Alert archive / Arizona / Flash Flood Warnings in 2021

Flash Flood Warning 140, NWS Flagstaff, AZ

August 1, 2021Apache County, Coconino County, Navajo County, Arizona

NWS Flagstaff, AZ issued this flash flood warning at Aug 1, 2021, 4:52 PM MST for Apache County, Coconino County, Navajo County, Arizona. It was in force for 3 hr. 1 report 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: Aug 1, 2021, 4:52 PM MST (23:52 UTC)
Expired: Aug 1, 2021, 8:00 PM MST
In force: 3 hr
Issued by: NWS Flagstaff, AZ
Area: Storm-based polygon
Damage threat: Considerable
Flood severity: None

Counties Apache County, AZ, Coconino County, AZ, Navajo County, AZ

The radar

The Flagstaff radar (KFSX), 160 km from the middle of the area, began a volume at 23:56 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
Aug 1, 7:05 PM MST	FLASH FLOOD	Polacca, AZ	WATER AND DEBRIS FLOWING OVER ROADWAY.

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 12:00Z, 11.9 hours before the alert went out and 133 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: 74 J/kg
Mixed-layer CIN: -65 J/kg
Mixed-layer LCL: 1273 m above ground
0-6 km bulk shear: 22 kt
0-1 km storm-relative helicity: 43 m²/s²
0-3 km storm-relative helicity: 71 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0

Open this sounding in Storm Lab

The text

As transmitted.

807 
WGUS55 KFGZ 012352
FFWFGZ
AZC001-005-017-020300-
/O.NEW.KFGZ.FF.W.0140.210801T2352Z-210802T0300Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
Flash Flood Warning
National Weather Service Flagstaff AZ
452 PM MST Sun Aug 1 2021

The National Weather Service in Flagstaff has issued a

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

* Until 800 PM MST.

* At 451 PM MST, Doppler radar indicated thunderstorms producing 
  heavy rain across the warned area. Between 1 and 2 inches of rain 
  have fallen. 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...
  Hard Rock, First Mesa, Forest Lake Chapter House, Low Mountain, 
  Whippoorwill Chapter House, Kykotsmovi Village, Second Mesa, 
  Shongopovi, Hotevilla, Polacca, and Pinon.

This includes the following highways...
	State Route 87 between mile markers 394 and 406.
	State Route 264 between mile markers 346 and 400.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

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

In hilly or mountainous terrain, there are many low water crossings 
which will become dangerous in heavy rain. Do not attempt to cross 
flooded roads. Find an alternate route.

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 3544 11080 3544 11090 3553 11101 3566 11104
      3573 11101 3582 11093 3585 11095 3596 11092
      3623 11071 3630 11058 3642 11042 3647 11031
      3641 11013 3632 11001 3614 10997 3602 11001
      3561 11049

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

$$

TM

2 follow-up statements

544 
WGUS75 KFGZ 020109
FFSFGZ

Flash Flood Statement
National Weather Service Flagstaff AZ
609 PM MST Sun Aug 1 2021

AZC001-020119-
/O.CAN.KFGZ.FF.W.0140.000000T0000Z-210802T0300Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Apache AZ-
609 PM MST Sun Aug 1 2021

...FLASH FLOOD WARNING IS CANCELLED FOR NORTHERN APACHE COUNTY...

Flooding is no longer expected to pose a threat. Please continue to 
heed remaining road closures.

LAT...LON 3544 11080 3544 11090 3553 11101 3566 11104
      3573 11101 3582 11093 3585 11095 3596 11092
      3623 11071 3630 11058 3642 11042 3647 11031
      3641 11013 3632 11003 3614 11001 3602 11003
      3561 11049

$$

AZC005-017-020300-
/O.CON.KFGZ.FF.W.0140.000000T0000Z-210802T0300Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Coconino AZ-Navajo AZ-
609 PM MST Sun Aug 1 2021

...FLASH FLOOD WARNING REMAINS IN EFFECT UNTIL 8 PM MST THIS EVENING 
FOR COCONINO AND NAVAJO COUNTIES...

