Alert archive / Colorado / Severe Thunderstorm Warnings in 1998

Severe Thunderstorm Warning 155, NWS Denver/Boulder, CO

August 11, 1998Adams County, Morgan County, Weld County, Colorado

NWS Denver/Boulder, CO issued this severe thunderstorm warning at Aug 11, 1998, 4:20 PM MDT for Adams County, Morgan County, Weld County, Colorado. It was in force for 60 min. No storm report in the archive falls 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.

The facts

Issued
Aug 11, 1998, 4:20 PM MDT (22:20 UTC)
Expired
Aug 11, 1998, 5:20 PM MDT
In force
60 min
Issued by
NWS Denver/Boulder, CO
Area
Whole counties; the outline is the Mesonet’s reconstruction

Counties Adams County, CO, Morgan County, CO, Weld County, CO

The radar

The Denver radar (KFTG), 57 km from the middle of the area, began a volume at 22:19 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.

The nearest sounding before it

Denver, CO (KDNR), launched 12:00Z, 10.3 hours before the alert went out and 79 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 12:00Z on 1998-08-11Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 93 joules per kilogram.LCLLFCEL10008507005003002001001 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 12:00Z on 1998-08-11The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity -24 square meters per square second.1939Sfc1 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
93 J/kg
Mixed-layer CIN
-174 J/kg
Mixed-layer LCL
1415 m above ground
0-6 km bulk shear
13 kt
0-1 km storm-relative helicity
-24 m²/s²
0-3 km storm-relative helicity
-22 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.

320 
WUUS1 KDEN 112223 RRA
SVRDEN
COC001-087-123-112320-

BULLETIN - IMMEDIATE BROADCAST REQUESTED
SEVERE THUNDERSTORM WARNING
NATIONAL WEATHER SERVICE DENVER CO
420 PM MDT TUE AUG 11 1998

THE NATIONAL WEATHER SERVICE IN DENVER HAS ISSUED A

* SEVERE THUNDERSTORM WARNING FOR...
     CENTRAL ADAMS...WESTERN AND SOUTHERN MORGAN AND EXTREME 
     SOUTH CENTRAL WELD COUNTY IN NORTHEAST COLORADO

* UNTIL 520 PM MDT

* AT 418 PM MDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED
  SEVERE THUNDERSTORMS 4 MILES SOUTHEAST OF ORCHARD...OR ABOUT 15
  MILES WEST OF FORT MORGAN...AND 7 MILES WEST OF WIGGINS...OR ABOUT
  22 MILES WEST OF FORT MORGAN MOVING SOUTHEAST AT 20 MILES PER HOUR.

LOCATIONS IN THE WARNING INCLUDE...ADENA...ADENA SCHOOL...BRUSH...
FORT MORGAN...GOODRICH...HOYT...LEADER...LOG LANE VILLAGE...
ORCHARD...TWELVE-MILE CORNER...WELDONA AND WIGGINS.

HAIL UP TO 1 1/2 INCHES IN DIAMETER AND VERY HEAVY RAINFALL IS 
POSSIBLE WITH THESE SEVERE THUNDERSTORMS. IF YOU ARE IN THE PATH OF 
THE STORMS...PUT YOUR CAR IN A GARAGE AND MOVE TO A SUBSTANTIAL 
SHELTER.

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

BAKER
LAT...LON 4005 10439 3982 10402 4026 10351 4037 10400 4036 10417

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, Aug 11, 11:15 AM MDT, 5 hours 5 minutes before
COZ030-032>050-120600-

SIGNIFICANT WEATHER OUTLOOK FOR NORTHEAST AND NORTH CENTRAL COLORADO
NATIONAL WEATHER SERVICE DENVER CO
1115 AM MDT TUE AUG 11 1998

THIS OUTLOOK PERTAINS TO THE FOLLOWING COLORADO COUNTIES

ADAMS     ARAPAHOE     BOULDER   CLEAR CREEK   DENVER       DOUGLAS
ELBERT    GILPIN       GRAND     JACKSON       JEFFERSON    LARIMER
LINCOLN   LOGAN        MORGAN    PARK          PHILLIPS     SEDGWICK
SUMMIT    WASHINGTON   WELD

SYNOPSIS: AN UPPER AIR DISTURBANCE WILL BE MOVING THROUGH THE EASTERN
PLAINS THIS AFTERNOON. THIS IN ADDITION TO ABUNDANT MOISTURE AND VERY
WEAK STEERING WINDS WILL ACT TO PRODUCE LOCALLY HEAVY RAINS AGAIN THIS
AFTERNOON. BEST CHANCES FOR HEAVY RA IN ARE IN THE AREA FROM AKRON
EASTWARD IN THE PLAINS AND HEAVY THUNDERSTORMS SHOULD NOT DEVELOP
BEFORE MID AFTERNOON.

SPOTTER ACTIVITATION MAY BE REQUIRED LATER.

