Alert archive / Colorado / Severe Thunderstorm Warnings in 1987

Severe Thunderstorm Warning 9, NWS Denver/Boulder, CO

June 9, 1987Arapahoe County, Douglas County, Jefferson County, Colorado

NWS Denver/Boulder, CO issued this severe thunderstorm warning at Jun 9, 1987, 3:30 PM MDT for Arapahoe County, Douglas County, Jefferson County, Colorado. It was in force for 60 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 9, 1987, 3:30 PM MDT (21:30 UTC)
Expired: Jun 9, 1987, 4:30 PM MDT
In force: 60 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 9, 4:39 PM MDT	Tornado F1	Jefferson, 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, 9.5 hours before the alert went out and 94 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: 51 J/kg
Mixed-layer CIN: -4 J/kg
Mixed-layer LCL: 690 m above ground
0-6 km bulk shear: 33 kt
0-1 km storm-relative helicity: 104 m²/s²
0-3 km storm-relative helicity: 141 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 092131
SVRDEN
COC005-059-035-092230-
 
BULLETIN...IMMEDIATE BROADCAST REQUESTED
SEVERE THUNDERSTORM WARNING
NATIONAL WEATHER SERVICE DENVER CO
330 PM MDT TUE JUN 09 1987
 
THE NATIONAL WEATHER SERVICE HAS ISSUED A SEVERE THUNDERSTORM
WARNING EFFECTIVE UNTIL 430 PM  MDT FOR PEOPLE IN THE
FOLLOWING COUNTIES OF NORTHEAST COLORADO:
 
     SOUTHWESTERN ARAPAHOE
     EAST CENTRAL JEFFERSON
     NORTHWESTERN DOUGLAS
     SOUTHWESTERN DENVER
INCLUDING THE FOLLOWING TOWNS/CITIES:
 
     ENGLEWOOD..LITTLETON..AND MORRISON AND SOUTHWEST DENVER
 
THE STORM IS LOCATED 16 MILES SOUTHWEST OF DENVER.
 
AT 330PM MDT SECURITY PERSONNEL SIGHTED A FUNNEL CLOUD
DIRECTLY OVER THE MARTIN MARIETTA PLANT IN WATERTON CANYON
NEAR CHATFIELD RESERVOIR.  THIS THUNDERSTORM IS MOVING TO
THE EAST ABOUT 20 MPH.

REMEMBER..A SEVERE THUNDERSTORM CAN PRODUCE LARGE DAMAGING
HAIL..DAMAGING WINDS OF OVER 60 MPH..DEADLY LIGHTNING..AND
HEAVY RAINS THAT CAN QUICKLY FLOOD A LOW LYING AREA.
 
THESE STORMS CAN PRODUCE A TORNADO WITH LITTLE OR NO ADVANCE
WARNING..SO BE ON THE LOOKOUT AND BE PREPARED TO MOVE TO A PLACE
OF SAFETY IF ONE IS SPOTTED.
 
A FLASH FLOOD WATCH REMAINS IN EFFECT FOR THE EASTERN FOOTHILLS OF
COLORADO UNTIL 9PM MDT.
 
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 NATIONAL WEATHER SERVICE
AT 361-0663.  DO NOT CALL THIS NUMBER FOR QINFORMATION.
 
 
LAT..LON  3966 10522 3970 10497 3948 10497 3947 10522

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 9, 12:14 PM MDT, 3 hours 16 minutes before

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE  DENVER CO
1210PM MDT   TUESDAY   JUNE 9 1987

             ...HEAVY RAIN IN MORGAN COUNTY COLORADO...

RADAR SHOWS A BAND OF HEAVY SHOWERS LOCATED OVER WESTERN MORGAN COUNTY.
THIS BAND IS VERY NARROW AND IS LOCATED FROM GOODRICH AND JACKSON
RESERVOIR TO ABOUT WIGGINS COLORADO.  A SPOTTER AT JACKSON LAKE REPORTED
VERY HEAVY RAIN AT NOON WITH 2 INCHES THUS FAR.  THESE SHOWERS HAVE
SHOWN VERY LITTLE MOVEMENT SINCE THEY FORMED.

