Alert archive / Colorado / Tornado Warnings in 1987
Tornado Warning 6, NWS Denver/Boulder, CO
NWS Denver/Boulder, CO issued this tornado warning at Jun 20, 1987, 2:06 PM MDT for Arapahoe County, Douglas County, Jefferson County, Colorado. It was in force for 29 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 20, 1987, 2:06 PM MDT (20:06 UTC)
- Expired
- Jun 20, 1987, 2:35 PM MDT
- In force
- 29 min
- Issued by
- NWS Denver/Boulder, CO
- Area
- Whole counties
Counties Arapahoe County, CO, Douglas County, CO, Jefferson County, CO
The radar
The WSR-88D network and its archive begin in 1991, so there is no radar volume for this alert.
What was reported inside it
| Time | Report | Where | Remark |
|---|---|---|---|
| Jun 20, 2:27 PM MDT | Hail 0.75 | Arapahoe, 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
Denver, CO (KDEN), launched 12:00Z, 8.1 hours before the alert went out and 143 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
- 791 J/kg
- Mixed-layer CIN
- -190 J/kg
- Mixed-layer LCL
- 1292 m above ground
- 0-6 km bulk shear
- 22 kt
- 0-1 km storm-relative helicity
- 52 m²/s²
- 0-3 km storm-relative helicity
- 2 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 tornado 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 20, 12:41 PM MDT, 1 hour 25 minutes before
SPECIAL WEATHER STATEMENT NATIONAL WEATHER SERVICE DENVER CO 1240 PM MDT SAT JUN 20 1987 ...THUNDERSTORMS DEVELOPING OVER THE NORTHEAST COLORADO FOOTHILLS... THUNDERSTORMS WERE DEVLOPING OVER THE NORTHEAST COLORADO FOOTHILLS AND OVER THE PIKES PEAK-PALMER LAKE DIVIDE. THE STRONGEST THUNDERSTORMS WERE LOCATED 35 MILES SOUTH SOUTHEAST OF DENVER IN SOUTHEAST DOUGLAS COUNTY...IN NORTHERN JEFFERSON AND EXTREME NORTHEAST CLEAR CREEK COUNTIES 10 TO 25 MILES WEST OF DENVER AND IN CENTRAL LARIMER COUNTY 45 TO 55 MILES NORTHWEST OF DENVER. THE THUNDERSTORMS WERE MOVING TO THE NORTHEAST AT 10 MPH. STRONG GUSTY WINDS...LOCALLY HEAVY RAIN...HAIL AND LIGHTNING ARE POSSIBLE WITH THE THUNDERSTOR_MS WHEN THEY BECOME STORNGER DURING THE AFTERNOON. BALINT
Special weather statement, Jun 20, 1:41 PM MDT, 25 minutes before
SPECIAL WEATHER STATEMENT NATIONAL WEATHER SERVICE DENVER CO 140 PM MDT SAT JUN 20 1987 ...THUNDERSTORMS OVER THE NORTHEAST COLORADO FOOTHILLS... THUNDERSTORMS CONTINUED TO DEVELOP OVER THE NORTHEAST COLORADO FOOTHILLS AND OVER THE ADJACENT PLAINS. THE STRONGEST THUNDERSTORMS WERE LOCATED 25 MILES SOUTH OF DENVER IN WEST CENTRAL DOUGLAS COUNTY...10 TO 15 MILES SOUTHWEST OF DENVER IN EAST CENTRAL JEFFERSON COUNTY...15 MILES NORTHEAST OF FORT COLLINS IN NORTHWEST WELD COUNTY. THE THUNDERSTORMS WERE MOVING TO THE NORTHEAST AT 10 MPH. STRONG GUSTY WINDS...LOCALLY HEAVY RAIN...HAIL AND LIGHTNING ARE POSSIBLE WITH THE THUNDERSTORMS AS THEY CONTINUE TO DEVELOP DURING THE AFTERNOON. BALINT
The office that day
Everything else NWS Denver/Boulder, CO issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Jun 20, 2:27 PM MDT | Tornado Warning | BOU | Adams | 28 min |
| Jun 20, 2:42 PM MDT | Severe Thunderstorm Warning | BOU | Arapahoe | 38 min |
| Jun 20, 3:02 PM MDT | Severe Thunderstorm Warning | BOU | Adams, Weld | 58 min |
| Jun 20, 4:35 PM MDT | Severe Thunderstorm Warning | BOU | Logan, Morgan, Weld | 50 min |
Nearby
Tornado Warnings in Colorado, 1987Every tornado warning in 1987Tornadoes in 1987
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.