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Tropical Storm Kenneth Discussion Number 7
NWS National Hurricane Center Miami FL EP132023
800 PM PDT Wed Sep 20 2023
It appears that southerly mid-level shear has set in over Kenneth
during the day, and the surface center is now located on the
southern side of the ongoing convective mass. Dvorak final-T
numbers are a consensus 3.0 from TAFB and SAB, so the initial
intensity remains 45 kt.
The shear appears to have pulled Kenneth's center farther to the
north, and as a result, the storm has turned northwestward with an
initial motion of 310/10 kt. A turn toward the north-northwest and
north is expected over the next 36 hours as Kenneth moves around
the western periphery of the subtropical ridge. Partly because of
the required adjustment of the initial position, the track guidance
has shifted significantly to the north and east on this cycle. The
new NHC track forecast lies very close to the GFS, ECMWF, TVCE, and
HCCA aids, particularly during the first 36 hours of the forecast,
and is as much as 30-40 n mi to the right of the previous
prediction.
As is often the case, the mid-level shear affecting the cyclone was
not foreseen, as nearly all shear diagnostics show that the shear in
a deeper layer of the atmosphere is currently very low. That said,
even the deep-layer shear is forecast to increase to
moderate-to-strong levels in the next 12-24 hours. Simultaneously,
Kenneth will be moving over increasingly cooler waters that are less
than 26 degrees Celsius. Therefore, weakening is expected to begin
by 24 hours, and strong shear and a drier, more stable atmosphere
should cause Kenneth to degenerate into a remnant low by late
Friday. The remnant low could hang around for a few days, opening
up into a trough by Sunday.
FORECAST POSITIONS AND MAX WINDS
INIT 21/0300Z 16.9N 125.2W 45 KT 50 MPH
12H 21/1200Z 17.6N 126.0W 45 KT 50 MPH
24H 22/0000Z 19.0N 126.8W 40 KT 45 MPH
36H 22/1200Z 20.7N 126.9W 35 KT 40 MPH
48H 23/0000Z 22.1N 126.8W 30 KT 35 MPH...POST-TROP/REMNT LOW
60H 23/1200Z 23.1N 126.8W 25 KT 30 MPH...POST-TROP/REMNT LOW
72H 24/0000Z 23.8N 127.2W 25 KT 30 MPH...POST-TROP/REMNT LOW
96H 25/0000Z...DISSIPATED
$$
Forecaster Berg
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