Alert archive / Arizona / Flash Flood Warnings in 2021

Flash Flood Warning 56, NWS Flagstaff, AZ

July 20, 2021Yavapai County, Arizona

NWS Flagstaff, AZ issued this flash flood warning at Jul 20, 2021, 11:53 AM 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: Jul 20, 2021, 11:53 AM MST (18:53 UTC)
Expired: Jul 20, 2021, 3:00 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), 113 km from the middle of the area, began a volume at 18:56 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
Jul 20, 12:30 PM MST	FLASH FLOOD	3 Ene Ponderosa Park, AZ	REPORT OF ESTIMATED TWO FEET OF WATER FLOWING THROUGH BANNING CREEK OVER THE LOW WATER CROSSING ON EAST SCHOOL HOUSE GULCH ROAD IN THE COMMUNITY OF GROOM CREEK.

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, 6.9 hours before the alert went out and 98 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: 396 J/kg
Mixed-layer CIN: -58 J/kg
Mixed-layer LCL: 1392 m above ground
0-6 km bulk shear: 14 kt
0-1 km storm-relative helicity: 16 m²/s²
0-3 km storm-relative helicity: 5 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0

Open this sounding in Storm Lab

The text

As transmitted.

606 
WGUS55 KFGZ 201853
FFWFGZ
AZC025-202200-
/O.NEW.KFGZ.FF.W.0056.210720T1853Z-210720T2200Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
Flash Flood Warning
National Weather Service Flagstaff AZ
1153 AM MST Tue Jul 20 2021

The National Weather Service in Flagstaff has issued a

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

* Until 300 PM MST.

* At 1152 AM MST, Doppler radar indicated thunderstorms producing 
  heavy rain in the area southeast of Prescott including Groom Creek 
  and Senator Highway. This includes Granite Creek and Groom Creek 
  drainages. One to two inches of rain has fallen in 30 minutes to 
  one hour. 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...
  Far east side of Prescott, Prescott Valley, Oak Knoll Village, 
  Groom Creek Subdivision, Lynx Lake Dam, Upper Wolf Creek Group 
  Campground and Lower Wolf Creek Campground.

This includes the following highways...
	State Route 69 near mile marker 296.
	State Route 89 between mile markers 312 and 315.

This includes the following streams and drainages...
  Bannon Creek, Granite Creek, Willow Creek, Wolf Creek, Hassayampa 
  River and Lynx Creek.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

Flooding of washes and creeks will occur, some dirt roads will 
become muddy and impassable. Paved roads and underpasses could 
become flooded as well.

&&

LAT...LON 3447 11247 3453 11247 3456 11246 3458 11244
      3458 11243 3456 11244 3454 11241 3453 11238
      3450 11238 3445 11239 3444 11247

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

$$

JJ

2 follow-up statements

238 
WGUS75 KFGZ 202109
FFSFGZ

Flash Flood Statement
National Weather Service Flagstaff AZ
209 PM MST Tue Jul 20 2021

AZC025-202200-
/O.CON.KFGZ.FF.W.0056.000000T0000Z-210720T2200Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Yavapai AZ-
209 PM MST Tue Jul 20 2021

...FLASH FLOOD WARNING REMAINS IN EFFECT UNTIL 3 PM MST THIS 
AFTERNOON FOR YAVAPAI COUNTY...

At 206 PM MST, Heavy rain has ended over the warned area, southeast 
of Prescott including Groom Creek and Senator Highway. This includes 
Granite Creek and Groom Creek. Between 1 and 3 inches of rain fell 
earlier this afternoon. Flash flooding is ongoing or expected to 
begin shortly. Reports were received of flooded washes and a car 
stuck in a wash in Groom Creek.

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...
  Oak Knoll Village, Groom Creek Subdivision, Lynx Lake Dam, Upper 
  Wolf Creek Group Campground and Lower Wolf Creek Campground.

This includes the following highways...
	State Route 69 between mile markers 295 and 296.
	State Route 89 between mile markers 312 and 314.

This includes the following streams and drainages...
  Bannon Creek, Granite Creek, Willow Creek, Wolf Creek, Hassayampa 
  River and Lynx Creek.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

Flooding of washes and creeks will occur, some dirt roads will 
become muddy and impassable. Paved roads and underpasses could 
become flooded as well.

&&

LAT...LON 3447 11247 3453 11247 3456 11246 3458 11244
      3458 11243 3456 11244 3454 11241 3453 11238
      3450 11238 3445 11239 3444 11247

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

$$

JJ

823 
WGUS75 KFGZ 202158
FFSFGZ

Flash Flood Statement
National Weather Service Flagstaff AZ
258 PM MST Tue Jul 20 2021

AZC025-202208-
/O.EXP.KFGZ.FF.W.0056.000000T0000Z-210720T2200Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Yavapai AZ-
258 PM MST Tue Jul 20 2021

...FLASH FLOOD WARNING WILL EXPIRE AT 3 PM MST THIS AFTERNOON FOR 
YAVAPAI COUNTY...

The heavy rain has ended. High flows could continue in a few 
locations for the next couple of hours, so please continue to heed 
remaining road closures and turn around if flooded roads are 
encountered.

LAT...LON 3447 11247 3453 11247 3456 11246 3458 11244
      3458 11243 3456 11244 3454 11241 3453 11238
      3450 11238 3445 11239 3444 11247

$$

JJ

The office that day

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

Issued	Product	Office	Counties	Lasted
Jul 19, 6:31 PM MST	Severe Thunderstorm Warning	FGZ	Gila	29 min
Jul 20, 11:44 AM MST	Severe Thunderstorm Warning	FGZ	Yavapai	35 min
Jul 20, 1:14 PM MST	Flash Flood Warning Considerable damage threat	FGZ	Yavapai	3 hr
Jul 20, 1:23 PM MST	Flash Flood Warning Considerable damage threat	FGZ	Coconino	3 hr
Jul 20, 1:39 PM MST	Flash Flood Warning Considerable damage threat	FGZ	Yavapai	3 hr
Jul 20, 3:45 PM MST	Flash Flood Warning Considerable damage threat	FGZ	Coconino	3 hr
Jul 20, 4:57 PM MST	Special Weather Statement	FGZ		48 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.