Alert archive / Arizona / Flash Flood Warnings in 2021

Flash Flood Warning 61, NWS Flagstaff, AZ

July 20, 2021Navajo County, Arizona

NWS Flagstaff, AZ issued this flash flood warning at Jul 20, 2021, 8:55 PM MDT for Navajo County, Arizona. It was in force for 2 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
Jul 20, 2021, 8:55 PM MDT (02:55 UTC)
Expired
Jul 20, 2021, 11:00 PM MDT
In force
2 hr
Issued by
NWS Flagstaff, AZ
Area
Storm-based polygon
Damage threat
Considerable
Flood severity
None

County Navajo County, AZ

The radar

The Flagstaff radar (KFSX), 80 km from the middle of the area, began a volume at 02:54 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, 2.9 hours before the alert went out and 151 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 2021-07-21Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 716 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 2021-07-21The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity -4 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
716 J/kg
Mixed-layer CIN
-31 J/kg
Mixed-layer LCL
1279 m above ground
0-6 km bulk shear
27 kt
0-1 km storm-relative helicity
-4 m²/s²
0-3 km storm-relative helicity
21 m²/s²
Significant tornado parameter
-0.0
Supercell composite
-0.0

Open this sounding in Storm Lab

The text

As transmitted.

914 
WGUS55 KFGZ 210255
FFWFGZ
AZC017-210500-
/O.NEW.KFGZ.FF.W.0061.210721T0255Z-210721T0500Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

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

The National Weather Service in Flagstaff has issued a

* Flash Flood Warning for...
  Navajo County in north central Arizona...

* Until 1000 PM MST.

* At 754 PM MST, Doppler radar indicated thunderstorms producing 
  heavy rain across the warned area. Between 1 and 2 inches of rain 
  have fallen. Additional rainfall amounts of 0.75 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...
  Dry Lake.

This includes the following highways...
	State Route 377 between mile markers 8 and 15.

This includes the following streams and drainages...
  Sevenmile Draw, Phoenix Park Wash, Scott Wash and Washboard Wash.

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.

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 3465 11033 3464 11020 3452 11027 3456 11043
      3464 11041

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

$$

TPS
2 follow-up statements
953 
WGUS75 KFGZ 210401
FFSFGZ

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

AZC017-210500-
/O.CON.KFGZ.FF.W.0061.000000T0000Z-210721T0500Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Navajo AZ-
901 PM MST Tue Jul 20 2021

...FLASH FLOOD WARNING REMAINS IN EFFECT UNTIL 10 PM MST THIS 
EVENING FOR NAVAJO COUNTY...

At 900 PM MST, Doppler radar indicated thunderstorms producing heavy 
rain have mostly diminished across the warned area. However, light 
to moderate rain continues to fall. Between 1.5 and 2.5 inches of 
rain have fallen. Additional rainfall amounts of 0.25 to 0.5 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...
  Dry Lake.

This includes the following highways...
	State Route 377 between mile markers 8 and 15.

This includes the following streams and drainages...
  Sevenmile Draw, Phoenix Park Wash, Scott Wash and Washboard Wash.

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.

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 3465 11033 3464 11020 3452 11027 3456 11043
      3464 11041

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

$$

TPS
492 
WGUS75 KFGZ 210452
FFSFGZ

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

AZC017-210502-
/O.EXP.KFGZ.FF.W.0061.000000T0000Z-210721T0500Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Navajo AZ-
952 PM MST Tue Jul 20 2021

...FLASH FLOOD WARNING WILL EXPIRE AT 10 PM MST THIS EVENING FOR 
NAVAJO COUNTY...

The heavy rain threat has ended near Dry Lake and State Highway 377. 
Flows will remain high through creek and washes over the next few 
hours so continue to use caution. Please continue to heed remaining 
road closures.

LAT...LON 3465 11033 3464 11020 3452 11027 3456 11043
      3464 11041

$$

TPS

The office that day

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

IssuedProductOfficeCountiesLasted
Jul 20, 7:16 PM MDTSpecial Weather StatementFGZ29 min
Jul 20, 8:32 PM MDTSevere Thunderstorm WarningFGZNavajo28 min
Jul 20, 9:33 PM MDTFlash Flood Warning Considerable damage threatFGZNavajo117 min
Jul 21, 1:17 AM MDTFlash Flood Warning Considerable damage threatFGZGila118 min
Jul 21, 3:38 AM MDTFlash Flood WatchFGZApache, Coconino, Gila, Navajo, Yavapai5 days
Jul 21, 11:19 AM MDTSpecial Weather StatementFGZYavapai26 min
Jul 21, 11:48 AM MDTFlash Flood Warning Considerable damage threatFGZYavapai2 hr
Jul 21, 1:03 PM MDTSpecial Weather StatementFGZYavapai42 min
Jul 21, 1:13 PM MDTFlash Flood Warning Considerable damage threatFGZYavapai56 min
Jul 21, 1:20 PM MDTFlash Flood Warning Considerable damage threatFGZYavapai114 min
Jul 21, 1:35 PM MDTSpecial Weather StatementFGZ40 min
Jul 21, 1:47 PM MDTFlash Flood Warning Considerable damage threatFGZCoconino118 min
Jul 21, 1:54 PM MDTSpecial Weather StatementFGZ36 min
Jul 21, 2:06 PM MDTFlash Flood Warning Considerable damage threatFGZCoconino92 min
Jul 21, 2:24 PM MDTFlash Flood Warning Considerable damage threatFGZCoconino110 min
Jul 21, 2:27 PM MDTFlash Flood Warning Considerable damage threatFGZYavapai74 min
Jul 21, 2:57 PM MDTSpecial Weather StatementFGZYavapai48 min
Jul 21, 3:01 PM MDTAreal Flood AdvisoryFGZYavapai119 min
Jul 21, 3:05 PM MDTFlash Flood Warning Considerable damage threatFGZCoconino2 hr
Jul 21, 3:22 PM MDTAreal Flood AdvisoryFGZCoconino3 hr
Jul 21, 3:30 PM MDTSpecial Weather StatementFGZ45 min
Jul 21, 3:36 PM MDTFlash Flood Warning Considerable damage threatFGZYavapai54 min
Jul 21, 3:53 PM MDTFlash Flood Warning Considerable damage threatFGZCoconino82 min
Jul 21, 3:57 PM MDTFlash Flood Warning Considerable damage threatFGZYavapai60 min
Jul 21, 3:59 PM MDTFlash Flood Warning Considerable damage threatFGZYavapai60 min
Jul 21, 4:21 PM MDTSevere Thunderstorm WarningFGZCoconino26 min
Jul 21, 4:34 PM MDTFlash Flood Warning Considerable damage threatFGZCoconino98 min
Jul 21, 4:49 PM MDTFlash Flood Warning Considerable damage threatFGZYavapai3 hr
Jul 21, 5:35 PM MDTFlash Flood Warning Considerable damage threatFGZCoconino115 min

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.