Alert archive / Arizona / Flash Flood Warnings in 2021

Flash Flood Warning 62, NWS Flagstaff, AZ

July 20, 2021Navajo County, Arizona

NWS Flagstaff, AZ issued this flash flood warning at Jul 20, 2021, 9:33 PM MDT for Navajo County, Arizona. It was in force for 117 min. 2 reports came from inside the area while it was in force.

The area

The outline as issued, with what was reported inside it.

The facts

Issued: Jul 20, 2021, 9:33 PM MDT (03:33 UTC)
Expired: Jul 20, 2021, 11:30 PM MDT
In force: 117 min
Issued by: NWS Flagstaff, AZ
Area: Storm-based polygon
Damage threat: Considerable
Flood severity: None

County Navajo County, AZ

The radar

The Flagstaff radar (KFSX), 103 km from the middle of the area, began a volume at 03:34 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.

What was reported inside it

Time	Report	Where	Remark
Jul 20, 10:30 PM MDT	FLASH FLOOD	1 S Snowflake, AZ	THE SNOWFLAKE-TAYLOR POLICE DEPT. REPORTED FLASH FLOODING THAT IS CURRENTLY ONGOING IN SNOWFLAKE, AZ WITH 6 INCHES OF WATER OVER THE ROADWAYS AND HOUSES THREATENED IN THE W 1ST STREET AREA.
Jul 20, 10:36 PM MDT	HEAVY RAIN 1.97	1 Se Snowflake, AZ	NAVAJO COUNTY RAIN GAUGE MEASURED 1.97 INCHES OF HEAVY RAIN WITHIN THE LAST HOUR.

Local storm reports filed while the alert was in force, from inside its polygon or its counties.

The nearest sounding before it

Flgstf/Belemont, AZ (KFGZ), launched 00:00Z, 3.6 hours before the alert went out and 175 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: 716 J/kg
Mixed-layer CIN: -31 J/kg
Mixed-layer LCL: 1279 m above ground
0-6 km bulk shear: 27 kt
0-1 km storm-relative helicity: -4 m²/s²
0-3 km storm-relative helicity: 21 m²/s²
Significant tornado parameter: -0.0
Supercell composite: -0.0

Open this sounding in Storm Lab

The text

As transmitted.

354 
WGUS55 KFGZ 210333
FFWFGZ
AZC017-210530-
/O.NEW.KFGZ.FF.W.0062.210721T0333Z-210721T0530Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
Flash Flood Warning
National Weather Service Flagstaff AZ
833 PM MST Tue Jul 20 2021

The National Weather Service in Flagstaff has issued a

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

* Until 1030 PM MST.

* At 831 PM MST, Doppler radar and automated rain gauges indicated 
  thunderstorms producing heavy rain in the Snowflake and Taylor 
  area including Silver Creek. Between 1 and 2 inches of rain have 
  fallen. Additional rainfall amounts of 1 to 2 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.

  SOURCE...Radar and automated gauges.

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

* Some locations that will experience flash flooding include...
  Taylor, Shumway and Snowflake.

This includes the following highways...
	State Route 77 between mile markers 354 and 367.
	State Route 277 between mile markers 330 and 336.

This includes the following streams and drainages...
  Cottonwood Wash, Silver Creek, Concho Flat Wash, Dodson Wash, Hay 
  Hollow Draw and Show Low Creek.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

Be especially cautious at night when it is harder to recognize the 
dangers of flooding.

&&

LAT...LON 3462 11008 3460 10992 3439 11002 3444 11021
      3455 11017

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

$$

TPS

2 follow-up statements

780 
WGUS75 KFGZ 210433
FFSFGZ

Flash Flood Statement
National Weather Service Flagstaff AZ
933 PM MST Tue Jul 20 2021

AZC017-210530-
/O.CON.KFGZ.FF.W.0062.000000T0000Z-210721T0530Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Navajo AZ-
933 PM MST Tue Jul 20 2021

...FLASH FLOOD WARNING REMAINS IN EFFECT UNTIL 1030 PM MST THIS 
EVENING FOR NAVAJO COUNTY...

At 931 PM MST, local law enforcement reported flash flooding is 
ongoing in Snowflake with water over roadways and houses threatened. 
Heavy rain has ended in the Snowflake and Taylor area including 
Silver Creek, but flooding remains a threat. Between 1.5 and 2.5 
inches of rain have fallen. Additional rainfall amounts up to 0.25 
inches are possible in the warned area.

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

SOURCE...Law enforcement reported.

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

Some locations that will experience flash flooding include...
  Taylor, Shumway and Snowflake.

This includes the following highways...
	State Route 77 between mile markers 354 and 368.
	State Route 277 between mile markers 331 and 336.

