Alert archive / Arizona / Flash Flood Warnings in 2023

Flash Flood Warning 29, NWS Phoenix, AZ

September 2, 2023Yuma County, Arizona; Imperial County, California

NWS Phoenix, AZ issued this flash flood warning at Sep 2, 2023, 12:43 PM MST for 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: Sep 2, 2023, 12:43 PM MST (19:43 UTC)
Expired: Sep 2, 2023, 3:45 PM MST
In force: 3 hr
Issued by: NWS Phoenix, AZ
Area: Storm-based polygon
Damage threat: Considerable
Flood severity: None

Counties Yuma County, AZ, Imperial County, CA

The radar

The Yuma radar (KYUX), 46 km from the middle of the area, began a volume at 19:44 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, 7.7 hours before the alert went out and 240 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: 6 J/kg
Mixed-layer CIN: -202 J/kg
Mixed-layer LCL: 573 m above ground
0-6 km bulk shear: 13 kt
0-1 km storm-relative helicity: 77 m²/s²
0-3 km storm-relative helicity: 104 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 Sep 2, 10:00 AM MST, 2 hours 43 minutes earlier.

Area forecast discussion, Sep 2, 10:00 AM MST, 2 hours 43 minutes before

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In the hours before

Special weather statement, Sep 2, 11:42 AM MST, 1 hour 1 minute before

Special Weather Statement
National Weather Service Phoenix AZ
1142 AM MST Sat Sep 2 2023

AZZ530-533-021930-
Parker Valley AZ-Central La Paz AZ-
1142 AM MST Sat Sep 2 2023

...A strong thunderstorm will impact portions of north central La Paz
County through 1230 PM MST...

At 1141 AM MST, Doppler radar was tracking a strong thunderstorm near
Bouse, or 17 miles southeast of Parker, moving north at 15 mph.

HAZARD...Winds in excess of 40 mph and heavy rainfall.

SOURCE...Radar indicated.

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

Locations impacted include...
Bouse.

This includes AZ Route 72 between mile markers 15 and 27.

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.

&&

LAT...LON 3386 11402 3387 11418 3415 11422 3419 11395
TIME...MOT...LOC 1841Z 178DEG 14KT 3392 11411

MAX HAIL SIZE...0.00 IN
MAX WIND GUST...40 MPH

TF

Special weather statement, Sep 2, 12:32 PM MST, 11 minutes before

Special Weather Statement
National Weather Service Phoenix AZ
1232 PM MST Sat Sep 2 2023

AZZ530>536-538>540-554-559-CAZ561-564-565-568>570-022230-
Sonoran Desert Natl Monument-Aguila Valley-Kofa-Southeast Yuma
County-Tonopah Desert-West Pinal County-Gila River
Valley-Buckeye/Avondale-Parker Valley-Gila Bend-Central La
Paz-Yuma-Chuckwalla Mountains-Imperial County Southeast-Palo Verde
Valley-Chuckwalla Valley-Chiriaco Summit-Joshua Tree NP East-
1232 PM MST Sat Sep 2 2023

...SCATTERED STRONG THUNDERSTORMS WITH HEAVY RAINFALL EXPECTED
ACROSS LA PAZ...YUMA... MARICOPA...PINAL...EASTERN IMPERIAL AND
RIVERSIDE COUNTIES...

Conditions are favorable this afternoon for scattered thunderstorms
across the region. Any storms that form will be capable of producing
brief heavy rainfall and wind gusts 30 to 40 mph.

Localized rainfall rates of 1 to 2 inches in an hour are possible
with localized flooding.

Remain alert for threatening storms. Never drive through flooded
roadways.

Locations impacted include...
Yuma, Goodyear, Buckeye, Somerton, Parker, Gila Bend, Alamo Lake,
Martinez Lake, Desert Center, Fortuna Foothills, Tonopah, Gadsden,
San Luis, Blythe, Estrella, Quartzsite, Wellton, Aguila, Kinter, and
Gladden.

LAT...LON 3249 11479 3262 11481 3272 11472 3270 11498
      3403 11571 3411 11552 3407 11532 3408 11444
      3431 11413 3421 11367 3431 11353 3432 11334
      3401 11333 3400 11292 3387 11282 3272 11212
      3268 11220 3251 11221 3250 11333 3204 11334
TIME...MOT...LOC 1927Z 240DEG 51KT 3295 11337

TF

The office that day

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

Issued	Product	Office	Counties	Lasted
Sep 1, 7:32 PM MST	Areal Flood Warning	PSR	La Paz	3 hr
Sep 2, 2:54 AM MST	Areal Flood Advisory	PSR	Yuma	111 min
Sep 2, 3:05 AM MST	Special Weather Statement	PSR		40 min
Sep 2, 11:42 AM MST	Special Weather Statement	PSR	La Paz	48 min
Sep 2, 12:16 PM MST	Flash Flood Warning Considerable damage threat	PSR	La Paz	7 hr
Sep 2, 12:32 PM MST	Special Weather Statement	PSR	La Paz, Yuma	3 hr
Sep 2, 2:24 PM MST	Flash Flood Warning Considerable damage threat	PSR	La Paz	4 hr
Sep 2, 2:34 PM MST	Flash Flood Warning Considerable damage threat	PSR	La Paz	4 hr
Sep 2, 2:46 PM MST	Flash Flood Warning Considerable damage threat	PSR	La Paz	4 hr
Sep 2, 2:48 PM MST	Areal Flood Advisory	PSR	Yuma	3 hr
Sep 2, 3:27 PM MST	Flash Flood Warning Considerable damage threat	PSR	Yuma	5 hr
Sep 2, 3:34 PM MST	Special Weather Statement	PSR	La Paz	86 min
Sep 2, 3:46 PM MST	Flash Flood Warning Considerable damage threat	PSR	La Paz, Yuma	3 hr
Sep 2, 4:36 PM MST	Flash Flood Warning Considerable damage threat	PSR	La Paz, Maricopa	5 hr
Sep 2, 4:46 PM MST	Areal Flood Advisory	PSR	Maricopa	3 hr
Sep 1, 5:52 PM MST	Areal Flood Warning	PSR	Imperial	5 hr
Sep 1, 8:29 PM MST	Areal Flood Warning	PSR	Riverside, San Bernardino	2 hr
Sep 1, 9:15 PM MST	Areal Flood Warning	PSR	Imperial, Riverside, San Bernardino	2 hr
Sep 2, 1:42 PM MST	Flash Flood Warning Considerable damage threat	PSR	Riverside	3 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.