Alert archive / Arizona / Snow Squall Warnings in 2021

Snow Squall Warning 4, NWS Flagstaff, AZ

March 13, 2021Coconino County, Yavapai County, Arizona

NWS Flagstaff, AZ issued this snow squall warning at Mar 13, 2021, 3:59 PM MST for Coconino County, Yavapai County, Arizona. It was in force for 46 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, 3:59 PM MST (22:59 UTC)
Expired
Mar 13, 2021, 4:45 PM MST
In force
46 min
Issued by
NWS Flagstaff, AZ
Area
Storm-based polygon

Counties Coconino County, AZ, Yavapai County, AZ

The radar

The Flagstaff radar (KFSX), 55 km from the middle of the area, began a volume at 23:01 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, 11.0 hours before the alert went out and 37 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°0°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.

158 
WWUS55 KFGZ 132301
SQWFGZ

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

AZC005-025-132345-
/O.NEW.KFGZ.SQ.W.0004.210313T2259Z-210313T2345Z/
Yavapai-Coconino-
359 PM MST Sat Mar 13 2021

The National Weather Service in Flagstaff has issued a

* Snow Squall Warning for...
  Yavapai County in west central Arizona...
  Coconino County in north central Arizona...

* Until 445 PM MST.

* At 359 PM MST, a dangerous snow squall was located along a line 
  extending from near Munds Park to near Village of Oak Creek, 
  moving southeast at 10 mph.

  HAZARD...Whiteout conditions. Zero visibility in 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 309 and 331.
 State Route 89A between mile markers 377 and 379, between mile
markers 385 and 387, and between mile markers 390 and 392.

Locations impacted include...
Munds Park, 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 3503 11152 3476 11153 3481 11173 3506 11174
TIME...MOT...LOC 2259Z 298DEG 9KT 3501 11165 3479 11171 

$$
JJ
1 follow-up statement
077 
WWUS55 KFGZ 132331
SQWFGZ

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

AZC005-025-132345-
/O.CON.KFGZ.SQ.W.0004.000000T0000Z-210313T2345Z/
Yavapai-Coconino-
426 PM MST Sat Mar 13 2021

...A SNOW SQUALL WARNING REMAINS IN EFFECT UNTIL 445 PM MST FOR
YAVAPAI AND COCONINO COUNTIES...

At 426 PM MST, a dangerous snow squall was located along a line
extending from near Munds Park to 6 miles west of Stoneman Lake,
moving southeast at 10 mph.

HAZARD...Whiteout conditions. Zero visibility in 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 309 and 331.
 State Route 89A between mile markers 377 and 379, between mile
 markers 385 and 387, and between mile markers 390 and 392.

Locations impacted include...
Munds Park, 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. Please check az511.com for road conditions, including 
any road closures.

&&

LAT...LON 3503 11152 3476 11153 3481 11173 3506 11174
TIME...MOT...LOC 2326Z 298DEG 9KT 3498 11158 3476 11164 

$$
JJ

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, 2:53 PM MSTSnow Squall WarningFGZCoconino22 min
Mar 13, 3:37 PM MSTSnow Squall WarningFGZCoconino23 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.