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Tropical Storm Karina Discussion Number 8
NWS National Hurricane Center Miami FL EP162020
Issued by NWS Central Pacific Hurricane Center Honolulu HI
200 PM PDT Mon Sep 14 2020
The morning visible images showed Karina's partially obscured low
level center under the northeast edge of the cyclone's deep
convection. The displacement of the center is due to the ongoing
presence of moderate vertical wind shear from the northeast. Cloud
top temperatures have generally warmed through most of the morning,
though the latest images showed a small burst of deep convection
south of the center. An ASCAT pass this morning showed a large
swath of 35 kt winds in the southeastern semicircle of Karina's
circulation. The initial wind radii have been increased to account
for the updated data. Dvorak fixes came in at 35 kt from SAB, and 45
kt from TAFB and PHFO. ASCAT peak winds were 37 kt. Based on a
blend of these data, and little change in Karina's appearance in
satellite imagery, the initial intensity will be held at 40 kt for
this
advisory.
Moderate shear is expected to continue to affect Karina for another
24 hours. The shear will become weak from 36 to 72 hours, but by
then the cyclone is expected to be over sub-26 degree C sea
surface temperatures. Most of the objective aids indicate that peak
intensity has been reached, and gradual weakening will occur after
24 hours. The intensity forecast closely follows HCCA, and has
Karina becoming a post-tropical remnant low by 96 hours, if not
sooner. This forecast trend keeps the intensity higher than the
statistical guidance.
The initial motion for this package is 305/9 kt. Karina is expected
to continue moving northwestward to the southwest of a mid-level
anticyclone. This motion is expected to continue through 60 to 72
hours. Karina should turn toward the southwest as deep convection
ceases and the cyclone becomes steered by the low level flow. The
forecast track has been adjusted a bit northward from the previous
forecast, in part due to an adjustment in the initial position, and
closely follows the HCCA guidance.
FORECAST POSITIONS AND MAX WINDS
INIT 14/2100Z 18.5N 118.8W 40 KT 45 MPH
12H 15/0600Z 19.4N 119.7W 40 KT 45 MPH
24H 15/1800Z 20.8N 121.2W 40 KT 45 MPH
36H 16/0600Z 21.9N 122.7W 35 KT 40 MPH
48H 16/1800Z 23.0N 124.2W 30 KT 35 MPH
60H 17/0600Z 23.7N 125.2W 25 KT 30 MPH
72H 17/1800Z 24.0N 125.9W 25 KT 30 MPH
96H 18/1800Z 23.5N 127.5W 25 KT 30 MPH...POST-TROP/REMNT LOW
120H 19/1800Z...DISSIPATED
$$
Forecaster Kodama
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