ZCZC MIATCDEP2 ALL TTAA00 KNHC DDHHMM Hurricane Linda Discussion Number 22 NWS National Hurricane Center Miami FL EP122021 500 AM HST Sun Aug 15 2021 As was hypothesized in the previous advisory, it appears that Linda is completing an eyewall replacement. An 0918 UTC GCOM AMSR2 pass revealed the last-remaining vestiges of an inner eyewall decaying within a newer, larger eye, which is estimated to be 35 n mi in diameter based on the 89-GHz channel imagery. While the microwave data still showed a few banding features on the western side of the circulation, the hurricane has taken on annular characteristics, with a relatively thick, solid ring of deep convection surrounding the eye. This evolution is confirmed by the objective annular hurricane screening algorithm. Cloud-top and eye temperatures have not changed much since the previous advisory, with Dvorak CI numbers ranging between 100-115 kt and objective estimates ranging between 90-100 kt. Therefore, the initial intensity remains 100 kt. Linda has begun to lose some latitude, and the initial motion is south of due west, or 265/10 kt. A strong mid-tropospheric high centered over the western United States is forecast to slide westward and southwestward over the Pacific during the next couple of days, which should push Linda toward the west-southwest during the next 36-48 hours. After that time, the ridge merges with another high farther north, which will likely allow Linda to turn back toward the west-northwest on days 3 through 5. The track models are showing a near to below-normal amount of spread, and therefore the NHC track forecast is of high confidence, lying near the middle of the guidance envelope. Vertical shear over Linda is expected to be less than 10 kt for the next 5 days. Therefore, the hurricane's future intensity is likely to be driven by thermodynamic factors, and its annular structure will come into play. Linda is expected to move over near-constant or gradually decreasing sea surface temperatures of 26-27 degrees Celsius for the next several days, a scenario which is typical of the gradual weakening noted by most annular hurricanes. Therefore, the NHC intensity forecast is above the consensus aids and keeps Linda at hurricane strength for the next 3 days. The weakening trend could be even more gradual than indicated here, if the statistical-dynamical SHIPS guidance ends up being correct. FORECAST POSITIONS AND MAX WINDS INIT 15/1500Z 19.0N 120.2W 100 KT 115 MPH 12H 16/0000Z 18.7N 121.7W 90 KT 105 MPH 24H 16/1200Z 18.1N 123.5W 85 KT 100 MPH 36H 17/0000Z 17.7N 125.2W 80 KT 90 MPH 48H 17/1200Z 17.6N 126.9W 75 KT 85 MPH 60H 18/0000Z 18.0N 128.7W 70 KT 80 MPH 72H 18/1200Z 18.6N 130.9W 65 KT 75 MPH 96H 19/1200Z 20.4N 135.7W 55 KT 65 MPH 120H 20/1200Z 22.3N 140.2W 40 KT 45 MPH $$ Forecaster Berg NNNN