Alert archive / Arizona / Flash Flood Warnings in 2021

Flash Flood Warning 215, NWS Flagstaff, AZ

August 18, 2021Yavapai County, Arizona

NWS Flagstaff, AZ issued this flash flood warning at Aug 18, 2021, 8:08 PM MST for Yavapai County, Arizona. It was in force for 6 hr. 1 report came from inside the area while it was in force.

The area

The outline as issued, with what was reported inside it.

The facts

Issued
Aug 18, 2021, 8:08 PM MST (03:08 UTC)
Expired
Aug 19, 2021, 2:15 AM MST
In force
6 hr
Issued by
NWS Flagstaff, AZ
Area
Storm-based polygon
Damage threat
Considerable
Flood severity
None

County Yavapai County, AZ

The radar

The Flagstaff radar (KFSX), 101 km from the middle of the area, began a volume at 03:11 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.

What was reported inside it

TimeReportWhereRemark
Aug 18, 8:08 PM MSTFLASH FLOOD1 Wnw Black Canyon City, AZAT 8:08 PM MST, EMERGENCY MANAGEMENT REPORTED A 4 FOOT RISE IN BLACK CANYON CREEK.

Local storm reports filed while the alert was in force, from inside its polygon or its counties.

The nearest sounding before it

Phoenix, AZ (KPSR), launched 00:00Z, 3.1 hours before the alert went out and 83 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, Phoenix, AZ at 00:00Z on 2021-08-19Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 510 joules per kilogram.LCLLFCEL10008507005003002001001 km2 km3 km6 km9 km12 km15 km-30°-20°-10°10°20°30°40°
Temperature in red, dew point in green, the mixed-layer parcel dashed.
HodographHodograph, Phoenix, AZ at 00:00Z on 2021-08-19The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 157 square meters per square second.1939Sfc1 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
510 J/kg
Mixed-layer CIN
-174 J/kg
Mixed-layer LCL
1692 m above ground
0-6 km bulk shear
24 kt
0-1 km storm-relative helicity
157 m²/s²
0-3 km storm-relative helicity
230 m²/s²
Significant tornado parameter
0.0
Supercell composite
1.7

Open this sounding in Storm Lab

The text

As transmitted.

603 
WGUS55 KFGZ 190308
FFWFGZ
AZC025-190715-
/O.NEW.KFGZ.FF.W.0215.210819T0308Z-210819T0715Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
Flash Flood Warning
National Weather Service Flagstaff AZ
808 PM MST Wed Aug 18 2021

The National Weather Service in Flagstaff has issued a

* Flash Flood Warning for...
  Yavapai County in west central Arizona...

* Until 1215 AM MST.

* At 808 PM MST, emergency management reported a 4 ft rise in Black 
  Canyon Creek. Flash flooding is ongoing in Black Canyon Creek and 
  will begin to impact low water crossings near Black Canyon City 
  and the Agua Fria River.

  HAZARD...Life-threatening flash flooding. Thunderstorms
           producing flash flooding.

  SOURCE...Emergency management reported.

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

* Some locations that will experience flash flooding include...
  mainly rural areas of Yavapai County

This includes the following highways...
	Interstate 17 near mile marker 245.

This includes the following streams and drainages...
Agua Fria River, Black Canyon Creek.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

LAT...LON 3424 11222 3424 11221 3422 11219 3420 11217
      3419 11216 3412 11216 3410 11214 3407 11215
      3406 11216 3406 11217 3410 11216 3411 11218
      3418 11218 3419 11220

FLASH FLOOD...OBSERVED
FLASH FLOOD DAMAGE THREAT...CONSIDERABLE

$$

ET
1 follow-up statement
793 
WGUS55 KFGZ 190705
FFWFGZ
AZC025-190915-
/O.EXT.KFGZ.FF.W.0215.000000T0000Z-210819T0915Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
Flash Flood Warning
National Weather Service Flagstaff AZ
1205 AM MST Thu Aug 19 2021

The National Weather Service in Flagstaff has extended the

* Flash Flood Warning for...
  Yavapai County in west central Arizona...

* Until 215 AM MST.

* At 1205 AM MST, emergency management reported a 4 ft rise in Black 
  Canyon Creek. Flash flooding is ongoing in Black Canyon Creek and 
  will begin to impact low water crossings near Black Canyon City 
  and the Agua Fria River.

  HAZARD...Life-threatening flash flooding. Thunderstorms
           producing flash flooding.

  SOURCE...Emergency management reported.

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

* Some locations that will experience flash flooding include...
  mainly rural areas of Yavapai County

This includes the following highways...
	Interstate 17 near mile marker 245.

This includes the following streams and drainages...
Agua Fria River, Black Canyon Creek.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

Be especially cautious at night when it is harder to recognize the 
dangers of flooding.

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 3424 11222 3424 11221 3422 11219 3420 11217
      3419 11216 3412 11216 3410 11214 3407 11215
      3406 11216 3406 11217 3410 11216 3411 11218
      3418 11218 3419 11220

FLASH FLOOD...OBSERVED
FLASH FLOOD DAMAGE THREAT...CONSIDERABLE

$$

Humphreys

The office that day

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

IssuedProductOfficeCountiesLasted
Aug 18, 5:13 PM MSTFlash Flood WarningFGZYavapai3 hr
Aug 18, 5:17 PM MSTFlash Flood Warning Considerable damage threatFGZCoconino, Yavapai4 hr
Aug 18, 5:31 PM MSTSpecial Weather StatementFGZYavapai29 min
Aug 18, 5:43 PM MSTSevere Thunderstorm WarningFGZCoconino23 min
Aug 18, 7:59 PM MSTFlash Flood Warning Considerable damage threatFGZGila4 hr
Aug 18, 10:41 PM MSTAreal Flood WarningFGZGila, Yavapai10 hr
Aug 18, 11:56 PM MSTFlash Flood Warning Considerable damage threatFGZCoconino8 hr

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; local storm reports from the same archive; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.