Alert archive / Arizona / Severe Thunderstorm Warnings in 2021

Severe Thunderstorm Warning 61, NWS Flagstaff, AZ

July 20, 2021Yavapai County, Arizona

NWS Flagstaff, AZ issued this severe thunderstorm warning at Jul 20, 2021, 11:44 AM MST for Yavapai County, Arizona. It was in force for 35 min. 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, 11:44 AM MST (18:44 UTC)
Expired: Jul 20, 2021, 12:19 PM MST
In force: 35 min
Issued by: NWS Flagstaff, AZ
Area: Storm-based polygon
Hail: 1.0 in
Wind: 50.0 mph

County Yavapai County, AZ

The radar

The Flagstaff radar (KFSX), 114 km from the middle of the area, began a volume at 18:46 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 12:00Z, 6.7 hours before the alert went out and 103 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.

442 
WUUS55 KFGZ 201844
SVRFGZ
AZC025-201930-
/O.NEW.KFGZ.SV.W.0061.210720T1844Z-210720T1930Z/

BULLETIN - IMMEDIATE BROADCAST REQUESTED
Severe Thunderstorm Warning
National Weather Service Flagstaff AZ
1144 AM MST Tue Jul 20 2021

The National Weather Service in Flagstaff has issued a

* Severe Thunderstorm Warning for...
  Yavapai County in west central Arizona...

* Until 1230 PM MST.

* At 1143 AM MST, a severe thunderstorm was located over Groom Creek
  Subdivision, or 7 miles south of Prescott Valley, and is nearly
  stationary.

  HAZARD...Quarter size hail.

  SOURCE...Radar indicated.

  IMPACT...Damage to vehicles is expected.

* Locations impacted include...
  Walker, Oak Knoll Village, Groom Creek Subdivision, Lower Wolf
  Creek Campground and Upper Wolf Creek Group Campground.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

For your protection move to an interior room on the lowest floor of a
building.

Torrential rainfall is occurring with this storm, and may lead to
flash flooding. Do not drive your vehicle through flooded roadways.

&&

LAT...LON 3452 11245 3451 11236 3438 11239 3441 11253
TIME...MOT...LOC 1843Z 011DEG 3KT 3447 11243 

HAIL...1.00IN
WIND...<50MPH
 
$$
JJ

1 follow-up statement

446 
WWUS55 KFGZ 201919
SVSFGZ

Severe Weather Statement
National Weather Service Flagstaff AZ
1219 PM MST Tue Jul 20 2021

AZC025-201928-
/O.CAN.KFGZ.SV.W.0061.000000T0000Z-210720T1930Z/
Yavapai-
1219 PM MST Tue Jul 20 2021

...THE SEVERE THUNDERSTORM WARNING FOR YAVAPAI COUNTY IS CANCELLED...
                
The storm which prompted the warning near Groom Creek has weakened 
below severe limits. Therefore, the warning has been cancelled. 
However very heavy rain is still occurring with this thunderstorm 
and a Flash Flood Warning has been issued.

LAT...LON 3452 11245 3451 11236 3438 11239 3441 11253
TIME...MOT...LOC 1912Z 011DEG 3KT 3444 11244 

$$
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, 11:53 AM MST	Flash Flood Warning Considerable damage threat	FGZ	Yavapai	3 hr
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

Severe Thunderstorm Warnings in Arizona, 2021 Every severe thunderstorm 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.