PERSONS IN WESTERN MORGAN COUNTY SHOULD AVOID LOW LYING AREAS AND SMALL
STREAMS AS THIS HEAVY RAIN MAY CAUSE LOCAL FLOODING.  MOTORISTS ON I-76
AND OTHER ROADS SHOULD DRIVE WITH CAUTION AND AVOID UNDERPASSES AND BE
ALERT FOR FLOODING OF STREET INTERSECTIONS.  ALL PERSONS IN ESSTERN
COLORADO SHOULD CONTINUE TO MONITOR LOCAL RADIO AND TV BROADCASTS OR
NOAA WEATHER RADIO FOR FUTURE STATEMENTS AND WARNINGS.  A FLASH FLOOD
WATCH REMAINS POSTED FOR THE EASTERN FOOTHILLS AND ADJACENT PLAINS
BELOW 7000 FEET FOR THIS AFTERNOON AND EVENING.

Special weather statement, Jun 9, 1:11 PM MDT, 2 hours 19 minutes before

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE  DENVER CO
110PM MDT TUESDAY   JUNE 9 1987

             ...LOCALLY HEAVY RAINS CONTINUE IN EASTERN COLORADO...

HEAVY THUNDERSTORMS CONTINUE IN MORGAN COUNTY WITH THE HEAVIEST STORM
AT 1PM REPORTED 10 MILES SOUTHWEST OF FORT MORGAN. LOCALLY HEAVY
SHOWERS AND THUNDERSTORMS ARE ARE DEVELOPING THROUGHOUT MUCH OF EASTERN
COLORADO AND DURING THE PAST HOUR HAVE BEGUN FORMING ALONG THE EASTERN
FOOTHILLS. THESE STORMS ARE MOVING MOSTLY TOWARD THE NORTH NORTHEAST
AT AROUND 10 TO 20 MILES PER HOUR.

THE FLASH FLOOD WATCH VALID FROM 3PM TO 9PM THIS AFTERNOON ALONG
MUCH OF THE EASTERN FOOTHILLS BELOW 7500 FEET REMAINS IN EFFECT.
STAY TUNED TO RADIO OR TV FOR FURTHER INFORMATION.

TUNNELL

Special weather statement, Jun 9, 2:44 PM MDT, 46 minutes before

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE  DENVER CO
3PM MDT TUESDAY   JUNE 9 1987

             ...WIDESPREAD RAIN OVER EASTERN COLORADO...

LOCALLY HEAVY SHOWERS AND THUNDERSTORMS CONTINUED OVER EASTERN
COLORADO AT 3PM WITH THE HEAVIEST STORM 3 MILES SOUTHEAST OF MERINO
IN LOGAN COUNTY. OTHER HEAVY SHOWERS WERE SPOTTED THROUGHOUT THE EASTERN
PLAINS AND WERE BEGINNING TO DEVELOP IN WESTERN JEFFERSON COUNTY. THESE
STORMS ARE MOVING MOSTLY TOWARD THE NORTH AT AROUND 15 TO 20 MILES PER
HOUR.

THE FLASH FLOOD WATCH VALID FROM 3PM TO 9PM THIS AFTERNOON ALONG
MUCH OF THE EASTERN FOOTHILLS BELOW 7500 FEET REMAINS IN EFFECT.
STAY TUNED TO RADIO OR TV FOR FURTHER INFORMATION.

TUNNELL

The office that day

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

Issued	Product	Office	Counties	Lasted
Jun 9, 3:30 PM MDT	Severe Thunderstorm Warning	BOU	Denver	60 min
Jun 9, 4:11 PM MDT	Tornado Warning	BOU	Adams, Arapahoe	29 min
Jun 9, 4:17 PM MDT	Tornado Warning	BOU	Arapahoe, Douglas	28 min
Jun 9, 4:41 PM MDT	Tornado Warning	BOU	Arapahoe	29 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.