Heavy Rain and Flash Flooding Concerns in California; Heavy Snow in the Sierra

An atmospheric river will bring heavy rainfall to lower elevations of California this week, and heavy snow to the Sierra Nevada mountains. Flash flooding, some of which may be locally considerable, will be a concern on the western foothills of the Sierra Nevada mountains through Tuesday. Landslides, rockfalls and mudslides are possible in the Southern California mountains. Read More >

Fire Weather Watch/Red Flag Warning Criteria

Specific conditions must be met for a Fire Weather Watch and/or a Red Flag Warning to be issued. These conditions are as follows:

1. KBDI greater that or equal to 600, and

2. Two minute ASOS winds greater than or equal to 17 kts (20 mph), or 20 foot winds greater than or equal to 14 kts (16 mph), and

3. Minimum relative humidity of less than 60% in one or more observations, and

4. Low 10-hr fuel moisture, typical less than 13.

5. Monthly precipitation less than two inches with a decrease and/or cessations of percolation (dew)can signal the onset of the fire season. Forecaster judgment must be used in the watch/warning decision making process.