Alert archive / Colorado / Severe Thunderstorm Warnings in 1991
Severe Thunderstorm Warning 103, NWS Denver/Boulder, CO
NWS Denver/Boulder, CO issued this severe thunderstorm warning at Jun 21, 1991, 2:26 PM MDT for Adams County, Boulder County, Jefferson County, Colorado. It was in force for 34 min. 1 report came from inside the area while it was in force.
The area
The counties it named, with what was reported inside it.
The facts
- Issued
- Jun 21, 1991, 2:26 PM MDT (20:26 UTC)
- Expired
- Jun 21, 1991, 3:00 PM MDT
- In force
- 34 min
- Issued by
- NWS Denver/Boulder, CO
- Area
- Whole counties
Counties Adams County, CO, Boulder County, CO, Jefferson County, CO
What was reported inside it
| Time | Report | Where | Remark |
|---|---|---|---|
| Jun 21, 2:26 PM MDT | Hail 1 | Boulder, CO |
NCEI Storm Data entries that began inside the alert's area while it was in force. Before 2003 the local storm report archive is thin, so this is the record of what happened rather than what was phoned in. Storm Data before 1996 records only tornadoes, thunderstorm wind and hail.
The nearest sounding before it
Fort Carson/Butt, CO (KFCS), launched 12:00Z, 8.4 hours before the alert went out and 132 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
- 10 J/kg
- Mixed-layer CIN
- -278 J/kg
- Mixed-layer LCL
- 2132 m above ground
- 0-6 km bulk shear
- 22 kt
- 0-1 km storm-relative helicity
- 4 m²/s²
- 0-3 km storm-relative helicity
- 25 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 0.0
The text
The text of this product is not in the archive. The NWS text archive before 2002 is incomplete.
What forecasters said that day
The local office's own words before this severe thunderstorm warning went out, as it sent them, from the Iowa Environmental Mesonet's archive of National Weather Service text.
In the hours before
Special weather statement, Jun 21, 10:25 AM MDT, 4 hours 1 minute before
COZ011>017-210900- SPECIAL WEATHER STATEMENT NATIONAL WEATHER SERVICE DENVER CO 1030 AM MDT FRI JUN 21 1991 ...ACTIVE THUNDERSTORM DAY EXPECTED OVER EASTERN COLORADO TODAY... STRONG THUNDERSTORMS WILL DEVELOP OVER PORTIONS OF EASTERN COLORADO AGAIN THIS AFTERNOON AND MAY LAST INTO LATE THIS EVENING. THESE THUNDERSTORMS WILL BE CAPABLE OF PRODUCING STRONG WINDS...HAIL... AND ESPECIALLY HEAVY RAIN. THE RAIN MAY BE HEAVY ENOUGH TO CAUSE AREAS OF URBAN AND SMALL STREAM FLOODING. PERSONS IN EASTERN COLORADO SHOULD BE ALERT TO THIS POSSIBILITY AND CONTINUE TO STAY ABREAST OF THE LATEST WEATHER INFORMATION. CONTINUE TO LISTEN TO NOAA WEATHER RADIO...COMMERCIAL RADIO...OR TELEVISION FOR BFURTHER STATEMENTS AND/OR WATCHES AND WARNINGS. HEITKAMP
Special weather statement, Jun 21, 1:44 PM MDT, 42 minutes before
