Alert archive / Colorado / Severe Thunderstorm Warnings in 1997

Severe Thunderstorm Warning 113, NWS Denver/Boulder, CO

August 11, 1997Denver County, Jefferson County, Colorado

NWS Denver/Boulder, CO issued this severe thunderstorm warning at Aug 11, 1997, 3:12 PM MDT for Denver County, Jefferson County, Colorado. It was in force for 48 min. 3 reports came from inside the area while it was in force.

The area

The outline the Iowa Environmental Mesonet reconstructed for it; the warning itself named whole counties, with what was reported inside it.

The facts

Issued: Aug 11, 1997, 3:12 PM MDT (21:12 UTC)
Expired: Aug 11, 1997, 4:00 PM MDT
In force: 48 min
Issued by: NWS Denver/Boulder, CO
Area: Whole counties; the outline is the Mesonet’s reconstruction

Counties Denver County, CO, Jefferson County, CO

The radar

The Denver radar (KFTG), 46 km from the middle of the area, began a volume at 21:16 UTC, the scan nearest the moment this went out.

Open the radar archive at this moment

The archived warnings, watches and discussions in force at that minute are drawn over the scan, this one among them.

What was reported inside it

Time	Report	Where
Aug 11, 3:32 PM MDT	Hail 0.75	Lakewood, CO
Aug 11, 3:40 PM MDT	Hail 1.5	South Denver, CO
Aug 11, 3:42 PM MDT	Hail 1	Lakewood, 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.

The nearest sounding before it

Grand Junction, CO (KGJT), launched 12:00Z, 9.2 hours before the alert went out and 302 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: 3 J/kg
Mixed-layer CIN: -197 J/kg
Mixed-layer LCL: 1483 m above ground
0-6 km bulk shear: 51 kt
0-1 km storm-relative helicity: 145 m²/s²
0-3 km storm-relative helicity: 159 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 112115 RRA
SVRDEN
COC031-059-112200-

BULLETIN - IMMEDIATE BROADCAST REQUESTED
SEVERE THUNDERSTORM WARNING
NATIONAL WEATHER SERVICE DENVER CO
312 PM MDT MON AUG 11 1997

THE NATIONAL WEATHER SERVICE IN DENVER HAS ISSUED A SEVERE
THUNDERSTORM WARNING EFFECTIVE UNTIL 400 PM MDT FOR PEOPLE IN THE
FOLLOWING COUNTIES...

IN NORTHEAST COLORADO
     EAST CENTRAL JEFFERSON AND WESTERN DENVER

INCLUDING THE FOLLOWING LOCATIONS
     SOUTHERN ARVADA...WESTERN DENVER...GOLDEN...LAKEWOOD...WHEAT    
     RIDGE...MORRISON...RED ROCKS PARK AND SHERIDAN

AT 312 PM MDT NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED A 
SEVERE THUNDERSTORM OVER THE FOOTHILLS BETWEEN GOLDEN AND MORRISON...OR 
ABOUT 15 MILES WEST OF DENVER.

THE STORM WAS MOVING NORTHEAST AT 20 MILES PER HOUR.

UP TO AN INCH OF RAIN IN 30 MINUTES IS POSSIBLE WITH THIS 
STORM...WITH HAIL UP TO THREE-QUARTERS OF AN INCH IN DIAMETER.
HEAVY RAINS MAY FLOOD LOW LYING AREAS SUCH AS DITCHES AND 
UNDERPASSES. AVOID THESE AREAS AND DO NOT CROSS FLOODED ROADS AS THEY
MAY BE WASHED OUT. WATER LEVELS OF SMALL STREAMS AND RIVERS MAY ALSO 
RISE...THEREFORE SEEK HIGHER GROUND IF THREATENED BY FLOOD WATERS.

REPORT SEVERE WEATHER TO THE NEAREST LAW ENFORCFEMENT AGENCY. THEY
WILL RELAY YOUR REPORT TO THE NATIONAL WEATHER SERVICE FORECAST
OFFICE IN DENVER.

LAT...LON 3984 10500 3966 10495 3962 10522 3976 10522

GIMMESTAD

The office that day

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

Issued	Product	Office	Counties	Lasted
Aug 11, 3:40 PM MDT	Severe Thunderstorm Warning	BOU	Adams, Arapahoe, Denver	35 min
Aug 11, 4:32 PM MDT	Severe Thunderstorm Warning	BOU	Douglas	43 min
Aug 11, 4:49 PM MDT	Severe Thunderstorm Warning	BOU	Adams, Arapahoe	41 min
Aug 11, 5:42 PM MDT	Severe Thunderstorm Warning	BOU	Elbert	33 min

Nearby

Severe Thunderstorm Warnings in Colorado, 1997 Every severe thunderstorm warning in 1997

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; radar from the NEXRAD Level II archive.