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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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