Alert archive / California / Flash Flood Warnings in 2021

Flash Flood Warning 1, NWS San Diego, CA

July 18, 2021San Bernardino County, California

NWS San Diego, CA issued this flash flood warning at Jul 18, 2021, 6:44 PM PDT for San Bernardino County, California. It was in force for 31 min. 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
Jul 18, 2021, 6:44 PM PDT (01:44 UTC)
Expired
Jul 18, 2021, 7:15 PM PDT
In force
31 min
Issued by
NWS San Diego, CA
Area
Storm-based polygon
Damage threat
Considerable
Flood severity
None

County San Bernardino County, CA

The radar

The Santa Ana Mts radar (KSOX), 89 km from the middle of the area, began a volume at 01:47 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
Jul 18, 7:00 PM PDTHEAVY RAIN 1.62 Ese Big Bear City, CAHEAVY RAIN FROM MONSOONAL THUNDERSTORMS WITH 1.60 INCHES OF RAIN MEASURED AT BIG BEAR CITY STATION, 0.29 INCHES OF WHICH FELL IN 5 MINUTES FROM 6:10 PM UNTIL 6:15 PM.

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

The nearest sounding before it

San Diego, CA (KNKX), launched 00:00Z, 1.7 hours before the alert went out and 168 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, San Diego, CA at 00:00Z on 2021-07-19Temperature 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, San Diego, CA at 00:00Z on 2021-07-19The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 62 square meters per square second.19395878Sfc1 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
2265 m above ground
0-6 km bulk shear
29 kt
0-1 km storm-relative helicity
62 m²/s²
0-3 km storm-relative helicity
88 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0

Open this sounding in Storm Lab

The text

As transmitted.

728 
WGUS56 KSGX 190144
FFWSGX
CAC071-190215-
/O.NEW.KSGX.FF.W.0001.210719T0144Z-210719T0215Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
Flash Flood Warning
National Weather Service San Diego CA
644 PM PDT Sun Jul 18 2021

The National Weather Service in San Diego has issued a

* Flash Flood Warning for...
  San Bernardino County in southern California...

* Until 715 PM PDT.

* At 644 PM PDT, Doppler radar indicated thunderstorms producing 
  heavy rain across the warned area. Between 0.75 and 1.25 inches of 
  rain have fallen. Flash flooding is ongoing or expected to begin 
  shortly.

  HAZARD...Life threatening flash flooding. Thunderstorms
           producing flash flooding.

  SOURCE...Doppler radar.

  IMPACT...Life threatening flash flooding of creeks and streams,
           urban areas, highways, streets and underpasses.

* Some locations that will experience flash flooding include...
  Big Bear City, northern Onyx Summit, eastern Lucerne Valley, Big 
  Bear Lake, Baldwin Lake, Hwy 18 Between Baldwin Lake And Lucerne 
  Valley, Hwy 38 Between Onyx Summit And Sugarloaf, Woodlands and 
  Fawnskin.

Additional rainfall amounts of 0.25 to 0.5 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.

A Flash Flood Warning means that flooding is imminent or occurring. 
If you are in the warned area move to higher ground immediately. 
Residents living along streams and creeks should take immediate 
precautions to protect life and property.

&&

LAT...LON 3428 11702 3420 11682 3419 11663 3434 11667
      3440 11697

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

$$

SS
1 follow-up statement
023 
WGUS76 KSGX 190213
FFSSGX

Flash Flood Statement
National Weather Service San Diego CA
713 PM PDT Sun Jul 18 2021

CAC071-190223-
/O.EXP.KSGX.FF.W.0001.000000T0000Z-210719T0215Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
San Bernardino CA-
713 PM PDT Sun Jul 18 2021

...FLASH FLOOD WARNING WILL EXPIRE AT 715 PM PDT THIS EVENING FOR 
SAN BERNARDINO COUNTY...

The heavy rain has ended. Flooding is no longer expected to pose a 
threat. Please continue to heed remaining road closures.

LAT...LON 3428 11702 3420 11682 3419 11663 3434 11667
      3440 11697

$$

SS

The office that day

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

IssuedProductOfficeCountiesLasted
Jul 18, 5:49 PM PDTSpecial Weather StatementSGXSan Diego41 min
Jul 18, 6:12 PM PDTAreal Flood AdvisorySGXSan Bernardino32 min
Jul 18, 6:38 PM PDTAreal Flood AdvisorySGXSan Bernardino52 min

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; local storm reports from the same archive; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.