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Hurricane Darby Discussion Number 23
NWS Central Pacific Hurricane Center Honolulu HI EP052022
500 PM HST Thu Jul 14 2022
Darby is becoming less organized on satellite with pulses of
increasingly ragged deep convection starting to become sheared from
the low level center. The UW-CIMSS deep layer shear analysis
suggests the core of Darby is now experiencing shear of 20 to 25
knots. Dvorak estimates from PHFO, SAB, PGTW all agree with the
latest UW-CIMSS ADT estimate of 77 kt, thus giving good confidence
with an initial intensity of 80 kt with this advisory.
The initial motion is 290/13. Little has changed with the synoptic
situation, with Darby continuing along the southwest periphery of a
mid-level ridge. Darby is moving on a track just north of west,
partly in response to an upper level trough to the northwest of the
system. As it moves further west over the next 24 hours, the upper
level trough will lose some of its influence on the system,
allowing Darby to take a more due west heading. During this time,
the system will weaken further, and the track will be influenced
more by the low level trade wind flow. After 24 hours, a high
pressure system north of the Hawaiian islands will help drive Darby
to the west. The track guidance remains tightly clustered. Our
official track remains close to the previous forecast track, which
remains just a bit north of the middle of the guidance envelope.
The forecast track into Saturday keeps Darby over sea surface
temperatures (SST) of 25-26C. Deep layer shear near the system is
expected to remain 20-25 kt for the next few days. This combination
of shear and marginal SST continue to support weakening. The
intensity guidance agrees and remains tightly clustered as well.
Initially our forecast remains on the higher side of the guidance
envelope, with Darby still expected to become a remnant low by
Saturday night.
FORECAST POSITIONS AND MAX WINDS
INIT 15/0300Z 17.5N 143.4W 80 KT 90 MPH
12H 15/1200Z 17.7N 145.4W 70 KT 80 MPH
24H 16/0000Z 17.7N 148.6W 60 KT 70 MPH
36H 16/1200Z 17.6N 151.9W 50 KT 60 MPH
48H 17/0000Z 17.4N 155.4W 40 KT 45 MPH
60H 17/1200Z 17.2N 158.9W 30 KT 35 MPH...POST-TROP/REMNT LOW
72H 18/0000Z...DISSIPATED
$$
Forecaster M Ballard/R Ballard
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