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Hurricane Douglas Discussion Number  23
NWS Central Pacific Hurricane Center Honolulu HI   EP082020
500 PM HST Sat Jul 25 2020
 
In spite of marginal SSTs near 26C and increasing vertical wind 
shear, convection increased around the center of Douglas a few 
hours ago, and a ragged eye briefly reemerged in conventional 
satellite imagery. As a result, data sampled by the U.S. Air Force 
53rd Weather Reconnaissance Squadron earlier in the day showed 
little change in the intensity of Douglas. A blend of adjusted 
flight levels winds and SFMR data supports holding the initial 
intensity at 80 kt with a central pressure of 982 mb. 
Reconnaissance aircraft will conduct another mission into Douglas 
tonight.

Aircraft and satellite data indicate that Douglas continues to move 
toward the west-northwest (290 deg) and that the forward motion has 
slowed to 14 kt. Douglas is being steered by a low- to mid-level 
ridge to the northeast and is approaching a weakness in the mid-
level ridge that is causing the slight deceleration. A continued 
motion toward the west-northwest will bring Douglas over, or very 
near, portions of the main Hawaiian Islands Sunday and Sunday 
night, then to parts of the Papahanaumokuakea Marine National 
Monument on Monday and Tuesday. The updated forecast track is very 
close to the previous forecast and during the next couple of 
days, remains near the ECMWF toward the southern end of a tightly 
clustered guidance envelope. Model spread increases on days four and 
five, when the official forecast trends toward the middle of the 
guidance envelope. 

Gradual weakening is expected through the forecast. SSTs will 
gradually warm along the forecast track. However, vertical wind 
shear will steadily increase over the next couple of days and is 
expected to be strong enough to induce weakening. The official 
intensity forecast has changed very little from the previous 
advisory, and continues to follow a blend of the corrected 
consensus and statistical model guidance.

Based on the latest forecast, a Tropical Storm Warning has been 
issued for Kauai County. A Tropical Storm Warning and Hurricane 
Watch remain in effect for Hawaii County and Maui County. A 
Tropical Storm Watch has also been issued for portions of the 
Papahanaumokuakea Marine National Monument from Nihoa to French 
Frigate Shoals. 

Key Messages: 

1. Douglas continues to approach the main Hawaiian Islands, and 
will pass 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 
acceleration 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  26/0300Z 19.9N 151.4W   80 KT  90 MPH
 12H  26/1200Z 20.6N 153.6W   75 KT  85 MPH
 24H  27/0000Z 21.5N 156.4W   65 KT  75 MPH
 36H  27/1200Z 22.3N 159.1W   60 KT  70 MPH
 48H  28/0000Z 23.0N 162.1W   55 KT  65 MPH
 60H  28/1200Z 23.6N 165.4W   50 KT  60 MPH
 72H  29/0000Z 24.0N 168.8W   45 KT  50 MPH
 96H  30/0000Z 24.6N 176.0W   40 KT  45 MPH
120H  31/0000Z 25.7N 178.0E   35 KT  40 MPH
 
$$
Forecaster Wroe
 
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