Alert archive / Arizona / Flash Flood Warnings in 2021

Flash Flood Warning 220, NWS Flagstaff, AZ

August 31, 2021Yavapai County, Arizona

NWS Flagstaff, AZ issued this flash flood warning at Aug 31, 2021, 2:51 PM MST for Yavapai County, Arizona. It was in force for 3 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 31, 2021, 2:51 PM MST (21:51 UTC)
Expired: Aug 31, 2021, 6:00 PM MST
In force: 3 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), 72 km from the middle of the area, began a volume at 21:53 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

Time	Report	Where	Remark
Aug 31, 6:00 PM MST	FLASH FLOOD	1 Sw Middle Verde, AZ	RISE FROM 2.49 FEET TO A CREST OF 4.39 FEET ON THE VERDE RIVER AT GAUGE VAVA3.

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

The nearest sounding before it

Flgstf/Belemont, AZ (KFGZ), launched 12:00Z, 9.9 hours before the alert went out and 65 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: 81 J/kg
Mixed-layer CIN: -113 J/kg
Mixed-layer LCL: 995 m above ground
0-6 km bulk shear: 13 kt
0-1 km storm-relative helicity: -50 m²/s²
0-3 km storm-relative helicity: 62 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0

Open this sounding in Storm Lab

The text

As transmitted.

335 
WGUS55 KFGZ 312151
FFWFGZ
AZC025-010100-
/O.NEW.KFGZ.FF.W.0220.210831T2151Z-210901T0100Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
Flash Flood Warning
National Weather Service Flagstaff AZ
251 PM MST Tue Aug 31 2021

The National Weather Service in Flagstaff has issued a

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

* Until 600 PM MST.

* At 250 PM MST, Doppler radar indicated thunderstorms producing 
  heavy rain across the warned area. Between 0.75 and 1.75 inches of 
  rain have fallen. Additional rainfall amounts of 0.25 to 1.25 
  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...
  Verde Village, Bridgeport and Cottonwood.

This includes the following highways...
	State Route 89A between mile markers 355 and 357.
	State Route 260 between mile markers 207 and 216.

This includes the following creeks, washes and rivers...
  Oak Wash, Oak Creek, Verde River and Cherry Creek.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

Stay away or be swept away! The banks of creeks and washes are 
unstable and unsafe during any flooding event.

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 3470 11209 3474 11197 3471 11194 3467 11193
      3463 11190 3461 11189 3459 11203

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

$$

Humphreys

2 follow-up statements

808 
WGUS75 KFGZ 312318
FFSFGZ

Flash Flood Statement
National Weather Service Flagstaff AZ
418 PM MST Tue Aug 31 2021

AZC025-010100-
/O.CON.KFGZ.FF.W.0220.000000T0000Z-210901T0100Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Yavapai AZ-
418 PM MST Tue Aug 31 2021

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

At 416 PM MST, Doppler radar indicated that the heavy rainfall had 
moved out of the warned area, however flooding remains a threat 
while area creeks and washes remain high. Between 1 and 2 inches of 
rain have fallen. 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...
  Verde Village, Bridgeport and Cottonwood.

This includes the following highways...
	State Route 89A between mile markers 355 and 357.
	State Route 260 between mile markers 207 and 216.

This includes the following creeks, washes and rivers...
  Oak Wash, Oak Creek, Verde River and Cherry Creek.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

Stay away or be swept away! The banks of creeks and washes are 
unstable and unsafe during any flooding event.

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 3470 11209 3474 11197 3471 11194 3467 11193
      3463 11190 3461 11189 3459 11203

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

$$

Humphreys

879 
WGUS75 KFGZ 010054
FFSFGZ

Flash Flood Statement
National Weather Service Flagstaff AZ
554 PM MST Tue Aug 31 2021

AZC025-010104-
/O.EXP.KFGZ.FF.W.0220.000000T0000Z-210901T0100Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Yavapai AZ-
554 PM MST Tue Aug 31 2021

...FLASH FLOOD WARNING WILL EXPIRE AT 6 PM MST THIS EVENING FOR 
YAVAPAI COUNTY...

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

A Flash Flood Watch remains in effect until 500 AM MST Thursday.

LAT...LON 3470 11209 3474 11197 3471 11194 3467 11193
      3463 11190 3461 11189 3459 11203

$$

Humphreys

The office that day

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

Issued	Product	Office	Counties	Lasted
Aug 31, 12:48 PM MST	Special Weather Statement	FGZ		12 min

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