Alert archive / Colorado / Severe Thunderstorm Warnings in 1987
Severe Thunderstorm Warning 12, NWS Denver/Boulder, CO
NWS Denver/Boulder, CO issued this severe thunderstorm warning at Jun 18, 1987, 4:11 PM MDT for Adams County, Denver County, Jefferson County, Colorado. It was in force for 59 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 18, 1987, 4:11 PM MDT (22:11 UTC)
- Expired
- Jun 18, 1987, 5:10 PM MDT
- In force
- 59 min
- Issued by
- NWS Denver/Boulder, CO
- Area
- Whole counties
Counties Adams County, CO, Denver 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 18, 4:14 PM MDT | Hail 1.5 | 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, 10.2 hours before the alert went out and 118 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
- 295 J/kg
- Mixed-layer CIN
- -96 J/kg
- Mixed-layer LCL
- 908 m above ground
- 0-6 km bulk shear
- 23 kt
- 0-1 km storm-relative helicity
- 19 m²/s²
- 0-3 km storm-relative helicity
- 77 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 0.7
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, Jun 18, 10:45 AM MDT, 5 hours 26 minutes before
SPECIAL WEATHER STATEMENT NATIONAL WEATHER SERVICE DENVER CO 1045 AM MDT THU JUN 18 1987 ...SEVERE THUNDERSTORMS POSSIBLE ACROSS EASTERN COLORADO THIS AFTERNOON AND EVENING... SEVERE THUNDERSTORMS WITH LARGE HAIL AND DAMAGING WINDS ARE POSSIBLE ACROSS ALL OF EASTERN COLORADO THIS AFTERNOON AND EVENING. LOW LEVEL UPSLOPE FLOW HAS BROUGHT MOISTURE INTO THE STATE FROM THE EAST AND PRODUCED AN UNSTABLE AIR MASS OVER THE HIGH PLAINS OF EASTERN COLORADO. THESE CONDITIONS ARE FAVORABLE FOR THE FORMATION OF SEVERE THUNDERSTORMS. HEAVY RAINS ARE ALSO POSSIBLE FROM SOME OF THESE THUNDERSTORMS CAUSING MINOR FLOODING OF SMALL STREAMS AND LOW LYING AREAS. WHILE NO MAJOR STREAM FLOODING IS ANTICIPATED AT THIS TIME...POTENTIAL RAINFALL AMOUNTS OF 1 TO 2 INCHES MAY PRODUCE BRIEF FLOODING OF HIGHWAYS...STREETS... UNDERPASSES AND FLOOD PRONE AREAS. ALL PERSONS IN EASTERN COLORADO...INCLUDING THE GREATER DENVER METROPOLITAN AREA...SHOULD MONITOR NOAA WEATHER RADIO OR OTHER MASS MEDIA COMMUNICATIONS FOR THE LATEST WEATHER UPDATES. GARD...WSFO DENVER
Special weather statement, Jun 18, 1:50 PM MDT, 2 hours 21 minutes before
SPECIAL WEATHER STATEMENT NATIONAL WEATHER SERVICE DENVER CO 150PM MDT THU JUN 18 1987 ...THUNDERSTORMS OVER THE NORTHEAST COLORADO FOOTHILLS... THUNDERSTORMS WERE DEVELOPING OVER THE NORTHEAST COLORADO FOOTHILLS THIS AFTERNOON. THE STONGEST THUNDERSTORM WAS LOCATED IN WESTERN BOULDER COUNTY...40 MILE NORTHWEST OF DENVER. THE THUNDERSTORMS WERE MOVING TO THE NORTHEAST AT 15 MPH. THE THUNDERSTORMS WILL CONTINUE TO DEVELOP THIS AFTERNOON MOVING OUT OVER THE PLAINS. A FEW OF THE THUNDERSTORMS MAY BECOME SEVERE WITH HAIL...STRONG GUSTY WINDS...LOCALLY HEAVY RAIN AND DANGEROUS LIGHTNING. THE HEAVY RAINS WITH THE THUNDERSTORMS THIS AFTERNOON CAN CAUSE LOCAL FLOODING OF SMALL STREAMS AND LOW LYING AREAS...LOCAL FLOODING OF HIGHWAYS...STREETS AND UNDERPASSES. ALL PERSONS IN EASTERN COLORADO...INCLUDING THE GREATER DENVER METROPOLITAN AREA...SHOULD MONITOR NOAA WEATHER RADIO OR OTHER MASS MEDIA COMMUNICATIONS FOR THE LATEST WEATHER UPDATES. BALINT...WSFO DENVER
