Flash Flooding and Debris Flows in California, November 27 to 29, 2019

Name: Flash Flooding and Debris Flows in California, November 27 to 29, 2019
Start: 2019-11-27T00:00
End: 2019-11-29T23:00
Location: California

November 27 to 29, 2019 · NWS SGX · 13 events in 6 counties and zones

Where it happened

Every event with a place to put it; 5 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: 1
Property damage: $830,000
Crop damage: $2.0 million
Events: 13

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 SGX wrote it up.

A cold unstable upper level low pressure system from the northwest brought widespread heavy rain, thunderstorms and mountain snow to southern California over the Thanksgiving holiday. One to three feet of snow fell above 5,500 feet in the mountains, impacting highways and passes. Big Bear and Mountain High reported 30 to 48 inches total. Highway 18 was closed through December 1st. Over 40 vehicles were stuck on Highway 74 and 371, while 20 vehicles were abandoned on Highway 38. There were 10 car accidents involving snow plows. Heavy rainfall of 1 to 3 inches fell at the coast and in the valleys. San Diego River reached 9.5 feet with flooding. Numerous roadways were flooded out, especially on November 28th when the heaviest rain fell. An RV park in La Mesa flooded out due to flash flooding. The San Diego River at Fashion Valley reached 9.5 feet. 2 separate episodes of severe thunderstorms occurred in San Diego County on Thanksgiving Day.

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 San Diego, CA wrote its last area forecast discussion before the first event at Nov 26, 9:48 PM PST, 2 hours 12 minutes earlier.

Area forecast discussion, Nov 26, 9:48 PM PST, 2 hours 12 minutes before

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The radar

The Edwards AFB radar (KEYX), 129 km away, was scanning. The volume nearest the first event began at 14:02 UTC.

Open the radar archive at this moment

Event by event

5 heavy snow, 5 flash flood, 2 debris flow, 1 thunderstorm wind. Local standard time, as filed.

Heavy Snow, San Bernardino County Mountains

When: November 27, 12:00 AM PST to November 29, 11:00 PM PST
Where: San Bernardino County Mountains forecast zone
Reported by: Trained Spotter
Coordinates: 34.841, -116.178 (the zone’s center; the record gives no point)

The San Bernardino Mountains reported 1 to 3 feet of snow, with locally higher amounts on the highest peaks. Mt. Baldy recorded the highest amount of snow with 50 inches. Yucaipa Ridge (Forest Falls) recorded 41 inches of snow. Wrightwood recorded 34 inches and Green Valley Lake recorded 33 inches. Numerous cars slid out on Highway 18. On highway 38, over 20 vehicles were abandoned, making it nearly impossible for the road to be plowed.

Heavy Snow, Riverside County Mountains

When: November 27, 12:00 AM PST to November 29, 11:00 PM PST
Where: Riverside County Mountains forecast zone
Reported by: Department of Highways
Coordinates: 33.744, -115.994 (the zone’s center; the record gives no point)

Heavy snow was observed in the Riverside County Mountains, where up to 20 inches of snow fell. On Highway 74, 45 cars were stuck on Highway 74 and Highway 371 due to heavy snow.

Heavy Snow, San Diego County Mountains

When: November 27, 12:00 AM PST to November 29, 11:00 PM PST
Where: San Diego County Mountains forecast zone
Reported by: Trained Spotter
Coordinates: 33.028, -116.770 (the zone’s center; the record gives no point)

Spotter reported 22 inches of storm total snow atop Palomar Mountain.

Heavy Snow, San Bernardino County Mountains

When: November 27, 8:00 PM PST to November 28, 8:00 AM PST
Where: San Bernardino County Mountains forecast zone
Crop damage: $2.0 million
Reported by: Newspaper
Coordinates: 34.841, -116.178 (the zone’s center; the record gives no point)

Dozens of trees fell and snapped at the Wildlands Conservancy in Oak Glen due to heavy, wet snow. The area received around 18 to 24 inches of snow from the storm. The hundreds of downed trees resulted in closed roads and trails as well as cut off power to the area. An estimated 2 million dollars in damage occurred.

