVEL CENTER. THE PAST 4 MICROWAVE
POSITIONS SUGGEST THAT THE LOW-LEVEL CENTER IS FARTHER SOUTH THAN
THE PREVIOUS POSITION AND FORECAST TRACK. HOWEVER...IT IS POSSIBLE
THAT THE LOW-LEVEL CENTER MAY BE DEVELOPING CLOSER TO THE DEEPER
CONVECTION NOW...SO THE THE INITIAL POSITION AND FORECAST TRACK WAS
ONLY SHIFTED SLIGHTLY TO THE LEFT. THE NHC MODEL GUIDANCE REMAINS
QUITE DIVERGENT...WITH THE GFDN AND NOGAPS MODELS TAKING NICHOLAS
ALMOST DUE NORTH FROM THE OUTSET. THESE ARE THE RIGHTMOST OF ALL
THE MODELS AND WERE DISCOUNTED. THE GFDL..GFS...AND UKMET MODELS
ARE CONSISTENT THROUGH 36 HOURS IN TAKING THE CYCLONE TOWARD THE
NORTHWEST. AFTER THAT...THEY ALSO DIVERGE SIGNIFICANTLY WITH THE
GFDL AND GFS FORECASTING A NORTHWARD MOTION...WHILE THE UKMET
MAINTAINS A GENERAL SLOW NORTHWESTWARD MOTION. THE UKMET SOLUTION
WAS CLOSELY FOLLOWED GIVEN THAT MODEL'S GOOD PERFORMANCE THE PAST
48 HOURS...AND THE FACT THAT ALL THE GLOBAL MODELS MAINTAIN SOME
MID-LEVEL RIDGING TO THE NORTH OF NICHOLAS THROUGHOUT THE PERIOD.
 
ALL OF THE GLOBAL MODELS AGREE THAT THE UPPER-LEVEL FLOW WILL BE
MOST FAVORABLE DURING THE NEXT 36 HOURS OR SO FOR ANY SIGNIFICANT
STRENGTHENING TO OCCUR. THE EXCEPTION IS THE UKMET WHICH KEEPS A
SMALL ANTICYCLONE ABOVE NICHOLAS THROUGH 72 HOURS. THE OFFICIAL
FORECAST IS A BLEND OF THE MUCH WEAKER SHIPS INTENSITY MODEL AND
THE STRONGER 86-KT GFDL MODEL. IF THE UKMET TRACK AND UPPER-LEVEL
FLOW PATTERN FORECASTS VERIFY...THEN NICHOLAS WILL PROBABLY BE
STRONGER AT 72-96 HOURS THAN THE OFFICIAL FORECAST IS INDICATING.
 
FORECASTER STEWART
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      16/0900Z 13.3N  45.8W    50 KT
 12HR VT     16/1800Z 14.1N  46.5W    55 KT
 24HR VT     17/0600Z 15.3N  47.5W    60 KT
 36HR VT     17/1800Z 16.3N  48.1W    65 KT
 48HR VT     18/0600Z 17.3N  48.9W    65 KT
 72HR VT     19/0600Z 18.0N  50.0W    65 KT
 96HR VT     20/0600Z 19.0N  51.0W    65 KT
120HR VT     21/0600Z 21.0N  52.0W    65 KT
 
 
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