Storm Summary Number 4 for California Atmospheric River
NWS Weather Prediction Center College Park MD
700 AM PST Tue Dec 23 2025

...Strong atmospheric river to bring a high risk of flash flooding
to southern California on Wednesday, and periods of heavy
precipitation to much of California into the Christmas holiday...

Flood Watches remain in effect for much of California into
southern Nevada and northwestern Arizona.

Winter Storm Warnings are in effect for the Sierra Nevada and into
the interior higher elevations of northern California.

High Wind Warnings and Advisories are in effect for the West Coast
including much of California and Nevada, portions of Oregon,
western Washington, and northwestern Arizona.

For a detailed graphical depiction of the latest watches, warnings
and advisories, please see www.weather.gov

At 600 AM PST...A stationary front associated with a strong
atmospheric river event remained draping across northern
California and through the northwestern U.S.  Meanwhile, a low
pressure system located about 500 miles west of southern
California, with an estimated central pressure of 1000 mb (29.53
inches of Hg), was moving northeastward along the stationary front
toward northern California.  National Weather Service Doppler
Radar and surface observations showed a swath of light to moderate
precipitation covering northwestern California into southwestern
Oregon.

...Selected preliminary Storm Total Snowfall in inches from 400 PM
PST Sat Dec 20 through 600 AM PST Tue Dec 23...

...CALIFORNIA...
HEAVENLY SKI BASE                     7.0                    
NORTHSTAR SKI BASE                    7.0                    

...NEVADA...
MT. ROSE SKI BASE                    11.0                    

...Selected preliminary Storm Total Rainfall in inches from 400 PM
PST Sat Dec 20 through 600 AM PST Tue Dec 23...

...CALIFORNIA...
STORRIE 7.2 S                       11.16                    
HONEYDEW 3.2 SSE                    11.08                    
HILLCREST 1.3 E                     10.68                    
BLUE CANYON                         10.61                    
JARBO GAP                            9.88                    
WHITETHORN 1.7 NNW                   9.87                    
CAZADERO 1.3 SSE                     9.60                    
MEADOW VALLEY 5.6 WSW                8.93                    
WHITETHORN 1.4 NW                    8.71                    
POTTER VALLEY 8.4 ENE                8.65                    
CASTELLA 1.8 E                       8.64                    
DUTCH FLAT 0.7 S                     8.01                    
LAYTONVILLE 1 SW                     7.72                    
ETTERSBURG 2.8 N                     7.52                    
GRASS VALLEY 1.3 NNE                 7.00                    
MAD RIVER 7 SE                       6.62                    
BENBOW 3.8 SSE                       5.90                    
EMIGRANT GAP                         5.85                    
GARBERVILLE 0.8 NW                   5.63                    
UKIAH 8 NW                           5.20                    
DOS RIOS 3 SSE                       5.15                    
BLUE LAKE 2 WNW                      5.03                    
REDDING 7.9 NNE                      4.95                    
CRESCENT CITY 16.0 ESE               4.15                    
RICHARDSON GROVE 5 E                 4.00                    
DINSMORE 2.3 W                       3.88                    
EUREKA 2.2 S                         3.56                    
SANTA ROSA 2.1 NNE                   3.42                    
TRINITY CENTER                       3.27                    
SAN RAFAEL 1.4 NW                    2.65                    
SAN FRANCISCO 3.1 W                  1.54                    

...Selected preliminary Peak Wind gusts in miles per hour earlier
in the event...

...CALIFORNIA...
WALKER 4 SSW                           90                    
MONO                                   84                    
INYO                                   80                    
ROUND VALLEY 2 SSW                     80                    
MAMMOTH LAKES                          70                    
EMIGRANT GAP                           51                    
REDDING                                51                    
RED BLUFF                              48                    

...NEVADA...
WASHOE                                 87                    
DOUGLAS                                66                    


After a lull in the precipitation from yesterday into this
morning, heavy rain associated with an intensifying low pressure
system off the coast of California will gradually edge toward
northern California, reaching the coastal region of northern
California by this evening and into coastal central California
later tonight.  By Wednesday, very heavy rainfall is forecast to
surge into southern California as moderate to heavy rain spreads
farther north into the lower elevations of California.  The high
rainfall rates will lead to a high risk of flash flooding along
the southern slopes of the Transverse Range of southern California
on Wednesday.  Urban flooding in the metro areas of southern
California will also be possible.  In addition, the persistent
nature of the moderate to heavy rain is expected to heighten the
threat of flash flooding, landslides, rockfalls, and mudslides for
the remainder of this week farther north into northern California.
 Meanwhile, very heavy snow measured in feet will impact the
higher elevations of the Sierra Nevada beginning on Wednesday. 
The prolonged heavy snow will likely lead to difficult if not
impossible travel across many of the higher mountain passes within
the Sierra.  Strong and very gusty winds will also likely
contribute to tree damage and possible power outages.

The next Storm Summary will be issued by the Weather Prediction
Center at 700 PM PST. Please refer to your local National Weather
Service office for additional information on this event.

Kong