000
WTPZ45 KNHC 100240
TCDEP5
 
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