Alert archive / Colorado / Snow Squall Warnings in 2021

Snow Squall Warning 2, NWS Denver/Boulder, CO

December 15, 2021Summit County, Colorado

NWS Denver/Boulder, CO issued this snow squall warning at Dec 15, 2021, 6:03 AM MST for Summit 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 15, 2021, 6:03 AM MST (13:03 UTC)
Expired
Dec 15, 2021, 7:00 AM MST
In force
57 min
Issued by
NWS Denver/Boulder, CO
Area
Storm-based polygon

County Summit County, CO

The radar

The Denver radar (KFTG), 136 km from the middle of the area, began a volume at 13:03 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, 1.1 hours before the alert went out and 211 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, Grand Junction, CO at 12:00Z on 2021-12-15Temperature 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, Grand Junction, CO at 12:00Z on 2021-12-15The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity -252 square meters per square second.1939587897117Sfc1 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
755 m above ground
0-6 km bulk shear
98 kt
0-1 km storm-relative helicity
-252 m²/s²
0-3 km storm-relative helicity
-57 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0

Open this sounding in Storm Lab

The text

As transmitted.

742 
WWUS55 KBOU 151303
SQWBOU

BULLETIN - IMMEDIATE BROADCAST REQUESTED
Snow Squall Warning
National Weather Service Denver CO
603 AM MST Wed Dec 15 2021

COC117-151400-
/O.NEW.KBOU.SQ.W.0002.211215T1303Z-211215T1400Z/
Summit CO-
603 AM MST Wed Dec 15 2021

The National Weather Service in Denver Colorado has issued a

* Snow Squall Warning for...
  Southeastern Summit County in central Colorado...

* Until 700 AM MST.

* At 601 AM MST, a dangerous snow squall was located over Minturn, 
  or 48 miles east of Glenwood Springs, moving east at 25 mph. Heavy 
  snow and whiteout conditions will move into Summit county soon.

  HAZARD...Whiteout conditions. Zero visibility in heavy snow.

  SOURCE...Radar indicated.

  IMPACT...Dangerous life-threatening travel.

* This includes Interstate 70 between mile markers 192 and 213.
 
Locations impacted include...
Breckenridge, Silverthorne, Frisco, Dillon, Blue River, Keystone and
Copper Mountain.

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 3955 10620 3961 10620 3960 10619 3961 10618
      3964 10618 3965 10620 3971 10620 3968 10595
      3962 10580 3950 10589 3937 10604 3938 10621
TIME...MOT...LOC 1301Z 267DEG 23KT 3956 10642 

$$

MEIER
1 follow-up statement
499 
WWUS55 KBOU 151342
SQWBOU

Snow Squall Warning
National Weather Service Denver CO
642 AM MST Wed Dec 15 2021

COC117-151400-
/O.CON.KBOU.SQ.W.0002.000000T0000Z-211215T1400Z/
Summit CO-
642 AM MST Wed Dec 15 2021

...A SNOW SQUALL WARNING REMAINS IN EFFECT UNTIL 700 AM MST FOR
SOUTHEASTERN SUMMIT COUNTY...

At 642 AM MST, a dangerous snow squall was located over Dillon, or 
61 miles west of Denver, moving east at 25 mph.

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

SOURCE...Radar and webcams.

IMPACT...Dangerous life-threatening travel.

This includes Interstate 70 between mile markers 192 and 213.
 
Locations impacted include...
Breckenridge, Silverthorne, Frisco, Dillon, Blue River, Keystone and
Copper Mountain.

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 3955 10620 3961 10620 3960 10619 3961 10618
      3964 10618 3965 10620 3971 10620 3968 10595
      3962 10580 3950 10589 3937 10604 3938 10621
TIME...MOT...LOC 1342Z 267DEG 23KT 3957 10608 

$$

SCHLATTER

The office that day

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

IssuedProductOfficeCountiesLasted
Dec 15, 6:49 AM MSTSnow Squall WarningBOUClear Creek, Gilpin, Grand, Summit56 min
Dec 15, 7:47 AM MSTSpecial Weather StatementBOUBoulder, Broomfield, Denver, Jefferson43 min
Dec 15, 8:12 AM MSTSpecial Weather StatementBOUDouglas48 min

Nearby

Snow Squall Warnings in Colorado, 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.