Alert archive / Arizona / Flash Flood Warnings in 2021

Flash Flood Warning 150, NWS Flagstaff, AZ

August 6, 2021Apache County, Arizona

NWS Flagstaff, AZ issued this flash flood warning at Aug 6, 2021, 7:31 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 6, 2021, 7:31 PM MST (02:31 UTC)
Expired
Aug 6, 2021, 10:30 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), 160 km from the middle of the area, began a volume at 02:32 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, 2.5 hours before the alert went out and 232 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-pSkew-T log-p diagram, Flgstf/Belemont, AZ at 00:00Z on 2021-08-07Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 49 joules per kilogram.LCLLFCEL10008507005003002001001 km2 km3 km6 km9 km12 km-30°-20°-10°10°20°30°40°
Temperature in red, dew point in green, the mixed-layer parcel dashed.
HodographHodograph, Flgstf/Belemont, AZ at 00:00Z on 2021-08-07The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 29 square meters per square second.193958Sfc1 km3 km6 km9 kmRMLM
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
49 J/kg
Mixed-layer CIN
-89 J/kg
Mixed-layer LCL
2530 m above ground
0-6 km bulk shear
17 kt
0-1 km storm-relative helicity
29 m²/s²
0-3 km storm-relative helicity
53 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0

Open this sounding in Storm Lab

The text

As transmitted.

381 
WGUS55 KFGZ 070231
FFWFGZ
AZC001-070530-
/O.NEW.KFGZ.FF.W.0150.210807T0231Z-210807T0530Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
Flash Flood Warning
National Weather Service Flagstaff AZ
731 PM MST Fri Aug 6 2021

The National Weather Service in Flagstaff has issued a

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

* Until 1030 PM MST.

* At 730 PM MST, Doppler radar indicated thunderstorms producing 
  heavy rain over areas already affected by heavy rain, south of 
  Concho and St Johns and west of Lyman Lake. 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...
  Eastern St Johns, Lyman Lake State Park and Lyman Lake.

This includes the following highways...
	State Route 61 between mile markers 378 and 381.
	Highway 180 between mile markers 356 and 366.
	Highway 180 191 between mile markers 373 and 385.

This includes the following streams and drainages...
  Big Hollow Wash and portions of the Little Colorado River near St 
  Johns.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

LAT...LON 3458 10941 3455 10941 3449 10940 3439 10935
      3431 10933 3426 10943 3427 10949 3430 10957
      3435 10959 3442 10957 3447 10954 3455 10947

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

$$

Peterson
1 follow-up statement
684 
WGUS75 KFGZ 070526
FFSFGZ

Flash Flood Statement
National Weather Service Flagstaff AZ
1026 PM MST Fri Aug 6 2021

AZC001-070536-
/O.EXP.KFGZ.FF.W.0150.000000T0000Z-210807T0530Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Apache AZ-
1026 PM MST Fri Aug 6 2021

...FLASH FLOOD WARNING WILL EXPIRE AT 1030 PM MST THIS EVENING FOR 
APACHE COUNTY...

At 1025 PM MST, National Weather Service Doppler radar indicated 
that rainfall had ended south of St Johns. No flooding reports were 
received and the Flash Flood Warning will be allowed to expire.

Areas creeks, washes and streams are likely still running high. 
Please continue to heed remaining road closures.

LAT...LON 3458 10941 3455 10941 3449 10940 3439 10935
      3431 10933 3426 10943 3427 10949 3430 10957
      3435 10959 3442 10957 3447 10954 3455 10947

$$

Peterson

Nearby

Flash Flood Warnings in Arizona, 2021Every 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.