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Hurricane Darby Discussion Number 11
NWS National Hurricane Center Miami FL EP052022
500 PM HST Mon Jul 11 2022
Darby has been generally steady in strength during the past several
hours and remains a category 4 hurricane on the Saffir-Simpson
Hurricane Wind Scale. It maintains a classic major hurricane
structure with well-defined outflow in all quadrants, a symmetric
cloud pattern, and a distinct small eye (less than 10 n mi in
diameter). Satellite images indicate that the eye has become even
more defined over the past few hours, but deep convection has been
weakening a little to the west of the eye. All of the satellite
intensity estimates have plateaued and suggest that Darby still has
peak winds of around 120 kt. Although the hurricane is very
powerful, it is quite compact with tropical-storm-force winds
estimated to only extend 50 n mi from the center.
The hurricane has been moving westward, or 275 degrees, at 15 kt. A
general west to west-northwest motion at a slightly slower pace is
expected during the next few days as Darby continues to move on the
south or southwest side of a mid-level ridge, taking the system into
the central Pacific basin in 60-72 hours. After that time, the
weakening system is expected to be steered due westward by the
low-level flow. There are some speed differences in the models, but
they generally show the same theme. This forecast lies near the
middle of the guidance envelope, and roughly between the GFS and
ECMWF models.
Darby is likely near its peak intensity. The major hurricane will
be moving over progressively cooler waters and crossing the 26
degree C isotherm in about 24 hours. In addition, Darby will be
moving into a drier airmass, which should accelerate the weakening
trend. In a few days when Darby is over the central Pacific, a mid-
to upper-level trough should induce strong westerly shear and cause
Darby to become a post-tropical cyclone in about 4 days. The NHC
intensity forecast is similar to the previous one and fairly close
to the IVCN and HCCA consensus models.
FORECAST POSITIONS AND MAX WINDS
INIT 12/0300Z 14.9N 126.6W 120 KT 140 MPH
12H 12/1200Z 15.0N 128.7W 120 KT 140 MPH
24H 13/0000Z 15.1N 131.3W 115 KT 130 MPH
36H 13/1200Z 15.5N 133.9W 100 KT 115 MPH
48H 14/0000Z 16.1N 136.4W 80 KT 90 MPH
60H 14/1200Z 16.7N 139.0W 65 KT 75 MPH
72H 15/0000Z 17.3N 141.6W 50 KT 60 MPH
96H 16/0000Z 17.6N 147.1W 35 KT 40 MPH...POST-TROPICAL
120H 17/0000Z 17.4N 153.5W 30 KT 35 MPH...POST-TROP/REMNT LOW
$$
Forecaster Cangialosi
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