Special weather statement, Jun 18, 2:56 PM MDT, 1 hour 15 minutes before
SPECIAL WEATHER STATEMENT NATIONAL WEATHER SERVICE DENVER CO 255 PM MDT THU JUN 18 1987 ...THUNDERSTORMS CONTINUE OVER THE NORTHEAST COLORADO FOOTHILLS... THUNDERSTORMS CONTINUED OVER THE THE NORTHEAST COLORADO FOOTHILLS SOUTH WEST OF DENVER NORTH TO THE WYOMING BORDER. THE STONGEST THUNDERSTORM WAS LOCATED NEAR BOULDER IN BOULDER COUNTY...25 MILES NORTHWEST OF DENVER. THE THUNDERSTORMS WERE MOVING TO THE NORTHEAST AT 15 MPH. THE THUNDERSTORMS WILL CONTINUE TO DEVELOP THIS AFTERNOON AND ARE BEGINNING TO MOVE OUT OVER THE PLAINS. A FEW OF THE THUNDERSTORMS MAY BECOME SEVERE WITH HAIL...STRONG GUSTY WINDS...LOCALLY HEAVY RAIN AND DANGEROUS LIGHTNING. ALL PERSONS IN EASTERN COLORA`DO...INCLUDING THE GREATER DENVER METROPOLITAN AREA...SHOULD MONITOR NOAA WEATHER RADIO OR OTHER MASS MEDIA COMMUNICATIONS FOR THE LATEST WEATHER UPDATES. BALINT...WSFO DENVER
Special weather statement, Jun 18, 3:55 PM MDT, 16 minutes before
SPECIAL WEATHER STATEMENT NATIONAL WEATHER SERVICE DENVER CO 355 PM MDT THU JUN 18 1987 ...THUNDERSTORMS CONTINUE ALONG AND NEAR THE NORTHEAST COLORADO FOOTHILLS... THUNDERSTORMS CONTINUED OVER THE THE NORTHEAST COLORADO FOOTHILLS SOUTH WEST OF DENVER NORTH TO THE WYOMING BORDER. THE STONGEST THUNDERSTORMS WERE LOCATED NEAR BOULDER IN BOULDER COUNTY...25 MILES NORTHWEST OF DENVER AND OVER NORTHERN JEFFERSON COUNTY 15 MILES WEST OF DENVER. THE THUNDERSTORMS WERE MOVING TO THE NORTHEAST AT 10 MPH. THE THUNDERSTORMS WILL CONTINUE TO DEVELOP THIS AFTERNOON. A FEW OF THE THUNDERSTORMS MAY BECOME SEVERE WITH HAIL...STRONG GUSTY WINDS...LOCALLY HEAVY RAIN AND DANGEROUS LIGHTNING. PEA SIZED HAIL WAS REPORTED NEAR BOULDER...25 MILS TO THE NORTHWEST OF DENVER AND NEAR GOLDEN 15 MILES WEST OF DENVER. ABOUT ONE HALF INCH OF RAIN WAS INDICATED NEAR WARD...35 MILES TO THE NORTHWEST OF DENVER. ALL PERSONS IN EASTERN COLORADO...INCLUDING THE GREATER DENVER METROPOLITAN AREA...SHOULD MONITOR NOAA WEATHER RADIO OR OTHER MASS MEDIA COMMUNICATIONS FOR THE LATEST WEATHER UPDATES. BALINT...WSFO DENVER
The office that day
Everything else NWS Denver/Boulder, CO issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Jun 17, 6:24 PM MDT | Severe Thunderstorm Warning | BOU | Washington, Yuma | 61 min |
| Jun 18, 4:11 PM MDT | Severe Thunderstorm Warning | BOU | Boulder | 59 min |
| Jun 18, 5:42 PM MDT | Severe Thunderstorm Warning | BOU | Douglas | 63 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.