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Tropical Storm OTTO (Text)

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TROPICAL STORM OTTO DISCUSSION NUMBER  16
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   AL172010
1100 PM AST SAT OCT 09 2010
 
CONVENTIONAL AND MICROWAVE SATELLITE IMAGERY INDICATE OTTO IS
QUICKLY COMING UNRAVELED. CLOUD TOPS HAVE WARMED SIGNIFICANTLY AND
THE OVERALL CONVECTIVE PATTERN HAS BECOME RATHER DISHEVELED
LOOKING. THE INITIAL INTENSITY OF 60 KT IS BASED ON A BLEND OF
SATELLITE CURRENT INTENSITY ESTIMATES OF T4.0/65 KT FROM TAFB AND
T3.5/55 KT FROM SAB...AND OTTO IS NOW A TROPICAL STORM. THE CENTRAL
PRESSURE IS BASED ON A PRESSURE REPORT OF 989.1 MB AT 23Z FROM
DRIFTING BUOY 62905 THAT OTTO PASSED OVER OR VERY CLOSE TO.

THE INITIAL MOTION ESTIMATE IS 060/33. OTTO CONTINUES TO ACCELERATE
AHEAD OF A SHARP DEEP-LAYERED TROUGH MOVING ACROSS THE CENTRAL
ATLANTIC. HOWEVER...ACCELERATION SHOULD LIKELY CEASE DURING THE
NEXT 12 HOURS OR SO AS THE LOW- AND UPPER-LEVEL CIRCULATIONS
DECOUPLE DUE TO VERTICAL SHEAR INCREASING TO MORE THAN 40 KT AND
SSTS COOLING TO BELOW 23C. BY 36 HOURS....OTTO SHOULD BE STEERED BY
THE WEAKER WESTERLY LOW-LEVEL FLOW AND SLOW DOWN AND TURN
EASTWARD...FOLLOWED BY A SOUTHEASTWARD TURN AS THE CYCLONE ROUNDS
THE TOP OF A MID-LEVEL RIDGE LOCATED WEST OF THE AZORES ISLANDS.
THE NHC TRACK GUIDANCE IS IN GOOD AGREEMENT ON THIS SCENARIO AND
THERE IS LESS SPREAD IN THE MODELS FOR THIS ADVISORY PACKAGE. THE
OFFICIAL FORECAST TRACK IS SIMILAR TO THE PREVIOUS ADVISORY...AND
REMAINS SOUTH OF THE MODEL CONSENSUS AFTER 48 HOURS.

INCREASING VERTICAL SHEAR...COMBINED WITH DECREASING SSTS AND DRY
AIR ENTRAINMENT FROM THE WEST...SHOULD HASTEN THE WEAKENING PROCESS
AND OTTO SHOULD TRANSITION TO AN EXTRATROPICAL CYCLONE IN 24 HOURS
OR LESS. THE NHC INTENSITY FORECAST IS SIMILAR TO THE SHIPS/LGEM
INTENSITY GUIDANCE.

FORECAST POSITIONS AND MAX WINDS
 
INITIAL      10/0300Z 33.9N  48.7W    60 KT
 12HR VT     10/1200Z 36.3N  43.4W    50 KT
 24HR VT     11/0000Z 39.7N  36.5W    45 KT...POST-TROP/EXTRATROP
 36HR VT     11/1200Z 42.0N  31.4W    40 KT...POST-TROP/EXTRATROP
 48HR VT     12/0000Z 43.5N  28.0W    40 KT...POST-TROP/EXTRATROP
 72HR VT     13/0000Z 42.0N  25.0W    35 KT...POST-TROP/EXTRATROP
 96HR VT     14/0000Z 39.0N  23.0W    30 KT...POST-TROP/EXTRATROP
120HR VT     15/0000Z 37.0N  21.5W    30 KT...POST-TROP/EXTRATROP
 
$$
FORECASTER STEWART
 
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