Alert archive / California / Flash Flood Warnings in 2017

Flash Flood Warning 19, NWS San Diego, CA

August 31, 2017Riverside County, San Bernardino County, California

NWS San Diego, CA issued this flash flood warning at Aug 31, 2017, 3:58 PM PDT for Riverside County, San Bernardino County, California. It was in force for 3 hr. 2 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
Aug 31, 2017, 3:58 PM PDT (22:58 UTC)
Expired
Aug 31, 2017, 7:00 PM PDT
In force
3 hr
Issued by
NWS San Diego, CA
Area
Storm-based polygon
Flood severity
None

Counties Riverside County, CA, San Bernardino County, CA

The radar

The Santa Ana Mts radar (KSOX), 36 km from the middle of the area, began a volume at 22:58 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
Aug 31, 4:41 PM PDTFLOODGlen Avon, CA#3 AND #4 LANES OF HIGHWAY 60 FLOODED WITH APPROXIMATELY 1 FOOT OF WATER.
Aug 31, 4:45 PM PDTFLOOD2 Sw Highgrove, CAFLOODING AND STALLED VEHICLES ALONG 215 AND 60 FREEWAYS IN RIVERSIDE DUE TO HEAVY RAIN.

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 12:00Z, 11.0 hours before the alert went out and 143 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 2017-08-31Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 123 joules per kilogram.LCLLFCEL10008507005003002001001 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 12:00Z on 2017-08-31The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 26 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
123 J/kg
Mixed-layer CIN
-747 J/kg
Mixed-layer LCL
2464 m above ground
0-6 km bulk shear
6 kt
0-1 km storm-relative helicity
26 m²/s²
0-3 km storm-relative helicity
35 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0

Open this sounding in Storm Lab

The text

As transmitted.

642 
WGUS56 KSGX 312258
FFWSGX
CAC065-071-010200-
/O.NEW.KSGX.FF.W.0019.170831T2258Z-170901T0200Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
Flash Flood Warning
National Weather Service San Diego CA
358 PM PDT THU AUG 31 2017

The National Weather Service in San Diego has issued a

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

* Until 700 PM PDT

* At 357 PM PDT, Doppler radar indicated thunderstorms producing
  heavy rain across the warned area. Flash flooding will likely begin
  shortly.

* Some locations that will likely experience flooding include...
  Riverside, San Bernardino, Fontana, Rialto, Rancho Cucamonga,
  Colton, Muscoy, Pedley, Rubidoux, Grand Terrace, Glen Avon and
  Highgrove.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

LAT...LON 3416 11733 3399 11729 3389 11739 3394 11750
      3415 11755 3423 11743

$$

JJT
3 follow-up statements
774 
WGUS76 KSGX 312319
FFSSGX

Flash Flood Statement
National Weather Service San Diego CA
419 PM PDT THU AUG 31 2017

CAC065-071-010200-
/O.CON.KSGX.FF.W.0019.000000T0000Z-170901T0200Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
San Bernardino CA-Riverside CA-
419 PM PDT THU AUG 31 2017

...THE FLASH FLOOD WARNING REMAINS IN EFFECT UNTIL 700 PM PDT FOR SAN
BERNARDINO AND RIVERSIDE COUNTIES...

At 417 PM PDT, Doppler radar indicated thunderstorms producing heavy 
rain across the warned area.  Storm total radar precipitation 
estimates are between 0.50 to 1.50 inches in the past 90 minutes. 
Flash flooding will likely begin shortly if not already occurring.

Some locations that will likely experience flooding include...
Riverside, San Bernardino, Fontana, Rialto, Rancho Cucamonga, Colton,
Muscoy, Pedley, Rubidoux, Grand Terrace, Glen Avon and Highgrove.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

LAT...LON 3416 11733 3399 11729 3389 11739 3394 11750
      3415 11755 3423 11743

$$

JJT
542 
WGUS76 KSGX 010047
FFSSGX

Flash Flood Statement
National Weather Service San Diego CA
547 PM PDT THU AUG 31 2017

CAC065-071-010200-
/O.CON.KSGX.FF.W.0019.000000T0000Z-170901T0200Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
San Bernardino CA-Riverside CA-
547 PM PDT THU AUG 31 2017

...THE FLASH FLOOD WARNING REMAINS IN EFFECT UNTIL 700 PM PDT FOR SAN
BERNARDINO AND RIVERSIDE COUNTIES...

At 546 PM PDT, Doppler radar indicated thunderstorms were weakening 
over the area. However...flash flooding will remain possible through 
7 pm. 

Some locations that will likely experience flooding include...
Riverside, San Bernardino, Fontana, Rialto, Rancho Cucamonga, Colton,
Muscoy, Pedley, Rubidoux, Grand Terrace, Glen Avon and Highgrove.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

LAT...LON 3416 11733 3399 11729 3389 11739 3394 11750
      3415 11755 3423 11743

$$

JJT
411 
WGUS76 KSGX 010154
FFSSGX

Flash Flood Statement
National Weather Service San Diego CA
654 PM PDT THU AUG 31 2017

CAC065-071-010200-
/O.EXP.KSGX.FF.W.0019.000000T0000Z-170901T0200Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
San Bernardino CA-Riverside CA-
654 PM PDT THU AUG 31 2017

...THE FLASH FLOOD WARNING FOR SAN BERNARDINO AND RIVERSIDE COUNTIES
WILL EXPIRE AT 700 PM PDT...

The heavy rain has ended. Flooding is no longer expected to pose a
threat.

LAT...LON 3416 11733 3399 11729 3389 11739 3394 11750
      3415 11755 3423 11743

$$

Maxwell

The office that day

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

IssuedProductOfficeCountiesLasted
Aug 31, 1:38 PM PDTAreal Flood AdvisorySGXSan Diego3 hr
Aug 31, 2:11 PM PDTAreal Flood AdvisorySGXRiverside3 hr
Aug 31, 2:25 PM PDTSevere Thunderstorm WarningSGXRiverside65 min
Aug 31, 3:04 PM PDTSevere Thunderstorm WarningSGXRiverside56 min
Aug 31, 3:35 PM PDTSevere Thunderstorm WarningSGXRiverside, San Bernardino55 min
Aug 31, 3:36 PM PDTAreal Flood AdvisorySGXOrange, Riverside, San Bernardino3 hr

Nearby

Flash Flood Warnings in California, 2017Every flash flood warning in 2017

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.