Alert archive / California / Flash Flood Warnings in 2022

Flash Flood Warning 65, NWS San Diego, CA

September 28, 2022Riverside County, San Bernardino County, California

NWS San Diego, CA issued this flash flood warning at Sep 28, 2022, 4:23 PM PDT for Riverside County, San Bernardino County, California. It was in force for 82 min. 5 reports 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
Sep 28, 2022, 4:23 PM PDT (23:23 UTC)
Expired
Sep 28, 2022, 5:45 PM PDT
In force
82 min
Issued by
NWS San Diego, CA
Area
Storm-based polygon
Damage threat
Considerable
Flood severity
None

Counties Riverside County, CA, San Bernardino County, CA

The radar

The Santa Ana Mts radar (KSOX), 55 km from the middle of the area, began a volume at 23:23 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
Sep 28, 4:30 PM PDTHEAVY RAIN 0.563 Ese Yucaipa, CATRAINED SPOTTER REPORTS STRONG CELL WITH A LOT OF LIGHTNING AND HEAVY RAIN. THE STORM LASTED AROUND 45 MINUTES.
Sep 28, 4:30 PM PDTHEAVY RAIN 1.062 Se Yucaipa, CAMESONET STATION CW1772 YUCAIPA 2 AT CALIMESA IN 1 HOUR DURATION AT 4 PM.
Sep 28, 4:43 PM PDTFLASH FLOOD1 Wnw Calimesa, CACHP REPORTS FLOODING ON INTERSTATE 10 EAST AT THE AT THE COUNTY LINE ROAD EXIT.
Sep 28, 5:08 PM PDTFLASH FLOOD1 Ne Calimesa, CACOUNTY LINE AND BRYANT ROAD INTERSECTION IN YUCAIPA CLOSED DUE TO FLOODING. CARS DRIVING THROUGH THE AREA, ESTIMATED FEW INCHES OVER THE ROADWAY. SOCIAL MEDIA REPORTS OF FLOOD DAMAGE TO INSIDE OF GARAGES AND BACKSIDE OF TWO HOMES IN THE AREA AS WELL. THIS CWOP
Sep 28, 5:18 PM PDTHEAVY RAIN 0.841 Se Yucaipa, CA0.84 INCHES IN 25 MINUTES. 1.06 INCHES IN 1 HOUR.

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

Did it verify

Verified. The Iowa Environmental Mesonet's Cow matched 2 storm reports to this flash flood warning; the first came 20 minutes after it went out.

Cow counts a report within 15 km of the polygon while the warning was in force: a tornado for a tornado warning; hail of 1 inch or more, a gust of 58 mph or more or wind damage for a severe thunderstorm warning; a flash flood report for a flash flood warning.

The nearest sounding before it

San Diego, CA (KNKX), launched 12:00Z, 11.4 hours before the alert went out and 134 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 12:00Z on 2022-09-28Temperature 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°0°10°20°30°40°
Temperature in red, dew point in green, the mixed-layer parcel dashed.
HodographHodograph, San Diego, CA at 12:00Z on 2022-09-28The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 1 square meters per square second.1939Sfc1 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
2402 m above ground
0-6 km bulk shear
8 kt
0-1 km storm-relative helicity
1 m²/s²
0-3 km storm-relative helicity
8 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0

Open this sounding in Storm Lab

The text

As transmitted.

778 
WGUS56 KSGX 282323
FFWSGX
CAC065-071-290045-
/O.NEW.KSGX.FF.W.0065.220928T2323Z-220929T0045Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
Flash Flood Warning
National Weather Service San Diego CA
Issued by National Weather Service Los Angeles/Oxnard CA
423 PM PDT Wed Sep 28 2022

The National Weather Service in San Diego has issued a

* Flash Flood Warning for...
  North Central Riverside County in southern California...
  Southeast San Bernardino County in southern California...

* Until 545 PM PDT.

* At 423 PM PDT, Doppler radar indicated thunderstorms producing 
  heavy rain across the warned area. Flash flooding is ongoing or 
  expected to begin shortly.

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

  SOURCE...Radar.

  IMPACT...Several roadways will likely become flooded and
           impassible. Dangerous flash flooding of creeks and
           streams, urban areas, highways, streets and
           underpasses. Shallow mud and debris flows possible on
           the southwest portion of the El Dorado burn scar.

* Some locations that will experience flash flooding include...
  Interstate 10 around Calimesa, Redlands, Yucaipa, and Beaumont.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

Be aware of your surroundings and do not drive on flooded roads.

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 3402 11724 3404 11726 3411 11700 3403 11692
      3393 11682 3383 11706

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

$$

RK
2 follow-up statements
302 
WGUS76 KSGX 290001
FFSSGX

Flash Flood Statement
National Weather Service San Diego CA
Issued by National Weather Service Los Angeles/Oxnard CA
501 PM PDT Wed Sep 28 2022

CAC065-071-290045-
/O.CON.KSGX.FF.W.0065.000000T0000Z-220929T0045Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Riverside CA-San Bernardino CA-
501 PM PDT Wed Sep 28 2022

...FLASH FLOOD WARNING REMAINS IN EFFECT UNTIL 545 PM PDT THIS 
AFTERNOON FOR WEST CENTRAL RIVERSIDE AND SOUTHWEST SAN BERNARDINO 
COUNTIES...

At 501 PM PDT, Doppler radar is indicating that the thunderstorms 
that produced heavy rain are rapidly weakening. With indications of 
around an inch of rain in less than an hour, ample flooding issues 
likely remain.

