Alert archive / California / Severe Thunderstorm Warnings in 2026

Severe Thunderstorm Warning 4, NWS Eureka, CA

September 16, 2026Mendocino County, Trinity County, California

NWS Eureka, CA issued this severe thunderstorm warning at Sep 16, 2026, 5:30 PM PDT for Mendocino County, Trinity County, California. It was in force for 45 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 16, 2026, 5:30 PM PDT (00:30 UTC)
Expired: Sep 16, 2026, 6:15 PM PDT
In force: 45 min
Issued by: NWS Eureka, CA
Area: Storm-based polygon
Hail: 1.0 in
Wind: 50.0 mph

Counties Mendocino County, CA, Trinity County, CA

The radar

The Eureka (Bunker Hill) radar (KBHX), 92 km from the middle of the area, began a volume at 00:32 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

Medford/Jackson, OR (KMFR), launched 00:00Z, 0.5 hours before the alert went out and 269 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: 268 J/kg
Mixed-layer CIN: -54 J/kg
Mixed-layer LCL: 2284 m above ground
0-6 km bulk shear: 11 kt
0-1 km storm-relative helicity: 40 m²/s²
0-3 km storm-relative helicity: 88 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0

Open this sounding in Storm Lab

The text

As transmitted.

333 
WUUS56 KEKA 170030
SVREKA
CAC045-105-170115-
/O.NEW.KEKA.SV.W.0004.260917T0030Z-260917T0115Z/

BULLETIN - IMMEDIATE BROADCAST REQUESTED
Severe Thunderstorm Warning
National Weather Service Eureka CA
530 PM PDT Wed Sep 16 2026

The National Weather Service in Eureka has issued a

* Severe Thunderstorm Warning for...
  North Central Mendocino County in northwestern California...
  Southern Trinity County in northwestern California...

* Until 615 PM PDT.

* At 530 PM PDT, a severe thunderstorm was located 15 miles northwest
  of Covelo, moving southwest at 10 mph.

  HAZARD...Quarter size hail.

  SOURCE...Radar indicated.

  IMPACT...Damage to vegetation expected.

* Locations impacted include...
  Mainly rural areas of North Central Mendocino and Southern Trinity
  Counties.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Seek shelter inside a well-built structure and stay away from
windows. This storm is capable of producing large hail.

&&

LAT...LON 4000 12354 4013 12337 4000 12322 3987 12338
      4000 12355
TIME...MOT...LOC 0029Z 50DEG 6KT 4001 12336

HAIL THREAT...RADAR INDICATED
MAX HAIL SIZE...1.00 IN
WIND THREAT...RADAR INDICATED
MAX WIND GUST...<50 MPH

$$

RPA

2 follow-up statements

446 
WWUS56 KEKA 170040
SVSEKA

Severe Weather Statement
National Weather Service Eureka CA
540 PM PDT Wed Sep 16 2026

CAC045-105-170115-
/O.CON.KEKA.SV.W.0004.000000T0000Z-260917T0115Z/
Mendocino CA-Trinity CA-
540 PM PDT Wed Sep 16 2026

...SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT UNTIL 615 PM PDT FOR
NORTH CENTRAL MENDOCINO AND SOUTHERN TRINITY COUNTIES...

At 540 PM PDT, a severe thunderstorm was located 15 miles northwest
of Covelo, moving southwest at 10 mph.

HAZARD...Quarter size hail.

SOURCE...Radar indicated.

IMPACT...Damage to vegetation expected.

Locations impacted include...
  Mainly rural areas of North Central Mendocino and Southern Trinity
  Counties.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Seek shelter inside a well-built structure and stay away from
windows. This storm is capable of producing large hail.

&&

LAT...LON 4000 12354 4012 12338 3998 12324 3987 12338
      4000 12355
TIME...MOT...LOC 0030Z 58DEG 9KT 4001 12337

HAIL THREAT...RADAR INDICATED
MAX HAIL SIZE...1.00 IN
WIND THREAT...RADAR INDICATED
MAX WIND GUST...<50 MPH

$$

RPA

936 
WWUS56 KEKA 170112
SVSEKA

Severe Weather Statement
National Weather Service Eureka CA
612 PM PDT Wed Sep 16 2026

CAC045-105-170122-
/O.EXP.KEKA.SV.W.0004.000000T0000Z-260917T0115Z/
Mendocino CA-Trinity CA-
612 PM PDT Wed Sep 16 2026

...SEVERE THUNDERSTORM WARNING WILL EXPIRE AT 615 PM PDT FOR NORTH
CENTRAL MENDOCINO AND SOUTHERN TRINITY COUNTIES...

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 4000 12354 4012 12338 3998 12324 3987 12338
      4000 12355
TIME...MOT...LOC 0040Z 58DEG 9KT 3999 12340

$$

The office that day

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

Issued	Product	Office	Counties	Lasted
Sep 16, 5:04 PM PDT	Special Weather Statement	EKA	Del Norte	26 min
Sep 16, 5:18 PM PDT	Special Weather Statement	EKA		27 min
Sep 16, 5:36 PM PDT	Special Weather Statement	EKA	Humboldt	39 min
Sep 16, 5:40 PM PDT	Special Weather Statement	EKA	Del Norte	35 min
Sep 16, 6:14 PM PDT	Special Weather Statement	EKA	Mendocino	31 min
Sep 16, 6:32 PM PDT	Special Weather Statement	EKA	Humboldt	28 min
Sep 16, 7:03 PM PDT	Special Weather Statement	EKA	Humboldt	27 min
Sep 17, 2:51 PM PDT	Small Craft Advisory	EKA		6 days
Sep 17, 4:23 PM PDT	Special Weather Statement	EKA	Trinity	37 min

Nearby

Severe Thunderstorm Warnings in California, 2026 Every severe thunderstorm warning in 2026

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.