Alert archive / Arizona / Flash Flood Warnings in 2021

Flash Flood Warning 208, NWS Flagstaff, AZ

August 18, 2021Coconino County, Arizona

NWS Flagstaff, AZ issued this flash flood warning at Aug 18, 2021, 1:47 PM MST for Coconino County, Arizona. It was in force for 118 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
Aug 18, 2021, 1:47 PM MST (20:47 UTC)
Expired
Aug 18, 2021, 3:45 PM MST
In force
118 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), 157 km from the middle of the area, began a volume at 20:46 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, 8.8 hours before the alert went out and 198 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-pSkew-T log-p diagram, Flgstf/Belemont, AZ at 12:00Z on 2021-08-18Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 590 joules per kilogram.LCLLFCEL10008507005003002001001 km2 km3 km6 km9 km12 km-30°-20°-10°10°20°30°40°
Temperature in red, dew point in green, the mixed-layer parcel dashed.
HodographHodograph, Flgstf/Belemont, AZ at 12:00Z on 2021-08-18The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 23 square meters per square second.193958Sfc1 km3 km6 km9 kmRMLM
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
590 J/kg
Mixed-layer CIN
-3 J/kg
Mixed-layer LCL
634 m above ground
0-6 km bulk shear
10 kt
0-1 km storm-relative helicity
23 m²/s²
0-3 km storm-relative helicity
46 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.4

Open this sounding in Storm Lab

The text

As transmitted.

015 
WGUS55 KFGZ 182047
FFWFGZ
AZC005-182245-
/O.NEW.KFGZ.FF.W.0208.210818T2047Z-210818T2245Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
Flash Flood Warning
National Weather Service Flagstaff AZ
147 PM MST Wed Aug 18 2021

The National Weather Service in Flagstaff has issued a

* Flash Flood Warning for...
  The Labyrinth Canyon watershed in...
  Coconino County in north central Arizona...

* Until 345 PM MST.

* At 147 PM MST, Doppler radar indicated thunderstorms producing 
  heavy rain over the Labyrinth Canyon watershed. Between 0.5 and 
  0.75 inches of rain have fallen. Additional rainfall amounts up to 
  0.25 inches are possible in the warned area. Flash flooding is 
  ongoing or expected to begin shortly.

  HAZARD...Life-threatening flash flooding. Thunderstorms
           producing flash flooding in and around the Labyrinth
           Canyon watershed.

  SOURCE...Radar.

  IMPACT...Life threatening flash flooding of areas in and around
           the Labyrinth Canyon watershed.

* Some locations that will experience flash flooding include...
  Glen Canyon National Recreation Area, Lake Powell and Navajo 
  Reservation.

This includes the following slot canyons...
	Labyrinth Canyon.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Get out of Labyrinth Canyon immediately! Deadly flash flooding is 
imminent or occurring.

Move any beached boats away from the mouth of Labyrinth Canyon 
immediately! Violent flood waters will drain into Lake Powell at 
this location.

&&

LAT...LON 3700 11132 3700 11128 3693 11123 3692 11124
      3693 11128

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

$$

DB
1 follow-up statement
202 
WGUS75 KFGZ 182248
FFSFGZ

Flash Flood Statement
National Weather Service Flagstaff AZ
348 PM MST Wed Aug 18 2021

AZC005-182258-
/O.EXP.KFGZ.FF.W.0208.000000T0000Z-210818T2245Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Coconino AZ-
348 PM MST Wed Aug 18 2021

...FLASH FLOOD WARNING FOR THE LABYRINTH CANYON WATERSHED HAS 
EXPIRED FOR COCONINO COUNTY...

The heavy rain has ended. Flooding is no longer expected to pose a 
threat. Please continue to heed remaining road closures.

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

LAT...LON 3700 11132 3700 11128 3693 11123 3692 11124
      3693 11128

$$

DB

The office that day

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

IssuedProductOfficeCountiesLasted
Aug 17, 5:02 PM MSTFlash Flood Warning Considerable damage threatFGZCoconino3 hr
Aug 17, 6:23 PM MSTFlash Flood Warning Considerable damage threatFGZCoconino2 hr
Aug 17, 8:30 PM MSTFlash Flood Warning Considerable damage threatFGZCoconino2 hr
Aug 17, 8:42 PM MSTSevere Thunderstorm WarningFGZCoconino33 min
Aug 17, 9:07 PM MSTFlash Flood WatchFGZApache, Coconino, Gila, Navajo, Yavapai26 hr
Aug 17, 10:42 PM MSTFlash Flood Warning Considerable damage threatFGZCoconino11 hr
Aug 18, 8:43 AM MSTSpecial Weather StatementFGZ47 min
Aug 18, 9:29 AM MSTFlash Flood Warning Considerable damage threatFGZCoconino3 hr
Aug 18, 9:44 AM MSTFlash Flood Warning Considerable damage threatFGZGila7 hr
Aug 18, 10:37 AM MSTSpecial Weather StatementFGZ38 min
Aug 18, 10:47 AM MSTFlash Flood Warning Considerable damage threatFGZYavapai3 hr
Aug 18, 11:11 AM MSTSpecial Weather StatementFGZ34 min
Aug 18, 11:54 AM MSTSpecial Weather StatementFGZ36 min
Aug 18, 12:01 PM MSTSpecial Weather StatementFGZ44 min
Aug 18, 12:07 PM MSTFlash Flood Warning Considerable damage threatFGZApache, Navajo3 hr
Aug 18, 12:24 PM MSTFlash Flood Warning Considerable damage threatFGZYavapai3 hr
Aug 18, 12:31 PM MSTFlash Flood Warning Considerable damage threatFGZYavapai3 hr
Aug 18, 12:51 PM MSTFlash Flood Warning Considerable damage threatFGZGila, Yavapai4 hr
Aug 18, 1:05 PM MSTSevere Thunderstorm WarningFGZGila, Yavapai40 min
Aug 18, 1:09 PM MSTFlash Flood Warning Considerable damage threatFGZCoconino3 hr
Aug 18, 1:37 PM MSTSevere Thunderstorm WarningFGZCoconino38 min
Aug 18, 2:19 PM MSTAreal Flood AdvisoryFGZNavajo3 hr
Aug 18, 2:44 PM MSTSpecial Weather StatementFGZYavapai31 min
Aug 18, 2:52 PM MSTFlash Flood WarningFGZNavajo3 hr
Aug 18, 3:32 PM MSTFlash Flood WarningFGZCoconino, Yavapai3 hr
Aug 18, 3:45 PM MSTSpecial Weather StatementFGZ30 min
Aug 18, 4:12 PM MSTFlash Flood Warning Considerable damage threatFGZYavapai3 hr

Nearby

Flash Flood Warnings in Arizona, 2021Every 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.