Central Pacific Basin Tropical Cyclones

Hurricane Darby Forecast Discussion

WTPA41 PHFO 150242

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.


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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