000
WTPA41 PHFO 142057
TCDCP1
 
Hurricane Darby Discussion Number  22
NWS Central Pacific Hurricane Center Honolulu HI   EP052022
1100 AM HST Thu Jul 14 2022
 
Although Darby's appearance was fairly impressive overnight, the 
hurricane has recently taken on a very ragged appearance, with the 
central dense overcast becoming much less symmetrical around the 
center as shear begins to impact the core convection.  The initial 
intensity was estimated to be 85 kt, a blend of the Dvorak estimates 
from PHFO (77 kt), PGTW (90 kt) and the latest UW-CIMSS ADT (87 
kt). 

The initial motion is 280/14, with Darby located on the southwest 
periphery of a mid-level ridge. An upper level trough to the NW of 
Darby has been drawing the TC a little north of due west. This 
motion is expected to continue for the next day or so, then turn 
more toward due west as Darby gets farther away from the influence 
of this trough, and becomes increasingly steered by the lower level 
flow. At that time, strong high pressure north of Hawaii will aid in 
an increase in forward speed. The track guidance remains tightly 
clustered, and our official forecast lies just north of the the 
middle of the guidance envelope.

Darby remains a small tropical cyclone over 26C sea surface 
temperatures, and is riding along a strong gradient of deep layer 
shear, currently about 20 kt near the center. The shear is 
expected to remain moderate, with marginal SSTs along the 
forecast track, so the guidance is unanimous about additional 
weakening. Our forecast remains just a touch more conservative with 
the rate of weakening shown by the guidance owing to the recent 
persistence of the well-developed core, but still shows Darby 
becoming a remnant low on Saturday.
 
 
FORECAST POSITIONS AND MAX WINDS
 
INIT  14/2100Z 17.0N 142.1W   85 KT 100 MPH
 12H  15/0600Z 17.3N 144.1W   75 KT  85 MPH
 24H  15/1800Z 17.4N 147.0W   60 KT  70 MPH
 36H  16/0600Z 17.4N 150.3W   50 KT  60 MPH
 48H  16/1800Z 17.2N 153.6W   40 KT  45 MPH
 60H  17/0600Z 17.0N 157.2W   30 KT  35 MPH...POST-TROP/REMNT LOW
 72H  17/1800Z...DISSIPATED
 
$$
Forecaster R Ballard/M Ballard