000 WTNT34 KWNH 280856 TCPAT4 BULLETIN Post-Tropical Cyclone Helene Advisory Number 20 NWS Weather Prediction Center College Park MD AL092024 400 AM CDT Sat Sep 28 2024 ...CATASTROPHIC, HISTORIC FLOODING CONTINUES OVER PORTIONS OF THE SOUTHERN APPALACHIANS, THOUGH THE RISK FOR ADDITIONAL HEAVY RAINFALL CONTINUES TO WANE... SUMMARY OF 400 AM CDT...0900 UTC...INFORMATION ---------------------------------------------- LOCATION...37.3N 87.9W ABOUT 135 MI...220 KM WSW OF LOUISVILLE KENTUCKY MAXIMUM SUSTAINED WINDS...25 MPH...35 KM/H PRESENT MOVEMENT...SE OR 140 DEGREES AT 3 MPH...6 KM/H MINIMUM CENTRAL PRESSURE...992 MB...29.30 INCHES WATCHES AND WARNINGS -------------------- There are no coastal watches or warnings in effect. Several flood warning and advisories, along with flash flood warnings, remain in effect across portions of the southern and central Appalachians, the Southeast, and the Ohio Valley through Saturday morning. DISCUSSION AND OUTLOOK ---------------------- At 400 AM CDT (0900 UTC), the center of Post-Tropical Cyclone Helene was located near latitude 37.3 North, longitude 87.9 West. The post-tropical cyclone is moving toward the southeast near 3 mph (6 km/h), and will drift slowly southeast and eventually eastward along the Kentucky-Tennessee border through the weekend. Maximum sustained winds are near 25 mph (35 km/h) with higher gusts. Continued weakening is expected during the next couple of days. The estimated minimum central pressure is 992 mb (29.30 inches). HAZARDS AFFECTING LAND ---------------------- Key Messages for Helene can be found in the Tropical Cyclone Discussion under AWIPS header MIATCDAT4 and WMO header WTNT44 KNHC and on the web at hurricanes.gov/text/MIATCDAT4.shtml RAINFALL: The remnant low of post tropical cyclone Helene is expected to produce an additional 1-2 inches of rainfall across portions of the Ohio Valley through early Sunday, with some isolated 3 inch totals possible. Most of the rainfall across the central and southern Appalachians has come to an end, although a few lingering showers are possible through Saturday. For a complete depiction of forecast rainfall associated with Tropical Storm Helene, please see the National Weather Service Storm Total Rainfall Graphic, available at hurricanes.gov/graphics_at4.shtml?rainqpf and the Flash Flood Risk graphic at hurricanes.gov/graphics_at4.shtml?ero. For a list of rainfall observations (and wind reports) associated this storm, see the companion storm summary at WBCSCCNS4 with the WMO header ACUS44 KWBC or at the following link: www.wpc.ncep.noaa.gov/discussions/nfdscc4.html. SURF: Swells generated by Helene will affect much the Atlantic Seaboard from Florida to Long Island NY through Saturday. These swells are likely to cause life-threatening surf and rip current conditions. Please consult products from your local weather office. NEXT ADVISORY ------------- Next complete advisory at 1000 AM CDT. $$ Forecaster Hurley