Alert archive / Arizona / Severe Thunderstorm Warnings in 2021

Severe Thunderstorm Warning 52, NWS Flagstaff, AZ

July 18, 2021Coconino County, Arizona

NWS Flagstaff, AZ issued this severe thunderstorm warning at Jul 18, 2021, 12:16 PM MST for Coconino County, Arizona. It was in force for 29 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 18, 2021, 12:16 PM MST (19:16 UTC)
Expired: Jul 18, 2021, 12:45 PM MST
In force: 29 min
Issued by: NWS Flagstaff, AZ
Area: Storm-based polygon
Hail: 0.75 in
Wind: 60.0 mph

County Coconino County, AZ

The radar

The Flagstaff radar (KFSX), 16 km from the middle of the area, began a volume at 19:16 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, 7.3 hours before the alert went out and 93 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: 191 J/kg
Mixed-layer CIN: -101 J/kg
Mixed-layer LCL: 1511 m above ground
0-6 km bulk shear: 16 kt
0-1 km storm-relative helicity: 14 m²/s²
0-3 km storm-relative helicity: 46 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0

Open this sounding in Storm Lab

The text

As transmitted.

214 
WUUS55 KFGZ 181916
SVRFGZ
AZC005-181945-
/O.NEW.KFGZ.SV.W.0052.210718T1916Z-210718T1945Z/

BULLETIN - IMMEDIATE BROADCAST REQUESTED
Severe Thunderstorm Warning
National Weather Service Flagstaff AZ
1216 PM MST Sun Jul 18 2021

The National Weather Service in Flagstaff has issued a

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

* Until 1245 PM MST.

* At 1214 PM MST, a severe thunderstorm was located over near 
  Highway 87 near Blue Ridge Reservoir moving northwest at 5 mph.

  HAZARD...60 mph wind gusts.

  SOURCE...Radar indicated.

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

* Locations impacted include...
  Starlight Pines, Blue Ridge Campground and Chavez Mountain. 

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

LAT...LON 3466 11089 3452 11108 3461 11135 3483 11107
TIME...MOT...LOC 1914Z 135DEG 6KT 3463 11111 

HAIL...<.75IN
WIND...60MPH
 
$$

ET

2 follow-up statements

282 
WWUS55 KFGZ 181930
SVSFGZ

Severe Weather Statement
National Weather Service Flagstaff AZ
1230 PM MST Sun Jul 18 2021

AZC005-181945-
/O.CON.KFGZ.SV.W.0052.000000T0000Z-210718T1945Z/
Coconino-
1230 PM MST Sun Jul 18 2021

...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT UNTIL 1245 PM MST
FOR COCONINO COUNTY...

At 1229 PM MST, a severe thunderstorm was near Highway 87 near Blue 
Ridge Reservoir.

HAZARD...60 mph wind gusts.

SOURCE...Radar indicated.

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

Locations impacted include...
Starlight Pines and Blue Ridge Campground. 

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

LAT...LON 3464 11105 3456 11112 3461 11128 3474 11115
TIME...MOT...LOC 1929Z 135DEG 6KT 3465 11113 

HAIL...<.75IN
WIND...60MPH
 
$$

ET

161 
WWUS55 KFGZ 181939
SVSFGZ

Severe Weather Statement
National Weather Service Flagstaff AZ
1239 PM MST Sun Jul 18 2021

AZC005-181949-
/O.EXP.KFGZ.SV.W.0052.000000T0000Z-210718T1945Z/
Coconino-
1239 PM MST Sun Jul 18 2021

...THE SEVERE THUNDERSTORM WARNING FOR COCONINO COUNTY WILL EXPIRE AT
1245 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 heavy rain
is still possible with this thunderstorm.

LAT...LON 3464 11105 3456 11112 3461 11128 3474 11115
TIME...MOT...LOC 1939Z 135DEG 6KT 3466 11114 

$$
ET

The office that day

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

Issued	Product	Office	Counties	Lasted
Jul 18, 10:58 AM MST	Severe Thunderstorm Warning	FGZ	Yavapai	32 min
Jul 18, 11:14 AM MST	Flash Flood Warning Considerable damage threat	FGZ	Yavapai	3 hr
Jul 18, 1:03 PM MST	Flash Flood Warning Considerable damage threat	FGZ	Navajo	3 hr
Jul 18, 1:08 PM MST	Special Weather Statement	FGZ		37 min
Jul 18, 1:34 PM MST	Flash Flood Warning Considerable damage threat	FGZ	Coconino	3 hr
Jul 18, 2:12 PM MST	Severe Thunderstorm Warning	FGZ	Gila, Navajo	33 min
Jul 18, 2:18 PM MST	Severe Thunderstorm Warning	FGZ	Gila	42 min
Jul 18, 2:31 PM MST	Areal Flood Advisory	FGZ	Coconino	100 min
Jul 18, 2:33 PM MST	Severe Thunderstorm Warning	FGZ	Navajo	42 min
Jul 18, 2:53 PM MST	Flash Flood Warning Considerable damage threat	FGZ	Gila, Navajo	102 min
Jul 18, 3:02 PM MST	Flash Flood Warning Considerable damage threat	FGZ	Coconino	108 min
Jul 18, 3:47 PM MST	Severe Thunderstorm Warning	FGZ	Gila	43 min
Jul 18, 3:54 PM MST	Special Weather Statement	FGZ		51 min
Jul 18, 4:10 PM MST	Flash Flood Warning Considerable damage threat	FGZ	Yavapai	51 min
Jul 18, 4:32 PM MST	Flash Flood Warning Considerable damage threat	FGZ	Navajo	4 hr
Jul 18, 4:59 PM MST	Severe Thunderstorm Warning	FGZ	Gila, Yavapai	46 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.