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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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