ZCZC MIATCDEP2 ALL TTAA00 KNHC DDHHMM 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 NNNN