535 
WTPA42 PHFO 280858
TCDCP2
 
Tropical Storm Douglas Discussion Number  32
NWS Central Pacific Hurricane Center Honolulu HI   EP082020
1100 PM HST Mon Jul 27 2020
 
Douglas finally relented to persistent south to southwest vertical 
wind shear earlier today, when the low-level circulation center 
became exposed in visible satellite imagery. Convection has been 
limited to the northern semicircle since, and detached well away 
from the center, leading to a rapid weakening trend over the past 
24 hours. Subjective Dvorak current intensity estimates for this 
advisory ranged from 3.0/45 kt from HFO/SAB and 3.5/55 kt from 
PGTW. Meanwhile, the multi-platform satellite surface wind analysis 
from RAMMB-CIRA suggested maximum winds up to 56 kt, albeit limited 
to the northern semicircle. A conservative blend of these estimates 
yields an initial intensity estimate of 50 kt. 

The initial motion for this advisory is 285/12 kt, with Douglas 
being steered by a low- to mid-level ridge to the north. As 
significant convection is not expected to be able to persist over 
the center, Douglas will become increasingly shallow the next 
day or two, degenerating to a post-tropical remnant low as it 
gradually spins down. The updated intensity forecast is close to 
HWRF guidance. As it weakens, dynamical global guidance indicates 
that Douglas will accelerate toward the west-northwest, and the 
official forecast follows suit. 

NDBC buoys 51001 and 51101 reported peak wave heights near 20 feet 
and sustained winds near 31 kt earlier today, verifying GFS- and 
ECWMF-based wave model guidance, which indicated peak values near 
21 feet in the same area. This data also led to a slight expansion 
of the gale radii in the northeast quadrant. 
 
FORECAST POSITIONS AND MAX WINDS
 
INIT  28/0900Z 23.4N 164.7W   50 KT  60 MPH...NEAR NECKER ISLAND
 12H  28/1800Z 23.8N 167.5W   40 KT  45 MPH
 24H  29/0600Z 24.3N 171.2W   35 KT  40 MPH
 36H  29/1800Z 24.7N 175.2W   30 KT  35 MPH
 48H  30/0600Z 25.6N 179.2W   30 KT  35 MPH...POST-TROP/REMNT LOW
 60H  30/1800Z 26.5N 177.0E   25 KT  30 MPH...POST-TROP/REMNT LOW
 72H  31/0600Z...DISSIPATED
 
$$
Forecaster Birchard