Storm Summary Number 4 for West Coast Atmospheric River
NWS Weather Prediction Center College Park MD
700 AM PST Mon Jan 16 2023

...Heavy rain and mountain snow continue over California and the
southern Great Basin as yet another atmospheric river moves
inland...

Winter Storm Warnings are in effect over the Sierra Nevada,
Transverse Range, and southern Great Basin.

Flood Warnings are in effect for select portions of the Central
Valley and in coastal southern California.

Flood Watches are in effect for coastal portions of central
California.

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

At 600 AM PST...A surface low was analyzed in the Central Valley
of California with a minimum pressure of 996 mb (29.41 in Hg). To
the south, an occluded front extended through central and southern
California to the triple point, located near Los Angeles,
California. From the triple point, the warm front extended
southeast along coastal California, while the cold front extended
to the southwest into the Pacific Ocean. A stream of moisture is
flowing into southern California and northern Mexico just ahead of
the cold front, bringing a swath a light to moderate precipitation
with it. The bulk of this precipitation has moved inland and is
falling over much of southern Arizona. Scattered showers were
observed to the north and west, including areas of southern
California, southern Nevada, and northwestern Arizona. Another
smaller, but heavier region of precipitation was located to the
southeast of the Bay Area, a disturbance directly associated with
the low pressure itself.

...Selected preliminary Storm Total Snowfall in inches from 700 AM
PST Fri Jan 13 through 600 AM PST Mon Jan 16...

...ARIZONA...
NWS FLAGSTAFF                        23.5                    
KACHINA VILLAGE                      20.0                    
WILLIAMS 2 SE                        19.0                    
BRIGHT ANGEL POINT 1 NNW             15.0                    

...CALIFORNIA...
TUOLUMNE 6 WSW                       41.0                    
MAMMOTH MOUNTAIN SKI BA              36.0                    
HETCH HETCHY 10 NE                   34.0                    
DONNER PEAK 1 W                      21.0                    
PALISADES TAHOE SKI BAS              21.0                    

...NEVADA...
SODA SPRINGS                         26.0                    
MT CHARLESTON 1 ESE                  13.0                    

...Selected preliminary Storm Total Rainfall in inches from 700 AM
PST Fri Jan 13 through 600 AM PST Mon Jan 16...

...ARIZONA...
HACKBERRY                            2.32                    
UPPER LITTLE SYCAMORE WASH           2.10                    

...CALIFORNIA...
MINING RIDGE                        15.45                    
HONEYDEW 3.2 SSE                     9.50                    
THREE PEAKS                          9.41                    
LAKE RANCH NORTH                     8.88                    
ANDERSON PEAK                        8.67                    
BLACK CONE                           8.20                    
LAS CUMBRES                          8.16                    
BOULDER CREEK 4.1 N                  6.43                    
CAZADERO 6.6 WNW                     5.48                    
BLACK BUTTE SADDLE                   4.79                    
WOODACRE 0.6 SW                      4.34                    
BASS LAKE                            4.32                    

...OREGON...
BROOKINGS 4.2 ENE                    6.24                    
GOLD BEACH 11.1 NNE                  5.30                    

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

...CALIFORNIA...
LAGUNA LAUNCH                          75                    
PLAOMAR MTN LOOKOUT                    74                    
HIGH GLADE LOOKOUT                     73                    
SCOTIA 4.3 SW                          70                    


As the atmospheric river moves inland, additional rounds of
moderate to heavy rain and mountain snow can be expected in
southern California before winding down into this evening. By
tomorrow, the bulk of the precipitation will move into the Great
Basin and Intermountain West. Given the antecedent saturated
conditions still in place over much of California, additional
precipitation impacts may result in flooding, mudslides, and other
associated damages. In the Sierra Nevada Range, additional
mountain snow of up to 3 feet is possible through tonight. Heavy
snow combined with high winds may lead to blowing snow and
whiteout conditions, which will make travel extremely hazardous.

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.

Genz/Asherman