Alert archive / Arizona / Severe Thunderstorm Warnings in 2021

Severe Thunderstorm Warning 35, NWS Flagstaff, AZ

July 12, 2021Coconino County, Yavapai County, Arizona

NWS Flagstaff, AZ issued this severe thunderstorm warning at Jul 12, 2021, 5:40 PM MST for Coconino County, Yavapai County, Arizona. It was in force for 35 min. 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 12, 2021, 5:40 PM MST (00:40 UTC)
Expired
Jul 12, 2021, 6:15 PM MST
In force
35 min
Issued by
NWS Flagstaff, AZ
Area
Storm-based polygon
Hail
0.88 in
Wind
60.0 mph

Counties Coconino County, AZ, Yavapai County, AZ

The radar

The Flagstaff radar (KFSX), 141 km from the middle of the area, began a volume at 00:42 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 12, 5:50 PM MSTHAIL 0.73 N Ash Fork, AZ

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 00:00Z, 0.7 hours before the alert went out and 64 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 2021-07-13Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 622 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 2021-07-13The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 40 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
622 J/kg
Mixed-layer CIN
-57 J/kg
Mixed-layer LCL
2672 m above ground
0-6 km bulk shear
17 kt
0-1 km storm-relative helicity
40 m²/s²
0-3 km storm-relative helicity
117 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0

Open this sounding in Storm Lab

The text

As transmitted.

482 
WUUS55 KFGZ 130040
SVRFGZ
AZC005-025-130115-
/O.NEW.KFGZ.SV.W.0035.210713T0040Z-210713T0115Z/

BULLETIN - IMMEDIATE BROADCAST REQUESTED
Severe Thunderstorm Warning
National Weather Service Flagstaff AZ
540 PM MST Mon Jul 12 2021

The National Weather Service in Flagstaff has issued a

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

* Until 615 PM MST.

* At 539 PM MST, a severe thunderstorm was located near Ash Fork and 
  moving moving southeast at 15 mph.

  HAZARD...60 mph wind gusts and nickel size hail.

  SOURCE...Radar indicated.

  IMPACT...Expect damage to roofs, siding, and trees.

* Locations impacted include...
  Ash Fork.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

LAT...LON 3522 11265 3537 11255 3529 11232 3511 11238
TIME...MOT...LOC 0039Z 298DEG 19KT 3527 11252 

HAIL...0.88IN
WIND...60MPH
 
$$
2 follow-up statements
908 
WWUS55 KFGZ 130102
SVSFGZ

Severe Weather Statement
National Weather Service Flagstaff AZ
602 PM MST Mon Jul 12 2021

AZC005-025-130115-
/O.CON.KFGZ.SV.W.0035.000000T0000Z-210713T0115Z/
Yavapai-Coconino-
602 PM MST Mon Jul 12 2021

...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT UNTIL 615 PM MST
FOR YAVAPAI AND COCONINO COUNTIES...

At 601 PM MST, a severe thunderstorm was located near Ash Fork and 
moving moving southeast at 20 mph.

HAZARD...60 mph wind gusts and quarter size hail.

SOURCE...Radar indicated.

IMPACT...Hail damage to vehicles is expected. Expect wind damage to 
         roofs, siding, and trees.

Locations impacted include...
Ash Fork.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

LAT...LON 3522 11265 3537 11255 3529 11232 3511 11238
TIME...MOT...LOC 0101Z 298DEG 19KT 3521 11239 

HAIL...1.00IN
WIND...60MPH
 
$$
482 
WWUS55 KFGZ 130115
SVSFGZ

Severe Weather Statement
National Weather Service Flagstaff AZ
615 PM MST Mon Jul 12 2021

AZC005-025-130123-
/O.EXP.KFGZ.SV.W.0035.000000T0000Z-210713T0115Z/
Yavapai-Coconino-
615 PM MST Mon Jul 12 2021

...THE SEVERE THUNDERSTORM WARNING FOR YAVAPAI AND COCONINO COUNTIES
WILL EXPIRE AT 615 PM MST...
                
The storm which prompted the Severe Thunderstorms Warning near Ash 
Fork has weakened below severe limits and no longer poses an 
immediate threat to life or property. Therefore, the warning will be 
allowed to expire.

However, wind gusts to 50 mph are still possible with this 
thunderstorm, especially along I-40 between Ash Fork and Williams 
through 645 PM MST.

LAT...LON 3522 11265 3537 11255 3529 11232 3511 11238
TIME...MOT...LOC 0113Z 298DEG 19KT 3518 11233 

$$

The office that day

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

IssuedProductOfficeCountiesLasted
Jul 12, 5:56 PM MSTSevere Thunderstorm WarningFGZCoconino34 min
Jul 12, 7:10 PM MSTAreal Flood AdvisoryFGZCoconino, Yavapai3 hr
Jul 13, 12:41 PM MSTFlash Flood Warning Considerable damage threatFGZCoconino, Navajo3 hr
Jul 13, 1:29 PM MSTFlash Flood Warning Considerable damage threatFGZCoconino3 hr
Jul 13, 1:57 PM MSTSpecial Weather StatementFGZ33 min
Jul 13, 2:25 PM MSTFlash Flood Warning Considerable damage threatFGZCoconino2 hr
Jul 13, 2:38 PM MSTFlash Flood Warning Considerable damage threatFGZCoconino112 min
Jul 13, 2:54 PM MSTSevere Thunderstorm WarningFGZYavapai29 min
Jul 13, 3:06 PM MSTSpecial Weather StatementFGZYavapai39 min
Jul 13, 3:27 PM MSTSevere Thunderstorm WarningFGZYavapai33 min
Jul 13, 4:14 PM MSTFlash Flood Warning Considerable damage threatFGZYavapai3 hr
Jul 13, 4:25 PM MSTAreal Flood AdvisoryFGZCoconino, Yavapai3 hr

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.