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Hurricane Linda Discussion Number  22
NWS National Hurricane Center Miami FL       EP122021
500 AM HST Sun Aug 15 2021
 
As was hypothesized in the previous advisory, it appears that Linda 
is completing an eyewall replacement.  An 0918 UTC GCOM AMSR2 pass 
revealed the last-remaining vestiges of an inner eyewall decaying 
within a newer, larger eye, which is estimated to be 35 n mi in 
diameter based on the 89-GHz channel imagery.  While the microwave 
data still showed a few banding features on the western side of the 
circulation, the hurricane has taken on annular characteristics, 
with a relatively thick, solid ring of deep convection surrounding 
the eye.  This evolution is confirmed by the objective annular 
hurricane screening algorithm.  Cloud-top and eye temperatures 
have not changed much since the previous advisory, with Dvorak CI 
numbers ranging between 100-115 kt and objective estimates ranging 
between 90-100 kt.  Therefore, the initial intensity remains 100 kt.

Linda has begun to lose some latitude, and the initial motion is 
south of due west, or 265/10 kt.  A strong mid-tropospheric high 
centered over the western United States is forecast to slide 
westward and southwestward over the Pacific during the next couple 
of days, which should push Linda toward the west-southwest during 
the next 36-48 hours.  After that time, the ridge merges with 
another high farther north, which will likely allow Linda to turn 
back toward the west-northwest on days 3 through 5.  The track 
models are showing a near to below-normal amount of spread, and 
therefore the NHC track forecast is of high confidence, lying near 
the middle of the guidance envelope.

Vertical shear over Linda is expected to be less than 10 kt for the 
next 5 days.  Therefore, the hurricane's future intensity is likely 
to be driven by thermodynamic factors, and its annular structure 
will come into play.  Linda is expected to move over near-constant 
or gradually decreasing sea surface temperatures of 26-27 degrees 
Celsius for the next several days, a scenario which is typical of
the gradual weakening noted by most annular hurricanes.  Therefore, 
the NHC intensity forecast is above the consensus aids and keeps 
Linda at hurricane strength for the next 3 days.  The weakening 
trend could be even more gradual than indicated here, if the 
statistical-dynamical SHIPS guidance ends up being correct.
 
FORECAST POSITIONS AND MAX WINDS
 
INIT  15/1500Z 19.0N 120.2W  100 KT 115 MPH
 12H  16/0000Z 18.7N 121.7W   90 KT 105 MPH
 24H  16/1200Z 18.1N 123.5W   85 KT 100 MPH
 36H  17/0000Z 17.7N 125.2W   80 KT  90 MPH
 48H  17/1200Z 17.6N 126.9W   75 KT  85 MPH
 60H  18/0000Z 18.0N 128.7W   70 KT  80 MPH
 72H  18/1200Z 18.6N 130.9W   65 KT  75 MPH
 96H  19/1200Z 20.4N 135.7W   55 KT  65 MPH
120H  20/1200Z 22.3N 140.2W   40 KT  45 MPH
 
$$
Forecaster Berg
 
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