A potent cold front swept through the region on January 16th bringing widespread rain, gusty winds, low elevation snow, and thunderstorms. This system brought widespread roadway flooding, downed trees, small hail, and snow as low as 2400 ft in elevation. Numerous flights were delayed or canceled at SFO due to the weather.

Flood in SAN FRANCISCO, CALIFORNIA
From 16-JAN-20 08:50:00 to 16-JAN-20 09:20:00 (PST-8)
Location: SAN FRANCISCO
Flood cause: Heavy Rain
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Law Enforcement

Roadway flooding at 455 8th St in San Francisco. Number 1, 2, and 3 lanes with water 1 foot deep.

Flood in ALAMEDA, CALIFORNIA
From 16-JAN-20 09:04:00 to 16-JAN-20 09:34:00 (PST-8)
Location: EMERYVILLE
Flood cause: Heavy Rain
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Law Enforcement

Roadway flooding at SR-24 E and Martin Luther King Jr off ramp.

Flood in MARIN, CALIFORNIA
From 16-JAN-20 09:09:00 to 16-JAN-20 09:39:00 (PST-8)
Location: LARKSPUR
Flood cause: Heavy Rain
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Law Enforcement

Roadway flooding on US-101 S and Tamalpais Dr off ramp.

Flood in SAN FRANCISCO, CALIFORNIA
From 16-JAN-20 09:15:00 to 16-JAN-20 09:45:00 (PST-8)
Location: SAN FRANCISCO
Flood cause: Heavy Rain
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Law Enforcement

Roadway flooding on I-280 N and Mariposa St off ramp. Right lane and off ramp under water.

Flood in ALAMEDA, CALIFORNIA
From 16-JAN-20 09:18:00 to 16-JAN-20 09:48:00 (PST-8)
Location: PIEDMONT
Flood cause: Heavy Rain
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Law Enforcement

Roadway flooding at 3601 Telegraph Ave near Oakland, 1 1/2 feet of water in lanes.

Flood in SAN MATEO, CALIFORNIA
From 16-JAN-20 09:23:00 to 16-JAN-20 09:53:00 (PST-8)
Location: BELMONT
Flood cause: Heavy Rain
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Law Enforcement

Roadway flooding on I-280 N and SR-92 connector. Water caused 1 vehicle to slide but were able to correct and continue.

Flood in CONTRA COSTA, CALIFORNIA
From 16-JAN-20 09:31:00 to 16-JAN-20 10:01:00 (PST-8)
Location: MARTINEZ
Flood cause: Heavy Rain
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Law Enforcement

Roadway flooding at SR-4 W and Alhambra Ave off ramp. Flooding across entire slow lane.

Flood in ALAMEDA, CALIFORNIA
From 16-JAN-20 09:32:00 to 16-JAN-20 10:02:00 (PST-8)
Location: OAKLAND
Flood cause: Heavy Rain
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Law Enforcement

Roadway flooding at I-580 W and Coolidge Ave off ramp. Number 1 lane flooded from Coolidge to Grand.

Flood in SAN FRANCISCO, CALIFORNIA
From 16-JAN-20 09:35:00 to 16-JAN-20 10:05:00 (PST-8)
Location: OCEAN VIEW
Flood cause: Heavy Rain
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Law Enforcement

Roadway flooding at I-280 S and Cesar Chavez St W on ramp. Vehicles swerving into left lane.

Flood in SAN MATEO, CALIFORNIA
From 16-JAN-20 09:35:00 to 16-JAN-20 10:05:00 (PST-8)
Location: COLMA
Flood cause: Heavy Rain
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Law Enforcement

Foot and a half of water on off ramp of I-280 S and Eastmoor Ave, vehicle stuck in water.

Flood in ALAMEDA, CALIFORNIA
From 16-JAN-20 09:45:00 to 16-JAN-20 10:15:00 (PST-8)
Location: EMERYVILLE
Flood cause: Heavy Rain
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Law Enforcement

Roadway flooding at I-580 W and W MacArthur Blvd on ramp. Approx 1 foot of water across on ramp.

Flood in SANTA CRUZ, CALIFORNIA
From 16-JAN-20 10:08:00 to 16-JAN-20 10:38:00 (PST-8)
Location: SCOTTS VLY
Flood cause: Heavy Rain
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Law Enforcement

Roadway flooding at SR-17 N near Mt Hermon Rd.

