Alert archive / Colorado / Severe Thunderstorm Warnings in 1991

Severe Thunderstorm Warning 112, NWS Denver/Boulder, CO

June 21, 1991Jefferson County, Colorado

NWS Denver/Boulder, CO issued this severe thunderstorm warning at Jun 21, 1991, 6:39 PM MDT for Jefferson County, Colorado. It was in force for 21 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 21, 1991, 6:39 PM MDT (00:39 UTC)
Expired
Jun 21, 1991, 7:00 PM MDT
In force
21 min
Issued by
NWS Denver/Boulder, CO
Area
Whole counties

County Jefferson County, CO

What was reported inside it

TimeReportWhereRemark
Jun 21, 6:42 PM MDTHail 1Jefferson, 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 00:00Z, 0.7 hours before the alert went out and 176 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-pSkew-T log-p diagram, Denver, CO at 00:00Z on 1991-06-22Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 0 joules per kilogram.LCL10008507005003002001001 km2 km3 km6 km9 km12 km15 km-30°-20°-10°0°10°20°30°40°
Temperature in red, dew point in green, the mixed-layer parcel dashed.
HodographHodograph, Denver, CO at 00:00Z on 1991-06-22The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 38 square meters per square second.193958Sfc1 km3 km6 km9 kmRMLM
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
0 J/kg
Mixed-layer CIN
No buoyant parcel
Mixed-layer LCL
2328 m above ground
0-6 km bulk shear
33 kt
0-1 km storm-relative helicity
38 m²/s²
0-3 km storm-relative helicity
260 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, Jun 21, 1:44 PM MDT, 4 hours 55 minutes before
COZ011-012-014-212100-

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE DENVER CO
140 PM MDT FRI JUN 21 1991

...SEVERE THUNDERSTORM WATCH IN EFFECT FOR THE NORTHERN FRONT RANGE AND
PARTS OF NORTHEAST COLORADO UNTIL 800 PM MDT...

THE NATIONAL SEVERE STORMS FORECAST CENTER IN KANSAS CITY HAS ISSUED A
SEVERE THUNDERSTORM WATCH FOR THE NORTHERN FRONT RANGE AND PARTS OF
NORTHEAST COLORADO UNTIL 800 PM MDT.  A WATCH MEANS THAT SEVERE
THUNDERSTORMS ARE POSSIBLE IN AND CLOSE TO THE WATCH AREA.  PEOPLE ALONG
THE NORTHERN FRONT RANGE AND PARTS OF NORTHEAST COLORADO SHOULD BE ON
THE LOOKOUT FOR THUNDERSTORMS THAT COULD PRODUCE VERY HEAVY RAIN...HAIL
3/4 INCH OR LARGER...AND WIND GUSTS OF 58 MPH OR GREATER.

AT 140 PM NATIONAL WEATHER SERVICE DOPPLER RADAR SHOWED THUNDERSTORMS
WITH VERY HEAVY RAIN RAPIDLY DEVLOPING ACROSS SOUTHERN BOULDER COUNTY
ABOUT 5 MILES SOUTHEAST OF BOULDER AND EAST CENTRAL JEFFERSON COUNTY
JUST TO THE EAST OF LAKEWOOD.   THESE STORMS WERE MOVING EAST AT 10
TO 15 MPH.

VERY MOIST AIR IS IN PLACE OVER EASTERN COLORADO AND ESPECIALLY ALONG
THE FRONT RANGE.  EASTERLY SURFACE WINDS WILL PROVIDE UPSLOPE CONDITIONS
ALONG THE FRONT RANGE TO ENHANCE THUNDERSTORM DEVELOPMENT THIS AFTERNOON
AND EVENING.

PERSONS IN EASTERN COLORADO SHOULD BE ALERT TO THE POSSIBILITY OF SEVERE
WEATHER AND CONTINUE TO STAY ABREAST OF THE LATEST WEATHER INFORMATION.
CONTINUE TO LISTEN TO NOAA WEATHER RADIO...COMMERCIAL RADIO...OR
TELEVISION FOR FURTHER STATEMENTS AND/OR WATCHES AND WARNINGS.
HOLMES
Special weather statement, Jun 21, 4:26 PM MDT, 2 hours 13 minutes before
COZ011-012-212300-

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE DENVER CO
425 PM MDT FRI JUN 21 1991

...STRONG THUNDERSTORMS IN NORTHEAST BOULDER...SOUTHEAST LARIMER AND
NORTHWEST WELD COUNTIES...

AT 421 PM NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED THREE STRONG
THUNDERSTORMS ALONG THE FRONT RANGE NORTH OF DENVER.  THE STRONGEST
STORM WAS LOCATED 7 MILES WEST SOUTHWEST OF NUNN IN WELD.  THE SECOND
STORM WAS LOCATED 8 MILES SOUTH SOUTHWEST OF FORT COLLINS IN LARIMER
COUNTY.  THE THIRD STORM WAS 7 MILES NORTHWEST OF LONGMONT IN NORTHEAST
BOULDER COUNTY.  ALL THESE THUNDERSTORMS ARE MOVING NORTHEAST AT 10
MILES AN HOUR.

HEAVY RAIN...HAIL AND STRONG GUSTY WINDS ARE POSSIBLE WITH THESE STORMS.
FLOODING OF URBAN AREAS AND LOW-LYING AND FLOOD PRONE AREAS IS LIKELY
WITH THESE STORMS.  A SEVERE THUNDERSTORM WATCH IS IN EFFECT FOR ALL
THIS AREA UNTIL 800 PM MDT.  ALSO...A FLASH FLOOD WATCH IS IN EFFECT FOR
BOULDER AND LARIMER COUNTIES UNTIL 800 PM MDT.  STAY TUNED TO THIS
STATIONS AS FURTHER STATEMENTS OR WARNINGS WILL BE ISSUED AS CONDITIONS
WARRANT.

WOLF

The office that day

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

IssuedProductOfficeCountiesLasted
Jun 21, 8:50 PM MDTSevere Thunderstorm WarningBOUAdams, Denver, Jefferson40 min
Jun 21, 9:25 PM MDTSevere Thunderstorm WarningBOUAdams, Denver25 min
Jun 21, 10:41 PM MDTSevere Thunderstorm WarningBOUDenver, Jefferson29 min
Jun 21, 11:09 PM MDTSevere Thunderstorm WarningBOUDenver26 min
Jun 21, 11:17 PM MDTSevere Thunderstorm WarningBOUAdams, Arapahoe28 min
Jun 22, 1:57 PM MDTSevere Thunderstorm WarningBOULarimer, Weld33 min
Jun 22, 2:11 PM MDTSevere Thunderstorm WarningBOUBoulder, Weld34 min
Jun 22, 2:11 PM MDTSevere Thunderstorm WarningBOUAdams34 min
Jun 22, 2:36 PM MDTTornado WarningBOULarimer, Weld39 min
Jun 22, 2:45 PM MDTSevere Thunderstorm WarningBOUWeld30 min
Jun 22, 3:15 PM MDTSevere Thunderstorm WarningBOUWeld45 min
Jun 22, 3:50 PM MDTSevere Thunderstorm WarningBOUMorgan, Weld40 min
Jun 22, 4:31 PM MDTSevere Thunderstorm WarningBOUMorgan, Weld44 min
Jun 22, 5:15 PM MDTTornado WarningBOUMorgan, Weld30 min
Jun 22, 5:47 PM MDTSevere Thunderstorm WarningBOULogan, Morgan, Weld43 min

Nearby

Severe Thunderstorm Warnings in Colorado, 1991Every severe thunderstorm warning in 1991

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.