This includes the following streams and drainages...
  Cottonwood Wash, Silver Creek, Concho Flat Wash, Dodson Wash, Hay 
  Hollow Draw and Show Low Creek.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

Be especially cautious at night when it is harder to recognize the 
dangers of flooding.

Flooding of washes and creeks will occur, some dirt roads will 
become muddy and impassable. Paved roads and underpasses could 
become flooded as well.

&&

LAT...LON 3462 11008 3460 10992 3439 11002 3444 11021
      3455 11017

FLASH FLOOD...OBSERVED
FLASH FLOOD DAMAGE THREAT...CONSIDERABLE

$$

TPS

403 
WGUS75 KFGZ 210527
FFSFGZ

Flash Flood Statement
National Weather Service Flagstaff AZ
1027 PM MST Tue Jul 20 2021

AZC017-210537-
/O.EXP.KFGZ.FF.W.0062.000000T0000Z-210721T0530Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Navajo AZ-
1027 PM MST Tue Jul 20 2021

...FLASH FLOOD WARNING WILL EXPIRE AT 1030 PM MST THIS EVENING FOR 
NAVAJO COUNTY...

The heavy rain threat has ended in the Snowflake and Taylor area. 
Creeks and washes will remain high through the next few hours so 
continue to use caution. Don't drive through any flooded roadways. 
Please continue to heed remaining road closures.

LAT...LON 3462 11008 3460 10992 3439 11002 3444 11021
      3455 11017

$$

TPS

The office that day

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

Issued	Product	Office	Counties	Lasted
Jul 20, 7:16 PM MDT	Special Weather Statement	FGZ		29 min
Jul 20, 8:32 PM MDT	Severe Thunderstorm Warning	FGZ	Navajo	28 min
Jul 20, 8:55 PM MDT	Flash Flood Warning Considerable damage threat	FGZ	Navajo	2 hr
Jul 21, 1:17 AM MDT	Flash Flood Warning Considerable damage threat	FGZ	Gila	118 min
Jul 21, 3:38 AM MDT	Flash Flood Watch	FGZ	Apache, Coconino, Gila, Navajo, Yavapai	5 days
Jul 21, 11:19 AM MDT	Special Weather Statement	FGZ	Yavapai	26 min
Jul 21, 11:48 AM MDT	Flash Flood Warning Considerable damage threat	FGZ	Yavapai	2 hr
Jul 21, 1:03 PM MDT	Special Weather Statement	FGZ	Yavapai	42 min
Jul 21, 1:13 PM MDT	Flash Flood Warning Considerable damage threat	FGZ	Yavapai	56 min
Jul 21, 1:20 PM MDT	Flash Flood Warning Considerable damage threat	FGZ	Yavapai	114 min
Jul 21, 1:35 PM MDT	Special Weather Statement	FGZ		40 min
Jul 21, 1:47 PM MDT	Flash Flood Warning Considerable damage threat	FGZ	Coconino	118 min
Jul 21, 1:54 PM MDT	Special Weather Statement	FGZ		36 min
Jul 21, 2:06 PM MDT	Flash Flood Warning Considerable damage threat	FGZ	Coconino	92 min
Jul 21, 2:24 PM MDT	Flash Flood Warning Considerable damage threat	FGZ	Coconino	110 min
Jul 21, 2:27 PM MDT	Flash Flood Warning Considerable damage threat	FGZ	Yavapai	74 min
Jul 21, 2:57 PM MDT	Special Weather Statement	FGZ	Yavapai	48 min
Jul 21, 3:01 PM MDT	Areal Flood Advisory	FGZ	Yavapai	119 min
Jul 21, 3:05 PM MDT	Flash Flood Warning Considerable damage threat	FGZ	Coconino	2 hr
Jul 21, 3:22 PM MDT	Areal Flood Advisory	FGZ	Coconino	3 hr
Jul 21, 3:30 PM MDT	Special Weather Statement	FGZ		45 min
Jul 21, 3:36 PM MDT	Flash Flood Warning Considerable damage threat	FGZ	Yavapai	54 min
Jul 21, 3:53 PM MDT	Flash Flood Warning Considerable damage threat	FGZ	Coconino	82 min
Jul 21, 3:57 PM MDT	Flash Flood Warning Considerable damage threat	FGZ	Yavapai	60 min
Jul 21, 3:59 PM MDT	Flash Flood Warning Considerable damage threat	FGZ	Yavapai	60 min
Jul 21, 4:21 PM MDT	Severe Thunderstorm Warning	FGZ	Coconino	26 min
Jul 21, 4:34 PM MDT	Flash Flood Warning Considerable damage threat	FGZ	Coconino	98 min
Jul 21, 4:49 PM MDT	Flash Flood Warning Considerable damage threat	FGZ	Yavapai	3 hr
Jul 21, 5:35 PM MDT	Flash Flood Warning Considerable damage threat	FGZ	Coconino	115 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; local storm reports from the same archive; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.