Red Flag Warning for Lake Tahoe starts Sunday night

8:30 p.m. UPDATE: The Fire Weather Watch has been upgraded to a Red Flag Warning. The warning is from 8:00 p.m. Sunday to 11:00 a.m. Monday. Expect thunderstorms and strong outflow wind guest 40 to 50 mph.

SOUTH LAKE TAHOE, Calif. - A Fire Weather Watch is in effect from Sunday at 8:00 p.m. through Tuesday at 11:00 a.m. for the Sierra, Northeast California and Western Nevada. The National Weather Service (NWS) in Reno is calling for thunderstorms and strong outflow winds in the area.

The affected area: Fire Zone 271 Western Lassen, Eastern Plumas, Eastern Sierra, and Eastern Nevada Counties, Fire Zone 272 Greater Lake Tahoe Area, Fire Zone 274 Southern Mono County, Fire Zone 278 Eastern Lassen County, Fire Zone 420 Northern Sierra Front including Carson City, Douglas, Storey, Southern Washoe, Western Lyon, and Far Southern Lassen Counties, Fire Zone 421 Southern Sierra Front including Alpine, Northern Mono, Southern Lyon and and Western Mineral Counties.

Isolated thunderstorms may develop as early as Sunday afternoon mainly south of Highway 50. The main period of concern for thunderstorm potential is Sunday evening through Monday morning, with faster moving storms producing lightning and limited rainfall. Another round of thunderstorms is possible Monday and Monday night, mainly south of Highway 50.

There is concern for lightning causing new fire starts, and combined with strong outflow winds, fires could grow quickly.

NWS Reno said this is a challenging forecast with abundant moisture and weak weather systems moving into the region, which will affect the coverage and location of showers and thunderstorms.

The Sunday and Monday forecast for South Lake Tahoe:

Sunday - Widespread haze. Mostly sunny, with a high near 87. Light and variable wind becoming west 5 to 10 mph in the morning.
Sunday Night - Scattered showers and thunderstorms. Widespread haze before 11pm. Mostly cloudy, with a low around 52. South wind around 5 mph becoming calm in the evening. Chance of precipitation is 30%.

Monday - A 20 percent chance of showers and thunderstorms. Mostly sunny, with a high near 84. Light southeast wind becoming southwest 5 to 10 mph in the afternoon.
Monday Night - Mostly clear, with a low around 54. Southwest wind 5 to 10 mph becoming light in the evening. Winds could gust as high as 20 mph.

Smoke and air quality concerns from California wildfires remain through Sunday, especially north of Highway 50. Improving air quality for many areas is possible by Monday.