Storm Summary Number 2 for West Coast Multi-Hazard Atmospheric
River Events
NWS Weather Prediction Center College Park MD
700 PM PST Thu Jan 05 2023

...Heavy rain/snow and high winds subsiding across California as
the next Atmospheric River arrives on Friday...

Flood Watches are in effect for much of the Central Valley of
California .

High Wind Warnings and Wind Advisories are in effect for portions
of California and Oregon.

Winter Storm Warnings are in effect for portions of the Sierra
Nevada, Transverse Range, and western Nevada.

Winter Weather Advisories are in effect for portions of the
Transverse Range and central Nevada.

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

At 600 PM PST...A low pressure center was analyzed over 300 miles
northwest of the Washington coastline with a minimum pressure of
976 mb (28.82 in Hg). Latest surface analysis depicted a dying
occluded front that extended to the southeast of this low into the
Pacific Northwest and Great Basin, to a triple point located just
north of Las Vegas. From the triple point, a cold front extended
to the south through southern California, while a warm front was
analyzed across Arizona. Latest surface observations and RADAR
depicted improving conditions across the California coastline, as
the heaviest precipitation was confined to the Sierra Nevada Range
due to upslope flow enhancing rainfall/snowfall rates along the
higher terrain. Outside of higher terrain, lingering onshore flow
continued to produce isolated light to moderate rain along coastal
portions of California, with the greatest coverage in the northern
region of the state. Precipitation ahead of the frontal boundary
had also begun to push eastward into the Intermountain West with
ongoing light to moderate rain/snow along a north-south axis from
southern Idaho into Arizona.

...Selected preliminary Storm Total Snowfall in inches from 700 AM
PST Wed Jan 04 through 600 PM PST Thu Jan 05...

...CALIFORNIA...
JUNE MOUNTAIN SKI BASE               18.0                    
MAMMOTH MOUNTAIN SKI BASE            16.0                    
HEAVENLY SKI BASE                    12.0                    
HETCH HETCHY 10 NE                   12.0                    
MT ROSE SKI BASE                     12.0                    

...Selected preliminary Storm Total Rainfall in inches from 700 AM
PST Wed Jan 04 through 600 PM PST Thu Jan 05...

...CALIFORNIA...
OLD MAN MOUNTAIN                     6.54                    
CALFIRE                              5.66                    
THREE PEAKS                          5.24                    
FRENCH GULCH                         5.13                    
LOS GATOS                            4.17                    
BURLINGAME 2.0 WSW                   2.96                    
MORAGA 2.4 NNW                       2.85                    
UKIAH MUNICIPAL APT                  2.64                    
K6BPM SANTA BARBARA                  2.36                    
ROHNERT PARK 0.9 SW                  2.30                    
ATASCADERO 2.3 NE                    2.13                    
THOUSAND OAKS 2.1 WSW                2.02                    
SACRAMENTO INTL APT                  1.84                    
SAN FRANCISCO INTL APT               1.81                    
LOS ANGELES INTL APT                 1.51                    
HOPLAND 8 SSE                        1.50                    
OXNARD NWS                           1.46                    
SANTA BARBARA MUNICIPAL APT          1.19                    

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

...CALIFORNIA...
KIRKWOOD MEADOWS 1.2 S                119                    
GRAPEVINE 3 SSE                       104                    
PULGA 2 NNW                           102                    
PABLO POINT                           101                    
YORKVILLE 5.5 NW                       95                    
CAPETOWN 6 ENE                         94                    
COBB RIDGE WEST                        91                    
ROAD TO RANCHES                        90                    
HIGH GLADE LOOKOUT                     89                    
FERNDALE 6.4 S                         88                    
MAGIC MOUNTAIN TRUCK TRL               87                    
AMERICAN HOUSE 6 NW                    84                    
AGUA DULCE 8 S                         81                    
BIG BEAR CITY 13 ESE                   72                    
MOUNTAIN GATE 3 NNE                    72                    
CRESCENT CITY 1 ESE                    69                    
JULIAN 9 S                             65                    
BLACK MOUNTAIN 7 E                     64                    


The low pressure center and associated frontal boundaries will
continue to weaken through tonight, with precipitation diminishing
across California. Areas where showers persist the longest could
see an additional 1"+ of rainfall through the morning hours, while
the higher elevations of the Sierra Nevada and Klamath ranges may
see another 6-12"+ before snowfall ends. As the impacts from this
event will shift eastward as the system disorganizes and
dissociates across the eastern Pacific Ocean, the next atmospheric
river event is forecast to arrive late Friday into northern
California, before spreading southward to the central portion of
the state on Saturday. The cumulative effect of an additonal
several inches of rainfall after recent precipitation will lead to
considerable flood impacts this weekend, including rapid water
rises and mudslides over northern and central California. Flash
flooding and debris flows are possible over burn scar areas.
Furthermore, an additional 1-2 feet of snow this weekend will lead
to dangerous travel above 5000 feet in the higher terrains of
northern and central California.

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

Russell