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Hurricane Linda Discussion Number  12
NWS National Hurricane Center Miami FL       EP122021
900 PM MDT Thu Aug 12 2021

Linda is starting to intensify more in earnest. This evening, the 
Central Dense Overcast has expanded some, especially to the 
northwest which had previously been more restricted by moderate 
northerly shear. A warm spot has been intermittently appearing on 
infrared satellite imagery, suggesting the development of a more 
well-defined eye. A SSMIS 2348 UTC microwave pass also indicated a 
closed mid-level eyewall had developed on the 91 GHz channel, though 
the 37 GHz channel still suggested the low-level eyewall may still 
be open to the west. Objective satellite estimates this evening 
have been steadily increasing with the latest UW-CIMSS ADT estimate 
up to T4.6/80 kt and the most recent SATCON estimate up to 76 kt. 
However, subjective Dvorak estimates from SAB and TAFB were lower. 
Given the improvement in Linda's structure this evening, the 
intensity is raised to 75-kt for this advisory. 

Linda continues to move to the west-northwest, with a slightly 
faster forward motion at 300/11 kt. Linda should continue a general 
west-northwest motion for the next several days as a mid-level ridge 
remains parked over Mexico and the southwestern United States. After 
48 hours, this ridge is forecast to build westward and become 
reoriented west-southwest to east-northeast ahead of Linda. This 
synoptic evolution should result in Linda turning to the west or 
even west-southwest after 72 hours through the end of the forecast 
period. The latest NHC track forecast is very similar to the 
previous forecast for the first 48-72 hours, but has been shifted a 
little further south thereafter. However, this forecast track is 
still poleward of the GFS, ECMWF, and reliable HCCA consensus 
guidance, and further southward adjustments may be needed in 
subsequent forecasts. 

Northerly vertical wind shear, which has slowed Linda's 
intensification rate over the last day or so, appears to be slowly 
subsiding, and the ECMWF-SHIPS guidance suggests this shear will 
gradually decrease to under 10 kt by 48 hours. During this period, 
Linda should remain in a moist environment and over 27-28 C 
sea-surface temperatures. These factors favor strengthening, and the 
improvement in Linda's inner-core structure argues for a faster rate 
of intensification over the next 12-24 hours. The latest intensity 
forecast was raised in the short-term, following the latest HCCA 
guidance, and calls for a peak intensity of 95 kt in 36-48 hours. It 
remains possible Linda could intensify a bit more than expected, as 
the latest HWRF, HMON, and COAMPS-TC regional hurricane models 
still show a peak intensity as a major hurricane. After 48 hours, 
Linda will be moving over sub 27 C sea-surface temperatures and into 
a drier environment, which should result in gradual weakening 
through the end of the forecast period.
 
FORECAST POSITIONS AND MAX WINDS
 
INIT  13/0300Z 15.8N 109.6W   75 KT  85 MPH
 12H  13/1200Z 16.6N 111.2W   85 KT 100 MPH
 24H  14/0000Z 17.6N 113.5W   90 KT 105 MPH
 36H  14/1200Z 18.5N 115.8W   95 KT 110 MPH
 48H  15/0000Z 18.9N 118.0W   95 KT 110 MPH
 60H  15/1200Z 19.0N 120.0W   90 KT 105 MPH
 72H  16/0000Z 18.9N 121.9W   80 KT  90 MPH
 96H  17/0000Z 18.3N 125.4W   65 KT  75 MPH
120H  18/0000Z 18.1N 129.4W   60 KT  70 MPH
 
$$
Forecaster Papin/Stewart
 
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