HAZARD...Dangerous and potentially damaging flash flooding.

SOURCE...Radar.

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

Some locations that will experience flash flooding include...
Redlands, Yucaipa, Calimesa including Highway 10. 

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

Be aware of your surroundings and do not drive on flooded roads.

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 3402 11724 3404 11726 3411 11700 3403 11692
      3393 11682 3383 11706

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

$$

RK
724 
WGUS76 KSGX 290041
FFSSGX

Flash Flood Statement
National Weather Service San Diego CA
Issued by National Weather Service Los Angeles/Oxnard CA
541 PM PDT Wed Sep 28 2022

CAC065-071-290051-
/O.EXP.KSGX.FF.W.0065.000000T0000Z-220929T0045Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Riverside CA-San Bernardino CA-
541 PM PDT Wed Sep 28 2022

...FLASH FLOOD WARNING WILL EXPIRE AT 545 PM PDT THIS AFTERNOON FOR 
NORTH CENTRAL RIVERSIDE AND SOUTH CENTRAL SAN BERNARDINO COUNTIES...

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

LAT...LON 3402 11724 3404 11726 3411 11700 3403 11692
      3393 11682 3383 11706

$$

JMS

What forecasters said that day

The local office's own words before this flash flood warning went out, as it sent them, from the Iowa Environmental Mesonet's archive of National Weather Service text.

NWS San Diego, CA wrote its last area forecast discussion before this flash flood warning went out at Sep 28, 2:20 PM PDT, 2 hours 3 minutes earlier.

Area forecast discussion, Sep 28, 2:20 PM PDT, 2 hours 3 minutes before
Area Forecast Discussion
National Weather Service San Diego CA
Issued by National Weather Service Los Angeles/Oxnard CA
220 PM PDT Wed Sep 28 2022

.SYNOPSIS...
The weather will turn gradually cooler through Saturday
as high pressure over the Southwest weakens. A shallow marine layer
will bring areas of dense fog to the coastal areas tonight and
Thursday morning. Low clouds and fog will spread into the western
valleys Friday and Saturday as the marine layer deepens.

&&

.DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE...
SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO
COUNTIES...

.SHORT TERM...

Thunderstorms over the mountains and deserts this afternoon will
dissipate this evening. The SPC mesoanalysis showed the precipitable
water jumped to 1.3” over the lower deserts today, fueling
convection with the heat of the day. CAPE values ranged from 500-
1000J/kg over the deserts. Moisture and CAPE decreases tonight and
Thursday with increasingly drier air moving in from the northwest.
Any thunderstorm activity over the mountains tomorrow will be more
isolated.

West of the mountains the return of a shallow marine layer brought
dense fog to the coastal zones, the beaches and the inner coastal
waters. Clouds and fog clung to a some of the Orange County and San
Diego County beaches this afternoon. The marine layer depth won’t
change much tonight so dense fog is likely again Thursday morning.

The marine layer will deepen Thursday night and Friday when a
Catalina Eddy spins up over the coastal waters, sending low clouds
and fog into inland Orange County and the western San Diego County
Valleys Friday and Saturday mornings where dense fog will be most
likely.

The overall trend Friday through Sunday is for cooler weather to
move in from west to east as a 500 mb trough moves across the
Pacific Northwest and northern California. This will bring a drier,
cooler airmass and stronger onshore flow through the weekend.

&&

.AVIATION...
.282045Z…Coast/Valleys…Some low clouds will linger near/just
offshore through this afternoon. Areas of low clouds/fog will
develop again this evening over the coasts and valleys. CIGS likely
after 03z Thu, bases 300-700 FT MSL and tops to near 900 FT MSL. VIS
0-4SM in BR/FG in portions of the coastal valleys and coastal mesas.
Low clouds/fog scatter out between 16-18z Thu.

Mtns/Deserts…Cumulus and CB based near 10000 FT MSL with SCT TSRA
developing in the mountains through 03z Thu, tops near 30-40K FT
MSL.  Gusty and erratic winds as well as heavy downpours expected
near any TSRA. Mostly clear skies then expected after 03z.

&&

.MARINE...
No hazardous marine conditions are expected through Sunday.

&&

.SKYWARN...
Skywarn activation is not requested. However weather spotters are
encouraged to report significant weather conditions.

&&

.SGX WATCHES/WARNINGS/ADVISORIES...
CA...Heat Advisory until 8 PM PDT this evening for Orange
     County Coastal Areas-San Diego County Coastal Areas-San Diego
     County Valleys-Santa Ana Mountains and Foothills.

     Excessive Heat Warning until 8 PM PDT this evening for Coachella
     Valley-Orange County Inland Areas-San Bernardino and
     Riverside County Valleys-The Inland Empire-San Diego County
     Deserts-San Gorgonio Pass Near Banning.

PZ...None.

&&

PUBLIC...Moede
AVIATION/MARINE...Adams

The office that day

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

IssuedProductOfficeCountiesLasted
Sep 28, 7:28 AM PDTDense Fog AdvisorySGXOrange, San Diego3 hr
Sep 28, 1:57 PM PDTAreal Flood AdvisorySGXRiverside, San Bernardino108 min
Sep 28, 2:22 PM PDTAreal Flood AdvisorySGXRiverside, San Diego113 min
Sep 28, 3:31 PM PDTAreal Flood AdvisorySGXRiverside119 min
Sep 28, 3:57 PM PDTAreal Flood AdvisorySGXRiverside, San Bernardino26 min

Nearby

Flash Flood Warnings in California, 2022Every flash flood warning in 2022

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.