Alert archive / Arizona / Flash Flood Warnings in 2021

Flash Flood Warning 156, NWS Flagstaff, AZ

August 9, 2021Coconino County, Arizona

NWS Flagstaff, AZ issued this flash flood warning at Aug 9, 2021, 4:51 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: Aug 9, 2021, 4:51 PM MST (23:51 UTC)
Expired: Aug 9, 2021, 8:00 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 Flagstaff radar (KFSX), 54 km from the middle of the area, began a volume at 23:54 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, 11.9 hours before the alert went out and 54 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: 0 J/kg
Mixed-layer CIN: No buoyant parcel
Mixed-layer LCL: 2142 m above ground
0-6 km bulk shear: 9 kt
0-1 km storm-relative helicity: -20 m²/s²
0-3 km storm-relative helicity: -74 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0

Open this sounding in Storm Lab

The text

As transmitted.

162 
WGUS55 KFGZ 092351
FFWFGZ
AZC005-100300-
/O.NEW.KFGZ.FF.W.0156.210809T2351Z-210810T0300Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
Flash Flood Warning
National Weather Service Flagstaff AZ
451 PM MST Mon Aug 9 2021

The National Weather Service in Flagstaff has issued a

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

* Until 800 PM MST.

* At 449 PM MST, Doppler radar indicated thunderstorms producing 
  heavy rain across the warned area. Between 1.5 and 3 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...
  Two Guns, Ashurst Lake Campgrounds and Navajo Reservation.

This includes the following highways...
	Interstate 40 between mile markers 222 and 230.

This includes the following streams and drainages...
  Diablo, Canyon, Little Colorado River, Yellow Jacket Canyon, 
  Anderson Canyon, Canyon Diablo Wash, Grapevine Canyon, San 
  Francisco Wash.

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.

&&

LAT...LON 3499 11145 3512 11128 3529 11103 3526 11097
      3506 11113 3487 11123 3490 11141

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

$$

MCT

2 follow-up statements

936 
WGUS75 KFGZ 100121
FFSFGZ

Flash Flood Statement
National Weather Service Flagstaff AZ
621 PM MST Mon Aug 9 2021

AZC005-100300-
/O.CON.KFGZ.FF.W.0156.000000T0000Z-210810T0300Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Coconino AZ-
621 PM MST Mon Aug 9 2021

...FLASH FLOOD WARNING REMAINS IN EFFECT UNTIL 8 PM MST THIS EVENING 
FOR COCONINO COUNTY...

At 619 PM MST, Doppler radar indicated heavy rain has moved out of 
the warned area with scattered light rain showers continuing. 
Between 1.5 and 4 inches of rain have already fallen. Flash flooding 
is ongoing or expected to begin shortly in Anderson Canyon, Yellow 
Jacket Canyon and Canyon Diablo.

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...
  Two Guns, Ashurst Lake Campgrounds and Navajo Reservation.

This includes the following highways...
	Interstate 40 between mile markers 222 and 230.

This includes the following streams and drainages...
  Diablo, Canyon, Little Colorado River, Yellow Jacket Canyon, 
  Anderson Canyon, and Canyon Diablo Wash.

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.

&&

LAT...LON 3499 11145 3512 11128 3529 11103 3526 11097
      3506 11113 3487 11123 3490 11141

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

$$

MCT

193 
WGUS75 KFGZ 100258
FFSFGZ

Flash Flood Statement
National Weather Service Flagstaff AZ
758 PM MST Mon Aug 9 2021

AZC005-100308-
/O.EXP.KFGZ.FF.W.0156.000000T0000Z-210810T0300Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Coconino AZ-
758 PM MST Mon Aug 9 2021

...FLASH FLOOD WARNING WILL EXPIRE AT 8 PM MST THIS EVENING FOR 
SOUTHEASTERN COCONINO COUNTY...

The heaviest rain has ended over the warned area with light rain 
showers continuing over the next hour. Elevated flows could still 
occur within the banks of washes, but flooding is no longer expected 
to pose a threat. Please continue to heed remaining road closures.

LAT...LON 3499 11145 3512 11128 3529 11103 3526 11097
      3506 11113 3487 11123 3490 11141

$$

NL

The office that day

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

Issued	Product	Office	Counties	Lasted
Aug 8, 5:16 PM MST	Special Weather Statement	FGZ		44 min
Aug 9, 12:30 PM MST	Special Weather Statement	FGZ	Yavapai	30 min
Aug 9, 2:27 PM MST	Flash Flood Warning Considerable damage threat	FGZ	Yavapai	2 hr
Aug 9, 2:39 PM MST	Flash Flood Warning Considerable damage threat	FGZ	Yavapai	3 hr
Aug 9, 3:42 PM MST	Flash Flood Warning Considerable damage threat	FGZ	Yavapai	3 hr
Aug 9, 3:53 PM MST	Flash Flood Warning Considerable damage threat	FGZ	Coconino	3 hr
Aug 9, 4:15 PM MST	Special Weather Statement	FGZ		30 min
Aug 9, 4:21 PM MST	Severe Thunderstorm Warning	FGZ	Coconino	24 min
Aug 9, 4:42 PM MST	Flash Flood Warning Considerable damage threat	FGZ	Coconino, Gila	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; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.