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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.
FORECAST POSITIONS AND MAX WINDS
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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