Alert archive / California / Flash Flood Warnings in 2021

Flash Flood Warning 6, NWS San Francisco Bay Area, CA

January 27, 2021Monterey County, California

NWS San Francisco Bay Area, CA issued this flash flood warning at Jan 27, 2021, 12:03 PM PST for Monterey County, California. It was in force for 3 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 27, 2021, 12:03 PM PST (20:03 UTC)
Expired: Jan 27, 2021, 3:15 PM PST
In force: 3 hr
Issued by: NWS San Francisco Bay Area, CA
Area: Storm-based polygon
Damage threat: Considerable
Flood severity: None

County Monterey County, CA

The radar

The San Francisco radar (KMUX), 82 km from the middle of the area, began a volume at 20:02 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, 8.1 hours before the alert went out and 151 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.

Skew-T log-p

Temperature in red, dew point in green, the mixed-layer parcel dashed.

Hodograph

The wind turning with height, colored by layer: ground to 1 km, 1 to 3 km, 3 to 6 km, 6 to 10 km.

Mixed-layer CAPE: 25 J/kg
Mixed-layer CIN: -15 J/kg
Mixed-layer LCL: 572 m above ground
0-6 km bulk shear: 94 kt
0-1 km storm-relative helicity: -42 m²/s²
0-3 km storm-relative helicity: 139 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0

Open this sounding in Storm Lab

The text

As transmitted.

337 
WGUS56 KMTR 272003
FFWMTR
CAC053-272315-
/O.NEW.KMTR.FF.W.0006.210127T2003Z-210127T2315Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
Flash Flood Warning
National Weather Service San Francisco CA
1203 PM PST Wed Jan 27 2021

The National Weather Service in San Francisco has issued a

* Flash Flood Warning for...
  The River Fire burn area in...
  Northwestern Monterey County in central California...

* Until 315 PM PST.

* At 1203 PM PST, Doppler radar indicated thunderstorms producing 
  heavy rain over the River Fire Burn Area. Flash flooding is 
  ongoing or expected to begin shortly.

Excessive rainfall over the burn area will result in debris flow 
moving through the River Fire burn area. The debris flow can consist 
of rock, mud, vegetation and other loose materials.

  HAZARD...Life threatening flash flooding. Thunderstorms
           producing flash flooding in and around the River Fire
           Burn Area.

  SOURCE...Doppler radar.

  IMPACT...Life threatening flash flooding of areas in and around
           the River Fire Burn Area.

* Some locations that will experience flash flooding include...
  mainly rural areas of Northwestern Monterey County

This is a life threatening situation for people in or near the River 
Fire burn area. Some drainage basins impacted include...Tularcitos 
Creek and Agua Mala Creek

PRECAUTIONARY/PREPAREDNESS ACTIONS...

This is a life-threatening situation.  If you observe movement of 
soils move to higher ground immediately.

&&

LAT...LON 3645 12163 3645 12161 3647 12161 3649 12164
      3652 12160 3657 12169 3660 12169 3660 12165
      3657 12161 3658 12159 3639 12144 3638 12145
      3643 12151 3642 12150 3640 12153 3639 12152
      3637 12152 3637 12153 3643 12158 3642 12160

FLASH FLOOD...RADAR INDICATED
FLASH FLOOD DAMAGE THREAT...CONSIDERABLE

$$

Palmer

The 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 Considerable damage threat	MTR	Sonoma	81 min
Jan 26, 10:22 PM PST	Areal Flood Advisory	MTR	Marin, Napa, Sonoma	4 hr
Jan 26, 10:56 PM PST	Flash Flood Warning Considerable damage threat	MTR	San Mateo, Santa Cruz	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 Considerable damage threat	MTR	Monterey	3 hr
Jan 27, 1:38 AM PST	Flash Flood Warning Considerable damage threat	MTR	Monterey	14 hr
Jan 27, 1:45 AM PST	Flash Flood Warning Considerable damage threat	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, 12:05 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, 2021 Every 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.