Pacific Hurricane Feed

Hurricane Darby Forecast Discussion

WTPZ45 KNHC 140249

Hurricane Darby Discussion Number  19
NWS National Hurricane Center Miami FL       EP052022
Issued by NWS Central Pacific Hurricane Center Honolulu HI
500 PM HST Wed Jul 13 2022

Darby continues to be a healthy tropical cyclone. In fact, the 
subjective intensity estimates from PHFO, TAFB, and SAB, and the 
objective ADT and CIMSS SATCON all came it at 102 kt. Based on this 
consensus, the initial intensity has been increased to 100 kt, 
making Darby a major hurricane once again. Satellite images from 
the past couple of hours indicated that the upper level outflow has 
started to become a bit asymmetric, which may indicate that Darby is 
starting to be affected by the large upper level trough to the 

The initial motion is 285/14 kt. The cyclone is being 
steered by a low- to mid-level ridge to the north of the system. 
This ridge is expected to maintain a general west-northwest motion 
over the next 24 hours or so. As Darby becomes impacted by vertical 
shear, it will weaken over the next 24 to 48 hours. As it becomes 
an increasingly shallow system, it should turn toward the west. The 
trusted dynamical models are in agreement with this scenario and are 
in a tightly clustered guidance envelope. The forecast track has 
also been quite consistent for several cycles, and current forecast 
follows the previous package with a slight northward shift based on 
recent movement trends.

Sea surface temperatures (SSTs) are between 25-26C around Darby and 
should remain marginal along the forecast track. The main question 
is when the forecasted vertical shear will begin to significantly 
affect the system. The combination of this vertical shear, marginal 
SSTs, and drier low- to mid-tropospheric air should result in a 
rapid weakening of Darby, especially considering the small size of 
the cyclone. Simulated IR data from the GFS and HWRF indicated that 
Darby could maintain an eye tonight, but it would finally collapse 
some time Thursday, with the low level circulation becoming 
exposed on Friday. The main intensity aids are projecting a rapid 
weakening over the next 3 days despite the recent intensification. 
The forecast for this advisory is consistent with the previous 
forecast and has Darby resuming its weakening trend soon, becoming 
a post-tropical/remnant low in 72 hours. 


INIT  14/0300Z 15.9N 138.5W  100 KT 115 MPH
 12H  14/1200Z 16.3N 140.3W   90 KT 105 MPH
 24H  15/0000Z 16.8N 142.9W   80 KT  90 MPH
 36H  15/1200Z 17.0N 145.4W   65 KT  75 MPH
 48H  16/0000Z 17.0N 148.2W   55 KT  65 MPH
 60H  16/1200Z 16.8N 151.4W   40 KT  45 MPH...POST-TROPICAL
 72H  17/0000Z 16.7N 154.7W   30 KT  35 MPH...POST-TROP/REMNT LOW
 96H  18/0000Z...DISSIPATED

Forecaster Kodama/M Ballard

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