TUNNELL
Special weather statement, Aug 11, 11:15 AM MDT, 5 hours 5 minutes before
COZ030-032>050-120600-

SIGNIFICANT WEATHER OUTLOOK FOR NORTHEAST AND NORTH CENTRAL COLORADO
NATIONAL WEATHER SERVICE DENVER CO
1115 AM MDT TUE AUG 11 1998

THIS OUTLOOK PERTAINS TO THE FOLLOWING COLORADO COUNTIES

ADAMS     ARAPAHOE     BOULDER   CLEAR CREEK   DENVER       DOUGLAS
ELBERT    GILPIN       GRAND     JACKSON       JEFFERSON    LARIMER
LINCOLN   LOGAN        MORGAN    PARK          PHILLIPS     SEDGWICK
SUMMIT    WASHINGTON   WELD

SYNOPSIS: AN UPPER AIR DISTURBANCE WILL BE MOVING THROUGH THE EASTERN
PLAINS THIS AFTERNOON. THIS IN ADDITION TO ABUNDANT MOISTURE AND VERY
WEAK STEERING WINDS WILL ACT TO PRODUCE LOCALLY HEAVY RAINS AGAIN THIS
AFTERNOON. BEST CHANCES FOR HEAVY RA IN ARE IN THE AREA FROM AKRON
EASTWARD IN THE PLAINS AND HEAVY THUNDERSTORMS SHOULD NOT DEVELOP
BEFORE MID AFTERNOON.

SPOTTER ACTIVITATION MAY BE REQUIRED LATER.

TUNNELL
Special weather statement, Aug 11, 2:13 PM MDT, 2 hours 7 minutes before
COZ030-033-035-038-039-042>044-048-112115-

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE DENVER CO
213 PM MDT TUE AUG 11 1998

...LINE OF THUNDERSTORMS MOVING INTO NORTHERN LARIMER...NORTHERN
WELD...AND WESTERN LOGAN COUNTIES OF COLORADO...

AT 210 PM MDT NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED
THUNDERSTORMS ALONG A LINE EXTENDING FROM NEAR HEREFORD IN NORTHEAST
WELD COUNTY TO 40 MILES NORTHWEST OF FORT COLLINS.  THIS LINE OF
STORMS WAS MOVING SOUTHEAST AT 20 MILES PER HOUR.

PERSONS IN THE PATH OF THESE THUNDERSTORMS SHOULD BE ON THE LOOKOUT
FOR THREATENING WEATHER AND MOVE TO A PLACE OF SAFETY IF BAD WEATHER
APPROACHES.

DANGEROUS LIGHTNING...HAIL...HEAVY RAIN...AND STRONG GUSTY WINDS
WILL OCCUR WITH THESE STORMS AS THEY MOVE SOUTHEAST ACROSS EASTERN
LARIMER...CENTRAL AND NORTHEAST WELD AND WESTERN LOGAN COUNTIES BY 3
PM.

BAKER
Special weather statement, Aug 11, 2:13 PM MDT, 2 hours 7 minutes before
COZ030-033-035-038-039-042>044-048-112115-

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE DENVER CO
213 PM MDT TUE AUG 11 1998

...LINE OF THUNDERSTORMS MOVING INTO NORTHERN LARIMER...NORTHERN
WELD...AND WESTERN LOGAN COUNTIES OF COLORADO...

AT 210 PM MDT NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED
THUNDERSTORMS ALONG A LINE EXTENDING FROM NEAR HEREFORD IN NORTHEAST
WELD COUNTY TO 40 MILES NORTHWEST OF FORT COLLINS.  THIS LINE OF
STORMS WAS MOVING SOUTHEAST AT 20 MILES PER HOUR.

PERSONS IN THE PATH OF THESE THUNDERSTORMS SHOULD BE ON THE LOOKOUT
FOR THREATENING WEATHER AND MOVE TO A PLACE OF SAFETY IF BAD WEATHER
APPROACHES.

DANGEROUS LIGHTNING...HAIL...HEAVY RAIN...AND STRONG GUSTY WINDS
WILL OCCUR WITH THESE STORMS AS THEY MOVE SOUTHEAST ACROSS EASTERN
LARIMER...CENTRAL AND NORTHEAST WELD AND WESTERN LOGAN COUNTIES BY 3
PM.

BAKER

The office that day

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

IssuedProductOfficeCountiesLasted
Aug 10, 6:15 PM MDTSevere Thunderstorm WarningBOUAdams, Weld45 min
Aug 10, 6:53 PM MDTSevere Thunderstorm WarningBOUWeld37 min
Aug 11, 3:15 PM MDTSevere Thunderstorm WarningBOUMorgan, Weld55 min
Aug 11, 4:20 PM MDTSevere Thunderstorm WarningBOULogan, Weld40 min

Nearby

Severe Thunderstorm Warnings in Colorado, 1998Every severe thunderstorm warning in 1998

Sources

The product and its follow-ups from the Iowa Environmental Mesonet's archive of National Weather Service and Storm Prediction Center text; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.