Alert archive / California / Flash Flood Warnings in 2021
Flash Flood Warning 2, NWS San Francisco Bay Area, CA
NWS San Francisco Bay Area, CA issued this flash flood warning at Jan 26, 2021, 10:56 PM PST for San Mateo County, Santa Cruz County, California. It was in force for 4 hr. No storm report in the archive falls inside the area while it was in force.
The area
The outline as issued.
The facts
- Issued
- Jan 26, 2021, 10:56 PM PST (06:56 UTC)
- Expired
- Jan 27, 2021, 3:10 AM PST
- In force
- 4 hr
- Issued by
- NWS San Francisco Bay Area, CA
- Area
- Storm-based polygon
- Damage threat
- Considerable
- Flood severity
- None
Counties San Mateo County, CA, Santa Cruz County, CA
The radar
The San Francisco radar (KMUX), 26 km from the middle of the area, began a volume at 06:55 UTC, the scan nearest the moment this went out.
Open the radar archive at this moment
The archived warnings, watches and discussions in force at that minute are drawn over the scan, this one among them.
The nearest sounding before it
Oakland, CA (KOAK), launched 00:00Z, 6.9 hours before the alert went out and 68 km from the middle of its area. This is the routine balloon launch nearest before it, the air the forecaster had in hand, not a measurement taken for the alert.
- Mixed-layer CAPE
- 1 J/kg
- Mixed-layer CIN
- No buoyant parcel
- Mixed-layer LCL
- 863 m above ground
- 0-6 km bulk shear
- 49 kt
- 0-1 km storm-relative helicity
- 118 m²/s²
- 0-3 km storm-relative helicity
- 329 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 0.0
The text
As transmitted.
308
WGUS56 KMTR 270656
FFWMTR
CAC081-087-271245-
/O.NEW.KMTR.FF.W.0002.210127T0656Z-210127T1245Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
BULLETIN - EAS ACTIVATION REQUESTED
Flash Flood Warning
National Weather Service San Francisco CA
1056 PM PST Tue Jan 26 2021
The National Weather Service in San Francisco has issued a
* Flash Flood Warning for...
The CZU Lightning Complex burn area in...
Southeastern San Mateo County in northern California...
Northwestern Santa Cruz County in northern California...
* Until 445 AM PST.
* At 1056 PM PST, Doppler radar and automated rain gauges indicated
heavy rain falling over the CZU Lightning Complex Burn Area.
Between 0.5 and 1 inch of rain has fallen. Flash flooding is
ongoing or expected to begin shortly.
Excessive rainfall over the burn area will result in debris flow
moving through the CZU Lightning Complex burn area. The debris flow
can consist of rock, mud, vegetation and other loose materials.
HAZARD...Life threatening flash flooding. Heavy rain producing
flash flooding in and around the CZU Lightning Complex
Burn Area.
SOURCE...Doppler radar and automated gauges.
IMPACT...Life threatening flash flooding of areas in and around
the CZU Lightning Complex Burn Area.
* Some locations that will experience flash flooding include...
Boulder Creek.
This is a life threatening situation for people in or near the CZU
Lightning Complex burn area. Some drainage basins impacted include...
Butano Creek...Gazos Creek...Waddell Creek...Scott Creek...Big Creek
and Boulder Creek.
Heavy rainfall will cause flash flooding of creeks and streams from
the CZU Lightning Complex burn area downstream. Anyone living or
traveling on roads in the CZU Lightning Complex burn area or along
secondary roads like Swanton Road...Jamison Creek Road...and Hwy 9
from Boulder Creek to Brookdale...should be alert for possible road
problems due to erosion...debris flows...rockfalls and debris.
Roadways and bridges may be washed away in places.
PRECAUTIONARY/PREPAREDNESS ACTIONS...
This is a life-threatening situation. If you observe movement of
soils move to higher ground immediately.
&&
LAT...LON 3714 12234 3720 12235 3727 12231 3725 12222
3718 12214 3713 12213 3714 12215 3711 12211
3704 12209 3702 12211 3703 12213 3706 12214
3707 12212 3708 12214 3707 12214 3703 12220
3711 12227
FLASH FLOOD...RADAR AND GAUGE INDICATED
FLASH FLOOD DAMAGE THREAT...CONSIDERABLE
EXPECTED RAINFALL...2-4 INCHES IN 6 HOURS
$$
RWW2 follow-up statements
103
WGUS76 KMTR 270906
FFSMTR
Flash Flood Statement
National Weather Service San Francisco CA
106 AM PST Wed Jan 27 2021
CAC081-087-271245-
/O.CON.KMTR.FF.W.0002.000000T0000Z-210127T1245Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
San Mateo CA-Santa Cruz CA-
106 AM PST Wed Jan 27 2021
...FLASH FLOOD WARNING FOR THE CZU LIGHTNING COMPLEX BURN AREA
REMAINS IN EFFECT UNTIL 445 AM PST EARLY THIS MORNING FOR
SOUTHEASTERN SAN MATEO AND NORTHWESTERN SANTA CRUZ COUNTIES...
At 106 AM PST, Doppler radar and automated rain gauges indicated
that heavy rain was falling over the CZU Lightning Complex Burn
Area. Between 1 and 2 inches of rain have fallen.
