National Weather Service United States Department of Commerce

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 >

Plaese go to the Space Weather Prediction Center for more information.
Items in grey italics apparently are older than 24 hours


696
WOXX13 KWNP 242056
WARK04

Space Weather Message Code: WARK04
Serial Number: 5197
Issue Time: 2025 Dec 24 2052 UTC

EXTENDED WARNING: Geomagnetic K-index of 4 expected
Extension to Serial Number: 5196
Valid From: 2025 Dec 21 0240 UTC
Now Valid Until: 2025 Dec 25 1200 UTC
Warning Condition: Persistence
www.swpc.noaa.gov/noaa-scales-explanation
Potential Impacts: Area of impact primarily poleward of 65 degrees Geomagnetic Latitude.
Induced Currents - Weak power grid fluctuations can occur.
Aurora - Aurora may be visible at high latitudes such as Canada and Alaska.

# Issued by the US Dept. of Commerce, NOAA, Space Weather Prediction Center
# Recent messages, data, and help at http://swpc.noaa.gov/alerts/
# Send questions to SWPC.Webmaster@noaa.gov



755
WOXX11 KWNP 240851
WARK05

Space Weather Message Code: WARK05
Serial Number: 2164
Issue Time: 2025 Dec 24 0849 UTC

EXTENDED WARNING: Geomagnetic K-index of 5 expected
Extension to Serial Number: 2163
Valid From: 2025 Dec 22 1407 UTC
Now Valid Until: 2025 Dec 24 1800 UTC
Warning Condition: Persistence
www.swpc.noaa.gov/noaa-scales-explanation
Potential Impacts: Area of impact primarily poleward of 60 degrees Geomagnetic Latitude.
Induced Currents - Weak power grid fluctuations can occur.
Spacecraft - Minor impact on satellite operations possible.
Aurora - Aurora may be visible at high latitudes, i.e., northern tier of the U.S. such as northern Michigan and Maine.

# Issued by the US Dept. of Commerce, NOAA, Space Weather Prediction Center
# Recent messages, data, and help at http://swpc.noaa.gov/alerts/
# Send questions to SWPC.Webmaster@noaa.gov