Tropical Storm OTTO

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TROPICAL STORM OTTO DISCUSSION NUMBER   6
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
10 PM EST WED DEC 01 2004
 
WHILE THE CONVECTIVE PATTERN IS NOT VERY IMPRESSIVE...A 01/2158Z
QUIKSCAT OVERPASS INDICATED THAT OTTO HAS MAINTAINED A WELL-DEFINED
LOW-LEVEL WIND FIELD CONTAINING SEVERAL 30-35 KT UN-FLAGGED WINDS.
DRIFTING BUOY 44623 JUST SOUTH OF THE CENTER REPORTED A PRESSURE OF
997.5 MB AT 00Z. THE INITIAL INTENSITY IS MAINTAINED AT 35 KT FOR
THIS ADVISORY BASED ON A DVORAK T-NUMBER OF T2.5...OR 35 KT...FROM
TAFB AND THE 35-KT QUIKSCAT WINDS. HOWEVER...THE LOWER CENTRAL
PRESSURE SUGGESTS THAT THE INTENSITY COULD BE A LITTLE STRONGER.
 
INITIAL MOTION OVER THE PAST 12 HOURS HAS BEEN 150/06.  THE LATEST
NHC MODEL SUITE IS QUITE DIVERGENT. THE UKMET IS THE LEFTMOST MODEL
AND TAKES OTTO DUE EAST WHILE THE NOGAPS MODEL IS THE RIGHTMOST OF
ALL THE MODELS AND TAKES THE CYCLONE ALMOST DUE SOUTH. HOWEVER...
ALL THE MODELS AGREE ON A SLOW FORWARD SPEED. AS THE MID-LATITUDE
WESTERLIES BECOME INCREASINGLY MORE ZONAL OVER THE FORECAST PERIOD
...WEAK 500 MB RIDGING IS EXPECTED TO OCCUR NORTH OF OTTO. THIS
SHOULD GRADUALLY NUDGE THE CYCLONE IN A GENERAL SOUTHEAST TO
SOUTHERLY DIRECTION. THIS IS ALSO CONSISTENT WITH THE FORECAST
NORTHWESTERLY COMPONENT OF THE VERTICAL SHEAR VECTOR...WHICH SHOULD
HELP KEEP THE CONVECTION DISPLACED TO THE SOUTHEAST OF THE CENTER
AND HELP TO DRAG IT IN A GENERAL SOUTHEASTWARD DIRECTION. THE
OFFICIAL TRACK IS A LITTLE TO THE RIGHT OF THE PREVIOUS FORECAST
TRACK AND CLOSE TO THE CONU CONSENSUS MODEL.

THE SHIPS MODEL GRADUALLY INCREASES THE 850-200 MB SHEAR TO 35 KT BY
36H AND DISSIPATES OTTO BY 48-60H. HOWEVER...GIVEN THAT OTTO
ORIGINATED FROM A COLD-CORE LOW AND LIKELY DOES NOT EXTEND TO THE
200 MB LEVEL...THE SHIPS SHEAR VALUES MAY BE EXCESSIVE..GIVEN THAT
THE 300 MB WIND ACROSS OTTO IS EXPECTED TO BE ABOUT 10 KT LESS THAN
AT THE 200 MB LEVEL. SINCE OTTO IS ALSO FORECAST TO MOVE OVER
GRADUALLY WARMER WATER...THE INTENSITY WAS HELD HIGHER THAN THE
SHIPS MODEL AND SIMILAR TO THE PREVIOUS INTENSITY FORECAST.
 
FORECASTER STEWART
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      02/0300Z 30.2N  49.7W    35 KT
 12HR VT     02/1200Z 29.6N  49.4W    35 KT
 24HR VT     03/0000Z 28.8N  48.7W    30 KT
 36HR VT     03/1200Z 27.8N  47.8W    30 KT
 48HR VT     04/0000Z 27.0N  47.0W    25 KT...DISSIPATING
 72HR VT     05/0000Z 25.5N  46.0W    25 KT...DISSIPATING
 96HR VT     06/0000Z 24.0N  46.0W    20 KT...REMNANT LOW
120HR VT     07/0000Z...DISSIPATED
 
 
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