Alert archive / Arizona / Severe Thunderstorm Warnings in 2021

Severe Thunderstorm Warning 93, NWS Flagstaff, AZ

August 9, 2021Coconino County, Arizona

NWS Flagstaff, AZ issued this severe thunderstorm warning at Aug 9, 2021, 4:21 PM MST for Coconino County, Arizona. It was in force for 24 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
Aug 9, 2021, 4:21 PM MST (23:21 UTC)
Expired
Aug 9, 2021, 4:45 PM MST
In force
24 min
Issued by
NWS Flagstaff, AZ
Area
Storm-based polygon
Hail
1.0 in
Wind
60.0 mph

County Coconino County, AZ

The radar

The Flagstaff radar (KFSX), 51 km from the middle of the area, began a volume at 23:22 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, 11.4 hours before the alert went out and 51 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 2021-08-09Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 0 joules per kilogram.LCL10008507005003002001001 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 2021-08-09The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity -20 square meters per square second.193958Sfc1 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
0 J/kg
Mixed-layer CIN
No buoyant parcel
Mixed-layer LCL
2142 m above ground
0-6 km bulk shear
9 kt
0-1 km storm-relative helicity
-20 m²/s²
0-3 km storm-relative helicity
-74 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0

Open this sounding in Storm Lab

The text

As transmitted.

506 
WUUS55 KFGZ 092321
SVRFGZ
AZC005-092345-
/O.NEW.KFGZ.SV.W.0093.210809T2321Z-210809T2345Z/

BULLETIN - IMMEDIATE BROADCAST REQUESTED
Severe Thunderstorm Warning
National Weather Service Flagstaff AZ
421 PM MST Mon Aug 9 2021

The National Weather Service in Flagstaff has issued a

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

* Until 445 PM MST.

* At 421 PM MST, a severe thunderstorm was located 10 miles northeast
  of Mormon Lake, or 22 miles southeast of Flagstaff, moving south at
  10 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.

* This severe thunderstorm will remain over mainly rural areas of
  Coconino County.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

Large hail and damaging winds and continuous cloud to ground
lightning is occurring with this storm. Move indoors immediately.
Lightning is one of nature's leading killers. Remember, if you can
hear thunder, you are close enough to be struck by lightning.

&&

LAT...LON 3510 11136 3509 11117 3491 11116 3492 11142
TIME...MOT...LOC 2321Z 001DEG 10KT 3501 11129 

HAIL THREAT...RADAR INDICATED
MAX HAIL SIZE...1.00 IN
WIND THREAT...RADAR INDICATED
MAX WIND GUST...60 MPH

$$

MCT
2 follow-up statements
642 
WWUS55 KFGZ 092333
SVSFGZ

Severe Weather Statement
National Weather Service Flagstaff AZ
433 PM MST Mon Aug 9 2021

AZC005-092345-
/O.CON.KFGZ.SV.W.0093.000000T0000Z-210809T2345Z/
Coconino-
433 PM MST Mon Aug 9 2021

...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT UNTIL 445 PM MST
FOR COCONINO COUNTY...

At 433 PM MST, a severe thunderstorm was located 9 miles east of
Mormon Lake, or 23 miles southeast of Flagstaff, and is nearly
stationary.

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.

This severe thunderstorm will remain over mainly rural areas of
Coconino County.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

Continuous cloud to ground lightning is occurring with this storm.
Move indoors immediately. Lightning is one of nature's leading
killers. Remember, if you can hear thunder, you are close enough to
be struck by lightning.

&&

LAT...LON 3510 11136 3509 11117 3491 11116 3492 11142
TIME...MOT...LOC 2333Z 001DEG 10KT 3499 11129 

HAIL THREAT...RADAR INDICATED
MAX HAIL SIZE...1.00 IN
WIND THREAT...RADAR INDICATED
MAX WIND GUST...60 MPH

$$

MCT
624 
WWUS55 KFGZ 092343
SVSFGZ

Severe Weather Statement
National Weather Service Flagstaff AZ
443 PM MST Mon Aug 9 2021

AZC005-092352-
/O.EXP.KFGZ.SV.W.0093.000000T0000Z-210809T2345Z/
Coconino-
443 PM MST Mon Aug 9 2021

...THE SEVERE THUNDERSTORM WARNING FOR COCONINO COUNTY WILL EXPIRE AT
445 PM MST...
                
The storm which prompted the warning 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 small
hail, gusty winds and heavy rain are still possible with this
thunderstorm.

LAT...LON 3510 11136 3509 11117 3491 11116 3492 11142
TIME...MOT...LOC 2342Z 001DEG 10KT 3497 11129 

$$

MCT

The office that day

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

IssuedProductOfficeCountiesLasted
Aug 8, 5:16 PM MSTSpecial Weather StatementFGZ44 min
Aug 9, 12:30 PM MSTSpecial Weather StatementFGZYavapai30 min
Aug 9, 2:27 PM MSTFlash Flood Warning Considerable damage threatFGZYavapai2 hr
Aug 9, 2:39 PM MSTFlash Flood Warning Considerable damage threatFGZYavapai3 hr
Aug 9, 3:42 PM MSTFlash Flood Warning Considerable damage threatFGZYavapai3 hr
Aug 9, 3:53 PM MSTFlash Flood Warning Considerable damage threatFGZCoconino3 hr
Aug 9, 4:15 PM MSTSpecial Weather StatementFGZ30 min
Aug 9, 4:42 PM MSTFlash Flood Warning Considerable damage threatFGZCoconino, Gila3 hr
Aug 9, 4:51 PM MSTFlash Flood Warning Considerable damage threatFGZCoconino3 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; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.