Flood in SAN MATEO, CALIFORNIA
From 16-JAN-20 10:09:00 to 16-JAN-20 10:39:00 (PST-8)
Location: HENDERSON
Flood cause: Heavy Rain
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Law Enforcement

Roadway flooding at SR-84 and University Ave on ramp, slow lane flooded.

Flood in SANTA CRUZ, CALIFORNIA
From 16-JAN-20 10:12:00 to 16-JAN-20 10:42:00 (PST-8)
Location: BROOKDALE
Flood cause: Heavy Rain
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Law Enforcement

Roadway flooding at Sr-9 and Mill Street.

Flood in SONOMA, CALIFORNIA
From 16-JAN-20 10:21:00 to 16-JAN-20 10:51:00 (PST-8)
Location: LARKFIELD
Flood cause: Heavy Rain
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Law Enforcement

Roadway flooding on Chalk Hill Rd at Spurgeon.

Flood in SAN FRANCISCO, CALIFORNIA
From 16-JAN-20 10:23:00 to 16-JAN-20 10:53:00 (PST-8)
Location: SAN FRANCISCO
Flood cause: Heavy Rain
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Law Enforcement

Roadway flooding at I-280 N and Mariposa St off ramp. Approx 2 feet of water in lanes.

Flood in ALAMEDA, CALIFORNIA
From 16-JAN-20 10:24:00 to 16-JAN-20 10:54:00 (PST-8)
Location: ELMHURST
Flood cause: Heavy Rain
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Public

Roadway flooding at I-580 W and Edwards Ave on ramp. Lots of water in right lane.

Flood in SAN MATEO, CALIFORNIA
From 16-JAN-20 10:38:00 to 16-JAN-20 11:08:00 (PST-8)
Location: LOMITA PARK
Flood cause: Heavy Rain
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Law Enforcement

Roadway flooding at I-280 N and Millbrae Ave off ramp.

Flood in ALAMEDA, CALIFORNIA
From 16-JAN-20 10:40:00 to 16-JAN-20 11:10:00 (PST-8)
Location: OAKLAND
Flood cause: Heavy Rain
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Law Enforcement

Roadway flooding at WB-580 and Coolidge, slow lane flooded.

Flood in ALAMEDA, CALIFORNIA
From 16-JAN-20 10:52:00 to 16-JAN-20 11:22:00 (PST-8)
Location: EMERYVILLE
Flood cause: Heavy Rain
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Law Enforcement

Roadway flooding at I-580 W and SR-24 E. Lanes totally flooded.

Flood in ALAMEDA, CALIFORNIA
From 16-JAN-20 10:53:00 to 16-JAN-20 11:23:00 (PST-8)
Location: EMERYVILLE
Flood cause: Heavy Rain
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Law Enforcement

Roadway flooding at SR-24 W and Broadway Ave off ramp, approx 1 1/2 ft deep.

Flood in SANTA CLARA, CALIFORNIA
From 16-JAN-20 10:58:00 to 16-JAN-20 11:28:00 (PST-8)
Location: BURBANK
Flood cause: Heavy Rain
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Law Enforcement

Roadway flooding at SR-87 S and Taylor St off ramp.

Flood in ALAMEDA, CALIFORNIA
From 16-JAN-20 10:59:00 to 16-JAN-20 11:29:00 (PST-8)
Location: ALAMEDA
Flood cause: Heavy Rain
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Law Enforcement

Roadway flooding at I-880 N and Broadway off ramp.

Flood in MONTEREY, CALIFORNIA
From 16-JAN-20 10:59:00 to 16-JAN-20 11:29:00 (PST-8)
Location: HALL
Flood cause: Heavy Rain
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Law Enforcement

Four to six inches of water running across the road at Johnson and Hall.

Flood in SAN FRANCISCO, CALIFORNIA
From 16-JAN-20 11:02:00 to 16-JAN-20 11:32:00 (PST-8)
Location: SAN FRANCISCO
Flood cause: Heavy Rain
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Public

Video on twitter showing flooding on Scott and Fell St in San Francisco.

Flood in CONTRA COSTA, CALIFORNIA
From 16-JAN-20 11:09:00 to 16-JAN-20 11:39:00 (PST-8)
Location: SAN RAMON
Flood cause: Heavy Rain
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Law Enforcement

Roadway flooding at I-680 S and Crow Canyon Rd off ramp. Vehicles hydroplaning.

