Overview
- Forecast models and local National Weather Service guidance show an active period starting Thursday with multiple rounds of showers and thunderstorms across southwest Montana and the Northern Rockies, with some storms capable of strong, erratic wind gusts, small hail and heavy downpours.
- The NWS warned rain concentrating along and south of I‑80 in the Chicago area could produce torrential downpours and localized flooding that may slow or flood morning and evening commutes.
- Logan Pass in Glacier National Park received several inches of early season snow this week, forcing a temporary closure of Going‑to‑the‑Sun Road and highlighting how late‑season cold pockets can quickly change mountain conditions.
- Forecasters expect drier, milder weather to return by Sunday or Monday in many places, but unusually high mid‑September moisture raises the risk of flash flooding where storms train or stall.
- The Climate Prediction Center says El Niño is strengthening with a high chance of a very strong event this fall and winter that often brings above‑normal precipitation to parts of the U.S., and meteorologists are also monitoring Atlantic Invest 98 which currently has low short‑term development odds.