Alert archive / Arizona / Flash Flood Warnings in 2021

Flash Flood Warning 80, NWS Flagstaff, AZ

July 21, 2021Coconino County, Arizona

NWS Flagstaff, AZ issued this flash flood warning at Jul 21, 2021, 6:53 PM MST for Coconino County, Arizona. It was in force for 112 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: Jul 21, 2021, 6:53 PM MST (01:53 UTC)
Expired: Jul 21, 2021, 8:45 PM MST
In force: 112 min
Issued by: NWS Flagstaff, AZ
Area: Storm-based polygon
Damage threat: Considerable
Flood severity: None

County Coconino County, AZ

The radar

The Cedar City radar (KICX), 153 km from the middle of the area, began a volume at 01:54 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 00:00Z, 1.9 hours before the alert went out and 138 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: 157 J/kg
Mixed-layer CIN: -137 J/kg
Mixed-layer LCL: 1562 m above ground
0-6 km bulk shear: 14 kt
0-1 km storm-relative helicity: -47 m²/s²
0-3 km storm-relative helicity: 1 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0

Open this sounding in Storm Lab

The text

As transmitted.

588 
WGUS55 KFGZ 220153
FFWFGZ
AZC005-220345-
/O.NEW.KFGZ.FF.W.0080.210722T0153Z-210722T0345Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
Flash Flood Warning
National Weather Service Flagstaff AZ
653 PM MST Wed Jul 21 2021

The National Weather Service in Flagstaff has issued a

* Flash Flood Warning for...
  The Havasu Creek basin in...
  Coconino County in north central Arizona...

* Until 845 PM MST.

* At 651 PM MST, The flash flood from earlier thunderstorms will 
  move through the area of Supai

  HAZARD...Flash flooding in and around the Havasu Creek basin.

  SOURCE...Radar.

  IMPACT...Flash flooding of areas in and around the Havasu Creek
           basin.

* Some locations that will experience flash flooding include...
  Supai and Havasupai Reservation.

This includes the following swimming holes...
	All swimming holes on Havasu Creek near Supai.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Campers and hikers should hustle to higher ground immediately! Stay 
away from creeks and washes!

Foot bridges will be washed out in Supai Campground. Some campsites 
will be flooded. Campers may be stranded in portions of the 
campground.

&&

LAT...LON 3629 11275 3630 11277 3631 11276 3632 11276
      3631 11273 3627 11269 3611 11258 3610 11263
      3620 11269 3615 11271 3611 11271 3613 11274
      3624 11272 3627 11273 3619 11274 3617 11276
      3624 11277

FLASH FLOOD...RADAR INDICATED
FLASH FLOOD DAMAGE THREAT...CONSIDERABLE

$$

McCollum

1 follow-up statement

975 
WGUS75 KFGZ 220340
FFSFGZ

Flash Flood Statement
National Weather Service Flagstaff AZ
840 PM MST Wed Jul 21 2021

AZC005-220350-
/O.EXP.KFGZ.FF.W.0080.000000T0000Z-210722T0345Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Coconino AZ-
840 PM MST Wed Jul 21 2021

...FLASH FLOOD WARNING FOR THE HAVASU CREEK BASIN WILL EXPIRE AT 845 
PM MST THIS EVENING FOR COCONINO COUNTY...

Flood waters have receded along Havasu Creek in Supai. The heavy 
rain has ended for now.

LAT...LON 3629 11275 3630 11277 3631 11276 3632 11276
      3631 11273 3627 11269 3611 11258 3610 11263
      3620 11269 3615 11271 3611 11271 3613 11274
      3624 11272 3627 11273 3619 11274 3617 11276
      3624 11277

$$

McCollum

The office that day

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

Issued	Product	Office	Counties	Lasted
Jul 21, 6:38 PM MST	Flash Flood Warning Considerable damage threat	FGZ	Gila	3 hr
Jul 22, 12:28 PM MST	Areal Flood Advisory	FGZ	Coconino	3 hr
Jul 22, 2:10 PM MST	Flash Flood Warning Considerable damage threat	FGZ	Coconino	3 hr
Jul 22, 3:01 PM MST	Severe Thunderstorm Warning	FGZ	Coconino	44 min
Jul 22, 3:31 PM MST	Flash Flood Warning Considerable damage threat	FGZ	Coconino	115 min
Jul 22, 3:58 PM MST	Flash Flood Warning Considerable damage threat	FGZ	Navajo	3 hr
Jul 22, 4:04 PM MST	Flash Flood Warning Considerable damage threat	FGZ	Coconino	116 min

Nearby

Flash Flood Warnings in Arizona, 2021 Every flash flood warning 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.