Alert archive / Arizona / Special Weather Statements in 2021

Special Weather Statement, NWS Phoenix, AZ

August 29, 2021

NWS Phoenix, AZ issued this special weather statement at Aug 29, 2021, 5:05 PM MST. It was in force for 25 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: Aug 29, 2021, 5:05 PM MST (00:05 UTC)
Expired: Aug 29, 2021, 5:30 PM MST
In force: 25 min
Issued by: NWS Phoenix, AZ
Hail: 0.00 in
Wind: 40

The radar

The Phoenix radar (KIWA), 165 km from the middle of the area, began a volume at 00:06 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

Phoenix, AZ (KPSR), launched 00:00Z, 0.1 hours before the alert went out and 133 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: 193 J/kg
Mixed-layer CIN: -82 J/kg
Mixed-layer LCL: 3484 m above ground
0-6 km bulk shear: 10 kt
0-1 km storm-relative helicity: -7 m²/s²
0-3 km storm-relative helicity: 9 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0

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 Aug 29, 5:05 PM MST, 0 minutes earlier.

Area forecast discussion, Aug 29, 5:05 PM MST, 0 minutes before

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In the hours before

Special weather statement, Aug 29, 1:14 PM MST, 3 hours 51 minutes before

Special Weather Statement
National Weather Service Phoenix AZ
114 PM PDT Sun Aug 29 2021

CAZ560-292045-
Joshua Tree NP West CA-
114 PM PDT Sun Aug 29 2021

...A strong thunderstorm will impact portions of San Bernardino and
Riverside Counties through 145 PM PDT...

At 113 PM PDT, Doppler radar was tracking a strong thunderstorm 10
miles southeast of Joshua Tree, or 12 miles southwest of Twentynine
Palms. This storm was nearly stationary.

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...
Key View.

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 3408 11627 3412 11626 3412 11611 3397 11607
      3391 11623 3394 11634 3407 11646
TIME...MOT...LOC 2013Z 152DEG 1KT 3400 11621

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

INS

Special weather statement, Aug 29, 3:30 PM MST, 1 hour 35 minutes before

Special Weather Statement
National Weather Service Phoenix AZ
330 PM PDT Sun Aug 29 2021

CAZ560-561-292300-
Joshua Tree NP West CA-Joshua Tree NP East CA-
330 PM PDT Sun Aug 29 2021

...A strong thunderstorm will impact portions of San Bernardino and
Riverside Counties through 400 PM PDT...

At 330 PM PDT, Doppler radar was tracking a strong thunderstorm 9
miles south of Twentynine Palms, moving northwest at 10 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...
Key View.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

If outdoors, consider seeking shelter inside a building.

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

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

&&

LAT...LON 3412 11626 3412 11606 3408 11604 3407 11600
      3403 11600 3404 11561 3378 11561 3380 11609
      3392 11620 3392 11628
TIME...MOT...LOC 2230Z 133DEG 9KT 3401 11601

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

INS

Special weather statement, Aug 29, 4:01 PM MST, 1 hour 4 minutes before

Special Weather Statement
National Weather Service Phoenix AZ
401 PM PDT Sun Aug 29 2021

CAZ560-561-292330-
Joshua Tree NP West CA-Joshua Tree NP East CA-
401 PM PDT Sun Aug 29 2021

...A strong thunderstorm will impact portions of San Bernardino and
Riverside Counties through 430 PM PDT...

At 401 PM PDT, Doppler radar was tracking a strong thunderstorm 14
miles south of Twentynine Palms Airport, or 16 miles southeast of
Twentynine Palms. This storm was nearly stationary.

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...
Key View.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

If outdoors, consider seeking shelter inside a building.

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

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 3412 11626 3412 11606 3408 11604 3407 11600
      3403 11600 3404 11561 3378 11561 3380 11609
      3392 11620 3392 11628
TIME...MOT...LOC 2301Z 133DEG 2KT 3393 11593

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

INS

Special weather statement, Aug 29, 4:31 PM MST, 34 minutes before

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Special weather statement, Aug 29, 5:05 PM MST, 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
Aug 29, 5:23 PM MST	Areal Flood Advisory	PSR	La Paz, Maricopa	2 hr
Aug 29, 6:07 PM MST	Special Weather Statement	PSR	Pinal	23 min
Aug 30, 12:42 AM MST	Areal Flood Advisory	PSR	Maricopa, Pinal	4 hr
Aug 30, 1:43 AM MST	Flash Flood Watch	PSR	Gila, La Paz, Maricopa, Pinal, Yuma	3 days
Aug 30, 1:41 PM MST	Special Weather Statement	PSR	La Paz	34 min
Aug 30, 1:55 PM MST	Severe Thunderstorm Warning	PSR	La Paz	50 min
Aug 30, 2:24 PM MST	Areal Flood Advisory	PSR	La Paz, Yuma	3 hr
Aug 30, 2:55 PM MST	Flash Flood Warning Considerable damage threat	PSR	La Paz	4 hr
Aug 30, 3:04 PM MST	Special Weather Statement	PSR	La Paz	26 min
Aug 30, 3:21 PM MST	Special Weather Statement	PSR		24 min
Aug 30, 3:32 PM MST	Special Weather Statement	PSR	La Paz	28 min
Aug 30, 3:47 PM MST	Dust Storm Advisory	PSR	La Paz	58 min
Aug 30, 4:48 PM MST	Special Weather Statement	PSR		42 min
Aug 30, 4:51 PM MST	Special Weather Statement	PSR	Gila	39 min
Aug 30, 4:56 PM MST	Dust Storm Advisory	PSR	Imperial, Riverside, San Bernardino	94 min

Nearby

Special Weather Statements in Arizona, 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.