Alert archive / Colorado / Severe Thunderstorm Warnings in 1998
Severe Thunderstorm Warning 18, NWS Denver/Boulder, CO
NWS Denver/Boulder, CO issued this severe thunderstorm warning at May 20, 1998, 6:22 PM MDT for Washington County, Colorado. It was in force for 38 min. 3 reports 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
- May 20, 1998, 6:22 PM MDT (00:22 UTC)
- Expired
- May 20, 1998, 7:00 PM MDT
- In force
- 38 min
- Issued by
- NWS Denver/Boulder, CO
- Area
- Whole counties
County Washington County, CO
The radar
The Denver radar (KFTG), 117 km from the middle of the area, began a volume at 00:25 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 | Remark |
|---|---|---|---|
| May 20, 6:35 PM MDT | Hail 1.75 | Anton, CO | |
| May 20, 6:44 PM MDT | Hail 2.75 | Anton, CO | |
| May 20, 7:00 PM MDT | Hail 1.5 | Elba, 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
Denver, CO (KDNR), launched 00:00Z, 0.4 hours before the alert went out and 11 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
- 87 J/kg
- Mixed-layer CIN
- -39 J/kg
- Mixed-layer LCL
- 3075 m above ground
- 0-6 km bulk shear
- 18 kt
- 0-1 km storm-relative helicity
- -42 m²/s²
- 0-3 km storm-relative helicity
- 46 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 0.0
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, May 20, 2:55 PM MDT, 3 hours 27 minutes before
COZ030-032>050-210600- SIGNIFICANT WEATHER OUTLOOK FOR NORTHEAST AND NORTH CENTRAL COLORADO NATIONAL WEATHER SERVICE DENVER CO 255 PM MDT WED MAY 20 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 ...SPOTTER ACTIVATION WILL STILL BE NEEDED TODAY...BUT MAINLY ACROSS FAR NORTHEAST COLORADO. SYNOPSIS: THE LOW LEVELS HAVE DRIED OUT SOME FROM THIS MORNING ACROSS THE URBAN CORRIDOR FROM LARIMER DOWN TO DOUGLAS COUNTIES. CONVECTION IS DEVELOPING OFF THE MOUNTAINS...BUT THE MAIN THREAT FROM FORT COLLINS DOWN TO CASTLE ROCK WILL BE GUSTY WINDS TO 45 MPH...BRIEF RAIN...BUT ONLY SMALL HAIL. THERE IS HOWEVER...A GREATER THREAT FOR SEVERE WEATHER FURTHER EAST ACROSS MORGAN COUNTY...WASHINGTON...AND ALL OF FAR NORTHEAST COLORADO. THE LOW LEVEL MOISTURE REMAINS HIGH ACROSS THE NORTHEASTERN PLAINS...ALONG WITH BETTER WIND SHEAR...WHICH WILL LEAD FOR STRONGER STORMS TO DEVELOP. STORMS WILL DEVELOP ACROSS MORGAN AND WASHINGTON COUNTIES BETWEEN 3 AND 5 PM...THEN ACROSS FAR NORTH EAST COLORADO AFTER 6 PM. THE MAIN SEVERE WEATHER THREAT WILL BE LARGE HAIL...GUSTY WINDS TO 50 MPH...AND AN OUTSIDE CHANCE OF A POSSIBLE TORNADO. OUTLOOK FOR THURSDAY...POTENTIAL ACTIVE DAY WITH DENVER CYCLONE OR PERHAPS A REAL CYCLONE DEVELOPING IN EASTERN COLORADO...ALONG WITH EXPECTED GOOD VERTICAL WIND SHEAR AND LOW LEVEL MOISTURE. SZOKE ENTREKIN/SZOKE
Special weather statement, May 20, 2:55 PM MDT, 3 hours 27 minutes before
