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Tropical Storm OTIS (Text)

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TROPICAL STORM OTIS DISCUSSION NUMBER   8
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
8 PM PDT THU SEP 29 2005
 
OTIS HAS BECOME BETTER ORGANIZED IN INFRARED IMAGERY THIS
EVENING...WITH CONVECTION NOW WRAPPING MOST OF THE WAY AROUND THE
CENTER AND THE DEVELOPMENT OF A WARM SPOT.  THIS IS SUPPORTED BY A
JUST RECEIVED SSM/I OVERPASS SHOWING A FORMATIVE EYE.  SATELLITE
INTENSITY ESTIMATES ARE 55 KT FROM TAFB AND SAB...AND 45 KT FROM
AFWA.  BASED ON THIS...THE INITIAL INTENSITY IS INCREASED TO 55 KT.
CIRRUS OUTFLOW IS GOOD OVER THE SOUTHERN SEMICIRCLE AND POOR
ELSEWHERE.

THE INITIAL MOTION IS AN UNCERTAIN 325/11...UNCERTAIN BECAUSE IT IS
UNCLEAR HOW MUCH MOTION IS DUE TO RE-FORMATION OF THE CENTER AS OTIS
CONSOLIDATES.  WATER VAPOR IMAGERY SHOWS A WEAK MID/UPPER-LEVEL
RIDGE NORTH OF OTIS ALONG 26N...WITH MID/UPPER-LEVEL LOWS OVER
SOUTHWESTERN UTAH AND NEAR 33N126W.  THE GFS...UKMET...AND CANDIAN
MODELS SUGGEST THE RIDGE WILL WEAKEN...WITH OTIS BEING GRADUALLY
TURNED NORTHWARD BY THE WESTERN UPPER-LEVEL LOW AND A LARGER
DEEP-LAYER TROUGH FORECAST TO FORM OVER THE NORTHEASTERN PACIFIC BY
72 HR.  ON THE OTHER HAND...THE NOGAPS AND ECMWF SUGGEST THAT OTIS
WILL NOT CONNECT WITH THE TROUGHS AND TURN MORE WEST-NORTHWESTWARD
WITH TIME.  THE MODELS ARE IN LESS AGREEMENT THAN THEY WERE 6 HR
AGO...AS THE GFDL AND NOGAPS HAVE SHIFTED THEIR TRACKS FAR ENOUGH
TO THE LEFT TO KEEP OTIS WEST OF BAJA CALIFORNIA.  HOWEVER...SINCE
THE CURRENT MOTION IS TO THE RIGHT OF THE GUIDANCE AND THE PREVIOUS
TRACK...THERE IS A RELUCTANCE TO MOVE THE FORECAST TRACK MUCH TO
THE LEFT.  THE NEW FORECAST TRACK IS SHIFTED TO THE RIGHT FOR THE
FIRST 48-72 HR ALONG THE RIGHT SIDE OF THE MAIN ENVELOPE OF MODEL
GUIDANCE.  AFTER 72 HR IT IS SIMILAR TO THE PREVIOUS FORECAST.

EASTERLY SHEAR HAS DECREASED OVER OTIS...AND CONDITION NOW APPEAR
FAVORABLE FOR STRENGTHENING UNTIL THE STORM REACHES COOLER SEA
SURFACE TEMPERATURES AFTER 36 HR.  THE SHIPS MODEL CALLS FOR OTIS
TO PEAK AT 75 KT IN 36-48 HR...THE FSU SUPERENSEMBLE CALLS FOR A
PEAK OF 76 KT IN 48 HR...AND THE GFDL CALLS FOR A 68 KT PEAK IN
ABOUT 30 HR.  GIVEN THE SIGNIFICANT INCREASE IN ORGANIZATION THIS
EVENING...THE INTENSITY FORECAST CALLS FOR A STRONGER STORM THAN
THE GUIDANCE WITH A PEAK OF 80 KT IN ABOUT 36 HR.  OTIS COULD
STRENGTHEN FASTER THAN CURRENTLY FORECAST.  IT SHOULD BE NOTED THAT
OTIS WILL BE MOVING ALMOST PARALLEL TO THE SEA SURFACE TEMPERATURE
ISOTHERMS AFTER 36-48 HR...AND SMALL CHANGES IN THE FORECAST TRACK
COULD RESULT IN LARGE CHANGES IN SSTS UNDER THE STORM LATER IN THE
FORECAST PERIOD.
 
WHILE THE FORECAST TRACK AND WIND RADII KEEP THE STRONGER WINDS
OFFSHORE...ANY MOTION TO THE RIGHT OF THE TRACK COULD BRING THE
CENTER NEAR SOUTHERN BAJA CALIFORNIA LATE FRIDAY OR FRIDAY NIGHT. 
THUS...A TROPICAL STORM WARNING AND HURRICANE WATCH ARE BEING
ISSUED AT THIS TIME.  INTERESTS ELSEWHERE NEAR THE BOTH COASTS OF
THE SOUTHERN AND CENTRAL BAJA CALIFORNIA PENINSULA SHOULD CLOSELY
MONITOR THE PROGRESS OF OTIS OVER THE NEXT FEW DAYS.
 
FORECASTER BEVEN
 
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      30/0300Z 19.9N 109.7W    55 KT
 12HR VT     30/1200Z 20.8N 110.5W    65 KT
 24HR VT     01/0000Z 21.6N 111.4W    75 KT
 36HR VT     01/1200Z 22.2N 112.0W    80 KT
 48HR VT     02/0000Z 22.7N 112.4W    75 KT
 72HR VT     03/0000Z 24.5N 113.5W    65 KT
 96HR VT     04/0000Z 26.5N 114.0W    50 KT
120HR VT     05/0000Z 29.5N 114.0W    35 KT...INLAND
 
 
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