Alert archive / Arizona / Severe Thunderstorm Warnings in 2021

Severe Thunderstorm Warning 55, NWS Flagstaff, AZ

July 18, 2021Navajo County, Arizona

NWS Flagstaff, AZ issued this severe thunderstorm warning at Jul 18, 2021, 3:33 PM MDT for Navajo County, Arizona. It was in force for 42 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, 3:33 PM MDT (21:33 UTC)
Expired: Jul 18, 2021, 4:15 PM MDT
In force: 42 min
Issued by: NWS Flagstaff, AZ
Area: Storm-based polygon
Hail: 1.0 in
Wind: 60.0 mph

County Navajo County, AZ

The radar

The Flagstaff radar (KFSX), 80 km from the middle of the area, began a volume at 21:35 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

Phoenix, AZ (KPSR), launched 12:00Z, 9.6 hours before the alert went out and 153 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: 453 J/kg
Mixed-layer CIN: -202 J/kg
Mixed-layer LCL: 2153 m above ground
0-6 km bulk shear: 14 kt
0-1 km storm-relative helicity: 7 m²/s²
0-3 km storm-relative helicity: 40 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.4

Open this sounding in Storm Lab

The text

As transmitted.

353 
WUUS55 KFGZ 182133
SVRFGZ
AZC017-182215-
/O.NEW.KFGZ.SV.W.0055.210718T2133Z-210718T2215Z/

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

The National Weather Service in Flagstaff has issued a

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

* Until 315 PM MST.

* At 232 PM MST, a severe thunderstorm was located 18 miles northwest
  of Carrizo moving northwest 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
  Navajo County.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

LAT...LON 3409 11044 3402 11059 3412 11072 3424 11047
TIME...MOT...LOC 2132Z 127DEG 10KT 3413 11057 

HAIL...1.00IN
WIND...60MPH
 
$$

ET

1 follow-up statement

624 
WWUS55 KFGZ 182212
SVSFGZ

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

AZC017-182222-
/O.EXP.KFGZ.SV.W.0055.000000T0000Z-210718T2215Z/
Navajo-
312 PM MST Sun Jul 18 2021

...THE SEVERE THUNDERSTORM WARNING FOR NAVAJO COUNTY WILL EXPIRE AT
315 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 3409 11044 3402 11059 3412 11072 3424 11047
TIME...MOT...LOC 2212Z 127DEG 10KT 3420 11067 

$$

EL

The office that day

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

Issued	Product	Office	Counties	Lasted
Jul 18, 11:58 AM MDT	Severe Thunderstorm Warning	FGZ	Yavapai	32 min
Jul 18, 12:14 PM MDT	Flash Flood Warning Considerable damage threat	FGZ	Yavapai	3 hr
Jul 18, 1:16 PM MDT	Severe Thunderstorm Warning	FGZ	Coconino	29 min
Jul 18, 2:03 PM MDT	Flash Flood Warning Considerable damage threat	FGZ	Navajo	3 hr
Jul 18, 2:08 PM MDT	Special Weather Statement	FGZ		37 min
Jul 18, 2:34 PM MDT	Flash Flood Warning Considerable damage threat	FGZ	Coconino	3 hr
Jul 18, 3:12 PM MDT	Severe Thunderstorm Warning	FGZ	Gila, Navajo	33 min
Jul 18, 3:18 PM MDT	Severe Thunderstorm Warning	FGZ	Gila	42 min
Jul 18, 3:31 PM MDT	Areal Flood Advisory	FGZ	Coconino	100 min
Jul 18, 3:53 PM MDT	Flash Flood Warning Considerable damage threat	FGZ	Gila, Navajo	102 min
Jul 18, 4:02 PM MDT	Flash Flood Warning Considerable damage threat	FGZ	Coconino	108 min
Jul 18, 4:47 PM MDT	Severe Thunderstorm Warning	FGZ	Gila	43 min
Jul 18, 4:54 PM MDT	Special Weather Statement	FGZ		51 min
Jul 18, 5:10 PM MDT	Flash Flood Warning Considerable damage threat	FGZ	Yavapai	51 min
Jul 18, 5:32 PM MDT	Flash Flood Warning Considerable damage threat	FGZ	Navajo	4 hr
Jul 18, 5:59 PM MDT	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.