ZCZC MIATCDEP5 ALL TTAA00 KNHC DDHHMM Post-Tropical Cyclone Irwin Discussion Number 12 NWS National Hurricane Center Miami FL EP102023 1100 AM HST Tue Aug 29 2023 Irwin has failed to produce any convection near its center during the last 15-18 h. Since it no longer satisfies the criteria of a tropical cyclone, Irwin is being designated as a post-tropical cyclone with this advisory. A recent scatterometer pass showed a broad area of winds at or slightly above 30 kt in the northwestern quadrant, and so the initial intensity remains 35 kt. The post-tropical cyclone is moving slightly south of due west (260/15 kt). A general westward motion at a gradually slower forward speed is expected over the next several days while Irwin is steered by a low-level ridge over the eastern Pacific. Gradual weakening is forecast as the shallow cyclone spins down over cooler waters and in a drier, more stable environment. While some intermittent bursts of convection could occur during the next couple of days, the overall environment does not appear conducive for Irwin to regenerate to a tropical cyclone. This is the last NHC advisory on Irwin. For additional information on the post-tropical cyclone, please see High Seas Forecasts issued by the National Weather Service, under AWIPS header NFDHSFEPI, WMO header FZPN02 KWBC, and on the web at ocean.weather.gov/shtml/NFDHSFEPI.php FORECAST POSITIONS AND MAX WINDS INIT 29/2100Z 19.1N 130.3W 35 KT 40 MPH...POST-TROPICAL 12H 30/0600Z 18.9N 132.4W 30 KT 35 MPH...POST-TROP/REMNT LOW 24H 30/1800Z 18.8N 134.7W 30 KT 35 MPH...POST-TROP/REMNT LOW 36H 31/0600Z 18.8N 136.5W 30 KT 35 MPH...POST-TROP/REMNT LOW 48H 31/1800Z 18.9N 138.0W 30 KT 35 MPH...POST-TROP/REMNT LOW 60H 01/0600Z 19.0N 139.3W 25 KT 30 MPH...POST-TROP/REMNT LOW 72H 01/1800Z 19.0N 140.3W 25 KT 30 MPH...POST-TROP/REMNT LOW 96H 02/1800Z 19.0N 141.5W 25 KT 30 MPH...POST-TROP/REMNT LOW 120H 03/1800Z 19.5N 143.5W 20 KT 25 MPH...POST-TROP/REMNT LOW $$ Forecaster Reinhart NNNN