Alert archive / Arizona / Flash Flood Warnings in 2021

Flash Flood Warning 81, NWS Flagstaff, AZ

July 22, 2021Coconino County, Arizona

NWS Flagstaff, AZ issued this flash flood warning at Jul 22, 2021, 2:10 PM MST for Coconino County, Arizona. 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 outline as issued.

The facts

Issued: Jul 22, 2021, 2:10 PM MST (21:10 UTC)
Expired: Jul 22, 2021, 4:45 PM MST
In force: 3 hr
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), 150 km from the middle of the area, began a volume at 21:13 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, 9.2 hours before the alert went out and 146 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: 196 J/kg
Mixed-layer CIN: -125 J/kg
Mixed-layer LCL: 1415 m above ground
0-6 km bulk shear: 14 kt
0-1 km storm-relative helicity: 11 m²/s²
0-3 km storm-relative helicity: 54 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0

Open this sounding in Storm Lab

The text

As transmitted.

176 
WGUS55 KFGZ 222110
FFWFGZ
AZC005-230015-
/O.NEW.KFGZ.FF.W.0081.210722T2110Z-210723T0015Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
Flash Flood Warning
National Weather Service Flagstaff AZ
210 PM MST Thu Jul 22 2021

The National Weather Service in Flagstaff has issued a

* Flash Flood Warning for...
  Coconino County in north central Arizona...

* Until 515 PM MST.

* At 207 PM MST, Doppler radar indicated thunderstorms producing 
  heavy rain across the warned area, west of Supai in the Little 
  Coyote Canyon and National Canyon drainages, down to the Colorado 
  River. Between 1 and 1.75 inches of rain have fallen. Additional 
  rainfall amounts of 0.5 to 1 inch are possible in the warned area. 
  Flash flooding is ongoing or expected to begin shortly.

  HAZARD...Life-threatening flash flooding. Thunderstorms
           producing flash flooding.

  SOURCE...Radar.

  IMPACT...Life-threatening flash flooding of low-water
           crossings, creeks, normally dry washes and roads.

* Some locations that will experience flash flooding include...
  Grand Canyon National Park, Hualapai Reservation and Havasupai 
  Reservation.

This includes the following streams and drainages...
  Havasu Creek, Albers Wash, Sandstone Wash and Little Coyote Canyon.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Turn around, don't drown when encountering flooded roads. Most flood 
deaths occur in vehicles.

Remain alert for flooding even in locations not receiving rain. 
Normally dry washes, slot canyons and creeks can become raging 
killer currents in a matter of minutes, even from distant rainfall.

&&

LAT...LON 3632 11276 3630 11273 3628 11272 3618 11274
      3602 11275 3602 11294 3624 11295 3624 11293
      3626 11292 3625 11290 3626 11289 3628 11287
      3628 11284 3629 11282 3628 11279 3630 11279
      3631 11277

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

$$

JJ

1 follow-up statement

274 
WGUS75 KFGZ 222345
FFSFGZ

Flash Flood Statement
National Weather Service Flagstaff AZ
445 PM MST Thu Jul 22 2021

AZC005-222355-
/O.CAN.KFGZ.FF.W.0081.000000T0000Z-210723T0015Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Coconino AZ-
445 PM MST Thu Jul 22 2021

...FLASH FLOOD WARNING IS CANCELLED FOR THE AREA WEST OF SUPAI IN 
COCONINO COUNTY...

The heavy rain has ended over the Little Coyote Canyon and National 
Canyon drainages west of Supai. Flow is likely to continue into the 
evening hours through these drainages, but additional flash flooding 
in not likely.

A Flash Flood Watch remains in effect until 1100 PM MST Saturday for 
portions of east central Arizona, north central Arizona, northeast 
Arizona and west central Arizona.

LAT...LON 3632 11276 3630 11273 3628 11272 3618 11274
      3602 11275 3602 11294 3624 11295 3624 11293
      3626 11292 3625 11290 3626 11289 3628 11287
      3628 11284 3629 11282 3628 11279 3630 11279
      3631 11277

$$

JJ

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 21, 6:53 PM MST	Flash Flood Warning Considerable damage threat	FGZ	Coconino	112 min
Jul 22, 12:28 PM MST	Areal Flood Advisory	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.