Alert archive / Colorado / Severe Thunderstorm Warnings in 1998
Severe Thunderstorm Warning 22, NWS Denver/Boulder, CO
NWS Denver/Boulder, CO issued this severe thunderstorm warning at May 21, 1998, 2:19 PM MDT for Weld County, Colorado. It was in force for 36 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
- May 21, 1998, 2:19 PM MDT (20:19 UTC)
- Expired
- May 21, 1998, 2:55 PM MDT
- In force
- 36 min
- Issued by
- NWS Denver/Boulder, CO
- Area
- Whole counties; the outline is the Mesonet’s reconstruction
County Weld County, CO
The radar
The Cheyenne radar (KCYS), 44 km from the middle of the area, began a volume at 20:22 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, 8.3 hours before the alert went out and 157 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
- 0 J/kg
- Mixed-layer CIN
- No buoyant parcel
- Mixed-layer LCL
- 2454 m above ground
- 0-6 km bulk shear
- 36 kt
- 0-1 km storm-relative helicity
- 56 m²/s²
- 0-3 km storm-relative helicity
- 158 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 0.0
The text
As transmitted, in the capitals the NWS used until 2016.
400
WUUS1 KDEN 212020 RRA
SVRDEN
COC123-212055-
BULLETIN - IMMEDIATE BROADCAST REQUESTED
SEVERE THUNDERSTORM WARNING
NATIONAL WEATHER SERVICE DENVER CO
219 PM MDT THU MAY 21 1998
THE NATIONAL WEATHER SERVICE IN DENVER HAS ISSUED A
* SEVERE THUNDERSTORM WARNING FOR...
NORTHWESTERN WELD COUNTY IN NORTHEAST COLORADO
* UNTIL 255 PM MDT
* AT 217 PM MDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED A
SEVERE THUNDERSTORM OVER NUNN...OR ABOUT 19 MILES NORTH OF
GREELEY...MOVING NORTHEAST AT 20 MILES PER HOUR.
* LOCATIONS IN THE WARNING INCLUDE...NUNN...PIERCE AND PURCELL
IF SEVERE WEATHER APPROACHES YOUR AREA...GO INSIDE A STURDY SHELTER
AWAY FROM CREEK BEDS AND OTHER FLOOD-PRONE AREAS. REMEMBER...A SEVERE
THUNDERSTORM CAN PRODUCE LARGE DAMAGING HAIL...DAMAGING WINDS OVER 60
MPH...DEADLY LIGHTNING...AND VERY HEAVY RAIN.
A TORNADO WATCH REMAINS IN EFFECT UNTIL 700 PM MDT FOR NORTHEAST
COLORADO.
ENTREKIN
LAT...LON 4072 10492 4059 10468 4081 10420 4101 10457What 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, May 21, 11:53 AM MDT, 2 hours 26 minutes before
COZ030-032>050-220600- SIGNIFICANT WEATHER OUTLOOK FOR NORTHEAST AND NORTH CENTRAL COLORADO NATIONAL WEATHER SERVICE DENVER COLORADO 1153 AM MDT THU MAY 21 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 SYSTEM PUSHED EAST OF THE AREA EARLIER THIS MORNING...BRINGING MORE STABLE AND DRY CONDITIONS...AS WELL AS DOWNSLOPE WINDS...TO PLAINS ADJACENT TO THE FOOTHILLS. HOWEVER...AT THE SURFACE AN AREA OF LOW PRESSURE WAS OVER SOUTHWEST WASHINGTON COUNTY AT THIS TIME...AND IS EXPECTED TO MOVE LITTLE THROUGH THE AFTERNOON. THE ASSOCIATED WIND FIELD WILL KEEP AREAS EAST AND NORTH OF THE LOW IN MORE MOIST UPSLOPE FLOW...AREAS TO THE SOUTH AND WEST WILL BE MUCH DRIER. SO THE SHOWERS AND THUNDERSTORMS THAT DEVELOP OVER THE ALPINE AREAS BY EARLY AFTERNOON WILL DISSIPATED WHEN THEY PUSH OFF THE FOOTHILLS INTO THESE DRY AREAS. EXPECT ONLY ISOLATED THUNDERSTORMS AFTER 4 