COZ030-032>050-210600- SIGNIFICANT WEATHER OUTLOOK FOR NORTHEAST AND NORTH CENTRAL COLORADO NATIONAL WEATHER SERVICE DENVER CO 255 PM MDT WED MAY 20 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 ...SPOTTER ACTIVATION WILL STILL BE NEEDED TODAY...BUT MAINLY ACROSS FAR NORTHEAST COLORADO. SYNOPSIS: THE LOW LEVELS HAVE DRIED OUT SOME FROM THIS MORNING ACROSS THE URBAN CORRIDOR FROM LARIMER DOWN TO DOUGLAS COUNTIES. CONVECTION IS DEVELOPING OFF THE MOUNTAINS...BUT THE MAIN THREAT FROM FORT COLLINS DOWN TO CASTLE ROCK WILL BE GUSTY WINDS TO 45 MPH...BRIEF RAIN...BUT ONLY SMALL HAIL. THERE IS HOWEVER...A GREATER THREAT FOR SEVERE WEATHER FURTHER EAST ACROSS MORGAN COUNTY...WASHINGTON...AND ALL OF FAR NORTHEAST COLORADO. THE LOW LEVEL MOISTURE REMAINS HIGH ACROSS THE NORTHEASTERN PLAINS...ALONG WITH BETTER WIND SHEAR...WHICH WILL LEAD FOR STRONGER STORMS TO DEVELOP. STORMS WILL DEVELOP ACROSS MORGAN AND WASHINGTON COUNTIES BETWEEN 3 AND 5 PM...THEN ACROSS FAR NORTH EAST COLORADO AFTER 6 PM. THE MAIN SEVERE WEATHER THREAT WILL BE LARGE HAIL...GUSTY WINDS TO 50 MPH...AND AN OUTSIDE CHANCE OF A POSSIBLE TORNADO. OUTLOOK FOR THURSDAY...POTENTIAL ACTIVE DAY WITH DENVER CYCLONE OR PERHAPS A REAL CYCLONE DEVELOPING IN EASTERN COLORADO...ALONG WITH EXPECTED GOOD VERTICAL WIND SHEAR AND LOW LEVEL MOISTURE. SZOKE ENTREKIN/SZOKE
Special weather statement, May 20, 3:16 PM MDT, 3 hours 6 minutes before
COZ040-041-045-202145- SPECIAL WEATHER STATEMENT NATIONAL WEATHER SERVICE DENVER CO 316 PM MDT WED MAY 20 1998 ...STRONG GUSTY THUNDERSTORM WINDS ACROSS CENTRAL ARAPAHOE COUNTY... AT 315 PM MDT NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED A THUNDERSTORM WITH STRONG MICROBURST WINDS ABOUT 8 MILES SOUTH OF WATKINS...OR ABOUT 23 MILES EAST OF DENVER...MOVING NORTH AT 20 MILES PER HOUR. PERSONS IN OR NEAR SOUTHEASTERN DENVER INTERNATIONAL AIRPORT...BENNETT...MANILA VILLAGE AND WATKINS SHOULD BE ON THE LOOKOUT FOR THESE STRONG DAMAGING WINDS. WIND SPEEDS COULD REACH UP TO 55 MPH WITH THIS STORM. STRONG AND DAMAGING WINDS ARE LIKELY FROM THIS STORM...BUT THERE WILL BE LITTLE RAIN. TAKE COVER IN A STURDY STRUCTURE UNTIL THE STORM PASSES. ENTREKIN
Special weather statement, May 20, 3:16 PM MDT, 3 hours 6 minutes before
COZ040-041-045-202145- SPECIAL WEATHER STATEMENT NATIONAL WEATHER SERVICE DENVER CO 316 PM MDT WED MAY 20 1998 ...STRONG GUSTY THUNDERSTORM WINDS ACROSS CENTRAL ARAPAHOE COUNTY... AT 315 PM MDT NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED A THUNDERSTORM WITH STRONG MICROBURST WINDS ABOUT 8 MILES SOUTH OF WATKINS...OR ABOUT 23 MILES EAST OF DENVER...MOVING NORTH AT 20 MILES PER HOUR. PERSONS IN OR NEAR SOUTHEASTERN DENVER INTERNATIONAL AIRPORT...BENNETT...MANILA VILLAGE AND WATKINS SHOULD BE ON THE LOOKOUT FOR THESE STRONG DAMAGING WINDS. WIND SPEEDS COULD REACH UP TO 55 MPH WITH THIS STORM. STRONG AND DAMAGING WINDS ARE LIKELY FROM THIS STORM...BUT THERE WILL BE LITTLE RAIN. TAKE COVER IN A STURDY STRUCTURE UNTIL THE STORM PASSES. ENTREKIN
The office that day
Everything else NWS Denver/Boulder, CO issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| 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, 2:19 PM MDT | Severe Thunderstorm Warning | BOU | Weld | 36 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; verification from NCEI's Storm Data; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.