Alert archive / California / Special Weather Statements in 2021

Special Weather Statement, NWS Phoenix, AZ

September 9, 2021Riverside County, California

NWS Phoenix, AZ issued this special weather statement at Sep 9, 2021, 4:15 PM PDT for Riverside 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 9, 2021, 4:15 PM PDT (23:15 UTC)
Expired: Sep 9, 2021, 5:00 PM PDT
In force: 45 min
Issued by: NWS Phoenix, AZ
Hail: 0.25 in
Wind: 50

County Riverside County, CA

The radar

The San Diego radar (KNKX), 152 km from the middle of the area, began a volume at 23:18 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, 11.3 hours before the alert went out and 172 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: 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.

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What forecasters said that day

The local office's own words before this special weather statement went out, as it sent them, from the Iowa Environmental Mesonet's archive of National Weather Service text.

NWS Phoenix, AZ wrote its last area forecast discussion before this special weather statement went out at Sep 9, 4:15 PM PDT, 0 minutes earlier.

Area forecast discussion, Sep 9, 4:15 PM PDT, 0 minutes before

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In the hours before

Special weather statement, Sep 9, 1:21 PM PDT, 2 hours 54 minutes before

Special Weather Statement
National Weather Service Phoenix AZ
121 PM PDT Thu Sep 9 2021

CAZ560-561-564-568-092045-
Chuckwalla Mountains CA-Chiriaco Summit CA-Joshua Tree NP West CA-
Joshua Tree NP East CA-
121 PM PDT Thu Sep 9 2021

...A strong thunderstorm will impact portions of Riverside County
through 145 PM PDT...

At 121 PM PDT, Doppler radar was tracking a strong thunderstorm near
Chiriaco Summit, moving northwest at 20 mph.

HAZARD...Wind gusts up to 50 mph.

SOURCE...Radar indicated.

IMPACT...Gusty winds could knock down tree limbs and blow around
         unsecured objects.

Locations impacted include...
Chiriaco Summit and Cottonwood Visitor Center.

This includes CA Interstate 10 between mile markers 85 and 100.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

If outdoors, consider seeking shelter inside a building.

Frequent cloud to ground lightning is occurring with this storm.
Lightning can strike 10 miles away from a thunderstorm. Seek a safe
shelter inside a building or vehicle.

&&

LAT...LON 3371 11547 3369 11548 3369 11545 3368 11544
      3359 11562 3373 11587 3387 11572 3387 11558
TIME...MOT...LOC 2021Z 137DEG 16KT 3371 11561

MAX HAIL SIZE...0.00 IN
MAX WIND GUST...50 MPH

INS

Special weather statement, Sep 9, 1:58 PM PDT, 2 hours 17 minutes before

Special Weather Statement
National Weather Service Phoenix AZ
158 PM PDT Thu Sep 9 2021

CAZ560-561-092130-
Joshua Tree NP West CA-Joshua Tree NP East CA-
158 PM PDT Thu Sep 9 2021

...A strong thunderstorm will impact portions of San Bernardino and
Riverside Counties through 230 PM PDT...

At 157 PM PDT, Doppler radar was tracking a strong thunderstorm near
Cottonwood Visitor Center, or 11 miles northwest of Chiriaco Summit,
moving northwest at 20 mph.

HAZARD...Wind gusts of 50 to 55 mph and pea size hail.

SOURCE...Radar indicated.

IMPACT...Gusty winds could knock down tree limbs and blow around
         unsecured objects. Minor damage to outdoor objects is
         possible.

This storm will remain over mainly rural areas of San Bernardino and
Riverside Counties.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

If outdoors, consider seeking shelter inside a building.

Frequent cloud to ground lightning is occurring with this storm.
Lightning can strike 10 miles away from a thunderstorm. Seek a safe
shelter inside a building or vehicle.

Persons in campgrounds should consider seeking sturdy shelter until
this storm passes.

&&

LAT...LON 3403 11600 3404 11583 3387 11571 3373 11586
      3389 11609 3404 11609 3405 11601
TIME...MOT...LOC 2057Z 138DEG 16KT 3382 11580

MAX HAIL SIZE...0.25 IN
MAX WIND GUST...55 MPH

INS

Special weather statement, Sep 9, 2:31 PM PDT, 1 hour 44 minutes before

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Special weather statement, Sep 9, 3:42 PM PDT, 33 minutes before

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Special weather statement, Sep 9, 4:15 PM PDT, 0 minutes before

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The office that day

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

Issued	Product	Office	Counties	Lasted
Sep 9, 1:21 PM PDT	Special Weather Statement	PSR	Riverside	24 min
Sep 9, 1:29 PM PDT	Severe Thunderstorm Warning	PSR	Riverside	46 min
Sep 9, 1:58 PM PDT	Special Weather Statement	PSR	Riverside	32 min
Sep 9, 2:00 PM PDT	Severe Thunderstorm Warning	PSR	Riverside	45 min
Sep 9, 2:31 PM PDT	Special Weather Statement	PSR	Riverside	29 min
Sep 9, 3:42 PM PDT	Special Weather Statement	PSR	Riverside	33 min

Nearby

Special Weather Statements in California, 2021 Every special weather statement 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.