Alert archive / Colorado / Severe Thunderstorm Warnings in 2021
Severe Thunderstorm Warning 153, NWS Denver/Boulder, CO
NWS Denver/Boulder, CO issued this severe thunderstorm warning at Sep 11, 2021, 7:25 PM MDT for Logan County, Colorado. It was in force for 50 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
- Sep 11, 2021, 7:25 PM MDT (01:25 UTC)
- Expired
- Sep 11, 2021, 8:15 PM MDT
- In force
- 50 min
- Issued by
- NWS Denver/Boulder, CO
- Area
- Storm-based polygon
- Hail
- 0.75 in
- Wind
- 60.0 mph
County Logan County, CO
The radar
The Cheyenne radar (KCYS), 165 km from the middle of the area, began a volume at 01:27 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 00:00Z, 1.4 hours before the alert went out and 107 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.
- Mixed-layer CAPE
- 403 J/kg
- Mixed-layer CIN
- -128 J/kg
- Mixed-layer LCL
- 3631 m above ground
- 0-6 km bulk shear
- 36 kt
- 0-1 km storm-relative helicity
- 30 m²/s²
- 0-3 km storm-relative helicity
- 139 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 0.3
The text
As transmitted.
970 WUUS55 KBOU 120125 SVRBOU COC075-120215- /O.NEW.KBOU.SV.W.0153.210912T0125Z-210912T0215Z/ BULLETIN - IMMEDIATE BROADCAST REQUESTED Severe Thunderstorm Warning National Weather Service Denver CO 725 PM MDT Sat Sep 11 2021 The National Weather Service in Denver Colorado has issued a * Severe Thunderstorm Warning for... Northeastern Logan County in northeastern Colorado... * Until 815 PM MDT. * At 724 PM MDT, severe thunderstorms were located along a line extending from 9 miles south of Potter to 8 miles southwest of Fleming, or along a line extending from 16 miles west of Sidney to 10 miles east of Sterling, moving east at 35 mph. HAZARD...60 mph wind gusts. SOURCE...Radar indicated. IMPACT...Expect damage to roofs, siding, and trees. * Severe thunderstorms will be near... Fleming around 740 PM MDT. PRECAUTIONARY/PREPAREDNESS ACTIONS... For your protection move to an interior room on the lowest floor of a building. Large hail and damaging winds and continuous cloud to ground lightning is occurring with these storms. Move indoors immediately. Lightning is one of nature's leading killers. Remember, if you can hear thunder, you are close enough to be struck by lightning. && LAT...LON 4066 10268 4066 10318 4100 10328 4100 10267 TIME...MOT...LOC 0124Z 254DEG 32KT 4108 10328 4063 10299 HAIL THREAT...RADAR INDICATED MAX HAIL SIZE...<.75 IN WIND THREAT...RADAR INDICATED MAX WIND GUST...60 MPH $$ RPK
2 follow-up statements
556 WWUS55 KBOU 120147 SVSBOU Severe Weather Statement National Weather Service Denver CO 747 PM MDT Sat Sep 11 2021 COC075-120215- /O.CON.KBOU.SV.W.0153.000000T0000Z-210912T0215Z/ Logan CO- 747 PM MDT Sat Sep 11 2021 ...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT UNTIL 815 PM MDT FOR NORTHEASTERN LOGAN COUNTY... At 747 PM MDT, severe thunderstorms were located along a line extending from near Sidney to 5 miles east of Fleming, or along a line extending from 29 miles west of Chappell to 23 miles west of Holyoke, moving east at 35 mph. HAZARD...60 mph wind gusts. SOURCE...Radar indicated. IMPACT...Expect damage to roofs, siding, and trees. These severe thunderstorms will remain over mainly rural areas of northeastern Logan County. PRECAUTIONARY/PREPAREDNESS ACTIONS... For your protection move to an interior room on the lowest floor of a building. Continuous cloud to ground lightning is occurring with these storms. Move indoors immediately. Lightning is one of nature's leading killers. Remember, if you can hear thunder, you are close enough to be struck by lightning. && LAT...LON 4066 10268 4066 10299 4100 10313 4100 10267 TIME...MOT...LOC 0147Z 254DEG 32KT 4114 10302 4069 10273 HAIL THREAT...RADAR INDICATED MAX HAIL SIZE...<.75 IN WIND THREAT...RADAR INDICATED MAX WIND GUST...60 MPH $$ RPK
907
WWUS55 KBOU 120206
SVSBOU
Severe Weather Statement
National Weather Service Denver CO
806 PM MDT Sat Sep 11 2021
COC075-120216-
/O.EXP.KBOU.SV.W.0153.000000T0000Z-210912T0215Z/
Logan CO-
806 PM MDT Sat Sep 11 2021
...THE SEVERE THUNDERSTORM WARNING FOR NORTHEASTERN LOGAN COUNTY WILL
EXPIRE AT 815 PM MDT...
The storms which prompted the warning have weakened below severe
limits, and no longer pose an immediate threat to life or property.
Therefore, the warning will be allowed to expire. However gusty
winds are still possible with these thunderstorms.
LAT...LON 4066 10268 4066 10299 4100 10313 4100 10267
TIME...MOT...LOC 0206Z 254DEG 32KT 4118 10282 4073 10253
$$
RPKThe office that day
Everything else NWS Denver/Boulder, CO issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Sep 11, 7:04 PM MDT | Severe Thunderstorm Warning | BOU | Logan | 26 min |
| Sep 11, 8:04 PM MDT | Special Weather Statement | BOU | Sedgwick | 26 min |
| Sep 11, 8:14 PM MDT | Special Weather Statement | BOU | Denver | 16 min |
| Sep 11, 8:31 PM MDT | Special Weather Statement | BOU | Denver | 29 min |
| Sep 12, 3:38 PM MDT | Special Weather Statement | BOU | Elbert | 52 min |
| Sep 12, 4:16 PM MDT | Special Weather Statement | BOU | Lincoln | 29 min |
| Sep 12, 5:27 PM MDT | Severe Thunderstorm Warning | BOU | Lincoln | 33 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; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.