Heavy Snow in California, March 11 to 12, 2010

Name: Heavy Snow in California, March 11 to 12, 2010
Start: 2010-03-11T22:56
End: 2010-03-12T21:16
Location: California

March 11 to 12, 2010 · NWS MFR · 3 events in 3 counties and zones

Upslope flow occurred across northern California with heavy snow accumulations as a result of the enhanced precipitation processes.

Where it happened

Every event with a place to put it; 3 filed by county or forecast zone are drawn at its center, in a lighter ring. Tap one for its entry below.

Tornadoes
Tropical storms and surge
Floods
Wind
Hail
Winter weather
Heat and drought
Cold
Fire, smoke and dust
Marine and coastal
Other

Open the live radar over this ground

The toll

Deaths: 0
Injuries: 0
Property damage: None recorded
Crop damage: None recorded
Events: 3

Deaths and injuries are direct and indirect together, as the offices filed them. Damage is property and crops in the dollars of the year, not adjusted for inflation, and only where an office estimated it.

What happened

The episode as NWS MFR wrote it up.

Upslope flow occurred across northern California with heavy snow accumulations as a result of the enhanced precipitation processes.

What forecasters said that day

The local office's own words before the first event, as it sent them, from the Iowa Environmental Mesonet's archive of National Weather Service text.

NWS Medford, OR wrote its last area forecast discussion before the first event at Mar 11, 9:03 PM PST, 1 hour 53 minutes earlier.

Area forecast discussion, Mar 11, 9:03 PM PST, 1 hour 53 minutes before

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Hazardous weather outlook, Mar 11, 4:37 AM PST, 18 hours 19 minutes before

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE MEDFORD OR
437 AM PST THU MAR 11 2010

ORZ021-022-120000-
SOUTH CENTRAL OREGON COAST-CURRY COUNTY COAST-
437 AM PST THU MAR 11 2010

THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF SOUTHWEST
OREGON.

.DAY ONE...TODAY AND TONIGHT

A HIGH SURF ADVISORY IS IN EFFECT AT 4 PM PST.

A HIGH WIND WARNING IS IN EFFECT AT 10 PM PST.

SEE WEATHER MESSAGES FOR SPECIFIC DETAILS.

.DAYS TWO THROUGH SEVEN...FRIDAY THROUGH WEDNESDAY

THE HIGH WIND WARNING IS IN EFFECT UNTIL 10 AM PST FRIDAY.

THE HIGH SURF ADVISORY IS IN EFFECT UNTIL 10 AM PST SATURDAY.

.SPOTTER INFORMATION STATEMENT...

WEATHER SPOTTERS ARE ENCOURAGED TO REPORT SIGNIFICANT WEATHER
CONDITIONS ACCORDING TO STANDARD OPERATING PROCEDURES.

CAZ081-120000-
CENTRAL SISKIYOU COUNTY-
437 AM PST THU MAR 11 2010

THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF NORTHERN
CALIFORNIA.

.DAY ONE...TODAY AND TONIGHT

NO SIGNIFICANT WEATHER IS EXPECTED FOR THE REST OF THURSDAY.

.DAYS TWO THROUGH SEVEN...FRIDAY THROUGH WEDNESDAY

A WIND ADVISORY IS IN EFFECT FROM 1 AM PST TO 1 PM PST FRIDAY.

A WINTER WEATHER ADVISORY FOR SNOW FOR ELEVATIONS ABOVE 3000 FEET
IS IN EFFECT FROM 1 PM PST TO 10 PM PST FRIDAY.

SEE WEATHER MESSAGES FOR SPECIFIC DETAILS.

.SPOTTER INFORMATION STATEMENT...

WEATHER SPOTTERS ARE ENCOURAGED TO REPORT SIGNIFICANT WEATHER
CONDITIONS ACCORDING TO STANDARD OPERATING PROCEDURES.

ORZ031-120000-
CENTRAL AND EASTERN LAKE COUNTY-
437 AM PST THU MAR 11 2010

THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF SOUTH CENTRAL
OREGON.

.DAY ONE...TODAY AND TONIGHT

NO SIGNIFICANT WEATHER IS EXPECTED FOR THE REST OF THURSDAY.

.DAYS TWO THROUGH SEVEN...FRIDAY THROUGH WEDNESDAY

A WIND ADVISORY IS IN EFFECT FROM 4 AM PST TO 4 PM PST FRIDAY. SEE
WEATHER MESSAGE FOR SPECIFIC DETAILS.

.SPOTTER INFORMATION STATEMENT...

WEATHER SPOTTERS ARE ENCOURAGED TO REPORT SIGNIFICANT WEATHER
CONDITIONS ACCORDING TO STANDARD OPERATING PROCEDURES.

CAZ080-082-120000-
WESTERN SISKIYOU COUNTY-SOUTH CENTRAL SISKIYOU COUNTY-
437 AM PST THU MAR 11 2010

THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF NORTHERN
CALIFORNIA.

.DAY ONE...TODAY AND TONIGHT

NO SIGNIFICANT WEATHER IS EXPECTED FOR THE REST OF THURSDAY.

.DAYS TWO THROUGH SEVEN...FRIDAY THROUGH WEDNESDAY

A WINTER STORM WARNING FOR HEAVY SNOW FOR ELEVATIONS ABOVE 4000
FEET IS IN EFFECT FROM 1 AM PST TO 10 PM PST FRIDAY.

