Alert archive / Arizona / Flash Flood Warnings in 2024

Flash Flood Warning 76, NWS Flagstaff, AZ

August 21, 2024Coconino County, Arizona

NWS Flagstaff, AZ issued this flash flood warning at Aug 21, 2024, 1:33 PM MST for Coconino County, Arizona. It was in force for 11 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 21, 2024, 1:33 PM MST (20:33 UTC)
Expired: Aug 22, 2024, 12:30 AM MST
In force: 11 hr
Issued by: NWS Flagstaff, AZ
Area: Storm-based polygon
Damage threat: Considerable
Flood severity: None

County Coconino County, AZ

The radar

The Flagstaff radar (KFSX), 150 km from the middle of the area, began a volume at 20:33 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

Flgstf/Belemont, AZ (KFGZ), launched 12:00Z, 8.6 hours before the alert went out and 68 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: 61 J/kg
Mixed-layer CIN: -172 J/kg
Mixed-layer LCL: 1768 m above ground
0-6 km bulk shear: 26 kt
0-1 km storm-relative helicity: 20 m²/s²
0-3 km storm-relative helicity: 55 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 Flagstaff, AZ wrote its last area forecast discussion before this flash flood warning went out at Aug 21, 1:24 PM MST, 9 minutes earlier.

Area forecast discussion, Aug 21, 1:24 PM MST, 9 minutes before

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In the hours before

Special weather statement, Aug 21, 11:39 AM MST, 1 hour 54 minutes before

Special Weather Statement
National Weather Service Flagstaff AZ
1139 AM MST Wed Aug 21 2024

AZZ006-007-211915-
Coconino Plateau-Grand Canyon Country-
1139 AM MST Wed Aug 21 2024

...A STRONG THUNDERSTORM WILL IMPACT COCONINO COUNTY THROUGH 1215 PM
MST...

At 1138 AM MST, Doppler radar was tracking a strong thunderstorm over
Grand Canyon National Park Airport, or 20 miles west of Desert View
Watchtower, moving northeast at 25 mph.

HAZARD...Wind gusts up to 40 mph and half inch hail.

SOURCE...Radar indicated.

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

Locations impacted include...
Devil's Corkscrew, Pipe Creek Resthouse, Tusayan, BuggeIn Picnic
Area, Monument Creek Vista, South Rim, Buddha Cloister, Grand Canyon
National Park Airport, Hopi Point, Grandview Point, Yaki Point,
Plateau Point, Shoshone Point, Grand Canyon Village, Maricopa Point,
Phantom Ranch, South Rim Visitors Center, Moran Point, Pipe Creek
Vista, and Skeleton Point.

This includes State Route 64 between mile markers 231 and 237.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

If outdoors, consider seeking shelter inside a building.

&&

LAT...LON 3588 11219 3596 11228 3616 11209 3599 11190
TIME...MOT...LOC 1838Z 230DEG 24KT 3596 11218

MAX HAIL SIZE...0.50 IN
MAX WIND GUST...40 MPH

McCollum

The office that day

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

Issued	Product	Office	Counties	Lasted
Aug 20, 5:18 PM MST	Special Weather Statement	FGZ		27 min
Aug 21, 11:39 AM MST	Special Weather Statement	FGZ	Coconino	36 min
Aug 21, 12:01 PM MST	Severe Thunderstorm Warning	FGZ	Yavapai	29 min
Aug 21, 12:13 PM MST	Flood Watch	FGZ	Coconino	35 hr
Aug 21, 12:31 PM MST	Severe Thunderstorm Warning	FGZ	Gila	15 min
Aug 21, 12:45 PM MST	Severe Thunderstorm Warning	FGZ	Yavapai	19 min
Aug 21, 2:01 PM MST	Severe Thunderstorm Warning	FGZ	Navajo	18 min
Aug 21, 2:48 PM MST	Flash Flood Warning Considerable damage threat	FGZ	Gila, Navajo	6 hr
Aug 21, 3:36 PM MST	Flash Flood Warning Considerable damage threat	FGZ	Coconino, Navajo	6 hr
Aug 21, 3:41 PM MST	Flash Flood Warning Considerable damage threat	FGZ	Coconino	6 hr
Aug 21, 3:44 PM MST	Flash Flood Warning Considerable damage threat	FGZ	Coconino	6 hr
Aug 21, 4:51 PM MST	Severe Thunderstorm Warning	FGZ	Gila, Navajo	24 min

Nearby

Flash Flood Warnings in Arizona, 2024 Every flash flood warning in 2024

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.