Alert archive / California / Flash Flood Warnings in 2021
Flash Flood Warning 13, NWS San Francisco Bay Area, CA
NWS San Francisco Bay Area, CA issued this flash flood warning at Oct 24, 2021, 12:28 PM PDT for Napa County, California. It was in force for 62 min. 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, 12:28 PM PDT (19:28 UTC)
- Expired
- Oct 24, 2021, 1:30 PM PDT
- In force
- 62 min
- Issued by
- NWS San Francisco Bay Area, CA
- Area
- Storm-based polygon
- Flood severity
- None
County Napa County, CA
The radar
The Sacramento radar (KDAX), 54 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 101 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.
420
WGUS56 KMTR 241928
FFWMTR
CAC055-242030-
/O.NEW.KMTR.FF.W.0013.211024T1928Z-211024T2030Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
BULLETIN - EAS ACTIVATION REQUESTED
Flash Flood Warning
National Weather Service San Francisco CA
1228 PM PDT Sun Oct 24 2021
The National Weather Service in San Francisco has issued a
* Flash Flood Warning for...
The Hennessey portion of the LNU Lightning Complex burn area in...
Central Napa County in northern California...
* Until 130 PM PDT.
* At 1228 PM PDT, Doppler radar and automated rain gauges indicated
heavy rain falling over the Hennessey portion of the LNU Lightning
Complex 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 Hennessey portion of the LNU Lightning Complex
burn area. The debris flow can consist of rock, mud, vegetation and
other loose materials.
HAZARD...Flash flooding caused by heavy rain in and around the
Hennessey portion of the LNU Lightning Complex Burn
Area.
SOURCE...Radar and automated gauges.
IMPACT...Flooding of areas in and around the Hennessey portion
of the LNU Lightning Complex Burn Area.
* Some locations that will experience flash flooding include...
mainly rural areas of Central Napa County
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 3886 12239 3884 12229 3868 12220 3863 12220
3868 12228 3861 12231 3852 12221 3851 12223
3849 12213 3856 12219 3857 12213 3832 12206
3847 12232 3865 12239 3868 12257 3880 12238
3863 12231 3875 12230
FLASH FLOOD...RADAR AND GAUGE INDICATED
EXPECTED RAINFALL...0.75-1 INCH IN 1 HOUR
$$
MTR1 follow-up statement
662
WGUS76 KMTR 242025
FFSMTR
Flash Flood Statement
National Weather Service San Francisco CA
125 PM PDT Sun Oct 24 2021
CAC055-242035-
/O.EXP.KMTR.FF.W.0013.000000T0000Z-211024T2030Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Napa CA-
125 PM PDT Sun Oct 24 2021
...FLASH FLOOD WARNING FOR THE HENNESSEY PORTION OF THE LNU
LIGHTNING COMPLEX BURN AREA WILL EXPIRE AT 130 PM PDT THIS AFTERNOON
FOR CENTRAL NAPA COUNTY...
Flooding is no longer expected to pose a threat. Please continue to
heed remaining road closures.
LAT...LON 3886 12239 3884 12229 3868 12220 3863 12220
3868 12228 3861 12231 3852 12221 3851 12223
3849 12213 3856 12219 3857 12213 3832 12206
3847 12232 3865 12239 3868 12257 3880 12238
3863 12231 3875 12230
$$
MTRThe 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, 12:27 PM PDT | Flash Flood Warning | MTR | Napa, Sonoma | 5 hr |
| 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.