Flood in ALAMEDA, CALIFORNIA
From 16-JAN-20 11:27:00 to 16-JAN-20 11:57:00 (PST-8)
Location: OAKLAND
Flood cause: Heavy Rain
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Law Enforcement

Roadway flooding at I-580 W and Coolidge Ave off ramp.

Flood in ALAMEDA, CALIFORNIA
From 16-JAN-20 11:28:00 to 16-JAN-20 11:58:00 (PST-8)
Location: BAUMBERG
Flood cause: Heavy Rain
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Law Enforcement

Roadway flooding at SR-92 E and Hesperian Blvd off ramp.

Flood in SAN MATEO, CALIFORNIA
From 16-JAN-20 11:31:00 to 16-JAN-20 12:01:00 (PST-8)
Location: BAYSHORE
Flood cause: Heavy Rain
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Law Enforcement

Roadway flooding at US-101 S and Grand Ave off ramp.

Flood in SAN MATEO, CALIFORNIA
From 16-JAN-20 11:36:00 to 16-JAN-20 12:06:00 (PST-8)
Location: ATHERTON
Flood cause: Heavy Rain
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Law Enforcement

Roadway flooding on US-101 S and Marsh Rd off ramp.

Flood in SANTA CLARA, CALIFORNIA
From 16-JAN-20 11:46:00 to 16-JAN-20 12:16:00 (PST-8)
Location: SAN JOSE
Flood cause: Heavy Rain
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Law Enforcement

Roadway flooding on SR-87 N and I-280 connector. Standing water in north bound and south bound lanes.

Flood in SANTA CLARA, CALIFORNIA
From 16-JAN-20 11:58:00 to 16-JAN-20 12:28:00 (PST-8)
Location: CAMPBELL
Flood cause: Heavy Rain
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Law Enforcement

Roadway flooding at SR-17 S and Hamilton Ave off ramp.

Flood in SANTA CLARA, CALIFORNIA
From 16-JAN-20 12:13:00 to 16-JAN-20 12:43:00 (PST-8)
Location: LOS ALTOS
Flood cause: Heavy Rain
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Law Enforcement

Roadway flooding at I-280 N and Magdalena Ave off ramp. Significant flooding on the off ramp.

Flood in SANTA CLARA, CALIFORNIA
From 16-JAN-20 12:34:00 to 16-JAN-20 13:04:00 (PST-8)
Location: EVERGREEN
Flood cause: Heavy Rain
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Law Enforcement

Roadway flooding at US-101 S and Hellyer Ave on ramp, vehicles hydroplaning.

Flood in SONOMA, CALIFORNIA
From 16-JAN-20 12:46:00 to 16-JAN-20 13:16:00 (PST-8)
Location: VALLEY FORD
Flood cause: Heavy Rain
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Law Enforcement

Roadway flooding on SR-1 and Johns Street.

Flood in SANTA CRUZ, CALIFORNIA
From 16-JAN-20 13:02:00 to 16-JAN-20 13:32:00 (PST-8)
Location: MESA VLG
Flood cause: Heavy Rain
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Law Enforcement

Roadway flooding at Paulsen Rd and Green Valley Rd.

Flood in SAN FRANCISCO, CALIFORNIA
From 16-JAN-20 13:26:00 to 16-JAN-20 13:56:00 (PST-8)
Location: SAN FRANCISCO
Flood cause: Heavy Rain
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Law Enforcement

Roadway flooding at US-101 North and I-80 East.

Flood in SAN FRANCISCO, CALIFORNIA
From 16-JAN-20 13:31:00 to 16-JAN-20 14:01:00 (PST-8)
Location: SAN FRANCISCO
Flood cause: Heavy Rain
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Law Enforcement

Roadway flooding at I-280 S and Mariposa St on ramp. Two feet deep flooding in slow lane.

Flood in MONTEREY, CALIFORNIA
From 16-JAN-20 15:24:00 to 16-JAN-20 15:54:00 (PST-8)
Location: SPRECKELS
Flood cause: Heavy Rain
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Law Enforcement

Roadway flooding at S Davis Rd and Foster Rd.

