Alert archive / Colorado / Severe Thunderstorm Warnings in 1987
Severe Thunderstorm Warning 40, NWS Denver/Boulder, CO
NWS Denver/Boulder, CO issued this severe thunderstorm warning at Jul 2, 1987, 4:02 PM MDT for Adams County, Arapahoe County, Weld County, Colorado. It was in force for 63 min. 2 reports 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
- Jul 2, 1987, 4:02 PM MDT (22:02 UTC)
- Expired
- Jul 2, 1987, 5:05 PM MDT
- In force
- 63 min
- Issued by
- NWS Denver/Boulder, CO
- Area
- Whole counties
Counties Adams County, CO, Arapahoe County, CO, Weld 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 |
|---|---|---|---|
| Jul 2, 4:04 PM MDT | Hail 0.75 | Weld, CO | |
| Jul 2, 4:08 PM MDT | Hail 0.75 | Weld, 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, 10.0 hours before the alert went out and 98 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
- 51 J/kg
- Mixed-layer CIN
- -313 J/kg
- Mixed-layer LCL
- 1747 m above ground
- 0-6 km bulk shear
- 30 kt
- 0-1 km storm-relative helicity
- -8 m²/s²
- 0-3 km storm-relative helicity
- 55 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, Jul 2, 2:59 PM MDT, 1 hour 3 minutes before
SPECIAL WEATHER STATEMENT NATIONAL WEATHER SERVICE DENVER CO 300 PM MDT THU JUL 2 1987 ...STRONG THUNDERSTORMS DEVELOPING ALONG THE FRONT RANGE... AT 255 PM MDT RADAR INDICATED THUNDERSTORMS DEVELOPING ALONG THE FRONT RANGE. THE STRONGEST STORMS WERE OVER LITTLETON IN WESTERN ARAPAHOE COUNTY.. AND ABOUT 10 MILES NORTHWEST OF BOULDER IN BOULDER COUNTY. THE STORMS ARE MOVING TOWARD THE EAST AT 10 TO 20 MPH. THE LITTLETON STORM HAS PRODUCED HAIL HALF AN INCH IN DIAMETER. THESE TWO STORMS MAY PRODUCE LOCAL BRIEF HEAVY RAIN..HAIL..AND STRONG GUSTY WINDS THIS AFTERNOON..AND OTHER THUNDERSTORMS ARE LIKELY TO DEVELOP. MARKKANEN
The office that day
Everything else NWS Denver/Boulder, CO issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Jul 1, 7:13 PM MDT | Severe Thunderstorm Warning | BOU | Phillips, Sedgwick | 42 min |
| Jul 1, 9:09 PM MDT | Severe Thunderstorm Warning | BOU | Larimer | 51 min |
| Jul 2, 3:02 PM MDT | Severe Thunderstorm Warning | BOU | Arapahoe, Douglas | 53 min |
| Jul 2, 3:34 PM MDT | Tornado Warning | BOU | Adams | 26 min |
| Jul 2, 4:46 PM MDT | Severe Thunderstorm Warning | BOU | Adams, Morgan, Washington | 59 min |
| Jul 2, 5:45 PM MDT | Severe Thunderstorm Warning | BOU | Douglas | 60 min |
Nearby
Severe Thunderstorm Warnings in Colorado, 1987Every severe thunderstorm warning 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.