Tropical Cyclone Discussion
722 WTPA44 PHFO 110234 TCDCP4 Post-Tropical Cyclone Lowell Discussion Number 60 NWS Central Pacific Hurricane Center Honolulu HI EP122026 Issued by NWS National Hurricane Center Miami FL 500 PM HST Thu Sep 10 2026 It has now been roughly 24 hours since Lowell produced more than just patches of deep convection on its northeast side. This activity has lacked much organization over this time span, with continued westerly vertical wind shear keeping the low-level circulation exposed. Given that Lowell has lacked organized convection near its center for about a day, and with most of the global and hurricane-regional model guidance not showing a return of deep convection for at least another 24 h, Lowell is being declared a post-tropical cyclone this advisory. The maximum sustained winds remain 45 kt, however, based on scatterometer data received after the prior advisory. The post-tropical low is still moving westward at 270/12 kt. Much of the forecast reasoning has not changed despite the cyclone's status change, with a deep-layer cutoff low expected to pick up the post-tropical low, pinwheeling it around to the northwest, west, then southward in the 24-72 h period. There continue to be differences in the model guidance on how sharp of a cyclonic turn around the upper-level low there will be, but ultimately the guidance shows the post-tropical low being deposited back south after the upper-level feature bypasses it to the east in 72-96 h. As mentioned above, most of the model guidance does not show deep convection returning near the post-tropical cyclone for the next day or so. However, an upper-level cutoff low is still forecast to drop southward and induce some sheared convection this weekend. However, given the disorganized state of the post-tropical cyclone, this brief period of favorable convective forcing does not appear to last long enough for the system to redevelop into a tropical cyclone, especially given that the GFS and ECMWF-based SHIPS guidance shows vertical wind shear remaining in the 30-40 kt range. After the upper-level cutoff passes it by to the east, the low is expected to slowly fill, with much of the model guidance showing the low opening up into a trough by 120 h, which is now reflected in the NHC forecast. This is the final advisory on Lowell unless regeneration occurs. For additional information on the post-tropical low please see High Seas Forecasts issued by the National Weather Service, under AWIPS header NFDHSFEPI, WMO header FZPN01 KWBC, and on the web at ocean.weather.gov/shtml/NFDHSFEPI.php KEY MESSAGES: 1. Post-storm safety: Follow advice of local officials and avoid areas of downed power lines and flooding. Ensure generators are properly ventilated and placed outside at least 20 feet away from dwellings and garages to avoid carbon monoxide poisoning. During clean up, be careful when using chainsaws and power tools. Drink plenty of water to avoid heat exhaustion. FORECAST POSITIONS AND MAX WINDS INIT 11/0300Z 29.0N 169.9W 45 KT 50 MPH...POST-TROPICAL 12H 11/1200Z 29.2N 171.3W 40 KT 45 MPH...POST-TROPICAL 24H 12/0000Z 30.6N 172.0W 40 KT 45 MPH...POST-TROPICAL 36H 12/1200Z 32.7N 172.8W 45 KT 50 MPH...POST-TROPICAL 48H 13/0000Z 34.0N 175.0W 40 KT 45 MPH...POST-TROPICAL 60H 13/1200Z 33.6N 176.7W 35 KT 40 MPH...POST-TROPICAL 72H 14/0000Z 32.9N 177.0W 30 KT 35 MPH...POST-TROP/REMNT LOW 96H 15/0000Z 31.5N 176.6W 25 KT 30 MPH...POST-TROP/REMNT LOW 120H 16/0000Z...DISSIPATED