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Hurricane Darby Discussion Number 21
NWS Central Pacific Hurricane Center Honolulu HI EP052022
500 AM HST Thu Jul 14 2022
Darby crossed longitude 140W and officially entered the central
Pacific basin just after midnight HST this morning. The cyclone's
satellite appearance has gone through some fluctuations since the
previous advisory, but an elongated and somewhat ragged 5-10 nm
wide eye has persisted. Pulsing convection continues to encircle the
center, but has become much less symmetric. The initial intensity is
estimated to be 90 kt, supported by a blend of the subjective Dvorak
intensity estimates from SAB and HFO, the latest UW-CIMSS objective
Dvorak estimate of 87 kt, and a SATCON near 83 kt.
Darby lies on the southwestern periphery of a ridge aloft, in an
area characterized by moderate southerly vertical wind shear. Darby
is moving closer to an upper-level trough to its northwest, into an
environment characterized by even stronger vertical wind shear, as
evidenced by transverse banding in the northwest semicircle. This
shear will allow the cyclone to efficiently ingest the dry mid-level
air that prevails, while moving over sub-26C SSTs. Since Darby
continues to be a small system, it will quickly respond to the
debilitating environment into which it is moving, with rapid
weakening expected over the next 48 hours before dissipation occurs
by 72 hours. The updated intensity forecast closely follows the
consensus IVCN, as well as the SHIPS guidance.
The initial motion estimate for this advisory is 290/14kt. As Darby
degrades to a shallow system over the next 48 hours, a persistent
strong surface high north of Hawaii will force it to accelerate as
it makes a turn toward the west. The updated track forecast is close
to the previous forecast, and lies very close to the GFEX.
FORECAST POSITIONS AND MAX WINDS
INIT 14/1500Z 16.6N 140.9W 90 KT 105 MPH
12H 15/0000Z 17.1N 142.9W 75 KT 85 MPH
24H 15/1200Z 17.2N 145.6W 60 KT 70 MPH
36H 16/0000Z 17.2N 148.7W 50 KT 60 MPH
48H 16/1200Z 17.1N 152.1W 40 KT 45 MPH
60H 17/0000Z 16.9N 155.7W 30 KT 35 MPH...POST-TROP/REMNT LOW
72H 17/1200Z...DISSIPATED
$$
Forecaster Birchard
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