Alert archive / Arizona / Flash Flood Warnings in 2021

Flash Flood Warning 112, NWS Flagstaff, AZ

July 26, 2021Coconino County, Arizona

NWS Flagstaff, AZ issued this flash flood warning at Jul 26, 2021, 7:03 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: Jul 26, 2021, 7:03 PM MST (02:03 UTC)
Expired: Jul 26, 2021, 10:15 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), 88 km from the middle of the area, began a volume at 02:03 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 00:00Z, 2.1 hours before the alert went out and 55 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: 401 J/kg
Mixed-layer CIN: -7 J/kg
Mixed-layer LCL: 1252 m above ground
0-6 km bulk shear: 14 kt
0-1 km storm-relative helicity: -8 m²/s²
0-3 km storm-relative helicity: 49 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0

Open this sounding in Storm Lab

The text

As transmitted.

089 
WGUS55 KFGZ 270203
FFWFGZ
AZC005-270515-
/O.NEW.KFGZ.FF.W.0112.210727T0203Z-210727T0515Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
Flash Flood Warning
National Weather Service Flagstaff AZ
703 PM MST Mon Jul 26 2021

The National Weather Service in Flagstaff has issued a

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

* Until 1015 PM MST.

* At 702 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 0.5 to 1.5 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...
  Wupatki National Monument and Navajo Reservation.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

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.

&&

LAT...LON 3531 11132 3534 11137 3554 11130 3549 11099
      3529 11105 3527 11120

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

$$

Humphreys

2 follow-up statements

938 
WGUS75 KFGZ 270344
FFSFGZ

Flash Flood Statement
National Weather Service Flagstaff AZ
844 PM MST Mon Jul 26 2021

AZC005-270515-
/O.CON.KFGZ.FF.W.0112.000000T0000Z-210727T0515Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Coconino AZ-
844 PM MST Mon Jul 26 2021

...FLASH FLOOD WARNING REMAINS IN EFFECT UNTIL 1015 PM MST THIS 
EVENING FOR COCONINO COUNTY...

At 843 PM MST, heavy rain had moved out of the the warned area, 
however flash flooding is expected to remain a threat while water 
recedes.

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...
  Wupatki National Monument and Navajo Reservation.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

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.

&&

LAT...LON 3531 11132 3534 11137 3554 11130 3549 11099
      3529 11105 3527 11120

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

$$

Humphreys

490 
WGUS75 KFGZ 270510
FFSFGZ

Flash Flood Statement
National Weather Service Flagstaff AZ
1010 PM MST Mon Jul 26 2021

AZC005-270520-
/O.EXP.KFGZ.FF.W.0112.000000T0000Z-210727T0515Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Coconino AZ-
1010 PM MST Mon Jul 26 2021

...FLASH FLOOD WARNING WILL EXPIRE AT 1015 PM MST THIS EVENING FOR 
COCONINO COUNTY...

Flood waters have receded and the heavy rain has ended. Flooding is 
no longer expected to pose a threat. Please continue to heed 
remaining road closures.

LAT...LON 3531 11132 3534 11137 3554 11130 3549 11099
      3529 11105 3527 11120

$$

Humphreys

The office that day

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

Issued	Product	Office	Counties	Lasted
Jul 26, 5:47 PM MST	Flash Flood Warning Considerable damage threat	FGZ	Coconino	8 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.