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Hurricane Douglas Discussion Number 22
NWS Central Pacific Hurricane Center Honolulu HI EP082020
1100 AM HST Sat Jul 25 2020
The satellite presentation of Douglas is degrading somewhat, likely
due to restricted outflow to the south and 26C SSTs. The U.S. Air
Force 53rd Weather Reconnaissance Squadron sampled the hurricane
this morning, and a blend of SFMR, flight level winds, and dropsonde
data from two passes supports decreasing the intensity to 80 kt with
a central pressure of 984 mb.
Douglas continues to move toward the west-northwest (290 deg) at 16
kt. Douglas is being steered by a low- to mid-level ridge to the
northeast and is nearing a weakness in the mid-level ridge. A
continued motion toward the west-northwest and a slight decrease in
forward motion will bring Douglas over or very near portions of the
main Hawaiian Islands on Sunday. On Monday, a mid-level ridge is
forecast to build to the north of Douglas, potentially inducing a
turn toward the west, with some increase in forward speed. The
updated forecast track is very close to the previous forecast and
lies close to the ECMWF toward the southern end of a rather tightly
clustered guidance envelope.
Weakening is expected through the forecast. Douglas will remain
over an area of 26C SST today, which is expected to continue the
gradual weakening trend. SSTs along the forecast track increase
tonight, at the same time that Douglas will move into an area of
increased vertical wind shear. This is expected to maintain a
weakening trend, although at a fairly slow rate. The official
intensity forecast has changed very little from the previous
advisory, and generally follows a blend of the corrected consensus
and statistical model guidance.
Based on the latest forecast, a Hurricane Warning has been issued
for Oahu. Tropical Storm Warnings remain in effect for Hawaii
County and Maui County. A Hurricane Watch remains in effect for
Hawaii County and Maui County, and a Tropical Storm Watch is in
effect for Kauai County.
1. Douglas continues to approach the main Hawaiian Islands,
potentially passing dangerously close to, or over, the islands late
tonight through Sunday night. The close passage of Douglas brings a
triple threat of hazards, including but not limited to damaging
winds, flooding rainfall, and dangerously high surf, especially
along east facing shores.
2. It is vital that you do not focus on the exact forecast track or
intensity of Douglas. Due to Douglas' angle of approach to the
islands, any small changes in the track could lead to significant
differences in where the worst weather occurs. Even if the center
remains offshore, severe impacts could still be realized over the
islands, as they extend well away from the center.
3. Terrain effects can cause strong localized acceleration of the
wind through gaps and where winds blow downslope. These
areas will shift with time as Douglas passes near the islands.
Hurricane force wind gusts are possible even within the tropical
storm warning area. Winds will also be stronger at the upper floors
of high rise buildings.
FORECAST POSITIONS AND MAX WINDS
INIT 25/2100Z 19.5N 150.1W 80 KT 90 MPH
12H 26/0600Z 20.1N 152.1W 75 KT 85 MPH
24H 26/1800Z 21.0N 154.9W 70 KT 80 MPH
36H 27/0600Z 21.8N 157.7W 65 KT 75 MPH
48H 27/1800Z 22.5N 160.4W 60 KT 70 MPH
60H 28/0600Z 23.1N 163.5W 55 KT 65 MPH
72H 28/1800Z 23.7N 167.0W 50 KT 60 MPH
96H 29/1800Z 24.5N 173.7W 45 KT 50 MPH
120H 30/1800Z 25.8N 180.0E 35 KT 40 MPH