Alert archive / Arizona / Flash Flood Warnings in 2021

Flash Flood Warning 44, NWS Flagstaff, AZ

July 18, 2021Coconino County, Arizona

NWS Flagstaff, AZ issued this flash flood warning at Jul 18, 2021, 1:34 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 18, 2021, 1:34 PM MST (20:34 UTC)
Expired: Jul 18, 2021, 4:06 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), 154 km from the middle of the area, began a volume at 20:34 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 137 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: 191 J/kg
Mixed-layer CIN: -101 J/kg
Mixed-layer LCL: 1511 m above ground
0-6 km bulk shear: 16 kt
0-1 km storm-relative helicity: 14 m²/s²
0-3 km storm-relative helicity: 46 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0

Open this sounding in Storm Lab

The text

As transmitted.

731 
WGUS55 KFGZ 182034
FFWFGZ
AZC005-182330-
/O.NEW.KFGZ.FF.W.0044.210718T2034Z-210718T2330Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
Flash Flood Warning
National Weather Service Flagstaff AZ
134 PM MST Sun Jul 18 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 430 PM MST.

* At 133 PM MST, Doppler radar indicated thunderstorms producing 
  heavy rain over the Havasu Creek basin. Between 1 and 1.5 inches 
  of rain have fallen. 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...
  Hualapai Hilltop, Grand Canyon National Park, 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.

Get out of washes and creeks if you are camping or hiking! Flooding 
is occurring or imminent and will inundate area drainages.

&&

LAT...LON 3629 11275 3630 11277 3631 11276 3632 11276
      3631 11273 3627 11269 3611 11258 3610 11263
      3620 11269 3615 11269 3603 11265 3603 11277
      3624 11272 3627 11273 3619 11274 3617 11276
      3624 11277

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

$$

ET

2 follow-up statements

644 
WGUS75 KFGZ 182224
FFSFGZ

Flash Flood Statement
National Weather Service Flagstaff AZ
324 PM MST Sun Jul 18 2021

AZC005-182330-
/O.CON.KFGZ.FF.W.0044.000000T0000Z-210718T2330Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Coconino AZ-
324 PM MST Sun Jul 18 2021

...FLASH FLOOD WARNING FOR THE HAVASU CREEK BASIN REMAINS IN EFFECT 
UNTIL 430 PM MST THIS AFTERNOON FOR COCONINO COUNTY...

At 323 PM MST, Doppler radar indicated thunderstorms producing 
moderate to heavy rainfall over the Havasu Creek basin. Between 1.25 
and 1.75 inches of rain have fallen. Flash flooding is expected.

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...
  Hualapai Hilltop, Grand Canyon National Park, 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.

Get out of washes and creeks if you are camping or hiking! Flooding 
is occurring or imminent and will inundate area drainages.

&&

LAT...LON 3629 11275 3630 11277 3631 11276 3632 11276
      3631 11273 3627 11269 3611 11258 3610 11263
      3620 11269 3615 11269 3603 11265 3603 11277
      3624 11272 3627 11273 3619 11274 3617 11276
      3624 11277

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

$$

EL

665 
WGUS75 KFGZ 182306
FFSFGZ

Flash Flood Statement
National Weather Service Flagstaff AZ
406 PM MST Sun Jul 18 2021

AZC005-182316-
/O.CAN.KFGZ.FF.W.0044.000000T0000Z-210718T2330Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Coconino AZ-
406 PM MST Sun Jul 18 2021

...FLASH FLOOD WARNING FOR THE HAVASU CREEK BASIN IS CANCELLED FOR 
COCONINO COUNTY...

The heavy rain has ended. Flooding is no longer expected to pose a 
threat. Water will flow in the Havasu Creek into the evening hours, 
however rise will be less than a foot. Please continue to heed 
remaining road closures.

LAT...LON 3629 11275 3630 11277 3631 11276 3632 11276
      3631 11273 3627 11269 3611 11258 3610 11263
      3620 11269 3615 11269 3603 11265 3603 11277
      3624 11272 3627 11273 3619 11274 3617 11276
      3624 11277

$$

EL

The office that day

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

Issued	Product	Office	Counties	Lasted
Jul 18, 10:58 AM MST	Severe Thunderstorm Warning	FGZ	Yavapai	32 min
Jul 18, 11:14 AM MST	Flash Flood Warning Considerable damage threat	FGZ	Yavapai	3 hr
Jul 18, 12:16 PM MST	Severe Thunderstorm Warning	FGZ	Coconino	29 min
Jul 18, 1:03 PM MST	Flash Flood Warning Considerable damage threat	FGZ	Navajo	3 hr
Jul 18, 1:08 PM MST	Special Weather Statement	FGZ		37 min
Jul 18, 2:12 PM MST	Severe Thunderstorm Warning	FGZ	Gila, Navajo	33 min
Jul 18, 2:18 PM MST	Severe Thunderstorm Warning	FGZ	Gila	42 min
Jul 18, 2:31 PM MST	Areal Flood Advisory	FGZ	Coconino	100 min
Jul 18, 2:33 PM MST	Severe Thunderstorm Warning	FGZ	Navajo	42 min
Jul 18, 2:53 PM MST	Flash Flood Warning Considerable damage threat	FGZ	Gila, Navajo	102 min
Jul 18, 3:02 PM MST	Flash Flood Warning Considerable damage threat	FGZ	Coconino	108 min
Jul 18, 3:47 PM MST	Severe Thunderstorm Warning	FGZ	Gila	43 min
Jul 18, 3:54 PM MST	Special Weather Statement	FGZ		51 min
Jul 18, 4:10 PM MST	Flash Flood Warning Considerable damage threat	FGZ	Yavapai	51 min
Jul 18, 4:32 PM MST	Flash Flood Warning Considerable damage threat	FGZ	Navajo	4 hr
Jul 18, 4:59 PM MST	Severe Thunderstorm Warning	FGZ	Gila, Yavapai	46 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.