Storm Summary Number 1 for Heavy Rain and Wind in California
NWS Weather Prediction Center College Park MD
800 PM PDT Sun Oct 24 2021

...Heavy rainfall and gusty winds continue to batter California as
a historically strong low pressure system and associated
atmospheric river impacts the West Coast...

Flood Watches extend along the California and Oregon coastline,
and further inland over the Sacramento Valley and Sierra Nevada
Mountains.

Wind Advisories are in effect in the Sacramento Valley and Coastal
California.

Winter Storm Warnings are in effect along the Sierra Nevada
Mountains.

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

At 700 PM PDT...A record breaking low pressure system with a
central pressure of 948 mb, or 27.99 in/Hg was analyzed southwest
of British Colombia, at 47.5, 130.3. An occluded front wrapped
around the low center and arced through the Pacific Northwest into
a cold front analyzed from East Oregion through North-Central
California. National Weather Service Doppler radar detected a
stream of moderate to heavy rainfall over portions of the Pacific
Northwest and North-Central California associated with its
associated atmospheric river.

...Selected preliminary Storm Total Rainfall in inches from 900 PM
PDT Sat Oct 23 through 700 PM PDT Mon Oct 24...

...CALIFORNIA...
FOUR TREES NEAR PARADISE             9.92                    
SANTA ROSA                           9.43                    
BLUE CANYON NYACK AIRPORT            8.87                    
DOTY RAVINE                          8.74                    
SODA CREEK                           8.61                    
COBB 2 NNW                           8.03                    
MANCHESTER 2 SSW                     5.95                    
OAKLAND NORTH                        5.21                    
SACRAMENTO MATHER AIRPORT            4.69                    
SAN FRANCISCO INTERNATIONAL AIRPORT  3.21                    
REDDING MUNICIPAL AIRPORT            3.03                    

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

...CALIFORNIA...
SHIP MOUNTAIN RAWS                     67                    
KNEELAND RAWS                          65                    
BOLAM                                  61                    

...OREGON...
SQUAW PEAK                             75                    
PORT ORFORD 5 SE                       73                    
ONION MOUNTAIN LOOKOUT                 69                    

...WASHINGTON...
CORRAL CREEK                           51                    
MISSION CREEK                          48                    
IRON MOUNTAIN                          44                    


The strong low pressure off the coast will continue to weaken as
it meanders toward the British Colombia coastline through Tuesday
and the Pacific Front presses east. However, a continued influx of
moisture will fuel another round of heavy rain and mountain snow
in North-Central California through Tuesday. Life threatening and
significant flash flooding remains possible for the upslope region
of the Sierra Nevada Range through Tuesday morning, where a High
Risk of Excessive Rainfall is in effect. The heavy rain threat is
then anticipated to shift south into Central California through
Tuesday as the atmospheric river eases. Heavy mountain snow is
also a distinct possibility in the peaks of the Sierra Nevada
Range, with over a foot possible by tomorrow evening.  

The next Storm Summary will be issued by the Weather Prediction
Center at 800 AM PDT. Please refer to your local National Weather
Service office for additional information on this event.

Asherman