Alert archive / Arizona / Flash Flood Warnings in 2023

Flash Flood Warning 18, NWS Phoenix, AZ

August 20, 2023La Paz County, Yuma County, Arizona; Imperial County, California

NWS Phoenix, AZ issued this flash flood warning at Aug 20, 2023, 3:06 PM MST for La Paz County, Yuma County, Arizona; Imperial County, California. It was in force for 3 hr. No storm report in the archive falls inside the area while it was in force.

The area

The counties it named.

The facts

Issued: Aug 20, 2023, 3:06 PM MST (22:06 UTC)
Expired: Aug 20, 2023, 6:30 PM MST
In force: 3 hr
Issued by: NWS Phoenix, AZ
Area: Storm-based polygon
Damage threat: Considerable
Flood severity: None

Counties La Paz County, AZ, Yuma County, AZ, Imperial County, CA

The radar

The Yuma radar (KYUX), 79 km from the middle of the area, began a volume at 22:07 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, 10.1 hours before the alert went out and 263 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: 0 J/kg
Mixed-layer CIN: No buoyant parcel
Mixed-layer LCL: 1111 m above ground
0-6 km bulk shear: 43 kt
0-1 km storm-relative helicity: 188 m²/s²
0-3 km storm-relative helicity: 325 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0

Open this sounding in Storm Lab

What forecasters said that day

The local office's own words before this flash flood warning 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 flash flood warning went out at Aug 20, 2:56 PM MST, 10 minutes earlier.

Area forecast discussion, Aug 20, 2:56 PM MST, 10 minutes before

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In the hours before

Local storm report, Aug 20, 1:29 PM MST, 1 hour 37 minutes before

Preliminary Local Storm Report
National Weather Service Phoenix AZ
129 PM MST Sun Aug 20 2023

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0119 PM     Non-Tstm Wnd Dmg 2 E Gordon's Well       32.71N 114.93W
08/20/2023                   Imperial           CA   Dept of Highways

            A couple semi trucks have flipped along I-8,
            blocking traffic.

&&

SB

Local storm report, Aug 20, 1:57 PM MST, 1 hour 9 minutes before

Preliminary Local Storm Report
National Weather Service Phoenix AZ
157 PM MST Sun Aug 20 2023

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

1209 PM     Non-Tstm Wnd Gst 4 S Yuma                32.65N 114.61W
08/20/2023  M62 MPH          Yuma               AZ   ASOS

0115 PM     Non-Tstm Wnd Dmg 1 S Yuma                32.69N 114.63W
08/20/2023                   Yuma               AZ   Emergency Mngr

            Power outages and several trees blown down
            across Yuma. Wind gusts exceeding 60 mph.

0115 PM     Dust Storm       Somerton                32.60N 114.71W
08/20/2023                   Yuma               AZ   Emergency Mngr

            Visibility down to below 1/8 mile in blowing
            dust. Winds gusting to 55 mph.

&&

Local storm report, Aug 20, 2:15 PM MST, 51 minutes before

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Special weather statement, Aug 20, 2:59 PM MST, 7 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 20, 12:40 PM MST	Blowing Dust Advisory	PSR	Yuma	2 hr
Aug 20, 1:24 PM MST	Blowing Dust Warning	PSR	Yuma	6 hr
Aug 20, 2:02 PM MST	Areal Flood Advisory	PSR	La Paz, Yuma	4 hr
Aug 20, 2:59 PM MST	Special Weather Statement	PSR	Gila	3 hr
Aug 20, 4:12 PM MST	Blowing Dust Advisory	PSR	La Paz, Yuma	3 hr
Aug 20, 11:31 AM MST	Severe Thunderstorm Warning	PSR	Imperial	44 min
Aug 20, 11:55 AM MST	Flash Flood Warning Considerable damage threat	PSR	Imperial	6 hr
Aug 20, 1:00 PM MST	Severe Thunderstorm Warning	PSR	Imperial, Riverside	45 min
Aug 20, 1:24 PM MST	Areal Flood Advisory	PSR	Imperial, Riverside	8 min
Aug 20, 1:32 PM MST	Flash Flood Warning Considerable damage threat	PSR	Imperial, Riverside	4 hr
Aug 20, 2:30 PM MST	Flash Flood Warning Considerable damage threat	PSR	Imperial, Riverside, San Bernardino	5 hr

Nearby

Flash Flood Warnings in Arizona, 2023 Flash Flood Warnings in California, 2023 Every flash flood warning in 2023

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.