Pacific Hurricane Feed

Tropical Storm Darby Forecast Discussion

WTPZ45 KNHC 101445

Tropical Storm Darby Discussion Number   4
NWS National Hurricane Center Miami FL       EP052022
500 AM HST Sun Jul 10 2022

Darby has become better organized this morning. A 0916 UTC AMSR2 and 
more recent 1216 UTC SSMIS microwave pass have revealed increased 
banding over the eastern semicircle of the storm and an improved 
low-level inner core structure.  Early-light visible satellite 
imagery also shows an increase in banding and the development of a 
small CDO feature.  Subjective Dvorak intensity estimates have 
responded accordingly and are now up to 45 and 55 kt from TAFB and 
SAB, respectively.  Therefore, the initial intensity has been raised 
to 50 kt for this advisory.

There still appears to be some entrainment of drier mid-level air 
over the northwestern portion of the circulation, but with low 
environmental shear and warm sea-surface temperatures (SSTs) ahead, 
Darby should be able to strengthen over the next 36-48 hours.  The 
updated NHC intensity forecast shows a faster rate of strengthening 
during the first day or so, primarily due to the higher initial 
intensity.  The new forecast calls for Darby to become a hurricane 
in about 24 hours, and then peak in intensity in a couple of days.  
After that time, gradually decreasing SSTs and a more stable 
environment should lead to steady weakening during the remainder of 
the forecast period.  The NHC wind speed forecast is near the high 
end of the guidance during the first 24-48 hours and is in best 
agreement with the European-based SHIPS model. Thereafter, it is 
close to the various consensus aids.

Darby continues to move westward at about 13 kt.  The cyclone should 
continue on a westward motion to the south of a mid-level ridge 
extending westward from the northern portion of Baja California.  In 
a few days the western portion of the ridge is forecast to weaken 
which should cause Darby to turn west-northwestward.  The track 
guidance is in general agreement on this scenario, though the UKMET 
model depicts a much weaker Darby and shows a faster westward 
motion.  The NHC forecast is closest to the ECMWF, which is a little 
slower than the consensus aids due to the contribution from the 
much faster UKMET model.


INIT  10/1500Z 14.3N 117.6W   50 KT  60 MPH
 12H  11/0000Z 14.3N 119.6W   60 KT  70 MPH
 24H  11/1200Z 14.3N 122.2W   70 KT  80 MPH
 36H  12/0000Z 14.4N 124.6W   75 KT  85 MPH
 48H  12/1200Z 14.8N 127.1W   80 KT  90 MPH
 60H  13/0000Z 15.2N 129.5W   75 KT  85 MPH
 72H  13/1200Z 15.8N 131.9W   65 KT  75 MPH
 96H  14/1200Z 17.3N 136.7W   50 KT  60 MPH
120H  15/1200Z 18.2N 141.5W   35 KT  40 MPH

Forecaster Brown

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