Alert archive / Arizona / Severe Thunderstorm Warnings in 2021

Severe Thunderstorm Warning 30, NWS Flagstaff, AZ

July 11, 2021Yavapai County, Arizona

NWS Flagstaff, AZ issued this severe thunderstorm warning at Jul 11, 2021, 4:25 PM MST for Yavapai County, Arizona. It was in force for 35 min. 3 reports 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 11, 2021, 4:25 PM MST (23:25 UTC)
Expired
Jul 11, 2021, 5:00 PM MST
In force
35 min
Issued by
NWS Flagstaff, AZ
Area
Storm-based polygon
Hail
1.25 in
Wind
70.0 mph

County Yavapai County, AZ

The radar

The Flagstaff radar (KFSX), 120 km from the middle of the area, began a volume at 23:24 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
Jul 11, 4:30 PM MSTTSTM WND DMGPrescott, AZLAW ENFORCEMENT DISPATCH REPORTED DAMAGE TO THE ROOF OF AN APARTMENT COMPLEX IN PRESCOTT.
Jul 11, 5:00 PM MSTTSTM WND DMG3 S Chino Valley, AZCAR PORT ROOF REPORTEDLY BLOWN OFF THE STRUCTURE AND ON THE GROUND.
Jul 11, 5:10 PM MSTTORNADO3 S Chino Valley, AZTRAINED SPOTTER OBSERVED A TORNADO WEST OF OUTER LOOP ROAD AND SR 89 FOR AROUND 45 SECONDS. INTERMITTENT CLOUD TO GROUND ROTATION WAS CONFIRMED. SPOTTER ID MAA19292.

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, 11.4 hours before the alert went out and 89 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 12:00Z on 2021-07-11Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 197 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 12:00Z on 2021-07-11The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 128 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
197 J/kg
Mixed-layer CIN
-303 J/kg
Mixed-layer LCL
2378 m above ground
0-6 km bulk shear
13 kt
0-1 km storm-relative helicity
128 m²/s²
0-3 km storm-relative helicity
126 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0

Open this sounding in Storm Lab

The text

As transmitted.

040 
WUUS55 KFGZ 112325
SVRFGZ
AZC025-120000-
/O.NEW.KFGZ.SV.W.0030.210711T2325Z-210712T0000Z/

BULLETIN - IMMEDIATE BROADCAST REQUESTED
Severe Thunderstorm Warning
National Weather Service Flagstaff AZ
425 PM MST Sun Jul 11 2021

The National Weather Service in Flagstaff has issued a

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

* Until 500 PM MST.

* At 424 PM MST, a severe thunderstorm was located near Prescott
  Airport, or near Prescott Valley, moving west at 10 mph.

  HAZARD...70 mph wind gusts and half dollar size hail.

  SOURCE...Trained spotters and automated observations.

  IMPACT...Hail damage to vehicles is expected. Expect considerable 
           tree damage. Wind damage is also likely to mobile homes, 
           roofs, and outbuildings.

* Locations impacted include...
  Chino Valley, Prescott Valley, Prescott, Yavapai Campground,
  Downtown Prescott, Prescott Airport, Williamson Valley, Indian Hill
  West Prescott and Iron Springs.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

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

&&

LAT...LON 3477 11243 3458 11234 3446 11262 3483 11271
TIME...MOT...LOC 2324Z 102DEG 8KT 3463 11248 

HAIL...1.25IN
WIND...70MPH
 
$$

RR
1 follow-up statement
418 
WWUS55 KFGZ 112340
SVSFGZ

Severe Weather Statement
National Weather Service Flagstaff AZ
440 PM MST Sun Jul 11 2021

AZC025-120000-
/O.CON.KFGZ.SV.W.0030.000000T0000Z-210712T0000Z/
Yavapai-
440 PM MST Sun Jul 11 2021

...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT UNTIL 500 PM MST
FOR YAVAPAI COUNTY...

At 440 PM MST, a severe thunderstorm was located over Yavapai
Campground, or 8 miles northwest of Prescott Valley, moving west at
10 mph.

HAZARD...70 mph wind gusts and quarter size hail.

SOURCE...Trained weather spotters.

IMPACT...Hail damage to vehicles is expected. Expect considerable 
         tree damage. Wind damage is also likely to mobile homes, 
         roofs, and outbuildings.

Locations impacted include...
Chino Valley, Prescott, Yavapai Campground, Williamson Valley and
Iron Springs.

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 3473 11245 3462 11243 3452 11263 3483 11271
TIME...MOT...LOC 2340Z 102DEG 8KT 3464 11252 

HAIL...1.00IN
WIND...70MPH
 
$$

RR

The office that day

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

IssuedProductOfficeCountiesLasted
Jul 10, 5:09 PM MSTSevere Thunderstorm WarningFGZCoconino, Gila, Yavapai51 min
Jul 10, 5:16 PM MSTSevere Thunderstorm WarningFGZApache, Coconino, Gila, Navajo44 min
Jul 10, 5:56 PM MSTSevere Thunderstorm WarningFGZGila, Yavapai49 min
Jul 10, 6:23 PM MSTFlash Flood Warning Considerable damage threatFGZGila, Navajo3 hr
Jul 10, 6:44 PM MSTSevere Thunderstorm WarningFGZGila, Yavapai35 min
Jul 11, 3:22 PM MSTSpecial Weather StatementFGZYavapai23 min
Jul 11, 3:35 PM MSTSevere Thunderstorm WarningFGZYavapai40 min
Jul 11, 3:49 PM MSTSevere Thunderstorm WarningFGZYavapai41 min
Jul 11, 4:46 PM MSTSevere Thunderstorm WarningFGZYavapai29 min
Jul 11, 4:58 PM MSTSevere Thunderstorm WarningFGZYavapai11 min

Nearby

Severe Thunderstorm Warnings in Arizona, 2021Every 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; local storm reports from the same archive; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.