Alert archive / Colorado / Snow Squall Warnings in 2021

Snow Squall Warning 1, NWS Denver/Boulder, CO

May 11, 2021Douglas County, Colorado

NWS Denver/Boulder, CO issued this snow squall warning at May 11, 2021, 2:38 PM MDT for Douglas County, Colorado. It was in force for 37 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
May 11, 2021, 2:38 PM MDT (20:38 UTC)
Expired
May 11, 2021, 3:15 PM MDT
In force
37 min
Issued by
NWS Denver/Boulder, CO
Area
Storm-based polygon

County Douglas County, CO

The radar

The Denver radar (KFTG), 68 km from the middle of the area, began a volume at 20:41 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

Denver, CO (KDNR), launched 12:00Z, 8.6 hours before the alert went out and 156 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, Denver, CO at 12:00Z on 2021-05-11Temperature 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, Denver, CO at 12:00Z on 2021-05-11The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity -4 square meters per square second.1939587897Sfc1 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
530 m above ground
0-6 km bulk shear
32 kt
0-1 km storm-relative helicity
-4 m²/s²
0-3 km storm-relative helicity
30 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0

Open this sounding in Storm Lab

The text

As transmitted.

381 
WWUS55 KBOU 112038
SQWBOU

BULLETIN - IMMEDIATE BROADCAST REQUESTED
Snow Squall Warning
National Weather Service Denver CO
238 PM MDT Tue May 11 2021

COC035-112115-
/O.NEW.KBOU.SQ.W.0001.210511T2038Z-210511T2115Z/
Douglas CO-
238 PM MDT Tue May 11 2021

The National Weather Service in Denver Colorado has issued a

* Snow Squall Warning for...
  Southeastern Douglas County in northeastern Colorado...

* Until 315 PM MDT.

* At 238 PM MDT, a dangerous snow squall was located 6 miles
  southwest of Elizabeth, or 29 miles north of Colorado Springs,
  moving east at 15 mph.

  HAZARD...Heavy snow.

  SOURCE...Radar indicated.

  IMPACT...Dangerous travel.

* This includes Interstate 25 between mile markers 164 and 178 and 
  the I-25 Gap Project.
 
Locations impacted include...
Southern Castle Rock, Larkspur, Greenland and Perry Park. 

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 3913 10493 3933 10498 3936 10467 3913 10466
TIME...MOT...LOC 2038Z 247DEG 11KT 3929 10466 

$$

SCHLATTER

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.