PM IN JEFFERSON...DENVER...DOUGLAS...ELBERT... LINCOLN...ARAPAHOE COUNTIES. THE UPPER SYSTEM THAT PUSHED THROUGH EARLIER HAS LEFT A FAIRLY STABLE AREA AT THE MID LEVELS OF THE ATMOSPHERE. THIS WILL MAKE THUNDERSTORMS DEVELOPMENT MORE DIFFICULT...EVEN IN THE MORE MOIST COUNTIES. EXPECTED WIDELY SCATTERED SHOWERS AND THUNDERSTORMS AFTER 2:30 PM IN BOULDER...LARIMER...WELD...MORGAN...ADAMS...WASHINGTON ...LOGAN...PHILLIPS...AND SEDGWICK COUNTIES. SPOTTER ACTIVATION MAY BE NEEDED AFTER 3 PM OVER THE FAR NORTHEAST BORDER COUNTIES OF COLORADO. RJK
Special weather statement, May 21, 12:25 PM MDT, 1 hour 54 minutes before
COZ030-032>050-220600- SIGNIFICANT WEATHER OUTLOOK FOR NORTHEAST AND NORTH CENTRAL COLORADO NATIONAL WEATHER SERVICE DENVER COLORADO 1153 AM MDT THU MAY 21 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 SYSTEM PUSHED EAST OF THE AREA EARLIER THIS MORNING...BRINGING MORE STABLE AND DRY CONDITIONS...AS WELL AS DOWNSLOPE WINDS...TO PLAINS ADJACENT TO THE FOOTHILLS. HOWEVER...AT THE SURFACE AN AREA OF LOW PRESSURE WAS OVER SOUTHWEST WASHINGTON COUNTY AT THIS TIME...AND IS EXPECTED TO MOVE LITTLE THROUGH THE AFTERNOON. THE ASSOCIATED WIND FIELD WILL KEEP AREAS EAST AND NORTH OF THE LOW IN MORE MOIST UPSLOPE FLOW...AREAS TO THE SOUTH AND WEST WILL BE MUCH DRIER. SO THE SHOWERS AND THUNDERSTORMS THAT DEVELOP OVER THE ALPINE AREAS BY EARLY AFTERNOON WILL DISSIPATED WHEN THEY PUSH OFF THE FOOTHILLS INTO THESE DRY AREAS. EXPECT ONLY ISOLATED THUNDERSTORMS AFTER 4 PM IN JEFFERSON...DENVER...DOUGLAS...ELBERT... LINCOLN...ARAPAHOE COUNTIES. THE UPPER SYSTEM THAT PUSHED THROUGH EARLIER HAS LEFT A FAIRLY STABLE AREA AT THE MID LEVELS OF THE ATMOSPHERE. THIS WILL MAKE THUNDERSTORMS DEVELOPMENT MORE DIFFICULT...EVEN IN THE MORE MOIST COUNTIES. EXPECTED WIDELY SCATTERED SHOWERS AND THUNDERSTORMS AFTER 2:30 PM IN BOULDER...LARIMER...WELD...MORGAN...ADAMS...WASHINGTON ...LOGAN...PHILLIPS...AND SEDGWICK COUNTIES. SPOTTER ACTIVATION MAY BE NEEDED AFTER 3 PM OVER THE FAR NORTHEAST BORDER C"OUNTIES OF COLORADO. RJK
The office that day
Everything else NWS Denver/Boulder, CO issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| May 20, 6:22 PM MDT | Severe Thunderstorm Warning | BOU | Washington | 38 min |
| May 20, 6:36 PM MDT | Severe Thunderstorm Warning | BOU | Washington | 24 min |
| May 20, 7:01 PM MDT | Severe Thunderstorm Warning | BOU | Washington | 39 min |
| May 21, 1:50 PM MDT | Severe Thunderstorm Warning | BOU | Logan | 55 min |
| May 21, 3:18 PM MDT | Severe Thunderstorm Warning | BOU | Weld | 42 min |
| May 21, 3:57 PM MDT | Severe Thunderstorm Warning | BOU | Weld | 48 min |
| May 21, 4:22 PM MDT | Tornado Warning | BOU | Weld | 28 min |
| May 21, 4:51 PM MDT | Severe Thunderstorm Warning | BOU | Logan, Weld | 39 min |
| May 21, 5:35 PM MDT | Severe Thunderstorm Warning | BOU | Logan | 35 min |
| May 21, 5:41 PM MDT | Tornado Warning | BOU | Phillips, Sedgwick | 39 min |
| May 21, 5:47 PM MDT | Tornado Warning | BOU | Phillips, Sedgwick | 33 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.