Alert archive / California / Flash Flood Warnings in 2021

Flash Flood Warning 11, 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, 7:05 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, 7:05 PM PST (03:05 UTC)
Expired
Jan 27, 2021, 10:15 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 03:10 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, 3.1 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-pSkew-T log-p diagram, Oakland, CA at 00:00Z on 2021-01-28Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 0 joules per kilogram.LCL10008507005003002001001 km2 km3 km6 km9 km12 km15 km-30°-20°-10°10°20°30°40°
Temperature in red, dew point in green, the mixed-layer parcel dashed.
HodographHodograph, Oakland, CA at 00:00Z on 2021-01-28The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 236 square meters per square second.1939587897117136Sfc1 km3 km6 km9 kmRMLM
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
0 J/kg
Mixed-layer CIN
No buoyant parcel
Mixed-layer LCL
685 m above ground
0-6 km bulk shear
76 kt
0-1 km storm-relative helicity
236 m²/s²
0-3 km storm-relative helicity
163 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0

Open this sounding in Storm Lab

The text

As transmitted.

254 
WGUS56 KMTR 280305
FFWMTR
CAC053-280615-
/O.NEW.KMTR.FF.W.0011.210128T0305Z-210128T0615Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
Flash Flood Warning
National Weather Service San Francisco CA
705 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 1015 PM PST.

* At 705 PM PST, Doppler radar and automated rain gauges indicated 
  heavy rain falling over the River Fire Burn Area. Between 0.5 and 
  0.75 inch of rain has fallen. Flash flooding is 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. Heavy rain producing
           flash flooding in and around the River Fire Burn Area.

  SOURCE...Doppler radar and automated gauges.

  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...

Move away from recently burned areas. Life-threatening flooding of 
creeks, roads and normally dry arroyos is likely. The heavy rains 
will likely trigger rockslides, mudslides and debris flows in steep 
terrain, especially in and around these areas.

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 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 AND GAUGE INDICATED
FLASH FLOOD DAMAGE THREAT...CONSIDERABLE
EXPECTED RAINFALL...0.5-1 INCH IN 1 HOUR 

$$

AS
1 follow-up statement
519 
WGUS76 KMTR 280607
FFSMTR

Flash Flood Statement
National Weather Service San Francisco CA
1007 PM PST Wed Jan 27 2021

CAC053-280617-
/O.EXP.KMTR.FF.W.0011.000000T0000Z-210128T0615Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Monterey CA-
1007 PM PST Wed Jan 27 2021

...FLASH FLOOD WARNING FOR THE RIVER FIRE BURN AREA WILL EXPIRE AT 
1015 PM PST THIS EVENING FOR NORTHWESTERN MONTEREY COUNTY...

The heavy rain has ended. Flooding is no longer expected to pose a 
threat. Additional rain showers are possible through Thursday. 
Please continue to heed remaining road closures.

A Flash Flood Watch remains in effect until 500 PM PST Thursday for 
a portion of western California.

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

$$

AS

The office that day

Everything else NWS San Francisco Bay Area, CA issued on the same UTC day.

IssuedProductOfficeCountiesLasted
Jan 27, 4:02 PM PSTAreal Flood AdvisoryMTRMonterey, San Benito3 hr
Jan 27, 4:19 PM PSTFlash Flood Warning Considerable damage threatMTRMonterey5 hr
Jan 27, 5:28 PM PSTSmall Craft AdvisoryMTR22 hr
Jan 27, 7:02 PM PSTFlash Flood Warning Considerable damage threatMTRMonterey3 hr
Jan 27, 7:32 PM PSTAreal Flood AdvisoryMTRMonterey, San Benito, Santa Clara, Santa Cruz3 hr
Jan 27, 10:39 PM PSTAreal Flood AdvisoryMTRMonterey, San Benito, Santa Clara, Santa Cruz4 hr
Jan 28, 4:33 AM PSTAreal Flood AdvisoryMTRMonterey, San Benito, Santa Clara, Santa Cruz11 hr
Jan 28, 4:59 AM PSTAreal Flood WarningMTRMonterey9 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.