Alert archive / Arizona / Snow Squall Warnings in 2021

Snow Squall Warning 2, NWS Flagstaff, AZ

March 13, 2021Coconino County, Arizona

NWS Flagstaff, AZ issued this snow squall warning at Mar 13, 2021, 2:53 PM MST for Coconino County, Arizona. It was in force for 22 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
Mar 13, 2021, 2:53 PM MST (21:53 UTC)
Expired
Mar 13, 2021, 3:15 PM MST
In force
22 min
Issued by
NWS Flagstaff, AZ
Area
Storm-based polygon

County Coconino County, AZ

The radar

The Flagstaff radar (KFSX), 50 km from the middle of the area, began a volume at 21:57 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, 9.9 hours before the alert went out and 44 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 2021-03-13Temperature 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 2021-03-13The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity -18 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
1041 m above ground
0-6 km bulk shear
22 kt
0-1 km storm-relative helicity
-18 m²/s²
0-3 km storm-relative helicity
19 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0

Open this sounding in Storm Lab

The text

As transmitted.

305 
WWUS55 KFGZ 132154
SQWFGZ

BULLETIN - IMMEDIATE BROADCAST REQUESTED
Snow Squall Warning
National Weather Service Flagstaff AZ
253 PM MST Sat Mar 13 2021

AZC005-132215-
/O.NEW.KFGZ.SQ.W.0002.210313T2153Z-210313T2215Z/
Coconino-
253 PM MST Sat Mar 13 2021

The National Weather Service in Flagstaff has issued a

* Snow Squall Warning for...
  Coconino County for I-17 near Munds Park in north central 
  Arizona...

* Until 315 PM MST.

* At 253 PM MST, a dangerous snow squall was located along a line
  extending from 8 miles southeast of Walnut Canyon National Monument
  to near Happy Jack, moving east at 25 mph.

  HAZARD...Whiteout conditions. Zero visibility in heavy snow and 
           blowing snow. Wind gusts up to 30 mph.

  SOURCE...Radar indicated.

  IMPACT...Dangerous life-threatening travel.

* 

This includes the following highways...
 Interstate 17 between mile markers 311 and 333.
 State Route 89A near mile marker 378, and between mile markers 385
and 393.

Locations impacted include...
Munds Park, Mountainaire, Cave Springs Campground, Sterling Fish
Hatchery and Pine Flat Campground.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Consider avoiding or delaying travel until the snow squall passes
your location. If you must travel, use extra caution and allow extra
time. Rapid changes in visibility and slick road conditions may lead
to accidents.

&&

LAT...LON 3480 11155 3480 11172 3508 11175 3509 11157
      3477 11154 3477 11155
TIME...MOT...LOC 2153Z 273DEG 21KT 3508 11142 3469 11146 

$$

ET
1 follow-up statement
658 
WWUS55 KFGZ 132210
SQWFGZ

Snow Squall Warning
National Weather Service Flagstaff AZ
310 PM MST Sat Mar 13 2021

AZC005-132220-
/O.EXP.KFGZ.SQ.W.0002.000000T0000Z-210313T2215Z/
Coconino-
310 PM MST Sat Mar 13 2021

...THE SNOW SQUALL WARNING FOR COCONINO COUNTY WILL EXPIRE AT 315 PM
MST...

The snow squall which prompted the warning has exited the area.
Therefore, the snow squall warning will be allowed to expire. Snow
and ice-covered roads will continue to make travel difficult.

LAT...LON 3480 11155 3480 11172 3508 11175 3509 11157
      3477 11154 3477 11155
TIME...MOT...LOC 2210Z 273DEG 21KT 3508 11136 3469 11140 

$$

ET

The office that day

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

IssuedProductOfficeCountiesLasted
Mar 13, 1:03 PM MSTWind AdvisoryFGZApache, Navajo30 hr
Mar 13, 2:15 PM MSTSnow Squall WarningFGZCoconino, Yavapai45 min
Mar 13, 3:37 PM MSTSnow Squall WarningFGZCoconino23 min
Mar 13, 3:59 PM MSTSnow Squall WarningFGZCoconino, Yavapai46 min
Mar 13, 4:46 PM MSTSnow Squall WarningFGZCoconino, Yavapai29 min

Nearby

Snow Squall Warnings in Arizona, 2021Every snow squall 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.