Alert archive / Colorado / Snow Squall Warnings in 2021

Snow Squall Warning 4, NWS Denver/Boulder, CO

December 26, 2021Grand County, Colorado

NWS Denver/Boulder, CO issued this snow squall warning at Dec 26, 2021, 1:33 PM MST for Grand County, Colorado. It was in force for 57 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: Dec 26, 2021, 1:33 PM MST (20:33 UTC)
Expired: Dec 26, 2021, 2:30 PM MST
In force: 57 min
Issued by: NWS Denver/Boulder, CO
Area: Storm-based polygon

County Grand County, CO

The radar

The Denver radar (KFTG), 156 km from the middle of the area, began a volume at 20:36 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

Grand Junction, CO (KGJT), launched 12:00Z, 8.6 hours before the alert went out and 223 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: 1 J/kg
Mixed-layer CIN: No buoyant parcel
Mixed-layer LCL: 1865 m above ground
0-6 km bulk shear: 113 kt
0-1 km storm-relative helicity: 165 m²/s²
0-3 km storm-relative helicity: 271 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0

Open this sounding in Storm Lab

The text

As transmitted.

780 
WWUS55 KBOU 262033
SQWBOU

BULLETIN - IMMEDIATE BROADCAST REQUESTED
Snow Squall Warning
National Weather Service Denver CO
133 PM MST Sun Dec 26 2021

COC049-262130-
/O.NEW.KBOU.SQ.W.0004.211226T2033Z-211226T2130Z/
Grand CO-
133 PM MST Sun Dec 26 2021

The National Weather Service in Denver Colorado has issued a

* Snow Squall Warning for...
  Central Grand County in north central Colorado...

* Until 230 PM MST.

* At 131 PM MST, a dangerous snow squall was located along a line
  extending from 7 miles southwest of Lake John to 21 miles northwest
  of Gypsum, or along a line extending from 66 miles southwest of 
  Laramie to 25 miles north of Glenwood Springs, moving east at 55 
  mph.

  HAZARD...Whiteout conditions. Zero visibility in snow and blowing 
           snow. Wind gusts greater than 40 mph.

  SOURCE...Radar indicated.

  IMPACT...Dangerous life-threatening travel along U.S 40 FROM 
           RABBIT EARS PASS TO TABERNASH


Locations impacted include...
Granby, Kremmling, Fraser, Hot Sulphur Springs, Parshall, Tabernash,
Elkdale, Hot Sulphur Spring and Williams Fork Reservoir.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Reduce your speed and turn on headlights! During snow squalls, the
visibility may suddenly drop to near zero in whiteout conditions.

&&

LAT...LON 4038 10657 4016 10620 4016 10584 3994 10582
      4001 10649 4038 10661
TIME...MOT...LOC 2031Z 255DEG 55KT 4074 10660 3989 10717 

$$

ENTREKIN

The office that day

Everything else NWS Denver/Boulder, CO issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Dec 26, 3:08 AM MST	High Wind Warning	BOU	Adams, Arapahoe, Douglas, Elbert, Lincoln, Washington	14 hr

Nearby

Snow Squall Warnings in Colorado, 2021 Every 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.