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Tropical Storm Kevin Discussion Number 18
NWS National Hurricane Center Miami FL EP112021
200 PM PDT Wed Aug 11 2021
Satellite imagery this afternoon shows that Kevin continues to
have a large circulation, but that the deep convection is
well-removed from the tropical storm's center. A blend of the
Dvorak classifications from SAB and TAFB suggest that the system
remains with an intensity of 40 kt, which is also supported by
1723Z SATCON estimate of 38 kt.
Kevin's short-term movement has been a bit more westward, perhaps
due to pulling by the remaining deep convection restricted to its
southwestern quadrant. The longer-term initial motion is estimated
as 290 degrees at 9 kt. The tropical storm is primarily being
steered along the southwestern periphery of a deep tropospheric
ridge. However, as the deep convection ceases completely in a day
or two, the system will increasingly be steered by the lower
tropospheric flow. A motion toward the west-northwest or northwest
at a slightly faster forward speed is anticipated until dissipation.
The official track forecast is based upon the HFIP Corrected
Consensus Approach (HCCA), which is midway between the GFS and ECMWF
global model solutions but substantially faster than the mesoscale
hurricane model output. This new forecast is slightly westward of
the previous advisory, due to the somewhat more westward position at
the initial time.
The tropical storm has already moved across the 26C SST isotherm and
is moving toward even cooler water, drier air, and a more stable
atmosphere. Additionally, Kevin is being affected by moderate NE
tropospheric vertical wind shear. The large system should gradually
weaken under these increasingly hostile conditions and it's likely
that Kevin will become a remnant low by late Thursday. The official
intensity forecast is based upon the IVCN statistical scheme and is
nearly the same as the previous advisory.
FORECAST POSITIONS AND MAX WINDS
INIT 11/2100Z 21.1N 117.8W 40 KT 45 MPH
12H 12/0600Z 22.2N 119.3W 35 KT 40 MPH
24H 12/1800Z 23.4N 121.6W 30 KT 35 MPH
36H 13/0600Z 24.7N 124.0W 25 KT 30 MPH...POST-TROP/REMNT LOW
48H 13/1800Z 26.2N 126.3W 25 KT 30 MPH...POST-TROP/REMNT LOW
60H 14/0600Z 27.9N 128.2W 20 KT 25 MPH...POST-TROP/REMNT LOW
72H 14/1800Z 29.5N 129.4W 20 KT 25 MPH...POST-TROP/REMNT LOW
96H 15/1800Z...DISSIPATED
$$
Forecaster Landsea
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