At 607 PM MST, Doppler radar indicated thunderstorms moving out of 
the area. Between 1 and 2 inches of rain have fallen. 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...
  Hard Rock, First Mesa, Forest Lake Chapter House, Low Mountain, 
  Whippoorwill Chapter House, Kykotsmovi Village, Second Mesa, 
  Shongopovi, Hotevilla, Polacca, and Pinon.

This includes the following highways...
	State Route 87 between mile markers 394 and 406.
	State Route 264 between mile markers 346 and 400.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

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

In hilly or mountainous terrain, there are many low water crossings 
which will become dangerous in heavy rain. Do not attempt to cross 
flooded roads. Find an alternate route.

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 3544 11080 3544 11090 3553 11101 3566 11104
      3573 11101 3582 11093 3585 11095 3596 11092
      3623 11071 3630 11058 3642 11042 3647 11031
      3641 11013 3632 11003 3614 11001 3602 11003
      3561 11049

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

$$

TM

217 
WGUS75 KFGZ 020255
FFSFGZ

Flash Flood Statement
National Weather Service Flagstaff AZ
755 PM MST Sun Aug 1 2021

AZC005-017-020305-
/O.EXP.KFGZ.FF.W.0140.000000T0000Z-210802T0300Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Coconino AZ-Navajo AZ-
755 PM MST Sun Aug 1 2021

...FLASH FLOOD WARNING WILL EXPIRE AT 8 PM MST THIS EVENING FOR 
COCONINO AND NAVAJO COUNTIES...

Flood waters have receded and the heavy rain has ended. Flooding is 
no longer expected to pose a threat.

Do not attempt to any cross flooded roads. Turn around, don't drown 
when encountering flooded roads. Please continue to heed remaining 
road closures.

LAT...LON 3544 11080 3544 11090 3553 11101 3566 11104
      3573 11101 3582 11093 3585 11095 3596 11092
      3623 11071 3630 11058 3642 11042 3647 11031
      3641 11013 3632 11003 3614 11001 3602 11003
      3561 11049

$$

Humphreys

The office that day

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

Issued	Product	Office	Counties	Lasted
Jul 31, 5:22 PM MST	Areal Flood Advisory	FGZ	Yavapai	113 min
Jul 31, 6:08 PM MST	Areal Flood Advisory	FGZ	Apache, Navajo	3 hr
Aug 1, 12:03 PM MST	Special Weather Statement	FGZ		27 min
Aug 1, 12:15 PM MST	Special Weather Statement	FGZ		30 min
Aug 1, 12:53 PM MST	Special Weather Statement	FGZ	Coconino	22 min
Aug 1, 1:08 PM MST	Special Weather Statement	FGZ		22 min
Aug 1, 1:14 PM MST	Special Weather Statement	FGZ		31 min
Aug 1, 1:30 PM MST	Special Weather Statement	FGZ	Navajo	30 min
Aug 1, 1:38 PM MST	Special Weather Statement	FGZ	Coconino	22 min
Aug 1, 1:53 PM MST	Special Weather Statement	FGZ		37 min
Aug 1, 2:03 PM MST	Special Weather Statement	FGZ	Navajo	27 min
Aug 1, 2:26 PM MST	Special Weather Statement	FGZ	Navajo	34 min
Aug 1, 2:55 PM MST	Special Weather Statement	FGZ		35 min
Aug 1, 3:12 PM MST	Special Weather Statement	FGZ		33 min
Aug 1, 3:15 PM MST	Special Weather Statement	FGZ		30 min
Aug 1, 3:21 PM MST	Special Weather Statement	FGZ		24 min
Aug 1, 3:58 PM MST	Flash Flood Warning	FGZ	Gila, Navajo	3 hr
Aug 1, 4:18 PM MST	Areal Flood Advisory	FGZ	Coconino	3 hr
Aug 1, 4:24 PM MST	Special Weather Statement	FGZ		51 min
Aug 1, 4:38 PM MST	Severe Thunderstorm Warning	FGZ	Apache, Navajo	37 min
Aug 1, 4:51 PM MST	Flash Flood Warning	FGZ	Gila, Navajo	3 hr

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.