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Tropical Storm Kenneth Discussion Number  20
NWS National Hurricane Center Miami FL       EP132017
200 AM PDT Wed Aug 23 2017

Conventional satellite imagery shows continued deterioration of
Kenneth's cloud pattern.  A moderate southwesterly wind shear regime
and oceanic temperatures of less than 24.5C have certainly taken its
toll on the cyclone.  A compromise of the subjective and objective
intensity estimates is the basis of lowering the initial intensity
to 50 kt for this advisory.  The aforementioned shear and cool
water, along with a continued intruding stable air mass from
the north, should result in a gradual spin down of Kenneth with
weakening to a remnant low in about 24 hours, and dissipation in 5
days.  The official intensity forecast follows the IVCN and
Decay-SHIPS models, and reflects the previous advisory's weakening
trend.

The initial motion is estimated to be north-northwestward, or
340/9 kt.  Kenneth should continue to move north-northwestward
during the next 36-48 hours in a break in a subtropical ridge
created by a high amplitude upper-level trough extending
northeastward from the eastern Hawaiian Islands.  Afterward, the
cyclone is forecast to degenerate to a vertically shallow remnant
low and move within the lower tropospheric southeasterly flow.
There is some increasing spread in the global models beyond day 3.
The UKMET and GFS indicate a more accelerated rate of weakening than
the ECMWF.  Consequently, the weaker Kenneth reflected in the
UKMET/GFS decreases significantly in forward speed and turns
west-northwestward in the shallow steering current while a more
vertically coherent cyclone in the ECMWF continues northwestward
with little reduction in speed. The NHC track forecast is a blend of
both of these solutions and is very close to the HFIP Corrected
Consensus model.

FORECAST POSITIONS AND MAX WINDS

INIT  23/0900Z 23.5N 134.3W   50 KT  60 MPH
 12H  23/1800Z 24.8N 135.0W   40 KT  45 MPH
 24H  24/0600Z 26.4N 135.8W   30 KT  35 MPH...POST-TROP/REMNT LOW
 36H  24/1800Z 27.6N 136.1W   25 KT  30 MPH...POST-TROP/REMNT LOW
 48H  25/0600Z 28.4N 136.4W   25 KT  30 MPH...POST-TROP/REMNT LOW
 72H  26/0600Z 29.4N 137.3W   20 KT  25 MPH...POST-TROP/REMNT LOW
 96H  27/0600Z 30.4N 138.9W   20 KT  25 MPH...POST-TROP/REMNT LOW
120H  28/0600Z...DISSIPATED

$$
Forecaster Roberts

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