Alert archive / California / Flash Flood Warnings in 2021
Flash Flood Warning 12, NWS San Francisco Bay Area, CA
NWS San Francisco Bay Area, CA issued this flash flood warning at Oct 24, 2021, 12:27 PM PDT for Napa County, Sonoma County, California. It was in force for 5 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
- Oct 24, 2021, 12:27 PM PDT (19:27 UTC)
- Expired
- Oct 24, 2021, 5:30 PM PDT
- In force
- 5 hr
- Issued by
- NWS San Francisco Bay Area, CA
- Area
- Storm-based polygon
- Damage threat
- Considerable
- Flood severity
- None
Counties Napa County, CA, Sonoma County, CA
The radar
The Sacramento radar (KDAX), 77 km from the middle of the area, began a volume at 19:29 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 12:00Z, 7.5 hours before the alert went out and 93 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
- 0 J/kg
- Mixed-layer CIN
- No buoyant parcel
- Mixed-layer LCL
- 470 m above ground
- 0-6 km bulk shear
- 76 kt
- 0-1 km storm-relative helicity
- 503 m²/s²
- 0-3 km storm-relative helicity
- 702 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 0.0
The text
As transmitted.
548
WGUS56 KMTR 241927
FFWMTR
CAC055-097-242030-
/O.NEW.KMTR.FF.W.0012.211024T1927Z-211024T2030Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
BULLETIN - EAS ACTIVATION REQUESTED
Flash Flood Warning
National Weather Service San Francisco CA
1227 PM PDT Sun Oct 24 2021
The National Weather Service in San Francisco has issued a
* Flash Flood Warning for...
The Glass burn area in...
West Central Napa County in northern California...
East Central Sonoma County in northern California...
* Until 130 PM PDT.
* At 1227 PM PDT, Doppler radar and automated rain gauges indicated
heavy rain falling over the Glass Burn Area. The expected rainfall
rate is 0.75 to 1 inch in 1 hour. Additional rainfall amounts up
to 1 inch are possible in the warned area. Flash flooding is
ongoing or expected to begin shortly.
Excessive rainfall over the burn area will result in debris flow
moving through the Glass Fire 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 Glass Burn Area.
SOURCE...Radar and automated gauges.
IMPACT...Life threatening flash flooding of areas in and around
the Glass Burn Area.
* Some locations that will experience flash flooding include...
Santa Rosa, St. Helena, Calistoga, Deer Park and Angwin.
PRECAUTIONARY/PREPAREDNESS ACTIONS...
This is a life-threatening situation. If you observe movement of
soils move to higher ground immediately.
Turn around, don't drown when encountering flooded roads. Most flood
deaths occur in vehicles.
&&
LAT...LON 3856 12260 3867 12258 3863 12246 3859 12247
3851 12244 3852 12248 3855 12249 3853 12251
3848 12247 3844 12250 3843 12256 3845 12261
3844 12264 3846 12263 3849 12266 3851 12264
3852 12266 3853 12262
FLASH FLOOD...RADAR AND GAUGE INDICATED
FLASH FLOOD DAMAGE THREAT...CONSIDERABLE
EXPECTED RAINFALL...0.75-1 INCH IN 1 HOUR
$$
MTR3 follow-up statements
066
WGUS56 KMTR 242020
FFWMTR
CAC055-097-242230-
/O.EXT.KMTR.FF.W.0012.000000T0000Z-211024T2230Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
BULLETIN - EAS ACTIVATION REQUESTED
Flash Flood Warning
National Weather Service San Francisco CA
120 PM PDT Sun Oct 24 2021
The National Weather Service in San Francisco has extended the
* Flash Flood Warning for...
The Glass burn area in...
West Central Napa County in northern California...
East Central Sonoma County in northern California...
* Until 330 PM PDT.
* At 120 PM PDT, Doppler radar and automated rain gauges indicated
heavy rain falling over the Glass Burn Area. The expected rainfall
rate is 0.75 to 1 inch in 1 hour. Additional rainfall amounts up
to 2 inches are possible in the warned area. Flash flooding is
ongoing or expected to begin shortly.
Excessive rainfall over the burn area will result in debris flow
moving through the Glass Fire burn area. The debris flow can consist
of rock, mud, vegetation and other loose materials.
HAZARD...Life threatening flash flooding. Heavy rain producing
flash flooding in and around the Glass Burn Area.
SOURCE...Radar and automated gauges.
IMPACT...Life threatening flash flooding of areas in and around
the Glass Burn Area.
* Some locations that will experience flash flooding include...
Santa Rosa, St. Helena, Calistoga, Deer Park and Angwin.
PRECAUTIONARY/PREPAREDNESS ACTIONS...
This is a life-threatening situation. If you observe movement of
soils move to higher ground immediately.
Turn around, don't drown when encountering flooded roads. Most flood
deaths occur in vehicles.
