000 WTPZ42 KNHC 130257 TCDEP2 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