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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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