Alert archive / California / Areal Flood Warnings in 2021

Areal Flood Warning 1, NWS Eureka, CA

October 24, 2021Lake County, Mendocino County, California

NWS Eureka, CA issued this areal flood warning at Oct 24, 2021, 10:28 AM PDT for Lake County, Mendocino County, California. It was in force for 8 hr. 1 report came from inside the area while it was in force.

The area

The outline as issued, with what was reported inside it.

The facts

Issued
Oct 24, 2021, 10:28 AM PDT (17:28 UTC)
Expired
Oct 24, 2021, 6:00 PM PDT
In force
8 hr
Issued by
NWS Eureka, CA
Area
Storm-based polygon
Flood severity
None

Counties Lake County, CA, Mendocino County, CA

The radar

The Beale AFB radar (KBBX), 103 km from the middle of the area, began a volume at 17:28 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.

What was reported inside it

TimeReportWhereRemark
Oct 24, 5:17 PM PDTHEAVY RAIN 8.032 Nnw Cobb, CATRAINED SPOTTER REPORTS A 24-HOUR TOTAL FROM 5 P.M. ON 10/23 TO 5 P.M. ON 10/24 OF 8.03 INCHES. ALSO REPORTS STREAMS AT THE TOPS OF THEIR BANKS IN THE AREA AND A TREE DOWN ON LOCH LOMOND RD.

Local storm reports filed while the alert was in force, from inside its polygon or its counties.

The nearest sounding before it

Oakland, CA (KOAK), launched 12:00Z, 5.5 hours before the alert went out and 156 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 12:00Z on 2021-10-24Temperature 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 12:00Z on 2021-10-24The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 503 square meters per square second.1939587897Sfc1 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
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

Open this sounding in Storm Lab

The text

As transmitted.

239 
WGUS46 KEKA 241728
FLWEKA

BULLETIN - IMMEDIATE BROADCAST REQUESTED
Flood Warning
National Weather Service Eureka CA
1028 AM PDT Sun Oct 24 2021

.A strong atmospheric river is bringing heavy rain to 
Lake county and this will continue through much of the day.

CAC033-045-242300-
/O.NEW.KEKA.FA.W.0001.211024T1728Z-211024T2300Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Lake CA-Mendocino CA-
1028 AM PDT Sun Oct 24 2021

The National Weather Service in Eureka has issued a

* Flood Warning for Urban area and small stream in...
  Lake County in central California...
  Southeastern Mendocino County in northwestern California...

* Until 400 PM PDT.

* At 1028 AM PDT, Doppler radar and automated rain gauges indicated 
  heavy rain. Flooding is ongoing or expected to begin shortly in 
  the warned area. Between 2 and 5 inches of rain have fallen.

* Some locations that will experience flooding include...
  Lakeport, Clear Lake, Middletown, Upper Lake and much of rural 
  Lake county

Additional rainfall amounts of 1 to 2 inches are possible in the 
warned area.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Turn around, don't drown when encountering flooded roads. Most flood 
deaths occur in vehicles.

&&

LAT...LON 3929 12304 3941 12312 3944 12274 3938 12278
      3936 12274 3928 12276 3921 12266 3921 12253
      3914 12247 3906 12249 3893 12235 3890 12242
      3882 12237 3878 12241 3877 12240 3867 12263
      3886 12280 3885 12290 3897 12304 3905 12309

$$

MKK
2 follow-up statements
002 
WGUS46 KEKA 242232
FLWEKA

BULLETIN - IMMEDIATE BROADCAST REQUESTED
Flood Warning
National Weather Service Eureka CA
332 PM PDT Sun Oct 24 2021

CAC033-045-250100-
/O.EXT.KEKA.FA.W.0001.000000T0000Z-211025T0100Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Lake CA-Mendocino CA-
332 PM PDT Sun Oct 24 2021

The National Weather Service in Eureka has extended the

* Flood Warning for Urban area and small stream in...
  Lake County in central California...
  Southeastern Mendocino County in northwestern California...

* Until 600 PM PDT.

* At 332 PM PDT, Between 4 and 7 inches of rain has fallen across 
  Lake County, with the highest amounts in southern portions near 
  Cobb and Hidden Valley Lake. Rain rates have lessened 
  substantially from earlier today, but moderate to heavy rain will 
  continue, especially in southern portions of the county for 
  another couple of hours.

* Thus far mainly minor flooding has occurred in areas of poor 
  drainage, resulting in some standing water near storm drains. 
  Streams may continue to rise until the rain tapers to showers this 
  evening, resulting in some flooding, which may result in some 
  localized road closures.

* Some locations that will experience flooding include...
  mainly rural areas of Lake and Southeastern Mendocino Counties

Additional rainfall amounts of 0.5 to 1.5 inches are possible in the 
warned area.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Turn around, don't drown when encountering flooded roads. Most flood 
deaths occur in vehicles.

In hilly terrain there are hundreds of low water crossings which are 
potentially dangerous in heavy rain. Do not attempt to cross flooded 
roads. Find an alternate route.

Please report observed flooding to local emergency services or law 
enforcement and request they pass this information to the National 
Weather Service when you can do so safely.

&&

LAT...LON 3929 12304 3941 12312 3944 12274 3938 12278
      3936 12274 3928 12276 3921 12266 3921 12253
      3914 12247 3906 12249 3893 12235 3890 12242
      3882 12237 3878 12241 3877 12240 3867 12263
      3886 12280 3885 12290 3897 12304 3905 12309

$$

AD
530 
WGUS86 KEKA 250107
FLSEKA

Flood Statement
National Weather Service Eureka CA
607 PM PDT Sun Oct 24 2021

CAC033-045-250117-
/O.EXP.KEKA.FA.W.0001.000000T0000Z-211025T0100Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Lake CA-Mendocino CA-
607 PM PDT Sun Oct 24 2021

...THE URBAN AREA AND SMALL STREAM FLOOD WARNING HAS ENDED FOR LAKE 
AND SOUTHEASTERN MENDOCINO COUNTIES...

Light to moderate rain will continue for couple of hours. While 
there will be some areas of standing water, and many creeks are 
running near bankfull, the threat of more widespread flooding 
impacts is ending. Please continue to heed any remaining road 
closures.

LAT...LON 3929 12304 3941 12312 3944 12274 3938 12278
      3936 12274 3928 12276 3921 12266 3921 12253
      3914 12247 3906 12249 3893 12235 3890 12242
      3882 12237 3878 12241 3877 12240 3867 12263
      3886 12280 3885 12290 3897 12304 3905 12309

$$

AD

The office that day

Everything else NWS Eureka, CA issued on the same UTC day.

IssuedProductOfficeCountiesLasted
Oct 24, 4:58 AM PDTAreal Flood AdvisoryEKALake, Mendocino3 hr
Oct 24, 5:48 AM PDTAreal Flood AdvisoryEKALake, Mendocino5 hr
Oct 24, 7:25 AM PDTAreal Flood AdvisoryEKAHumboldt, Trinity4 hr
Oct 24, 8:24 AM PDTAreal Flood AdvisoryEKALake, Mendocino7 hr
Oct 24, 9:06 AM PDTRiver Flood WatchEKAMendocino3 hr
Oct 24, 11:57 AM PDTRiver Flood WarningEKAMendocino16 hr
Oct 24, 3:52 PM PDTRiver Flood WarningEKAMendocino5 hr

Nearby

Areal Flood Warnings in California, 2021Every areal 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; local storm reports from the same archive; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.