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Tropical Storm Darby Discussion Number 2
NWS National Hurricane Center Miami FL EP052022
900 PM MDT Sat Jul 09 2022
Darby is a small tropical cyclone. Conventional satellite data and
passive microwave imagery indicate its inner core convection has
waned a bit this evening, but it has maintained some curved
convective bands around its center and signs of healthy upper-level
outflow. Hopefully, scatterometer data becomes available overnight
to better assess its current intensity. A blend of the subjective
Dvorak estimates from SAB (T2.5/35 kt) and TAFB (T3.0/45 kt)
supports an initial intensity of 40 kt for this advisory.
Environmental conditions appear quite favorable for Darby to
strengthen during the next couple of days or so. Deep-layer shear is
expected to remain weak (less than 10 kt) as the small storm moves
over SSTs of 28-28.5 degrees Celsius within a moist mid-level
environment. If the inner-core structure of Darby improves
overnight, there is some potential for significant intensification.
In fact, the latest ECMWF SHIPS-RII guidance shows a 41 percent
chance of Darby strengthening by 55 kt during the next 48 h. The
official NHC intensity forecast still lies on the higher end of the
guidance envelope through early next week, close to the SHIPS
guidance and just slightly above the HFIP corrected consensus
approach (HCCA). By 72 h, the storm is forecast to reach cooler
waters and encounter a drier environment, which should induce
weakening that continues through the remainder of the period.
Darby continues to move quickly westward, or 280/15 kt. A deep-layer
ridge centered over the southwestern United States is expected to
steer Darby quickly westward over the next couple of days. Once
Darby reaches a weakness in the ridge by the middle of next week,
the cyclone is forecast to slow down a bit and turn toward the
west-northwest on days 4-5. The official NHC track forecast is very
similar to the previous one, and it remains close to the TVCE and
HCCA aids.
FORECAST POSITIONS AND MAX WINDS
INIT 10/0300Z 14.3N 114.9W 40 KT 45 MPH
12H 10/1200Z 14.4N 117.2W 45 KT 50 MPH
24H 11/0000Z 14.4N 120.1W 55 KT 65 MPH
36H 11/1200Z 14.4N 122.8W 65 KT 75 MPH
48H 12/0000Z 14.5N 125.2W 75 KT 85 MPH
60H 12/1200Z 14.8N 127.7W 80 KT 90 MPH
72H 13/0000Z 15.3N 129.9W 80 KT 90 MPH
96H 14/0000Z 16.6N 134.3W 65 KT 75 MPH
120H 15/0000Z 18.0N 139.5W 45 KT 50 MPH
$$
Forecaster Reinhart/Flynn
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