COZ011-012-014-212100- SPECIAL WEATHER STATEMENT NATIONAL WEATHER SERVICE DENVER CO 140 PM MDT FRI JUN 21 1991 ...SEVERE THUNDERSTORM WATCH IN EFFECT FOR THE NORTHERN FRONT RANGE AND PARTS OF NORTHEAST COLORADO UNTIL 800 PM MDT... THE NATIONAL SEVERE STORMS FORECAST CENTER IN KANSAS CITY HAS ISSUED A SEVERE THUNDERSTORM WATCH FOR THE NORTHERN FRONT RANGE AND PARTS OF NORTHEAST COLORADO UNTIL 800 PM MDT. A WATCH MEANS THAT SEVERE THUNDERSTORMS ARE POSSIBLE IN AND CLOSE TO THE WATCH AREA. PEOPLE ALONG THE NORTHERN FRONT RANGE AND PARTS OF NORTHEAST COLORADO SHOULD BE ON THE LOOKOUT FOR THUNDERSTORMS THAT COULD PRODUCE VERY HEAVY RAIN...HAIL 3/4 INCH OR LARGER...AND WIND GUSTS OF 58 MPH OR GREATER. AT 140 PM NATIONAL WEATHER SERVICE DOPPLER RADAR SHOWED THUNDERSTORMS WITH VERY HEAVY RAIN RAPIDLY DEVLOPING ACROSS SOUTHERN BOULDER COUNTY ABOUT 5 MILES SOUTHEAST OF BOULDER AND EAST CENTRAL JEFFERSON COUNTY JUST TO THE EAST OF LAKEWOOD. THESE STORMS WERE MOVING EAST AT 10 TO 15 MPH. VERY MOIST AIR IS IN PLACE OVER EASTERN COLORADO AND ESPECIALLY ALONG THE FRONT RANGE. EASTERLY SURFACE WINDS WILL PROVIDE UPSLOPE CONDITIONS ALONG THE FRONT RANGE TO ENHANCE THUNDERSTORM DEVELOPMENT THIS AFTERNOON AND EVENING. PERSONS IN EASTERN COLORADO SHOULD BE ALERT TO THE POSSIBILITY OF SEVERE WEATHER AND CONTINUE TO STAY ABREAST OF THE LATEST WEATHER INFORMATION. CONTINUE TO LISTEN TO NOAA WEATHER RADIO...COMMERCIAL RADIO...OR TELEVISION FOR FURTHER STATEMENTS AND/OR WATCHES AND WARNINGS. HOLMES
The office that day
Everything else NWS Denver/Boulder, CO issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Jun 20, 8:59 PM MDT | Severe Thunderstorm Warning | BOU | Yuma | 31 min |
| Jun 20, 10:14 PM MDT | Severe Thunderstorm Warning | BOU | Washington | 31 min |
| Jun 20, 10:45 PM MDT | Severe Thunderstorm Warning | BOU | Kit Carson, Washington, Yuma | 30 min |
| Jun 21, 1:51 PM MDT | Severe Thunderstorm Warning | BOU | Adams, Arapahoe, Denver, Jefferson | 39 min |
| Jun 21, 2:30 PM MDT | Severe Thunderstorm Warning | BOU | Arapahoe, Denver, Douglas, Jefferson | 45 min |
| Jun 21, 3:02 PM MDT | Tornado Warning | BOU | Arapahoe, Douglas | 28 min |
| Jun 21, 3:04 PM MDT | Severe Thunderstorm Warning | BOU | Denver, Jefferson | 41 min |
| Jun 21, 3:27 PM MDT | Severe Thunderstorm Warning | BOU | Arapahoe, Douglas | 33 min |
| Jun 21, 3:45 PM MDT | Severe Thunderstorm Warning | BOU | Jefferson | 30 min |
| Jun 21, 4:40 PM MDT | Severe Thunderstorm Warning | BOU | Larimer | 35 min |
| Jun 21, 4:55 PM MDT | Severe Thunderstorm Warning | BOU | Weld | 35 min |
| Jun 21, 5:29 PM MDT | Severe Thunderstorm Warning | BOU | Arapahoe, Douglas | 46 min |
| Jun 21, 5:50 PM MDT | Severe Thunderstorm Warning | BOU | Arapahoe, Denver, Jefferson | 25 min |
Nearby
Severe Thunderstorm Warnings in Colorado, 1991Every severe thunderstorm warning in 1991
Sources
The product and its follow-ups from the Iowa Environmental Mesonet's archive of National Weather Service and Storm Prediction Center text; verification from NCEI's Storm Data; the sounding from the Mesonet's radiosonde archive.