Alert archive / Arizona / Flash Flood Warnings in 2021

Flash Flood Warning 31, NWS Flagstaff, AZ

July 14, 2021Coconino County, Arizona

NWS Flagstaff, AZ issued this flash flood warning at Jul 14, 2021, 6:29 PM MST for Coconino County, Arizona. It was in force for 2 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 14, 2021, 6:29 PM MST (01:29 UTC)
Expired: Jul 14, 2021, 8:30 PM MST
In force: 2 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), 153 km from the middle of the area, began a volume at 01:33 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 00:00Z, 1.5 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: 22 J/kg
Mixed-layer CIN: -222 J/kg
Mixed-layer LCL: 1650 m above ground
0-6 km bulk shear: 24 kt
0-1 km storm-relative helicity: -21 m²/s²
0-3 km storm-relative helicity: 2 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0

Open this sounding in Storm Lab

The text

As transmitted.

550 
WGUS55 KFGZ 150129
FFWFGZ
AZC005-150330-
/O.NEW.KFGZ.FF.W.0031.210715T0129Z-210715T0330Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
Flash Flood Warning
National Weather Service Flagstaff AZ
629 PM MST Wed Jul 14 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 830 PM MST.

* At 627 PM MST, Doppler radar indicated thunderstorms producing 
  heavy rain over the Havasu Creek basin. Between 0.5 and 1.25 
  inches of rain have fallen. The stream gauge on Havasu Creek at 
  Supai reported a 1.5 foot rise as of 6:10 PM MST. Flash flooding 
  is ongoing or expected to begin shortly.

  HAZARD...Life-threatening flash flooding. Thunderstorms
           producing flash flooding in and around the Havasu
           Creek basin.

  SOURCE...Radar.

  IMPACT...Life threatening flash flooding of areas in and around
           the Havasu Creek basin.

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

Stay away or be swept away! The banks of creeks and washes are 
unstable and unsafe during any flooding event.

&&

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

$$

MCT

2 follow-up statements

510 
WGUS75 KFGZ 150217
FFSFGZ

Flash Flood Statement
National Weather Service Flagstaff AZ
717 PM MST Wed Jul 14 2021

AZC005-150330-
/O.CON.KFGZ.FF.W.0031.000000T0000Z-210715T0330Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Coconino AZ-
717 PM MST Wed Jul 14 2021

...FLASH FLOOD WARNING FOR THE HAVASU CREEK BASIN REMAINS IN EFFECT 
UNTIL 830 PM MST THIS EVENING FOR COCONINO COUNTY...

At 715 PM MST, Doppler radar indicated heavy rain over the Havasu 
Creek basin. Between 0.5 and 1.25 inches of rain have fallen. The 
stream gauge on Havasu Creek at Supai reported just under a 2 foot 
rise and the water is just beginning to recede.

HAZARD...Life-threatening flash flooding. Heavy rain producing
         flash flooding in and around the Havasu Creek basin.

SOURCE...Radar.

IMPACT...Life threatening flash flooding of areas in and around
         the Havasu Creek basin.

Some locations that will experience flash flooding include...
  Grand Canyon National Park, Hualapai Hilltop, 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.

Stay away or be swept away! The banks of creeks and washes are 
unstable and unsafe during any flooding event.

&&

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

$$

MCT

113 
WGUS75 KFGZ 150324
FFSFGZ

Flash Flood Statement
National Weather Service Flagstaff AZ
824 PM MST Wed Jul 14 2021

AZC005-150334-
/O.EXP.KFGZ.FF.W.0031.000000T0000Z-210715T0330Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Coconino AZ-
824 PM MST Wed Jul 14 2021

...FLASH FLOOD WARNING FOR THE HAVASU CREEK BASIN WILL EXPIRE AT 830 
PM MST THIS EVENING FOR COCONINO COUNTY...

Flood waters along Havasu Creek continue to recede. Flooding is no 
longer expected to pose a threat.

A Flash Flood Watch remains in effect until 1200 AM MST for portions 
of north central Arizona and northeast Arizona with additional heavy 
rain possible. Continue to monitor weather sources tonight.

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

$$

MCT

The office that day

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

Issued	Product	Office	Counties	Lasted
Jul 14, 7:40 PM MST	Flash Flood Warning Considerable damage threat	FGZ	Coconino	2 hr
Jul 14, 10:39 PM MST	Areal Flood Advisory	FGZ	Coconino	5 hr
Jul 15, 12:41 AM MST	Special Weather Statement	FGZ		49 min
Jul 15, 1:38 AM MST	Special Weather Statement	FGZ	Navajo	37 min
Jul 15, 3:52 AM MST	Special Weather Statement	FGZ	Yavapai	38 min
Jul 15, 1:15 PM MST	Flash Flood Warning Considerable damage threat	FGZ	Yavapai	3 hr
Jul 15, 3:51 PM MST	Flash Flood Warning Considerable damage threat	FGZ	Coconino, Yavapai	3 hr
Jul 15, 4:55 PM MST	Special Weather Statement	FGZ		35 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.