Alert archive / California / Severe Thunderstorm Warnings in 2021

Severe Thunderstorm Warning 110, NWS Phoenix, AZ

September 24, 2021Imperial County, California

NWS Phoenix, AZ issued this severe thunderstorm warning at Sep 24, 2021, 7:33 AM PDT for Imperial County, California. It was in force for 42 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 24, 2021, 7:33 AM PDT (14:33 UTC)
Expired
Sep 24, 2021, 8:15 AM PDT
In force
42 min
Issued by
NWS Phoenix, AZ
Area
Storm-based polygon
Hail
0.75 in
Wind
60.0 mph

County Imperial County, CA

The radar

The Yuma radar (KYUX), 69 km from the middle of the area, began a volume at 14:35 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, 2.6 hours before the alert went out and 179 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 2021-09-24Temperature 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°10°20°30°40°
Temperature in red, dew point in green, the mixed-layer parcel dashed.
HodographHodograph, San Diego, CA at 12:00Z on 2021-09-24The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity -36 square meters per square second.1939587897Sfc1 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
1990 m above ground
0-6 km bulk shear
4 kt
0-1 km storm-relative helicity
-36 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.

888 
WUUS55 KPSR 241433
SVRPSR
CAC025-241515-
/O.NEW.KPSR.SV.W.0110.210924T1433Z-210924T1515Z/

BULLETIN - IMMEDIATE BROADCAST REQUESTED
Severe Thunderstorm Warning
National Weather Service Phoenix AZ
733 AM PDT Fri Sep 24 2021

The National Weather Service in Phoenix has issued a

* Severe Thunderstorm Warning for...
  South central Imperial County in southeastern California...

* Until 815 AM PDT.

* At 732 AM PDT, a severe thunderstorm was located near Holtville, or
  15 miles east of Imperial, and is nearly stationary.

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

  SOURCE...Radar indicated.

  IMPACT...Expect damage to roofs, siding, and trees.

* Locations impacted include...
  Holtville, Gordon's Well, Bonds Corner, Alamorio and Heber. 

This includes the following highways...
CA Interstate 8 between mile markers 41 and 74.
CA Route 78 between mile markers 15 and 35.
CA Route 111 between mile markers 5 and 22.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

Large hail and damaging winds and 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.

Torrential rainfall is occurring with this storm, and may lead to
flash flooding. Do not drive your vehicle through flooded roadways.

&&

LAT...LON 3273 11551 3299 11551 3301 11528 3289 11488
      3270 11494 3267 11540
TIME...MOT...LOC 1432Z 309DEG 4KT 3284 11529 

HAIL THREAT...RADAR INDICATED
MAX HAIL SIZE...0.75 IN
WIND THREAT...RADAR INDICATED
MAX WIND GUST...60 MPH

$$

INS
2 follow-up statements
204 
WWUS55 KPSR 241447
SVSPSR

Severe Weather Statement
National Weather Service Phoenix AZ
747 AM PDT Fri Sep 24 2021

CAC025-241515-
/O.CON.KPSR.SV.W.0110.000000T0000Z-210924T1515Z/
Imperial CA-
747 AM PDT Fri Sep 24 2021

...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT UNTIL 815 AM PDT
FOR SOUTH CENTRAL IMPERIAL COUNTY...

At 747 AM PDT, a severe thunderstorm was located near Holtville, or
14 miles northeast of Calexico, moving south at 10 mph.

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

SOURCE...Radar indicated.

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

Locations impacted include...
Holtville, Gordon's Well, Bonds Corner, Alamorio and Heber. 

This includes the following highways...
CA Interstate 8 between mile markers 41 and 74.
CA Route 78 between mile markers 15 and 35.
CA Route 111 between mile markers 5 and 22.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

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.

Torrential rainfall is occurring with this storm, and may lead to
flash flooding. Do not drive your vehicle through flooded roadways.

&&

LAT...LON 3273 11551 3299 11551 3301 11528 3289 11488
      3270 11494 3267 11540
TIME...MOT...LOC 1447Z 005DEG 8KT 3280 11531 

HAIL THREAT...RADAR INDICATED
MAX HAIL SIZE...1.00 IN
WIND THREAT...RADAR INDICATED
MAX WIND GUST...60 MPH

$$

INS
738 
WWUS55 KPSR 241515
SVSPSR

Severe Weather Statement
National Weather Service Phoenix AZ
815 AM PDT Fri Sep 24 2021

CAC025-241525-
/O.EXP.KPSR.SV.W.0110.000000T0000Z-210924T1515Z/
Imperial CA-
815 AM PDT Fri Sep 24 2021

...THE SEVERE THUNDERSTORM WARNING FOR SOUTH CENTRAL IMPERIAL COUNTY
HAS EXPIRED...
                
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 has been allowed to expire.  However gusty
winds and heavy rain are still possible with this thunderstorm.

To report severe weather, contact your nearest law enforcement 
agency. They will relay your report to the National Weather Service 
in Phoenix.

LAT...LON 3273 11551 3299 11551 3301 11528 3289 11488
      3270 11494 3267 11540
TIME...MOT...LOC 1515Z 309DEG 4KT 3278 11528 

$$

INS

The office that day

Everything else NWS Phoenix, AZ issued on the same UTC day.

IssuedProductOfficeCountiesLasted
Sep 24, 7:10 AM PDTSpecial Weather StatementPSRImperial50 min
Sep 24, 7:28 AM PDTAreal Flood AdvisoryPSRImperial46 min
Sep 24, 8:00 AM PDTSpecial Weather StatementPSRImperial45 min
Sep 24, 8:14 AM PDTFlash Flood Warning Considerable damage threatPSRImperial4 hr
Sep 24, 8:18 AM PDTSpecial Weather StatementPSRImperial42 min
Sep 24, 9:03 AM PDTFlash Flood WatchPSRImperial, Riverside, San Bernardino10 hr

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.