Hurricane OTTO

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HURRICANE OTTO DISCUSSION NUMBER  11
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   AL172010
500 PM AST FRI OCT 08 2010

OTTO CONTINUES TO MAINTAIN A CENTRAL DENSE OVERCAST WITH CLOUD TOPS
COLDER THAN -80C NEAR THE CENTER...ALONG WITH AN AREA OF OUTER
BANDING OVER THE EASTERN SEMICIRCLE.  SATELLITE INTENSITY ESTIMATES
ARE 77 KT FROM SAB AND 65 KT FROM TAFB...AND THERE IS A RECENT
CIMSS AMSU INTENSITY ESTIMATE OF 63 KT.  THE INITIAL INTENSITY IS
INCREASED TO 70 KT AS A BLEND OF THESE DATA.  THE CIRRUS OUTFLOW IS
GOOD IN THE NORTHEASTERN SEMICIRCLE AND FAIR/POOR ELSEWHERE.

THE INITIAL MOTION IS NOW 055/18.  THERE IS LITTLE CHANGE IN THE
FORECAST PHILOSOPHY...GUIDANCE...OR FORECAST TRACK DURING THE FIRST
72 HR OF THE FORECAST.  OTTO IS BECOMING EMBEDDED IN THE STRONG
SOUTHWESTERLY FLOW OVER THE CENTRAL ATLANTIC...AND IT SHOULD MOVE
RAPIDLY NORTHEASTWARD FOR THE NEXT THREE DAYS OR SO.  AFTER 72
HR...THE GUIDANCE HAS BECOME DIVERGENT.  WHILE THE GFS...GFS
ENSEMBLE MEAN...AND HWRF STILL SHOW A TURN TOWARD THE SOUTHEAST...
THE UKMET...CANADIAN...NOGAPS...AND GFDL NOW SHOW A CONTINUED
NORTHEASTWARD MOTION.  THE ECMWF IS IN BETWEEN THESE CAMPS...
FORECASTING OTTO TO MOVE NORTHEASTWARD FOR 84-96 HR BEFORE SHARPLY
TURNING IT DUE SOUTH.  THE NEW FORECAST TRACK GENERALLY FOLLOWS THE
GFS SCENARIO...BUT IS SHIFTED TO THE NORTH OUT OF RESPECT FOR THE
OTHER MODELS.  HOWEVER...THIS PART OF THE FORECAST TRACK STILL LIES
WELL TO THE RIGHT OF THE CENTER OF THE GUIDANCE ENVELOPE...AND MORE
NORTHWARD ADJUSTMENT OF THE TRACK COULD BE NEEDED LATER.
 
OTTO WILL SPEND 12-24 HR IN A LIGHT VERTICAL WIND SHEAR/WARM SEA
SURFACE TEMPERATURE ENVIRONMENT...AND THE INTENSITY FORECAST THUS
SHOWS A LITTLE MORE STRENGTHENING DURING THAT TIME.  AFTER 24 HR...
INCREASING SHEAR AND DECREASING SEA SURFACE TEMPERATURES SHOULD
START A WEAKENING TREND.  EXTRATROPICAL TRANSITION IS EXPECTED TO
BEGIN AT ABOUT 48 HR AND BE COMPLETE BY 72 HR.  HOWEVER...THERE IS
STILL A FAIR AMOUNT OF UNCERTAINTY REGARDING THE COMPLETION OF THIS
PROCESS DUE TO DISAGREEMENT IN THE DYNAMICAL MODELS ON HOW CLOSE
OTTO WILL BE TO THE MAIN BAROCLINIC ZONE OVER THE NORTH ATLANTIC.
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      08/2100Z 26.8N  62.3W    70 KT
 12HR VT     09/0600Z 28.7N  59.5W    75 KT
 24HR VT     09/1800Z 31.3N  54.6W    75 KT
 36HR VT     10/0600Z 34.3N  48.2W    70 KT
 48HR VT     10/1800Z 38.2N  40.6W    65 KT
 72HR VT     11/1800Z 42.0N  30.0W    50 KT...POST-TROP/EXTRATROP
 96HR VT     12/1800Z 41.0N  25.0W    40 KT...POST-TROP/EXTRATROP
120HR VT     13/1800Z 39.0N  20.0W    40 KT...POST-TROP/EXTRATROP
 
$$
FORECASTER BEVEN
 
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