000 WTPZ41 KNHC 190238 TCDEP1 Hurricane Estelle Discussion Number 15 NWS National Hurricane Center Miami FL EP062022 900 PM MDT Mon Jul 18 2022 Estelle's structure has continued to go downhill this afternoon and evening. While upper-level outflow is fanning out westward ahead of the hurricane, last light visible satellite imagery continues to indicate that the low-level center remains displaced to the northwest of the coldest cloud tops. In fact, an earlier AMSR2 microwave pass at 2057 UTC showed increasing separation between the low-level center on the 37-GHz channel and the mid-level center on the 89-GHz channel. This southeast tilt with height also appears to be captured well on the most recent HWRF run, and is likely the result of continued northwesterly shear undercutting the outflow layer, helping import dry stable air into Estelle's core. Satellite intensity estimates have been gradually decreasing, though an earlier ASCAT-C pass at 1722 UTC still showed peak winds of 61-kt in the northeast quadrant of the circulation. Assuming some undersampling, the initial intensity is lowered to only 65 kt this advisory, though this could be generous. It seems that Estelle's time left to intensify has run out. In fact, the hurricane has already been gradually weakening over the past day or so. While the current moderate northwesterly shear is expected to subside some over the next 24 hours, the cyclone will be moving over sub 26 C sea-surface temperatures (SSTs) by that time span. Thus, the latest intensity forecast now shows Estelle gradually weakening over the next 24-48 hours, with more pronounced weakening thereafter when SSTs drop below 23 C. Simulated IR brightness temperature data from the ECMWF and CMC models suggest Estelle will cease to produce organized deep convection by 72 hours, and the system is forecast to become a post-tropical remnant low by then. The latest NHC intensity forecast is now more in line with the intensity guidance consensus, though early on favors a blend of the HWRF/HMON forecasts, which appear to be correctly capturing the current tilted structure of the cyclone well. Estelle has been taking a slight leftward bend in its recent track, but in general has maintained a west-northwestward heading at 285/12 kt. A prominent mid-level ridge located to the northeast of Estelle should maintain the cyclone on a west-northwest heading at a similar motion for the next 2-3 days. Thereafter, as the system becomes more vertically shallow, its track is forecast to bend back westward as it becomes more steered by the low-level easterly trade winds. The latest track forecast is very close to the prior forecast, taking a blend of the consensus aids HCCA and TVCE. Estelle is expected to continue producing rough surf and rip current conditions along the coast of southwestern and west-central Mexico as well as the southern tip of the Baja California peninsula during the next day or so. FORECAST POSITIONS AND MAX WINDS INIT 19/0300Z 18.3N 113.6W 65 KT 75 MPH 12H 19/1200Z 18.7N 115.3W 60 KT 70 MPH 24H 20/0000Z 19.4N 117.5W 55 KT 65 MPH 36H 20/1200Z 20.3N 119.8W 55 KT 65 MPH 48H 21/0000Z 21.3N 122.0W 50 KT 60 MPH 60H 21/1200Z 22.1N 124.0W 40 KT 45 MPH 72H 22/0000Z 22.8N 125.8W 30 KT 35 MPH...POST-TROP/REMNT LOW 96H 23/0000Z 23.3N 128.7W 25 KT 30 MPH...POST-TROP/REMNT LOW 120H 24/0000Z 23.0N 131.5W 20 KT 25 MPH...POST-TROP/REMNT LOW $$ Forecaster Papin