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Hurricane Douglas Discussion Number  10
NWS National Hurricane Center Miami FL       EP082020
1100 AM HST Wed Jul 22 2020
 
Douglas's structure has continued to improve, with a more 
well-defined eye becoming apparent in visible and microwave 
satellite images.  Subjective Dvorak intensity estimates from TAFB 
and SAB range from T4.0/65 kt and T5.0/90 kt, while the latest 
UW-CIMSS ADT is 4.0.  Douglas's initial intensity is therefore 
raised to 70 kt as a blend of the satellite estimates. 

The hurricane has begun to gain some latitude, and the initial 
motion is just north of due west, or 275/14 kt.  The track forecast 
reasoning has not changed since earlier this morning, with a 
persistent mid-tropospheric ridge to Douglas's north expected to be 
the main driving force for the entire 5-day forecast period.  
Douglas is forecast to turn west-northwestward by this evening, and 
then maintain that heading with some increase in forward speed 
through day 4 as it approaches the Hawaiian Islands.  A bend back 
to the west is then expected at the end of the forecast period.  
The new NHC track forecast lies right along the forecast path from 
the previous advisory through 60 hours, although it has been 
shifted slightly north on days 3-5 based on an overall shift of the 
guidance envelope at those times.  Confidence in the track forecast 
at this stage is rather high.

Intensity-wise, low shear and sea surface temperature of 28-29C 
favor continued strengthening, potentially at a rapid rate for the 
next 24 hours.  SHIPS, HCCA, and the Florida State Superensemble 
all bring the intensity near or at major hurricane strength in 
24-36 hours, which qualifies as rapid intensification.  The NHC 
intensity forecast is in line with these models and lies near the 
upper bound of the guidance envelope given the favorable 
conditions.  Some weakening is expected to begin by 48 hours due to 
cooler waters, but since vertical shear is not expected to increase 
until around day 4, the weakening rate is likely to be gradual.  
This forecast increases the chance that Douglas could maintain 
hurricane intensity as it approaches the Hawaiian Islands, and all 
interests on the islands should monitor the forecasts as they 
evolve over the next few days.
 
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 and heavy rainfall could affect portions
of the state beginning on 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.
 
FORECAST POSITIONS AND MAX WINDS
 
INIT  22/2100Z 12.1N 130.9W   70 KT  80 MPH
 12H  23/0600Z 12.7N 132.9W   85 KT 100 MPH
 24H  23/1800Z 13.8N 135.8W  100 KT 115 MPH
 36H  24/0600Z 15.1N 138.9W  100 KT 115 MPH
 48H  24/1800Z 16.4N 141.9W   90 KT 105 MPH
 60H  25/0600Z 17.6N 145.0W   80 KT  90 MPH
 72H  25/1800Z 18.7N 148.0W   75 KT  85 MPH
 96H  26/1800Z 20.0N 154.0W   65 KT  75 MPH...NEAR HAWAII
120H  27/1800Z 21.0N 160.0W   55 KT  65 MPH...NEAR HAWAII
 
$$
Forecaster Berg
 
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