Excessive rainfall over the burn area will result in debris flow
moving through the CZU Lightning Complex burn area. The debris flow
can consist of rock, mud, vegetation and other loose materials.
HAZARD...Life threatening flash flooding. Heavy rain producing
flash flooding in and around the CZU Lightning Complex
Burn Area.
SOURCE...Doppler radar and automated gauges.
IMPACT...Life threatening flash flooding of areas in and around
the CZU Lightning Complex Burn Area.
Some locations that will experience flash flooding include...
Boulder Creek.
This is a life threatening situation for people in or near the CZU
Lightning Complex burn area. Some drainage basins impacted include...
Butano Creek...Gazos Creek...Waddell Creek...Scott Creek...Big Creek
and Boulder Creek.
Heavy rainfall will cause flash flooding of creeks and streams from
the CZU Lightning Complex burn area downstream. Anyone living or
traveling on roads in the CZU Lightning Complex burn area or along
secondary roads like Swanton Road...Jamison Creek Road...and Hwy 9
from Boulder Creek to Brookdale...should be alert for possible road
problems due to erosion...debris flows...rockfalls and debris.
Roadways and bridges may be washed away in places.
PRECAUTIONARY/PREPAREDNESS ACTIONS...
Be especially cautious at night when it is harder to recognize the
dangers of flooding.
This is a life-threatening situation. If you observe movement of
soils move to higher ground immediately.
&&
LAT...LON 3714 12234 3720 12235 3727 12231 3725 12222
3718 12214 3713 12213 3714 12215 3711 12211
3704 12209 3702 12211 3703 12213 3706 12214
3707 12212 3708 12214 3707 12214 3703 12220
3711 12227
FLASH FLOOD...RADAR AND GAUGE INDICATED
FLASH FLOOD DAMAGE THREAT...CONSIDERABLE
EXPECTED RAINFALL...1-3 INCHES IN 4 HOURS
$$
RWW112
WGUS76 KMTR 271110
FFSMTR
Flash Flood Statement
National Weather Service San Francisco CA
310 AM PST Wed Jan 27 2021
CAC081-087-271120-
/O.CAN.KMTR.FF.W.0002.000000T0000Z-210127T1245Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
San Mateo CA-Santa Cruz CA-
310 AM PST Wed Jan 27 2021
...FLASH FLOOD WARNING FOR THE CZU LIGHTNING COMPLEX BURN AREA IS
CANCELLED FOR SOUTHEASTERN SAN MATEO AND NORTHWESTERN SANTA CRUZ
COUNTIES...
The heavy rain has ended. Flooding is no longer expected to pose a
threat. Please continue to heed remaining road closures.
A Flash Flood Watch remains in effect until 400 PM PST Thursday for
the CZU Lightning Complex Burn Area.
LAT...LON 3714 12234 3720 12235 3727 12231 3725 12222
3718 12214 3713 12213 3714 12215 3711 12211
3704 12209 3702 12211 3703 12213 3706 12214
3707 12212 3708 12214 3707 12214 3703 12220
3711 12227
$$
RWWThe office that day
Everything else NWS San Francisco Bay Area, CA issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Jan 26, 9:39 PM PST | Flash Flood Warning | MTR | Sonoma | 81 min |
| Jan 26, 10:22 PM PST | Areal Flood Advisory | MTR | Marin, Napa, Sonoma | 4 hr |
| Jan 26, 11:18 PM PST | Areal Flood Advisory | MTR | Alameda, City and County of San Francisco, San Mateo, Santa Clara | 4 hr |
| Jan 26, 11:46 PM PST | Special Marine Warning | MTR | 14 min | |
| Jan 27, 1:31 AM PST | Flash Flood Warning | MTR | Monterey | 3 hr |
| Jan 27, 1:38 AM PST | Flash Flood Warning | MTR | Monterey | 14 hr |
| Jan 27, 1:45 AM PST | Flash Flood Warning | MTR | Monterey | 3 hr |
| Jan 27, 2:06 AM PST | Special Marine Warning | MTR | 24 min | |
| Jan 27, 2:18 AM PST | Areal Flood Advisory | MTR | Monterey, Santa Cruz | 117 min |
| Jan 27, 2:23 AM PST | Gale Warning | MTR | 3 hr | |
| Jan 27, 2:23 AM PST | Small Craft Advisory | MTR | 55 hr | |
| Jan 27, 5:27 AM PST | Gale Warning | MTR | 21 hr | |
| Jan 27, 12:03 PM PST | Flash Flood Warning | MTR | Monterey | 3 hr |
| Jan 27, 12:05 PM PST | Flash Flood Warning | MTR | Monterey | 3 hr |
| Jan 27, 12:33 PM PST | Flash Flood Warning | MTR | San Mateo, Santa Cruz | 6 hr |
| Jan 27, 12:53 PM PST | Special Marine Warning | MTR | 52 min | |
| Jan 27, 2:11 PM PST | Areal Flood Advisory | MTR | Alameda, Monterey, San Benito, San Mateo, Santa Clara, Santa Cruz | 5 hr |
Nearby
Flash Flood Warnings in California, 2021Every flash flood warning in 2021
Sources
The product and its follow-ups from the Iowa Environmental Mesonet's archive of National Weather Service and Storm Prediction Center text; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.