Debris Flow, Orange

When: November 28, 6:00 AM PST to 8:00 PM PST
Where: Orange County, 1.56 mi N of San Juan Hot Spgs to 5.3 mi ENE of San Juan Hot Spgs
Cause: Heavy Rain
Injuries: 0 direct, 1 indirect
Property damage: $10,000
Reported by: Emergency Manager
Coordinates: 33.602, -117.503

Motorist struck a 500 pound boulder on state highway 74 Ortega highway through the mountain pass. Heavy rainfall occurred the entire day which likely caused the debris flow and large boulder to be released.

Heavy Snow, San Bernardino County Mountains

When: November 28, 8:00 AM PST to 11:00 AM PST
Where: San Bernardino County Mountains forecast zone
Reported by: Department of Highways
Coordinates: 34.841, -116.178 (the zone’s center; the record gives no point)

Heavy snow and gusty winds knocked down a tree and nearby power line in Crestline.

Flash Flood, Orange

When: November 28, 9:00 AM PST to 5:00 PM PST
Where: Orange County, 2.05 mi WNW of Huntington Beach to 2.04 mi WNW of Huntington Beach
Cause: Heavy Rain
Reported by: Department of Highways
Coordinates: 33.681, -118.033

Pacific Coast Highway was closed from Seapoint Street to Warner Avenue due to flooding.

Flash Flood, San Diego

When: November 28, 10:00 AM PST to 2:00 PM PST
Where: San Diego County, 0.74 mi ENE of La Mesa to 0.75 mi ENE of La Mesa
Cause: Heavy Rain
Property damage: $20,000
Reported by: Emergency Manager
Coordinates: 32.773, -117.038

Numerous cars piled up in an RV park in La Mesa due to flash flooding.

Flash Flood, Riverside

When: November 28, 10:00 AM PST to 4:00 PM PST
Where: Riverside County, 2.77 mi NNE of Ordway to 2.81 mi NNE of Ordway
Cause: Heavy Rain
Property damage: $760,000
Reported by: Department of Highways
Coordinates: 34.036, -117.150

A sinkhole opened up on the shoulder of I-10 in Redlands due to heavy rain. Total cost to repair the large sinkhole was $760,000.

Flash Flood, San Diego

When: November 28, 11:00 AM PST to 3:00 PM PST
Where: San Diego County, 1.02 mi W of National City to 1 mi W of National City
Cause: Heavy Rain
Reported by: Fire Department/Rescue
Coordinates: 32.682, -117.087

Swift water rescue occurred in National City.

Thunderstorm Wind, San Diego

When: November 28, 12:00 PM PST to 6:00 PM PST
Where: San Diego County, 1.86 mi E of Carlsbad to 1.94 mi E of Carlsbad
Measured: 41 kt (47 mph) estimated gust
Property damage: $10,000
Reported by: Trained Spotter
Coordinates: 33.171, -117.318

Spotter reported straight line winds and roof damage in Carlsbad from thunderstorm wind outflow on November 28th.

Flash Flood, San Diego

When: November 28, 1:00 PM PST to 10:00 PM PST
Where: San Diego County, 2.09 mi ENE of Sorrento to 2.12 mi ENE of Sorrento
Cause: Heavy Rain
Property damage: $30,000
Reported by: Department of Highways
Coordinates: 32.908, -117.185

Driver was rescued from his BMW after driving through 2 feet of water in Sorrento Valley. The vehicle was a total loss.

Debris Flow, San Diego

When: November 28, 10:00 PM PST to November 29, 2:00 AM PST
Where: San Diego County, 1.64 mi NNE of San Ysidro to 1.67 mi NNE of San Ysidro
Cause: Heavy Rain
Reported by: Department of Highways
Coordinates: 32.572, -117.041

A large mudslide occurred on I-805 at the intersection of Hwy 905 in Otay Mesa.

What these are

Heavy Snow: Snowfall reaching the local warning threshold without the other hazards of a winter storm.
Debris Flow: A fast-moving slurry of mud, rock and debris, usually on a slope soaked by heavy rain or stripped by a fire.
Flash Flood: Flooding that begins within six hours of the rain that causes it, or of a dam or levee failure or ice jam release, often with deadly speed.
Thunderstorm Wind: Winds from a thunderstorm of 50 knots (58 mph) or more, or lower winds that caused damage or casualties. Measured gusts are marked MG, estimated EG.

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

The same day elsewhere

Every storm in California in 2019 Every state in 2019 This day in weather history Warnings in California, November 2019

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: 866217, 866636, 866637, 868612, 867055, 866208, 866209, 866210, 866214, 866216, 866213, 866212, 866211.