A WINTER WEATHER ADVISORY FOR SNOW FOR ELEVATIONS BETWEEN 3000 AND
4000 FEET IS IN EFFECT FROM 1 PM PST TO 10 PM PST FRIDAY.

SEE WEATHER MESSAGES FOR SPECIFIC DETAILS.

.SPOTTER INFORMATION STATEMENT...

WEATHER SPOTTERS ARE ENCOURAGED TO REPORT SIGNIFICANT WEATHER
CONDITIONS ACCORDING TO STANDARD OPERATING PROCEDURES.

CAZ083-120000-
NORTH CENTRAL AND SOUTHEAST SISKIYOU COUNTY-
437 AM PST THU MAR 11 2010

THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF NORTHERN
CALIFORNIA.

.DAY ONE...TODAY AND TONIGHT

NO SIGNIFICANT WEATHER IS EXPECTED FOR THE REST OF THURSDAY.

.DAYS TWO THROUGH SEVEN...FRIDAY THROUGH WEDNESDAY

A WINTER STORM WARNING FOR HEAVY SNOW IS IN EFFECT FROM 1 AM PST
TO 10 PM PST FRIDAY. SEE WEATHER MESSAGE FOR SPECIFIC DETAILS.

.SPOTTER INFORMATION STATEMENT...

WEATHER SPOTTERS ARE ENCOURAGED TO REPORT SIGNIFICANT WEATHER
CONDITIONS ACCORDING TO STANDARD OPERATING PROCEDURES.

KS

In the hours before

Local storm report, Mar 11, 8:33 PM PST, 2 hours 23 minutes before

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Local storm report, Mar 11, 9:38 PM PST, 1 hour 18 minutes before

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The radar

The national radar mosaic for the moment the first event began.

Open the radar archive at this moment

Event by event

3 heavy snow. Local standard time, as filed.

Heavy Snow, South Central Siskiyou County

When: March 11, 10:56 PM PST to March 12, 5:56 PM PST
Where: South Central Siskiyou County forecast zone
Reported by: ASOS
Coordinates: 41.593, -122.540 (the zone’s center; the record gives no point)

The Mt. Shasta ASOS (elevation 3533 feet) measured 0.96 inches of precipitation in a 19 hour period between 11/2256 PST and 12/1756 PST. Using a wet snow ratio of 7:1, produces 7 inches of snow with surface temperatures observed between 29F to 36F. It is assumed that measuring of precipitation was delayed until snow melt and that Heavy Snow Warning criteria was met for CAZ082 earlier in the day. The Mount Shasta City RAWS recorded 1.13 inches of precipitation in 19 hours between 12/2252 and 13/1752 PST with a temperature ranging from 29F to 35F. At higher elevations, this likely translated to at least 8 inches of snow. The Caltrans Snowmans Summit station (elevation 4478 feet) measured 1.37 inches of precipitation in a 19 hour period between 11/2340 PST and 12/1810 PST. Using a wet snow ratio of 7:1, produces 10 inches of snow with surface temperatures observed between 28F to 31F, which meets Heavy Snow Warning criteria.

Heavy Snow, North Central & Southeast Siskiyou County

When: March 11, 11:40 PM PST to March 12, 6:10 PM PST
Where: North Central & Southeast Siskiyou County forecast zone
Reported by: Department of Highways
Coordinates: 41.593, -122.540 (the zone’s center; the record gives no point)

The Caltrans Snowmans Summit station (elevation 4478 feet) measured 1.37 inches of precipitation in a 19 hour period between 11/2340 PST and 12/1810 PST. Using a wet snow ratio of 7:1, produces 10 inches of snow with surface temperatures observed between 28F to 31F, which meets Heavy Snow Warning criteria. This station is in zone CAZ082, but it is representative of portions of CAZ083.

Heavy Snow, Western Siskiyou County

When: March 12, 2:16 AM PST to 9:16 PM PST
Where: Western Siskiyou County forecast zone
Reported by: RAWS
Coordinates: 41.593, -122.540 (the zone’s center; the record gives no point)

The Somes Bar RAWS (elevation 920 feet) measured 1.45 inches of precipitation in a 19 hour period between 12/0216 PST and 12/2116 PST. Using a wet snow ratio of 7:1, produces 10 inches of snow with surface temperatures observed between 37F to 47F. It is assumed that measuring of precipitation was delayed until snow melt and that Heavy Snow Warning criteria was met for CAZ080 earlier in the day. In addition, the Scott Mt weather station (elevation 5900 feet) measured 1.13 inches of precipitation in 7 hours with surface temperatures 26F to 33F between 12/1000 PST and 12/1700 PST, which comes out to 8 inches in the 7 hours, meeting Heavy Snow Warning criteria. Lastly, the Happy Camp portable weather station (1500 feet) measured 1.22 inches of precipitation between 12/0445 PST and 12/2145 PST with surface temperatures between 32F and 43F (delayed measurement due to snowfall not melting into gage until temperatures rose above freezing).

What these are

Heavy Snow: Snowfall reaching the local warning threshold without the other hazards of a winter storm.

After NWS Directive 10-1605, the rules offices file Storm Data by.

The same day elsewhere

Every storm in California in 2010 Every state in 2010 This day in weather history Warnings in California, March 2010

Sources

NOAA National Centers for Environmental Information, Storm Events Database, compiled from the National Weather Service’s monthly Storm Data. Complete through 2026-06; NCEI adds each month about 75 days after it ends and revises past years a few times a year. Rebuilt 2026-09-30. Each event’s entry at NCEI: 211463, 211464, 211461.