Alert archive / California / Flash Flood Warnings in 2017

Flash Flood Warning 91, NWS Las Vegas, NV

August 12, 2017San Bernardino County, California

NWS Las Vegas, NV issued this flash flood warning at Aug 12, 2017, 1:31 PM PDT for San Bernardino 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
Aug 12, 2017, 1:31 PM PDT (20:31 UTC)
Expired
Aug 12, 2017, 4:30 PM PDT
In force
3 hr
Issued by
NWS Las Vegas, NV
Area
Storm-based polygon
Flood severity
None

County San Bernardino County, CA

The radar

The Las Vegas radar (KESX), 134 km from the middle of the area, began a volume at 20:33 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

Las Vegas, NV (KVEF), launched 12:00Z, 8.5 hours before the alert went out and 224 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, Las Vegas, NV at 12:00Z on 2017-08-12Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 845 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, Las Vegas, NV at 12:00Z on 2017-08-12The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 21 square meters per square second.193958Sfc1 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
845 J/kg
Mixed-layer CIN
-148 J/kg
Mixed-layer LCL
2429 m above ground
0-6 km bulk shear
32 kt
0-1 km storm-relative helicity
21 m²/s²
0-3 km storm-relative helicity
13 m²/s²
Significant tornado parameter
0.0
Supercell composite
-0.0

Open this sounding in Storm Lab

The text

As transmitted.

776 
WGUS55 KVEF 122031
FFWVEF
CAC071-122330-
/O.NEW.KVEF.FF.W.0091.170812T2031Z-170812T2330Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
Flash Flood Warning
National Weather Service Las Vegas NV
131 PM PDT SAT AUG 12 2017

The National Weather Service in Las Vegas has issued a

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

* Until 430 PM PDT

* At 129 PM PDT, Doppler radar indicated thunderstorms producing 
  heavy rain across southeastern San Bernardino County. Flash 
  flooding is expected to begin shortly.

* Some locations that will experience flooding include...
  Highway 95 south of mile marker 43.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

LAT...LON 3432 11468 3453 11491 3470 11472 3465 11444
      3462 11444 3461 11443 3460 11443 3459 11444
      3456 11440 3431 11451

$$

AA
2 follow-up statements
226 
WGUS75 KVEF 122158
FFSVEF

Flash Flood Statement
National Weather Service Las Vegas NV
258 PM PDT SAT AUG 12 2017

CAC071-122330-
/O.CON.KVEF.FF.W.0091.000000T0000Z-170812T2330Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
San Bernardino CA-
258 PM PDT SAT AUG 12 2017

...THE FLASH FLOOD WARNING REMAINS IN EFFECT UNTIL 430 PM PDT FOR
EASTERN SAN BERNARDINO COUNTY...

At 257 PM PDT, Doppler radar indicated thunderstorms producing heavy 
rain across southeastern San Bernardino County.  Flash flooding is 
expected to begin shortly.

Some locations that will experience flooding include...
Highway 95 south of Mile Marker 35.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

LAT...LON 3432 11468 3453 11491 3470 11472 3465 11444
      3462 11444 3461 11443 3460 11443 3459 11444
      3456 11440 3431 11451

$$

AA
174 
WGUS75 KVEF 122323
FFSVEF

Flash Flood Statement
National Weather Service Las Vegas NV
423 PM PDT SAT AUG 12 2017

CAC071-122333-
/O.EXP.KVEF.FF.W.0091.000000T0000Z-170812T2330Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
San Bernardino CA-
423 PM PDT SAT AUG 12 2017

...THE FLASH FLOOD WARNING FOR EASTERN SAN BERNARDINO COUNTY WILL
EXPIRE AT 430 PM PDT...

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

LAT...LON 3432 11468 3453 11491 3470 11472 3465 11444
      3462 11444 3461 11443 3460 11443 3459 11444
      3456 11440 3431 11451

$$

AA

The office that day

Everything else NWS Las Vegas, NV issued on the same UTC day.

IssuedProductOfficeCountiesLasted
Aug 11, 5:32 PM PDTFlash Flood WarningVEFSan 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; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.