Alert archive / Colorado / Severe Thunderstorm Warnings in 1987

Severe Thunderstorm Warning 48, NWS Denver/Boulder, CO

July 4, 1987Adams County, Arapahoe County, Colorado

NWS Denver/Boulder, CO issued this severe thunderstorm warning at Jul 4, 1987, 4:04 PM MDT for Adams County, Arapahoe County, Colorado. It was in force for 56 min. 3 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 4, 1987, 4:04 PM MDT (22:04 UTC)
Expired: Jul 4, 1987, 5:00 PM MDT
In force: 56 min
Issued by: NWS Denver/Boulder, CO
Area: Whole counties

Counties Adams County, CO, Arapahoe 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
Jul 4, 4:12 PM MDT	Hail 1.25	Arapahoe, CO
Jul 4, 4:45 PM MDT	Hail 0.75	Adams, CO
Jul 4, 5:00 PM MDT	Tornado F1	Adams, 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, 10.1 hours before the alert went out and 95 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.

Skew-T log-p

Temperature in red, dew point in green, the mixed-layer parcel dashed.

Hodograph

The wind turning with height, colored by layer: ground to 1 km, 1 to 3 km, 3 to 6 km, 6 to 10 km.

Mixed-layer CAPE: 362 J/kg
Mixed-layer CIN: -341 J/kg
Mixed-layer LCL: 1220 m above ground
0-6 km bulk shear: 27 kt
0-1 km storm-relative helicity: -24 m²/s²
0-3 km storm-relative helicity: 38 m²/s²
Significant tornado parameter: 0.0
Supercell composite: -0.0

Open this sounding in Storm Lab

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 4, 3:33 PM MDT, 31 minutes before

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE  DENVER CO
335 PM MDT SAT JUL 4 1987

           ...THUNDERSTORMS IN NORTHEAST COLORADO...

THUNDERSTORMS HAVE DEVELOPED IN CENTRAL ADAMS COUNTY NORTH OF BYERS.
ADDITIONAL THUNDERSTORM DEVELOPMENT IS EXPECTED BETWEEN NOW AND 430 PM
MDT IN CENTRAL AND WESTERN ADAMS AND ARAPAHOE COUNTIES...DENVER
COUNTY...SOUTHEAST WELD COUNTY AND NORTHERN DOUGLAS COUNTY.

SEVERE WEATHER IS NOT ANTICIPATED BUT THE STRONGEST STORMS COULD PRODUCE
STRONG GUSTY WINDS TO 40 MPH OR MORE...BRIEF HEAVY RAINS AND SMALL HAIL.

KAPLAN

The office that day

Everything else NWS Denver/Boulder, CO issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Jul 3, 9:00 PM MDT	Severe Thunderstorm Warning	BOU	Weld	60 min
Jul 3, 10:31 PM MDT	Severe Thunderstorm Warning	BOU	Morgan, Washington	59 min
Jul 4, 4:15 PM MDT	Severe Thunderstorm Warning	BOU	Arapahoe	60 min
Jul 4, 5:04 PM MDT	Severe Thunderstorm Warning	BOU	Morgan, Weld	61 min
Jul 4, 5:45 PM MDT	Severe Thunderstorm Warning	BOU	Weld	60 min

Nearby

Severe Thunderstorm Warnings in Colorado, 1987 Every 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.