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Tropical Storm Linda Discussion Number 8
NWS National Hurricane Center Miami FL EP122021
900 PM MDT Wed Aug 11 2021
While deep convection continues to pulse near and just south of the
estimated center of Linda, recent satellite imagery suggests the
center is now along the northwestern edge of the cirrus canopy. A
series of microwave passes, first from AMSR-2 at 2036 UTC and then
SSMIS at 2340 UTC indicated that the mid-level eye that was observed
earlier today has become poorly defined. This degradation in
structure could be attributed to dry air being imported into the
inner core of Linda by persistent 15-20 kt of northerly vertical
wind shear. The current intensity this advisory is held at 60 kt,
taking a blend of the latest subjective intensity estimates from
TAFB (T3.5/55 kt) and SAB (T4.0/65 kt), though this might be
somewhat generous given that the most recent UW-CIMSS ADT estimate
is down to T3.1/47 kt.
Linda appears to be back on a due west heading, though a bit slower
at 270/6 kt. Linda is reaching the western extent of a large
deep-layer ridge located poleward over the western United States,
which is also forecast to become eroded by a mid-tropospheric trough
located just offshore California. Thus, Linda is forecast to start
gaining latitude tomorrow, remaining on a track to the
west-northwest for the next 2-3 days. The track guidance remains in
good agreement on this forecast evolution, and the latest NHC track
forecast lies close to the HCCA consensus aid. This track forecast
roughly splits the difference between the further south and west
ECMWF and north and east GFS forecast, and is just slightly further
north compared to the previous track forecast.
After intensifying today despite continued moderate northerly
vertical wind shear, Linda appears to be taking a pause as dry air
has been entrained into its inner core, disrupting its convective
structure. Over the next 24-36 hours, this shear is expected to
slowly decrease as diagnosed by the ECMWF-SHIPS guidance, and should
provide an opportunity for Linda to intensify, especially as the
storm remains in a moist environment and over sea-surface
temperatures above 28 C. However, given the current structure, only
slow intensification is now anticipated over the next 24 hours.
Linda is forecast to peak around 85 kt between 48-72 hours, though
it remains possible the storm could become stronger as suggested in
the latest HWRF and HMON forecasts. The latest NHC intensity
forecast is slightly under the HCCA consensus aid over the first 24
hours, but is now near the peak intensity of this guidance aid.
After 72 hours, gradual weakening is anticipated as Linda begins to
move over cooler ocean waters.
FORECAST POSITIONS AND MAX WINDS
INIT 12/0300Z 13.6N 106.5W 60 KT 70 MPH
12H 12/1200Z 14.1N 107.8W 65 KT 75 MPH
24H 13/0000Z 15.0N 109.7W 70 KT 80 MPH
36H 13/1200Z 16.0N 111.7W 80 KT 90 MPH
48H 14/0000Z 17.0N 113.9W 85 KT 100 MPH
60H 14/1200Z 17.9N 115.9W 85 KT 100 MPH
72H 15/0000Z 18.5N 118.1W 85 KT 100 MPH
96H 16/0000Z 18.9N 122.1W 75 KT 85 MPH
120H 17/0000Z 18.9N 125.5W 60 KT 70 MPH
$$
Forecaster Papin/Stewart
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