&&
LAT...LON 3856 12260 3867 12258 3863 12246 3859 12247
3851 12244 3852 12248 3855 12249 3853 12251
3848 12247 3844 12250 3843 12256 3845 12261
3844 12264 3846 12263 3849 12266 3851 12264
3852 12266 3853 12262
FLASH FLOOD...RADAR AND GAUGE INDICATED
FLASH FLOOD DAMAGE THREAT...CONSIDERABLE
EXPECTED RAINFALL...0.75-1 INCH IN 1 HOUR
$$
MTR054
WGUS56 KMTR 242221
FFWMTR
CAC055-097-250030-
/O.EXT.KMTR.FF.W.0012.000000T0000Z-211025T0030Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
BULLETIN - EAS ACTIVATION REQUESTED
Flash Flood Warning
National Weather Service San Francisco CA
321 PM PDT Sun Oct 24 2021
The National Weather Service in San Francisco has extended the
* Flash Flood Warning for...
The Glass burn area in...
West Central Napa County in northern California...
East Central Sonoma County in northern California...
* Until 530 PM PDT.
* At 321 PM PDT, Doppler radar and automated rain gauges indicated
heavy rain falling over the Glass Burn Area. Between 6 and 9
inches of rain have fallen. The expected rainfall rate is 0.25 to
0.5 inches in 1 hour. Additional rainfall amounts of 1 to 2 inches
are possible in the warned area. Flash flooding is ongoing or
expected to begin shortly. There have been reports of boulders
falling down the slopes in the burn area.
Excessive rainfall over the burn area will result in debris flow
moving through the Glass Fire 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 Glass Burn Area.
SOURCE...Radar and automated gauges.
IMPACT...Life threatening flash flooding of areas in and around
the Glass Burn Area.
* Some locations that will experience flash flooding include...
Santa Rosa, St. Helena, Calistoga, Deer Park and Angwin.
PRECAUTIONARY/PREPAREDNESS ACTIONS...
This is a life-threatening situation. If you observe movement of
soils move to higher ground immediately.
Turn around, don't drown when encountering flooded roads. Most flood
deaths occur in vehicles.
&&
LAT...LON 3856 12260 3867 12258 3863 12246 3859 12247
3851 12244 3852 12248 3855 12249 3853 12251
3848 12247 3844 12250 3843 12256 3845 12261
3844 12264 3846 12263 3849 12266 3851 12264
3852 12266 3853 12262
FLASH FLOOD...RADAR AND GAUGE INDICATED
FLASH FLOOD DAMAGE THREAT...CONSIDERABLE
EXPECTED RAINFALL...0.25-0.5 INCHES IN 1 HOUR
$$
BB448
WGUS76 KMTR 250027
FFSMTR
Flash Flood Statement
National Weather Service San Francisco CA
527 PM PDT Sun Oct 24 2021
CAC055-097-250037-
/O.EXP.KMTR.FF.W.0012.000000T0000Z-211025T0030Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Napa CA-Sonoma CA-
527 PM PDT Sun Oct 24 2021
...FLASH FLOOD WARNING FOR THE GLASS BURN AREA WILL EXPIRE AT 530 PM
PDT THIS AFTERNOON FOR WEST CENTRAL NAPA AND EAST CENTRAL SONOMA
COUNTIES...
The heaviest rain has diminished. Flooding is no longer expected to
pose a threat. Light rain will continue through the evening, so
please continue to heed remaining road closures.
A Flash Flood Watch remains in effect until 1100 PM PDT for a
portion of northern California.
LAT...LON 3856 12260 3867 12258 3863 12246 3859 12247
3851 12244 3852 12248 3855 12249 3853 12251
3848 12247 3844 12250 3843 12256 3845 12261
3844 12264 3846 12263 3849 12266 3851 12264
3852 12266 3853 12262
$$
DKThe office that day
Everything else NWS San Francisco Bay Area, CA issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Oct 24, 5:28 AM PDT | Areal Flood Advisory | MTR | Marin, Napa, Sonoma | 18 hr |
| Oct 24, 7:50 AM PDT | Areal Flood Warning | MTR | Sonoma | 3 hr |
| Oct 24, 10:54 AM PDT | Areal Flood Warning | MTR | Sonoma | 48 hr |
| Oct 24, 12:14 PM PDT | Areal Flood Warning | MTR | Napa, Sonoma | 14 hr |
| Oct 24, 12:28 PM PDT | Flash Flood Warning | MTR | Napa | 62 min |
| Oct 24, 1:35 PM PDT | River Flood Warning | MTR | Napa | 6 hr |
| Oct 24, 1:58 PM PDT | Areal Flood Advisory | MTR | Marin | 9 hr |
| Oct 24, 3:00 PM PDT | Areal Flood Warning | MTR | Marin | 3 hr |
| Oct 24, 3:13 PM PDT | Small Craft Advisory | MTR | 60 hr | |
| Oct 24, 3:23 PM PDT | Areal Flood Warning | MTR | Napa | 3 hr |
| Oct 24, 3:49 PM PDT | Areal Flood Warning | MTR | Sonoma | 11 hr |
| Oct 24, 3:55 PM PDT | Areal Flood Advisory | MTR | Marin | 7 hr |
| Oct 24, 4:15 PM PDT | Areal Flood Advisory | MTR | Alameda, Contra Costa | 10 hr |
| Oct 24, 4:19 PM PDT | Areal Flood Advisory | MTR | City and County of San Francisco, San Mateo, Santa Clara, Santa Cruz | 10 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.