Overview
- Flood warnings are in effect in northern California as a Pacific atmospheric river brings heavy rain, flash‑flood risk, and the threat of debris flows on burn scars, with Sierra snowfall projected to top two feet in places.
- Southern California faces a flood watch starting Tuesday with periods of heavy rain and strong winds from Tuesday night into Wednesday, raising the risk of travel delays at West Coast airports.
- A fast clipper will bring light snow and a wintry mix to parts of the Upper Midwest, Great Lakes and Northeast early Tuesday, with minor accumulations, slick morning commutes, and a quick change to rain near coastal areas.
- Much of the central and southern U.S. will be unseasonably warm through Christmas, with temperatures 15–30 degrees above normal and near‑record highs in Texas and the Gulf Coast; South Florida also has a small craft advisory with 20–30 kt winds and 7–10 ft seas.
- Flight disruptions have already appeared at JFK, Chicago and Atlanta, and forecasters are monitoring a stronger system on Friday with precipitation type and track still in question for parts of the Northeast.