Debris Flow in MARIN, CALIFORNIA
From 16-JAN-20 09:22:00 to 16-JAN-20 09:52:00 (PST-8)
Location: SAUSALITO
Flood cause: Heavy Rain
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Law Enforcement

Mud/dirt/rocks reported on US-101 S and Marin City on ramp. Mud and dirt falling from right hand side.

Hail in SANTA CRUZ, CALIFORNIA
From 16-JAN-20 09:36:00 to 16-JAN-20 09:41:00 (PST-8)
Location: BEN LOMOND
Magnitude: 0.25 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Public

Public reporting hail in Ben Lomond.

Hail in SANTA CLARA, CALIFORNIA
From 16-JAN-20 09:37:00 to 16-JAN-20 09:42:00 (PST-8)
Location: CHEMEKETA PARK
Magnitude: 0.13 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Spotter reported accumulating small hail mixed with rain.

Hail in SANTA CLARA, CALIFORNIA
From 16-JAN-20 09:55:00 to 16-JAN-20 10:00:00 (PST-8)
Location: HOLY CITY
Magnitude: 0.25 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Spotter reported pea sized hail and lightning.

Hail in SANTA CRUZ, CALIFORNIA
From 16-JAN-20 10:11:00 to 16-JAN-20 10:16:00 (PST-8)
Location: SCOTTS VLY
Magnitude: 0.25 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Fire Department/Rescue

Santa Clara County Fire Department tweeted a picture of accumulating hail on Hwy 17 near the summit.

Winter Weather in SANTA CRUZ MOUNTAINS, CALIFORNIA
From 16-JAN-20 10:38:00 to 16-JAN-20 10:58:00 (PST-8)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Snow reported on Mt. Umunhum, road closed to vehicle traffic. One car wiped out in the snow.

Heavy Snow in EAST BAY HILLS AND THE DIABLO RANGE, CALIFORNIA
From 16-JAN-20 11:00:00 to 16-JAN-20 11:30:00 (PST-8)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Law Enforcement

CHP reports heavy snow on SR-130 near the Lick Observatory on Mount Hamilton. Several inches of snow, could end up being 1 foot.

Winter Weather in SANTA CRUZ MOUNTAINS, CALIFORNIA
From 16-JAN-20 11:31:00 to 16-JAN-20 11:51:00 (PST-8)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Snow reported about 8 miles east of Hwy 17 in the Santa Cruz Mountains at approximately 2400 ft.

Strong Wind in SANTA CRUZ MOUNTAINS, CALIFORNIA
From 16-JAN-20 11:58:00 to 16-JAN-20 12:03:00 (PST-8)
Magnitude: 40.00 EG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Law Enforcement

Tree down near Brook Knoll Elementary School on Brook Knoll Dr.

Hail in SAN FRANCISCO, CALIFORNIA
From 16-JAN-20 13:19:00 to 16-JAN-20 13:24:00 (PST-8)
Location: SAN FRANCISCO
Magnitude: 0.13 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Multiple spotters reported small hail in San Francisco, location approximate.

Strong Wind in EAST BAY INTERIOR VALLEYS, CALIFORNIA
From 16-JAN-20 13:27:00 to 16-JAN-20 13:32:00 (PST-8)
Magnitude: 40.00 EG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Law Enforcement

Downed power line partially in roadway.

Hail in ALAMEDA, CALIFORNIA
From 16-JAN-20 13:48:00 to 16-JAN-20 13:53:00 (PST-8)
Location: PIEDMONT
Magnitude: 0.13 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Rice sized hail reported by spotter.

Hail in SAN MATEO, CALIFORNIA
From 16-JAN-20 13:59:00 to 16-JAN-20 14:04:00 (PST-8)
Location: EL GRANADA
Magnitude: 0.25 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Spotter reported pea sized hail mixed with rain around Half Moon Bay.

Strong Wind in SOUTHERN MONTEREY BAY AND BIG SUR COAST, CALIFORNIA
From 16-JAN-20 15:41:00 to 16-JAN-20 15:46:00 (PST-8)
Magnitude: 40.00 EG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Law Enforcement

Tree down across roadway on Scenic Dr at Shepherds Knoll Rd.

Hail in SANTA CRUZ, CALIFORNIA
From 16-JAN-20 15:42:00 to 16-JAN-20 15:47:00 (PST-8)
Location: SANTA CRUZ
Magnitude: 0.25 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Social Media

Video on twitter showing small hail in Santa Cruz.