Alert archive / California / Severe Thunderstorm Warnings in 2020

Severe Thunderstorm Warning 13, NWS Las Vegas, NV

August 22, 2020San Bernardino County, California

NWS Las Vegas, NV issued this severe thunderstorm warning at Aug 22, 2020, 2:00 PM PDT for San Bernardino County, California. It was in force for 45 min. 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 22, 2020, 2:00 PM PDT (21:00 UTC)
Expired: Aug 22, 2020, 2:45 PM PDT
In force: 45 min
Issued by: NWS Las Vegas, NV
Area: Storm-based polygon
Hail: 1.0 in
Wind: 60.0 mph

County San Bernardino County, CA

The radar

The Las Vegas radar (KESX), 61 km from the middle of the area, began a volume at 21:00 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

Time	Report	Where	Remark
Aug 22, 2:15 PM PDT	HAIL 0.75	Mountain Pass, CA	REPORTS OF DIME SIZE HAIL AT MOUNTAIN PASS.
Aug 22, 2:15 PM PDT	HAIL 1.75	Mountain Pass, CA	HAIL JUST UNDER GOLF BALL SIZE REPORTED AT MOUNTAIN PASS ON I-15. DAMAGE TO CARS AND BROKEN WINDSHIELDS REPORTED. HAIL ACCUMULATING ON HIGHWAY SEVERAL INCHES DEEP IN PLACES, CAUSING SLICK ICY ROADS AND TRAVEL ISSUES.

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

The nearest sounding before it

Las Vegas, NV (KVEF), launched 12:00Z, 9.0 hours before the alert went out and 100 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-p

Temperature in red, dew point in green, the mixed-layer parcel dashed.

Hodograph

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: 424 J/kg
Mixed-layer CIN: -402 J/kg
Mixed-layer LCL: 2877 m above ground
0-6 km bulk shear: 14 kt
0-1 km storm-relative helicity: -22 m²/s²
0-3 km storm-relative helicity: 15 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0

Open this sounding in Storm Lab

The text

As transmitted.

436 
WUUS55 KVEF 222100
SVRVEF
CAC071-222145-
/O.NEW.KVEF.SV.W.0013.200822T2100Z-200822T2145Z/

BULLETIN - IMMEDIATE BROADCAST REQUESTED
Severe Thunderstorm Warning
National Weather Service Las Vegas NV
200 PM PDT Sat Aug 22 2020

The National Weather Service in Las Vegas has issued a

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

* Until 245 PM PDT.

* At 159 PM PDT, a severe thunderstorm was located over Mountain
  Pass, or 11 miles southwest of Primm, and is nearly stationary.

  HAZARD...60 mph wind gusts and quarter size hail.

  SOURCE...Radar indicated.

  IMPACT...Hail damage to vehicles is expected. Expect wind damage 
           to roofs and trees.

* Locations impacted include...
  Mountain Pass and Nipton And Ivanpah Roads. 

This includes Interstate 15 in California between mile markers 164
and 180.
 
PRECAUTIONARY/PREPAREDNESS ACTIONS...

Prepare immediately for large hail and damaging winds. People outside
should move immediately to shelter inside a strong building. Stay
away from windows.

Continuous cloud to ground lightning is occurring with this storm. 
Move indoors immediately. Lightning is one of nature's leading 
killers. Remember, if you can hear thunder, you are close enough to 
be struck by lightning.

&&

LAT...LON 3558 11553 3547 11535 3530 11544 3546 11571
TIME...MOT...LOC 2059Z 035DEG 1KT 3547 11550 

HAIL...1.00IN
WIND...60MPH
 
$$

Morgan

2 follow-up statements

864 
WWUS55 KVEF 222122
SVSVEF

Severe Weather Statement
National Weather Service Las Vegas NV
222 PM PDT Sat Aug 22 2020

CAC071-222145-
/O.CON.KVEF.SV.W.0013.000000T0000Z-200822T2145Z/
San Bernardino CA-
222 PM PDT Sat Aug 22 2020

...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT UNTIL 245 PM PDT
FOR NORTH CENTRAL SAN BERNARDINO COUNTY...

At 220 PM PDT, a severe thunderstorm was located over Mountain Pass, 
or 12 miles southwest of Primm, and is nearly stationary. This storm 
has had very clear radar indications of hail, and may be producing 
gusty winds and heavy rain as well.

HAZARD...60 mph wind gusts and quarter size hail.

SOURCE...Radar indicated.

IMPACT...Hail damage to vehicles is expected. Expect wind damage to 
         roofs and trees.

Locations impacted include...
Mountain Pass and Nipton And Ivanpah Roads. 

This includes Interstate 15 in California between mile markers 164
and 180.
 
PRECAUTIONARY/PREPAREDNESS ACTIONS...

Prepare immediately for large hail and damaging winds. People outside
should move to a shelter, inside a strong building and away from
windows.

Continuous cloud to ground lightning is occurring with this storm.
Move indoors immediately. Lightning is one of nature's leading
killers. Remember, if you can hear thunder, you are close enough to
be struck by lightning.

&&

LAT...LON 3558 11553 3547 11535 3530 11544 3546 11571
TIME...MOT...LOC 2120Z 035DEG 1KT 3547 11550 

HAIL...1.00IN
WIND...60MPH
 
$$

Morgan

260 
WWUS55 KVEF 222137
SVSVEF

Severe Weather Statement
National Weather Service Las Vegas NV
237 PM PDT Sat Aug 22 2020

CAC071-222145-
/O.EXP.KVEF.SV.W.0013.000000T0000Z-200822T2145Z/
San Bernardino CA-
237 PM PDT Sat Aug 22 2020

...THE SEVERE THUNDERSTORM WARNING FOR NORTH CENTRAL SAN BERNARDINO
COUNTY WILL EXPIRE AT 245 PM PDT...
                
The storm over Mountain Pass has weakened slightly. Therefore, the 
warning will be allowed to expire. However, lots of hail and rain 
fell on Interstate 15, so driving conditions will continue to be 
dangerous until the road dries.

LAT...LON 3558 11553 3547 11535 3530 11544 3546 11571
TIME...MOT...LOC 2135Z 035DEG 1KT 3547 11550 

$$

Morgan

The office that day

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

Issued	Product	Office	Counties	Lasted
Aug 22, 4:07 PM PDT	Flash Flood Warning Considerable damage threat	VEF	San Bernardino	3 hr

Nearby

Severe Thunderstorm Warnings in California, 2020 Every severe thunderstorm warning in 2020

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.