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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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