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Tropical Storm Darby Discussion Number 30
NWS Central Pacific Hurricane Center Honolulu HI EP052022
1100 AM HST Sat Jul 16 2022
Deep convection redeveloped in the northern semicircle near the
center last night. High clouds from this convection briefly obscured
the center but it has become exposed once again. The convection
appears to be poorly organized and is not persistent near the center
over time. This pulsing of convection is typical behavior of a
central Pacific tropical cyclone as it goes through its weakening
process toward dissipation. The center of Darby is visible in the
South Point radar data and indicates the center passing south of the
Big Island at this time. The current satellite intensity estimate
from PHFO came in at 2.0/30 kt. This was the only subjective
estimate available. The CIMSS ADT was 2.0/30 kt, and the latest
available SATCON from 1208 UTC was 37 kt. The initial intensity for
this advisory is 35 kt, though this may be generous.
Darby is a shallow system and is being steered by the low- to
mid-level easterly flow. This steering current will remain in place
until the system dissipates. The forecast track is just an update
to the previous track.
Although SSTs are expected to slowly increase along the remaining
forecast track, vertical shear is forecast to increase above 30 kt
tonight in both the GFS and ECMWF SHIPS guidance. Thus,
reintensification is not expected. Thus, the forecast keeps the
weakening trajectory of the previous forecast, which makes Darby a
post-tropical system tonight and dissipates it by Sunday. If
additional data are received that indicate the circulation has
opened up to a trough, or if deep convection does not persist near
the center, the system could be dropped as a tropical cyclone
sooner.
FORECAST POSITIONS AND MAX WINDS
INIT 16/2100Z 17.7N 155.5W 35 KT 40 MPH
12H 17/0600Z 17.7N 158.7W 30 KT 35 MPH...POST-TROP/REMNT LOW
24H 17/1800Z...DISSIPATED
$$
Forecaster Kodama
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