Alert archive / Colorado / Severe Thunderstorm Warnings in 2021

Severe Thunderstorm Warning 115, NWS Denver/Boulder, CO

July 30, 2021Larimer County, Weld County, Colorado

NWS Denver/Boulder, CO issued this severe thunderstorm warning at Jul 30, 2021, 3:26 PM MDT for Larimer County, Weld County, Colorado. It was in force for 49 min. 2 reports 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 30, 2021, 3:26 PM MDT (21:26 UTC)
Expired
Jul 30, 2021, 4:15 PM MDT
In force
49 min
Issued by
NWS Denver/Boulder, CO
Area
Storm-based polygon
Hail
1.0 in
Wind
60.0 mph

Counties Larimer County, CO, Weld County, CO

The radar

The Cheyenne radar (KCYS), 47 km from the middle of the area, began a volume at 21:29 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

TimeReportWhereRemark
Jul 30, 3:54 PM MDTHAIL 11 Sse Wellington, CODELAYED REPORT. COCORAHS OBSERVER CO-LR-1146 WELLINGTON 0.6 SSE. TIME ESTIMATED BY OBSERVER AND RADAR.
Jul 30, 3:55 PM MDTHAIL 11 Nne Wellington, COREPORT VIA TWITTER. TIME ESTIMATED BY RADAR.

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

The nearest sounding before it

Denver, CO (KDNR), launched 12:00Z, 9.4 hours before the alert went out and 177 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 2021-07-30Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 0 joules per kilogram.LCLLFCEL10008507005003002001001 km2 km3 km6 km9 km12 km15 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 2021-07-30The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity -18 square meters per square second.1939Sfc1 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
2523 m above ground
0-6 km bulk shear
18 kt
0-1 km storm-relative helicity
-18 m²/s²
0-3 km storm-relative helicity
2 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0

Open this sounding in Storm Lab

The text

As transmitted.

933 
WUUS55 KBOU 302126
SVRBOU
COC069-123-302215-
/O.NEW.KBOU.SV.W.0115.210730T2126Z-210730T2215Z/

BULLETIN - IMMEDIATE BROADCAST REQUESTED
Severe Thunderstorm Warning
National Weather Service Denver CO
326 PM MDT Fri Jul 30 2021

The National Weather Service in Denver Colorado has issued a

* Severe Thunderstorm Warning for...
  West central Weld County in northeastern Colorado...
  East central Larimer County in north central Colorado...

* Until 415 PM MDT.

* At 326 PM MDT, a severe thunderstorm was located 5 miles north of
  Wellington, or 15 miles north of Fort Collins, moving southeast at
  10 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...
  Northeastern Fort Collins, Wellington, Pierce and Nunn. 

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

Torrential rainfall is occurring with this storm, and may lead to
flash flooding. Do not drive your vehicle through flooded roadways.

&&

LAT...LON 4081 10508 4089 10495 4062 10470 4062 10503
TIME...MOT...LOC 2126Z 336DEG 10KT 4077 10498 

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

BARJENBRUCH
1 follow-up statement
014 
WWUS55 KBOU 302151
SVSBOU

Severe Weather Statement
National Weather Service Denver CO
351 PM MDT Fri Jul 30 2021

COC069-123-302215-
/O.CON.KBOU.SV.W.0115.000000T0000Z-210730T2215Z/
Weld CO-Larimer CO-
351 PM MDT Fri Jul 30 2021

...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT UNTIL 415 PM MDT
FOR WEST CENTRAL WELD AND EASTERN LARIMER COUNTIES...

At 351 PM MDT, a severe thunderstorm was located near Wellington, or
12 miles northeast of Fort Collins, moving southeast at 10 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...
Northeastern Fort Collins, Wellington and Pierce. 

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

Torrential rainfall is occurring with this storm, and may lead to
flash flooding. Do not drive your vehicle through flooded roadways.

&&

LAT...LON 4075 10506 4081 10490 4062 10474 4062 10503
TIME...MOT...LOC 2151Z 336DEG 10KT 4070 10494 

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

BARJENBRUCH

The office that day

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

IssuedProductOfficeCountiesLasted
Jul 29, 6:37 PM MDTAreal Flood AdvisoryBOUGrand83 min
Jul 29, 7:27 PM MDTAreal Flood AdvisoryBOUGrand93 min
Jul 29, 7:50 PM MDTFlash Flood WarningBOUJackson, Larimer3 hr
Jul 29, 8:14 PM MDTFlash Flood WarningBOUGrand112 min
Jul 29, 9:32 PM MDTSpecial Weather StatementBOUJackson28 min
Jul 29, 10:19 PM MDTAreal Flood AdvisoryBOULarimer86 min
Jul 30, 1:01 PM MDTFlash Flood WarningBOULarimer7 hr
Jul 30, 1:08 PM MDTAreal Flood AdvisoryBOULarimer6 min
Jul 30, 1:14 PM MDTFlash Flood Warning Considerable damage threatBOULarimer3 hr
Jul 30, 1:34 PM MDTFlash Flood Warning Considerable damage threatBOULarimer6 hr
Jul 30, 2:07 PM MDTFlash Flood WarningBOULarimer5 hr
Jul 30, 2:30 PM MDTFlash Flood WarningBOUClear Creek, Grand3 hr
Jul 30, 2:48 PM MDTAreal Flood AdvisoryBOULarimer87 min
Jul 30, 2:51 PM MDTFlash Flood WarningBOUGrand4 hr
Jul 30, 3:02 PM MDTFlash Flood WarningBOUGrand3 hr
Jul 30, 3:02 PM MDTSpecial Weather StatementBOULarimer43 min
Jul 30, 3:45 PM MDTAreal Flood AdvisoryBOUGrand2 hr
Jul 30, 3:59 PM MDTAreal Flood AdvisoryBOULarimer, Weld61 min
Jul 30, 4:11 PM MDTSevere Thunderstorm WarningBOULarimer, Weld49 min
Jul 30, 4:16 PM MDTFlash Flood WarningBOUGrand3 hr
Jul 30, 4:28 PM MDTFlash Flood WarningBOUPark3 hr
Jul 30, 4:30 PM MDTFlash Flood WarningBOULarimer4 hr
Jul 30, 5:36 PM MDTFlash Flood Warning EmergencyCatastrophic damage threatBOULarimer3 hr
Jul 30, 5:37 PM MDTFlash Flood WarningBOUGrand99 min

Nearby

Severe Thunderstorm Warnings in Colorado, 2021Every 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.