Alert archive / Arizona / Flash Flood Warnings in 2021

Flash Flood Warning 168, NWS Flagstaff, AZ

August 11, 2021Coconino County, Arizona

NWS Flagstaff, AZ issued this flash flood warning at Aug 11, 2021, 1:48 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 11, 2021, 1:48 PM MST (20:48 UTC)
Expired: Aug 11, 2021, 4:45 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), 98 km from the middle of the area, began a volume at 20:51 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 20 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: 82 J/kg
Mixed-layer CIN: -165 J/kg
Mixed-layer LCL: 1265 m above ground
0-6 km bulk shear: 8 kt
0-1 km storm-relative helicity: 84 m²/s²
0-3 km storm-relative helicity: 153 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0

Open this sounding in Storm Lab

The text

As transmitted.

527 
WGUS55 KFGZ 112048
FFWFGZ
AZC005-112345-
/O.NEW.KFGZ.FF.W.0168.210811T2048Z-210811T2345Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
Flash Flood Warning
National Weather Service Flagstaff AZ
148 PM MST Wed Aug 11 2021

The National Weather Service in Flagstaff has issued a

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

* Until 445 PM MST.

* At 146 PM MST, Doppler radar indicated thunderstorms producing 
  heavy rain across the warned area. Between 1 and 2 inches of rain 
  have fallen. Additional rainfall amounts of 0.75 to 1.75 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.

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

* Some locations that will experience flash flooding include...
  Parks, Bellemont, Raymond Boy Scout Camp, White Horse Lake 
  Campground and Dogtown Lake Campground.

This includes the following swimming holes...
Sycamore Falls, Lower Sycamore Falls "The Golden Pond" and Paradise 
Forks.

This includes the following highways...
	Interstate 40 between mile markers 169 and 188.

This includes the following streams and drainages...
  Pumphouse Wash, Volunteer Wash, Sycamore Creek, JD Dam Wash, 
  Dogtown Wash, Hell Canyon, Sinclair Wash, Bear Canyon and Tule 
  Tank Wash.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Turn around, don't drown when encountering flooded roads. Most flood 
deaths occur in vehicles. Use caution when driving during heavy 
rainfall.

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 3514 11220 3527 11209 3528 11188 3522 11177
      3512 11173 3510 11193 3503 11207 3507 11217

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

$$

Humphreys

2 follow-up statements

143 
WGUS75 KFGZ 112114
FFSFGZ

Flash Flood Statement
National Weather Service Flagstaff AZ
214 PM MST Wed Aug 11 2021

AZC005-112345-
/O.CON.KFGZ.FF.W.0168.000000T0000Z-210811T2345Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Coconino AZ-
214 PM MST Wed Aug 11 2021

...FLASH FLOOD WARNING REMAINS IN EFFECT UNTIL 445 PM MST THIS 
AFTERNOON FOR COCONINO COUNTY...

At 213 PM MST, Doppler radar indicated that rainfall rates have 
decreased across the warned area, however flooding still remains a 
concern. Between 1 and 2 inches of rain have fallen. Additional 
rainfall amounts of 0.25 to 1 inch 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.

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

Some locations that will experience flash flooding include...
  Parks, Bellemont, Raymond Boy Scout Camp, White Horse Lake 
  Campground and Dogtown Lake Campground.

This includes the following swimming holes...
Sycamore Falls, Lower Sycamore Falls "The Golden Pond" and Paradise 
Forks.

This includes the following highways...
	Interstate 40 between mile markers 169 and 189.

This includes the following streams and drainages...
  Pumphouse Wash, Volunteer Wash, Sycamore Creek, JD Dam Wash, 
  Dogtown Wash, Hell Canyon, Sinclair Wash, Bear Canyon and Tule 
  Tank Wash.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Turn around, don't drown when encountering flooded roads. Most flood 
deaths occur in vehicles. Use caution when driving during heavy 
rainfall.

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 3514 11220 3527 11209 3528 11188 3522 11177
      3512 11173 3510 11193 3503 11207 3507 11217

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

$$

Humphreys

896 
WGUS75 KFGZ 112342
FFSFGZ

Flash Flood Statement
National Weather Service Flagstaff AZ
442 PM MST Wed Aug 11 2021

AZC005-112352-
/O.EXP.KFGZ.FF.W.0168.000000T0000Z-210811T2345Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Coconino AZ-
442 PM MST Wed Aug 11 2021

...FLASH FLOOD WARNING WILL EXPIRE AT 445 PM MST THIS AFTERNOON FOR 
COCONINO COUNTY...

The heavy rain has ended across the area extending from Bellemont 
and Williams to Sycamore Canyon. Flooding is no longer expected to 
pose a threat. Please heed any road closures.

LAT...LON 3514 11220 3527 11209 3528 11188 3522 11177
      3512 11173 3510 11193 3503 11207 3507 11217

$$

McCollum

The office that day

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

Issued	Product	Office	Counties	Lasted
Aug 11, 9:30 AM MST	Flash Flood Warning Considerable damage threat	FGZ	Yavapai	3 hr
Aug 11, 1:38 PM MST	Flash Flood Warning Considerable damage threat	FGZ	Yavapai	3 hr
Aug 11, 2:25 PM MST	Special Weather Statement	FGZ		35 min
Aug 11, 2:49 PM MST	Flash Flood Warning Considerable damage threat	FGZ	Apache	3 hr
Aug 11, 3:11 PM MST	Special Weather Statement	FGZ		34 min
Aug 11, 4:24 PM MST	Flash Flood Warning Considerable damage threat	FGZ	Yavapai	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.