[Tropical] Tropical Cyclone Discussion

[EMWIN Server]

WTNT42 KNHC 092031
TCDAT2
HURRICANE OTTO DISCUSSION NUMBER  15
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   AL172010
500 PM AST SAT OCT 09 2010

SATELLITE IMAGES INDICATE THAT OTTO IS GRADUALLY WEAKENING. WARMING
CLOUD TOPS ARE PRIMARILY LOCATED NORTH OF THE CIRCULATION CENTER AS
A CONSEQUENCE OF CONTINUED MODERATE SOUTHWESTERLY SHEAR. HOWEVER...
SATELLITE CLASSIFICATIONS SUPPORT MAINTAINING OTTO AS A HURRICANE
FOR THIS ADVISORY. FURTHER WEAKENING IS FORECAST AS OTTO ENCOUNTERS
A HIGH SHEAR ENVIRONMENT AND PASSES OVER PROGRESSIVELY COOLER
WATERS DURING THE NEXT FEW DAYS. EXTRATROPICAL TRANSITION APPEARS
TO BE UNDERWAY AS EVIDENCED BY CURRENT CONVECTIVE TRENDS AND
COLDER...DRIER AIR IMPINGING ON THE CIRCULATION FROM THE WEST.
GLOBAL MODELS INDICATE THAT THIS PROCESS SHOULD BE COMPLETE BY 36
HOURS...ALTHOUGH IT COULD FINISH EARLIER. THE OFFICIAL NHC
INTENSITY FORECAST IS ABOUT THE SAME AS THE PREVIOUS ONE AND IS IN
LINE WITH THE SHIPS/LGEM GUIDANCE.

OTTO IS STILL ACCELERATING...AND THE INITIAL MOTION ESTIMATE IS
055/28. SOME FURTHER ACCELERATION TOWARD THE NORTHEAST IS LIKELY
DURING THE NEXT 12-24 HOURS AS THE CYCLONE IS EMBEDDED IN A DEEP
LAYER OF STRONG SOUTHWESTERLY FLOW AHEAD OF A LARGE MID-LATITUDE
TROUGH OVER THE WESTERN ATLANTIC. AFTER 36 HOURS....OTTO SHOULD
ABRUPTLY DECELERATE AND TURN EASTWARD AND THEN SOUTHEASTWARD AS IT
STEERED AROUND THE CIRCULATION OF A DEEP LAYER CYCLONE OVER THE
NORTHEAST ATLANTIC. THE MODEL GUIDANCE...EXCEPT FOR THE NOGAPS AND
THE CANADIAN...IS IN GOOD AGREEMENT ON THIS SCENARIO...AND THE
OFFICIAL TRACK FORECAST IS CLOSE TO THE PREVIOUS ONE AND THE
MULTI-MODEL CONSENSUS.


FORECAST POSITIONS AND MAX WINDS

INITIAL      09/2100Z 32.4N  52.6W    65 KT
 12HR VT     10/0600Z 34.7N  47.6W    60 KT
 24HR VT     10/1800Z 38.0N  40.3W    55 KT
 36HR VT     11/0600Z 41.3N  33.6W    50 KT...POST-TROP/EXTRATROP
 48HR VT     11/1800Z 43.4N  29.4W    45 KT...POST-TROP/EXTRATROP
 72HR VT     12/1800Z 43.0N  25.5W    35 KT...POST-TROP/EXTRATROP
 96HR VT     13/1800Z 39.0N  24.0W    30 KT...POST-TROP/EXTRATROP
120HR VT     14/1800Z 37.0N  22.0W    30 KT...POST-TROP/EXTRATROP

$$
FORECASTER KIMBERLAIN


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