Alert archive / Colorado / Severe Thunderstorm Warnings in 2021
Severe Thunderstorm Warning 104, NWS Denver/Boulder, CO
NWS Denver/Boulder, CO issued this severe thunderstorm warning at Jul 9, 2021, 3:58 PM MDT for Logan County, Colorado. It was in force for 47 min. 4 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 9, 2021, 3:58 PM MDT (21:58 UTC)
- Expired
- Jul 9, 2021, 4:45 PM MDT
- In force
- 47 min
- Issued by
- NWS Denver/Boulder, CO
- Area
- Storm-based polygon
- Hail
- 1.0 in
- Wind
- 60.0 mph
County Logan County, CO
The radar
The Cheyenne radar (KCYS), 132 km from the middle of the area, began a volume at 22:00 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 9, 4:45 PM MDT | TSTM WND GST 70 | 5 Sw Iliff, CO | TRAINED SPOTTED ESTIMATED 70 MPH WIND GUST BETWEEN STERLING AND ILIFF. |
| Jul 9, 4:50 PM MDT | TSTM WND DMG | 1 Ne Sterling, CO | WIND DAMAGE FROM FALLEN TREE ON POWERLINES. OTHER REPORT OF BROKEN TREE LIMBS FALLING AND DAMAGING A CAR. |
| Jul 9, 4:52 PM MDT | TSTM WND GST 66 | 2 Ese Sterling, CO | CORRECTS PREVIOUS NON-TSTM WND GST REPORT FROM 2 ESE STERLING. MESONET STATION CO035 076E125 STERLING. |
| Jul 9, 4:52 PM MDT | NON-TSTM WND GST 66 | 2 Ese Sterling, CO | MESONET STATION CO035 076E125 STERLING. |
Local storm reports filed while the alert was in force, from inside its polygon or its counties.
The watch it was issued in
The SPC watch in force over the same counties when this warning went out.
| Issued | Product | Office | Lasted |
|---|---|---|---|
| Jul 9, 2:16 PM MDT | Severe Thunderstorm Watch | SPC | 9 hr |
The nearest sounding before it
Denver, CO (KDNR), launched 12:00Z, 10.0 hours before the alert went out and 103 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
- 5 J/kg
- Mixed-layer CIN
- -346 J/kg
- Mixed-layer LCL
- 3383 m above ground
- 0-6 km bulk shear
- 29 kt
- 0-1 km storm-relative helicity
- 70 m²/s²
- 0-3 km storm-relative helicity
- 50 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 0.0
The text
As transmitted.
178
WUUS55 KBOU 092158
SVRBOU
COC075-092245-
/O.NEW.KBOU.SV.W.0104.210709T2158Z-210709T2245Z/
BULLETIN - IMMEDIATE BROADCAST REQUESTED
Severe Thunderstorm Warning
National Weather Service Denver CO
358 PM MDT Fri Jul 9 2021
The National Weather Service in Denver Colorado has issued a
* Severe Thunderstorm Warning for...
Western Logan County in northeastern Colorado...
* Until 445 PM MDT.
* At 358 PM MDT, a severe thunderstorm was located 5 miles north of
Westplains, or 21 miles southeast of Kimball, moving southeast at
50 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...
Sterling, Iliff, Proctor, Padroni, Westplains, Logan Corners and
North Sterling Reservoir.
PRECAUTIONARY/PREPAREDNESS ACTIONS...
For your protection move to an interior room on the lowest floor of a
building.
Heavy rainfall is occurring with this storm, and may lead to flash
flooding. Do not drive your vehicle through flooded roadways.
&&
LAT...LON 4071 10357 4099 10357 4100 10323 4086 10287
4049 10304
TIME...MOT...LOC 2158Z 315DEG 42KT 4095 10348
HAIL...1.00IN
WIND...60MPH
$$
RJK1 follow-up statement
527
WWUS55 KBOU 092220
SVSBOU
Severe Weather Statement
National Weather Service Denver CO
420 PM MDT Fri Jul 9 2021
COC075-092245-
/O.CON.KBOU.SV.W.0104.000000T0000Z-210709T2245Z/
Logan CO-
420 PM MDT Fri Jul 9 2021
...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT UNTIL 445 PM MDT
FOR CENTRAL LOGAN COUNTY...
At 420 PM MDT, a severe thunderstorm was located 5 miles northwest of
North Sterling Reservoir, or 17 miles northwest of Sterling, moving
southeast at 40 mph.
HAZARD...60 mph wind gusts and quarter size hail.
SOURCE...Radar indicated.
IMPACT...Expect damage to roofs, siding, and trees. Hail damage to
vehicles is expected.
Locations impacted include...
Sterling, Iliff, North Sterling Reservoir, Proctor and Padroni.
PRECAUTIONARY/PREPAREDNESS ACTIONS...
For your protection move to an interior room on the lowest floor of a
building.
Heavy rainfall is occurring with this storm, and may lead to flash
flooding. Do not drive your vehicle through flooded roadways.
&&
LAT...LON 4073 10344 4094 10343 4098 10320 4086 10287
4053 10309
TIME...MOT...LOC 2220Z 311DEG 34KT 4085 10333
HAIL...1.00IN
WIND...60MPH
$$
RJKThe office that day
Everything else NWS Denver/Boulder, CO issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Jul 8, 6:02 PM MDT | Special Weather Statement | BOU | Phillips | 43 min |
| Jul 9, 2:34 PM MDT | Severe Thunderstorm Warning | BOU | Weld | 41 min |
| Jul 9, 3:00 PM MDT | Areal Flood Advisory | BOU | Grand | 2 hr |
| Jul 9, 3:25 PM MDT | Severe Thunderstorm Warning | BOU | Weld | 38 min |
| Jul 9, 4:44 PM MDT | Severe Thunderstorm Warning | BOU | Logan | 36 min |
| Jul 9, 5:22 PM MDT | Special Weather Statement | BOU | Phillips | 38 min |
| Jul 9, 5:40 PM MDT | Special Weather Statement | BOU | Morgan | 35 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.