Alert archive / Colorado / Severe Thunderstorm Warnings in 2021

Severe Thunderstorm Warning 114, NWS Denver/Boulder, CO

July 29, 2021Jackson County, Colorado

NWS Denver/Boulder, CO issued this severe thunderstorm warning at Jul 29, 2021, 5:21 PM MDT for Jackson County, Colorado. It was in force for 24 min. 1 report came from inside the area while it was in force.

The area

The outline as issued, with what was reported inside it.

The facts

Issued: Jul 29, 2021, 5:21 PM MDT (23:21 UTC)
Expired: Jul 29, 2021, 5:45 PM MDT
In force: 24 min
Issued by: NWS Denver/Boulder, CO
Area: Storm-based polygon
Hail: 1.0 in
Wind: 60.0 mph

County Jackson County, CO

The radar

The Cheyenne radar (KCYS), 143 km from the middle of the area, began a volume at 23:22 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.

What was reported inside it

Time	Report	Where	Remark
Jul 29, 5:30 PM MDT	HAIL 1	6 Wsw Walden, CO

Local storm reports filed while the alert was in force, from inside its polygon or its counties.

The nearest sounding before it

Grand Junction, CO (KGJT), launched 12:00Z, 11.4 hours before the alert went out and 248 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: 12 J/kg
Mixed-layer CIN: -398 J/kg
Mixed-layer LCL: 1614 m above ground
0-6 km bulk shear: 23 kt
0-1 km storm-relative helicity: 26 m²/s²
0-3 km storm-relative helicity: 69 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0

Open this sounding in Storm Lab

The text

As transmitted.

124 
WUUS55 KBOU 292321
SVRBOU
COC057-292345-
/O.NEW.KBOU.SV.W.0114.210729T2321Z-210729T2345Z/

BULLETIN - IMMEDIATE BROADCAST REQUESTED
Severe Thunderstorm Warning
National Weather Service Denver CO
521 PM MDT Thu Jul 29 2021

The National Weather Service in Denver Colorado has issued a

* Severe Thunderstorm Warning for...
  Central Jackson County in north central Colorado...

* Until 545 PM MDT.

* At 520 PM MDT, a severe thunderstorm was located 5 miles northeast
  of Coalmont, or 62 miles southwest of Laramie, moving north at 5
  mph.

  HAZARD...60 mph wind gusts and quarter size hail.

  SOURCE...Radar indicated.

  IMPACT...Expect damage to roofs, siding, and trees. Hail damage to 
           vehicles is expected.

* Locations impacted include...
  Walden, Lake John and Coalmont. 

PRECAUTIONARY/PREPAREDNESS ACTIONS...

For your protection move to an interior room on the lowest floor of a
building.

&&

LAT...LON 4057 10650 4078 10649 4078 10614 4055 10622
TIME...MOT...LOC 2320Z 169DEG 5KT 4062 10636 

HAIL...1.00IN
WIND...60MPH
 
$$

DANIELSON

2 follow-up statements

584 
WWUS55 KBOU 292333
SVSBOU

Severe Weather Statement
National Weather Service Denver CO
533 PM MDT Thu Jul 29 2021

COC057-292345-
/O.CON.KBOU.SV.W.0114.000000T0000Z-210729T2345Z/
Jackson CO-
533 PM MDT Thu Jul 29 2021

...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT UNTIL 545 PM MDT
FOR CENTRAL JACKSON COUNTY...

At 532 PM MDT, a severe thunderstorm was located 6 miles northeast of
Coalmont, or 61 miles southwest of Laramie, moving north at 5 mph.

HAZARD...60 mph wind gusts and quarter size hail.

SOURCE...Radar indicated.

IMPACT...Expect damage to roofs, siding, and trees. Hail damage to 
         vehicles is expected.

Locations impacted include...
Walden and Lake John. 

PRECAUTIONARY/PREPAREDNESS ACTIONS...

For your protection move to an interior room on the lowest floor of a
building.

&&

LAT...LON 4078 10649 4078 10614 4061 10621 4061 10650
TIME...MOT...LOC 2332Z 169DEG 5KT 4064 10636 

TORNADO...POSSIBLE
HAIL...1.00IN
WIND...60MPH
 
$$

DANIELSON

056 
WWUS55 KBOU 292344
SVSBOU

Severe Weather Statement
National Weather Service Denver CO
544 PM MDT Thu Jul 29 2021

COC057-292351-
/O.EXP.KBOU.SV.W.0114.000000T0000Z-210729T2345Z/
Jackson CO-
544 PM MDT Thu Jul 29 2021

...THE SEVERE THUNDERSTORM WARNING FOR CENTRAL JACKSON COUNTY WILL
EXPIRE AT 545 PM MDT...
                
The storm which prompted the warning has weakened below severe
limits, and no longer poses an immediate threat to life or property.
Therefore, the warning will be allowed to expire.  However small
hail, gusty winds and heavy rain are still possible with this
thunderstorm.

LAT...LON 4078 10649 4078 10614 4061 10621 4061 10650
TIME...MOT...LOC 2341Z 169DEG 5KT 4065 10636 

$$

DANIELSON

The office that day

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

Issued	Product	Office	Counties	Lasted
Jul 29, 2:03 PM MDT	Flash Flood Watch	BOU	Adams, Arapahoe, Boulder, Broomfield, Clear Creek, Denver and 10 more	55 hr
Jul 29, 4:59 PM MDT	Special Weather Statement	BOU	Jackson	31 min
Jul 29, 5:38 PM MDT	Areal Flood Advisory	BOU	Jackson, Larimer	2 hr

Nearby

Severe Thunderstorm Warnings in Colorado, 2021 Every severe thunderstorm 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; local storm reports from the same archive; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.