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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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