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Hurricane Douglas Discussion Number  20
NWS Central Pacific Hurricane Center Honolulu HI   EP082020
1100 PM HST Fri Jul 24 2020
 
Douglas remains a powerful hurricane this evening as confirmed by 
the U.S. Air Force 53rd Weather Reconnaissance Squadron. The 
Hurricane Hunters found maximum flight level winds of 108 knots (97 
knots with appropriate wind reduction factor to the surface from 
the 700 mb flight level) and SFMR winds of 93 knots. Based on 
these data and recent trends showing a degraded satellite 
presentation, the initial intensity for this advisory will be 
lowered to 95 knots. Douglas continues to move rapidly to the west-
northwest, with an initial motion set at 295/16 knots.

Despite relatively low vertical wind shear values forecast to 
affect the tropical cyclone during the next day or so, SSTs will 
remain below 26C. As a result, the official intensity forecast 
calls for slow but steady weakening during the next couple days as 
Douglas nears Hawaii, with the cyclone expected to be a minimal 
category 1 hurricane or strong tropical storm approaching the 
eastern end of the state late Saturday night or Sunday. Continued 
weakening is then forecast as Douglas tracks westward over or near 
the other main Hawaiian islands and west of the state early next 
week. 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.

Douglas is forecast to move rapidly off to the west-northwest 
during the next couple days toward a weakness in the sub-tropical 
ridge north of the Hawaiian islands. The subtropical ridge is 
forecast to strengthen north of the state over the weekend, and 
this should steer the tropical cyclone westward over or very near 
the Hawaiian Islands late Saturday night through Sunday 
night, before exiting to the west of the state early next week. The 
official track forecast is virtually identical to the 
previous advisory, and continues to hug the southern end of the 
guidance envelope. This track is roughly in between the corrected 
consensus guidance HCCA and the ECMWF and GFS ensemble mean tracks. 

Based on the latest intensity and track forecast, Tropical Storm 
Warnings have been issued for Hawaii County and Maui County. A 
Hurricane Watch remains in effect for Hawaii County, Maui County and 
Oahu. A Hurricane or Tropical Storm Warning may be required for Oahu 
on Saturday. A Hurricane or Tropical Storm Watch may be required 
for Kauai County on Saturday.
 
Key Messages
 
1. Douglas continues to approach the main Hawaiian Islands,
potentially passing dangerously close to, or over, the islands
Saturday night 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, and remain prepared for changes to the
forecast. 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
acceleration areas will shift with time as Douglas passes near the
islands. Winds will also be stronger at the upper floors of
high rise buildings.
 
 
FORECAST POSITIONS AND MAX WINDS
 
INIT  25/0900Z 18.5N 146.7W   95 KT 110 MPH
 12H  25/1800Z 19.3N 149.0W   85 KT 100 MPH
 24H  26/0600Z 20.3N 151.9W   75 KT  85 MPH
 36H  26/1800Z 21.1N 154.8W   70 KT  80 MPH
 48H  27/0600Z 21.8N 157.7W   65 KT  75 MPH
 60H  27/1800Z 22.4N 160.8W   60 KT  70 MPH
 72H  28/0600Z 22.9N 164.1W   55 KT  65 MPH
 96H  29/0600Z 24.0N 171.0W   45 KT  50 MPH
120H  30/0600Z 25.0N 177.5W   35 KT  40 MPH
 
$$
Forecaster Jelsema
 
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