Alert archive / Colorado / Tornado Warnings in 1987

Tornado Warning 15, NWS Denver/Boulder, CO

July 7, 1987Weld County, Colorado

NWS Denver/Boulder, CO issued this tornado warning at Jul 7, 1987, 4:54 PM MDT for Weld County, Colorado. It was in force for 31 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 7, 1987, 4:54 PM MDT (22:54 UTC)
Expired: Jul 7, 1987, 5:25 PM MDT
In force: 31 min
Issued by: NWS Denver/Boulder, CO
Area: Whole counties

County 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 7, 5:00 PM MDT	Hail 0.75	Weld, CO
Jul 7, 5:25 PM MDT	Tornado F1	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, 10.9 hours before the alert went out and 125 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: 93 J/kg
Mixed-layer CIN: -293 J/kg
Mixed-layer LCL: 1387 m above ground
0-6 km bulk shear: 23 kt
0-1 km storm-relative helicity: 2 m²/s²
0-3 km storm-relative helicity: 17 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0

Open this sounding in Storm Lab

The text

As transmitted, in the capitals the NWS used until 2016.

000 
TTAA00 KDEN 072257
TORDEN
COC123-072325-
 
BULLETIN...EBS ACTIVATION REQUESTED
TORNADO WARNING
NATIONAL WEATHER SERVICE DENVER CO
454 PM MDT TUE JUL 07 1987
 
THE NATIONAL WEATHER SERVICE HAS ISSUED A TORNADO WARNING
EFFECTIVE UNTIL 525 PM  MDT FOR PEOPLE IN THE FOLLOWING
COUNTIES OF NORTHEAST COLORADO:
 
     CENTRAL WELD
 
INCLUDING THE FOLLOWING TOWNS/CITIES:
 
     KERSEY...GREELEY...LA SALLE...GILL
 
AT 455 PM MDT RADAR INDICATED A SEVERE THUNDERSTORM JUST EAST OF
GREELEY.  SEVERAL SIGHTINGS OF TORNADOES AND FUNNEL CLOUDS HAVE OCCURRED
IN GREELEY AND THE SURROUNDING AREAS.
 
IN HOMES GO TO THE BASEMENT OR INTO A CLOSET OR BATHROOM.
IN SCHOOLS..HIGH RISES AND HOSPITALS GO TO AN INTERIOR
HALLWAY ON THE LOWEST FLOOR.  IF IN MOBILE HOMES OR VEHICLES..
EVACUATE THEM AND GO TO A SUBSTANTIAL SHELTER.  IF NO SHELTER
IS AVAILABLE..LIE FLAT IN THE NEAREST DITCH OR OTHER LOW SPOT.
IN ALL CASES..STAY AWAY FROM WINDOWS..DOORS AND OUTSIDE WALLS.
 
A TORNADO WATCH REMAINS IN EFFECT FOR MOST OF EASTERN COLORADO UNTIL 9
PM MDT TUESDAY.

TO REPORT SEVERE WEATHER HAVE THE NEAREST LAW ENFORCEMENT
AGENCY RELAY YOUR REPORT TO THE NATIONAL WEATHER SERVICE OFFICE
IN DENVER..OR CALL YOUR REPORT TO THE NA6TIONAL WEATHER SERVICE
AT 361-0663.  DO NOT CALL THIS NUMBER FOR INFORMATION.
 
E.T.
 
LAT..LON  4055 10466 4056 10431 4034 10431 4033 10465

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, Jul 7, 2:13 PM MDT, 2 hours 41 minutes before

SPECIAL WEATHER STATEMENT/SHORT RANGE FORECAST
NATIONAL WEATHER SERVICE  DENVER CO
215 PM MDT TUE JUL 7 1987

             ...STRONG THUNDERSTORM NEAR DECKERS...

AT 200 PM MDT DOPPLER RADAR INDICATED A STRONG THUNDERSTORM JUST
SOUTHWEST OF THE TOWN OF DECKERS ALONG THE SOUTH PLATTE RIVER IN
JEFFERSON COUNTY.  HEAVY RAIN...HAIL...FREQUENT LIGHTNING AND STRONG
GUSTY WINDS CAN BE ANTICIPATED WITH THIS STORM.  A WEATHER SPOTTER IN
DECKERS REPORTED PEA SIZE HAIL AT AROUND 200 PM.

PRESENT INDICATIONS SHOW THE STORM MOVING TO THE EAST AT BETWEEN 5 TO 10
MPH.  THE STORM MAY INTENSIFY AS IT MOVES OUT OF THE FOOTHILLS AND ONTO
THE PLAINS SO PERSONS IN SOUTHERN JEFFERSON AND WESTERN DOUGLAS COU5NTIES
SHOULD KEEP AN EYE ON THE WEATHER AND MOVE TO A PLACE OF SAFETY SHOULD
THREATENING WEATHER APPROACH.
E.T.

The office that day

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

Issued	Product	Office	Counties	Lasted
Jul 7, 2:37 PM MDT	Tornado Warning	BOU	Douglas	28 min
Jul 7, 4:15 PM MDT	Severe Thunderstorm Warning	BOU	Adams, Weld	60 min
Jul 7, 4:30 PM MDT	Tornado Warning	BOU	Weld	25 min
Jul 7, 5:17 PM MDT	Severe Thunderstorm Warning	BOU	Morgan, Weld	58 min

Nearby

Tornado Warnings in Colorado, 1987 Every tornado warning in 1987 Tornadoes 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.