Alert archive / California / Severe Thunderstorm Warnings in 2021

Severe Thunderstorm Warning 70, NWS Las Vegas, NV

September 9, 2021San Bernardino County, California

NWS Las Vegas, NV issued this severe thunderstorm warning at Sep 9, 2021, 2:31 PM PDT for San Bernardino County, California. It was in force for 59 min. No storm report in the archive falls inside the area while it was in force.

The area

The outline as issued.

The facts

Issued
Sep 9, 2021, 2:31 PM PDT (21:31 UTC)
Expired
Sep 9, 2021, 3:30 PM PDT
In force
59 min
Issued by
NWS Las Vegas, NV
Area
Storm-based polygon
Hail
0.75 in
Wind
60.0 mph

County San Bernardino County, CA

The radar

The Santa Ana Mts radar (KSOX), 131 km from the middle of the area, began a volume at 21:35 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

San Diego, CA (KNKX), launched 12:00Z, 9.5 hours before the alert went out and 185 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 2021-09-09Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 15 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 2021-09-09The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 44 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
15 J/kg
Mixed-layer CIN
-787 J/kg
Mixed-layer LCL
1710 m above ground
0-6 km bulk shear
28 kt
0-1 km storm-relative helicity
44 m²/s²
0-3 km storm-relative helicity
112 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.1

Open this sounding in Storm Lab

The text

As transmitted.

122 
WUUS55 KVEF 092131
SVRVEF
CAC071-092230-
/O.NEW.KVEF.SV.W.0070.210909T2131Z-210909T2230Z/

BULLETIN - IMMEDIATE BROADCAST REQUESTED
Severe Thunderstorm Warning
National Weather Service Las Vegas NV
231 PM PDT Thu Sep 9 2021

The National Weather Service in Las Vegas has issued a

* Severe Thunderstorm Warning for...
  South central San Bernardino County in southern California...

* Until 330 PM PDT.

* At 231 PM PDT, a severe thunderstorm was located near Joshua Tree
  Lake Campground, or near Twentynine Palms, moving northwest at 25
  mph.

  HAZARD...60 mph wind gusts.

  SOURCE...Radar indicated.

  IMPACT...Expect damage to roofs and trees.

* Locations impacted include...
  Twentynine Palms, Yucca Valley, Twentynine Palms Base, Twentynine
  Palms Airport, Amboy, Ludlow, Joshua Tree Lake Campground, Joshua
  Tree, Morongo Valley, Pioneertown and Johnson Valley.

This includes Interstate 40 in California between mile markers 42 and
83.
 
PRECAUTIONARY/PREPAREDNESS ACTIONS...

For your protection move to an interior room on the lowest floor of a
building.

&&

LAT...LON 3410 11660 3414 11647 3426 11644 3432 11648
      3436 11641 3453 11642 3453 11646 3460 11647
      3461 11650 3469 11649 3474 11642 3481 11561
      3403 11560 3403 11600 3412 11605 3412 11626
      3408 11627 3408 11644 3403 11648 3403 11661
TIME...MOT...LOC 2131Z 141DEG 21KT 3416 11617 

HAIL THREAT...RADAR INDICATED
MAX HAIL SIZE...<.75 IN
WIND THREAT...RADAR INDICATED
MAX WIND GUST...60 MPH

$$

BKP
2 follow-up statements
283 
WWUS55 KVEF 092200
SVSVEF

Severe Weather Statement
National Weather Service Las Vegas NV
300 PM PDT Thu Sep 9 2021

CAC071-092230-
/O.CON.KVEF.SV.W.0070.000000T0000Z-210909T2230Z/
San Bernardino CA-
300 PM PDT Thu Sep 9 2021

...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT UNTIL 330 PM PDT
FOR SOUTH CENTRAL SAN BERNARDINO COUNTY...

At 259 PM PDT, a severe thunderstorm was located near Joshua Tree
Lake Campground, or 14 miles northwest of Twentynine Palms, moving
northwest at 20 mph.

HAZARD...60 mph wind gusts.

SOURCE...Radar indicated.

IMPACT...Expect damage to roofs and trees.

Locations impacted include...
Twentynine Palms, Twentynine Palms Base, Twentynine Palms Airport,
Ludlow, Joshua Tree Lake Campground, Joshua Tree, Pioneertown and
Johnson Valley.

This includes Interstate 40 in California between mile markers 45 and
49.
 
PRECAUTIONARY/PREPAREDNESS ACTIONS...

For your protection move to an interior room on the lowest floor of a
building.

&&

LAT...LON 3414 11647 3426 11644 3432 11648 3436 11641
      3453 11642 3453 11646 3460 11647 3461 11650
      3469 11649 3474 11642 3470 11584 3403 11579
      3403 11600 3412 11605 3412 11626 3408 11627
      3411 11638
TIME...MOT...LOC 2159Z 144DEG 19KT 3427 11625 

HAIL THREAT...RADAR INDICATED
MAX HAIL SIZE...<.75 IN
WIND THREAT...RADAR INDICATED
MAX WIND GUST...60 MPH

$$

BKP
229 
WWUS55 KVEF 092225
SVSVEF

Severe Weather Statement
National Weather Service Las Vegas NV
325 PM PDT Thu Sep 9 2021

CAC071-092235-
/O.EXP.KVEF.SV.W.0070.000000T0000Z-210909T2230Z/
San Bernardino CA-
325 PM PDT Thu Sep 9 2021

...THE SEVERE THUNDERSTORM WARNING FOR SOUTH CENTRAL SAN BERNARDINO
COUNTY WILL EXPIRE AT 330 PM PDT...
                
The storm which prompted the warning has weakened below severe
limits, and no longer poses an immediate threat to life or property.
Therefore, the warning will be allowed to expire.

LAT...LON 3414 11647 3426 11644 3432 11648 3436 11641
      3453 11642 3453 11646 3460 11647 3461 11650
      3469 11649 3474 11642 3470 11584 3403 11579
      3403 11600 3412 11605 3412 11626 3408 11627
      3411 11638
TIME...MOT...LOC 2225Z 141DEG 21KT 3438 11635 

$$

BKP

The office that day

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

IssuedProductOfficeCountiesLasted
Sep 9, 1:47 PM PDTSevere Thunderstorm WarningVEFSan Bernardino58 min

Nearby

Severe Thunderstorm Warnings in California, 2021Every severe thunderstorm 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; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.