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Hurricane Darby Discussion Number 16
NWS National Hurricane Center Miami FL EP052022
1100 PM HST Tue Jul 12 2022
Darby has been gradually weakening over ocean surface temperatures
near or just below 26 degrees Celsius. Satellite imagery show the
eye has filled in and the extent of the cold cloud tops has shrunk.
A scatterometer pass at 0545 UTC over the inner core revealed a
very small storm. Dvorak CI-numbers from SAB and TAFB estimated
the intensity of Darby at 90 kt. However, objective satellite
intensity estimates ranged between 82 to 87 kt from UW/CIMSS ADT and
SATCON and have been decreasing. The initial intensity has been
lowered to 85 kt to represent a blend of all of these estimates and
the current trend.
The less conducive environmental conditions appear to be taking a
toll on this tiny storm. Based on satellite imagery, Darby is
completely surrounded by a dry mid-level air mass. The hurricane
is also expected to remain over marginal sea surface temperatures
and these two factors should continue to gradually weaken Darby
over the next day or so. The vertical wind shear is predicted to
increase quickly in a couple of days which should rapidly weaken
Darby into a remnant low in about 72 hours. The official intensity
forecast is shifted slightly lower than the previous advisory and
below much of the consensus guidance. Given the small size of
this cyclone, it would not be surprising if Darby weakened even
faster than indicated here.
Darby continues to move westward at about 14 kt while it is
steered by a subtropical ridge to its north. Over the next 24
hours, the system is expected to reach a slight weakness in the
ridge and turn west-northwestward temporarily. While Darby
weakens further it will likely turn west once again and follow the
low-level steering flow until it dissipates. The NHC track forecast
is slightly south of the previous prediction beyond 36 hours and
close to the model consensus aids.
FORECAST POSITIONS AND MAX WINDS
INIT 13/0900Z 14.7N 133.9W 85 KT 100 MPH
12H 13/1800Z 15.0N 136.0W 80 KT 90 MPH
24H 14/0600Z 15.7N 138.6W 70 KT 80 MPH
36H 14/1800Z 16.2N 141.2W 60 KT 70 MPH
48H 15/0600Z 16.5N 143.6W 50 KT 60 MPH
60H 15/1800Z 16.6N 146.4W 40 KT 45 MPH
72H 16/0600Z 16.5N 149.5W 30 KT 35 MPH...POST-TROP/REMNT LOW
96H 17/0600Z 16.3N 156.2W 25 KT 30 MPH...POST-TROP/REMNT LOW
120H 18/0600Z...DISSIPATED
$$
Forecaster Pasch/Bucci
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