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Hurricane Douglas Discussion Number  15
NWS National Hurricane Center Miami FL       EP082020
500 PM HST Thu Jul 23 2020
 
Douglas remains a well organized hurricane in visible and infrared
satellite imagery.  The 15-nmi-wide eye remains very distinct and
the surrounding cloud tops have cooled since the previous advisory. 
Although not evident in conventional satellite imagery, a recent 
AMSR-2 microwave satellite image showed evidence of concentric
eyewalls.  Subjective Dvorak T-numbers from TAFB and SAB are 
6.0 (115 kt) and recent UW/CIMSS ADT estimates have been creeping 
upward, and now also close to T6.0.  Based on these estimates, 
the initial wind speed has been raised to 115 kt, making Douglas a 
category 4 hurricane on the Saffir-Simpson Hurricane Wind Scale. 

Douglas has likely reached its peak intensity as it will be moving 
over cooler SSTs during the next day or so. Although the predicted 
track of the hurricane will bring it over warmer waters when 
Douglas approaches the Hawaiian Islands, vertical shear is forecast 
to increase at that time.  This is expected to result in continued 
gradual weakening, however Douglas is forecast to be near 
hurricane strength when it moves close to Hawaii. Despite the 
slight increase in the initial intensity, the updated NHC wind 
speed forecast is unchanged from the previous advisory through 36 
hours, and then follows the intensity consensus guidance 
thereafter.

Douglas continues moving quickly west-northwestward or 295/16 kt.  
The hurricane is forecast to remain on this heading with some 
slight reduction in forward speed during the next day or so as it 
remains to the south of a large mid-level ridge.  After that time, 
Douglas is forecast to turn westward to the south of another strong 
mid-level ridge the is predicted to build well north of the 
Hawaiian Islands later in the weekend.  The new NHC track forecast 
is very similar to the previous advisory and lies just south of the 
various consensus aids out of respect of the ECMWF and its ensemble 
mean which lie along the southern edge of the track envelope. 


Key Messages:
 
1.  Douglas is expected to move near or over portions of the
Hawaiian Islands this weekend, and there is an increasing chance
that strong winds, dangerous surf, and heavy rainfall could affect
portions of the state beginning Saturday night or Sunday.  
Interests on the Hawaiian Islands should continue to monitor the 
progress of Douglas and the official forecasts as they evolve over 
the next few days. Watches could be issued on Friday.
 
 
FORECAST POSITIONS AND MAX WINDS
 
INIT  24/0300Z 14.9N 138.8W  115 KT 130 MPH
 12H  24/1200Z 15.9N 141.2W  110 KT 125 MPH
 24H  25/0000Z 17.1N 144.3W  100 KT 115 MPH
 36H  25/1200Z 18.2N 147.4W   90 KT 105 MPH
 48H  26/0000Z 19.2N 150.4W   75 KT  85 MPH
 60H  26/1200Z 20.0N 153.2W   65 KT  75 MPH
 72H  27/0000Z 20.5N 156.0W   60 KT  70 MPH
 96H  28/0000Z 21.3N 161.8W   50 KT  60 MPH
120H  29/0000Z 21.8N 168.5W   45 KT  50 MPH
 
$$
Forecaster Brown
 
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