Alert archive / Arizona / Flash Flood Warnings in 2021

Flash Flood Warning 169, NWS Flagstaff, AZ

August 11, 2021Apache County, Arizona

NWS Flagstaff, AZ issued this flash flood warning at Aug 11, 2021, 2:49 PM MST for Apache 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, 2:49 PM MST (21:49 UTC)
Expired: Aug 11, 2021, 5:54 PM MST
In force: 3 hr
Issued by: NWS Flagstaff, AZ
Area: Storm-based polygon
Damage threat: Considerable
Flood severity: None

County Apache County, AZ

The radar

The Flagstaff radar (KFSX), 196 km from the middle of the area, began a volume at 21:49 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, 9.8 hours before the alert went out and 218 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.

249 
WGUS55 KFGZ 112149
FFWFGZ
AZC001-120100-
/O.NEW.KFGZ.FF.W.0169.210811T2149Z-210812T0100Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

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

The National Weather Service in Flagstaff has issued a

* Flash Flood Warning for...
  Apache County in northeastern Arizona...

* Until 600 PM MST.

* At 249 PM MST, Doppler radar indicated thunderstorms producing 
  heavy rain across the warned area. Between 0.5 and 1.25 inches of 
  rain have fallen. Additional rainfall amounts of 0.25 to 0.75 
  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...
  Klagetoh, Wide Ruins and Navajo Reservation.

This includes the following highways...
	Highway 191 between mile markers 388 and 408.
	State Route 264 between mile markers 452 and 459.

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.

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 3575 10939 3567 10927 3537 10948 3537 10952
      3565 10957

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

$$

EL

2 follow-up statements

856 
WGUS75 KFGZ 112251
FFSFGZ

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

AZC001-120100-
/O.CON.KFGZ.FF.W.0169.000000T0000Z-210812T0100Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Apache AZ-
351 PM MST Wed Aug 11 2021

...FLASH FLOOD WARNING REMAINS IN EFFECT UNTIL 6 PM MST THIS EVENING 
FOR APACHE COUNTY...

At 350 PM MST, Doppler radar indicated that rainfall rates have 
decreased across the warned area, however flooding still remains a 
concern while flood waters recede. Between 0.75 and 1.75 inches of 
rain have fallen. Additional rainfall amounts of 0.25 to 0.75 inches 
are possible in the warned area.

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...
  Klagetoh, Wide Ruins and Navajo Reservation.

This includes the following highways...
	Highway 191 between mile markers 388 and 408.
	State Route 264 between mile markers 453 and 458.

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.

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 3575 10939 3567 10927 3537 10948 3537 10952
      3565 10957

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

$$

Humphreys

084 
WGUS75 KFGZ 120054
FFSFGZ

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

AZC001-120104-
/O.CAN.KFGZ.FF.W.0169.000000T0000Z-210812T0100Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Apache AZ-
554 PM MST Wed Aug 11 2021

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

The heavy rain southeast of Ganado has ended. Flooding is no longer 
expected to pose a threat. Please heed any road closures and avoid 
driving through flowing water on roadways.

LAT...LON 3575 10939 3567 10927 3537 10948 3537 10952
      3565 10957

$$

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, 1:48 PM MST	Flash Flood Warning Considerable damage threat	FGZ	Coconino	3 hr
Aug 11, 2:25 PM MST	Special Weather Statement	FGZ		35 min
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.