Alert archive / Colorado / Tornado Warnings in 1998

Tornado Warning 18, NWS Denver/Boulder, CO

July 15, 1998Weld County, Colorado

NWS Denver/Boulder, CO issued this tornado warning at Jul 15, 1998, 6:01 PM MDT for Weld County, Colorado. It was in force for 29 min. 2 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
Jul 15, 1998, 6:01 PM MDT (00:01 UTC)
Expired
Jul 15, 1998, 6:30 PM MDT
In force
29 min
Issued by
NWS Denver/Boulder, CO
Area
Whole counties

County Weld County, CO

The radar

The Cheyenne radar (KCYS), 75 km from the middle of the area, began a volume at 00:03 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

TimeReportWhereRemark
Jul 15, 6:25 PM MDTHail 1Grover, CO
Jul 15, 6:25 PM MDTThunderstorm Wind 56Grover, COStrong thunderstorm winds to 64 mph (53 kts) and large hail did an undetermined amount of damage to cropland in the area.

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

N. Platte/Lee Bi, NE (KLBF), launched 00:00Z, 0.0 hours before the alert went out and 325 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, N. Platte/Lee Bi, NE at 00:00Z on 1998-07-16Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 901 joules per kilogram.LCLLFCEL10008507005003002001001 km2 km3 km6 km9 km12 km15 km-30°-20°-10°10°20°30°40°
Temperature in red, dew point in green, the mixed-layer parcel dashed.
HodographHodograph, N. Platte/Lee Bi, NE at 00:00Z on 1998-07-16The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity -20 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
901 J/kg
Mixed-layer CIN
-68 J/kg
Mixed-layer LCL
2298 m above ground
0-6 km bulk shear
23 kt
0-1 km storm-relative helicity
-20 m²/s²
0-3 km storm-relative helicity
-12 m²/s²
Significant tornado parameter
0.0
Supercell composite
-0.4

Open this sounding in Storm Lab

The text

As transmitted, in the capitals the NWS used until 2016.

000 
TTAA00 KDEN 160007 COR
TORDEN
COC123-160030-

BULLETIN - EAS ACTIVATION REQUESTED...CORRECTION...
TORNADO WARNING
NATIONAL WEATHER SERVICE DENVER CO
601 PM MDT WED JUL 15 1998

THE NATIONAL WEATHER SERVICE IN DENVER HAS ISSUED A

* TORNADO WARNING FOR...
     NORTH CENTRAL WELD COUNTY IN NORTHEAST COLORADO

* UNTIL 630 PM MDT

* AT 558 PM MDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED A
  THUNDERSTORM WITH A POSSIBLE TORNADO 3 MILES NORTHWEST OF GROVER...
  OR ABOUT 41 MILES NORTHEAST OF GREELEY...MOVING SOUTHEAST AT 30
  MILES PER HOUR.

LOCATIONS IN THE WARNING INCLUDE...GROVER AND HEREFORD

IF YOU ARE CAUGHT OUTSIDE...SEEK SHELTER IN A NEARBY REINFORCED
BUILDING. AS A LAST RESORT...SEEK SHELTER IN A CULVERT...DITCH OR LOW
SPOT AND COVER YOUR HEAD WITH YOUR HANDS.

THUNDERSTORMS MOVING THROUGH NORTH CENTRAL WELD COUNTY MAY ALSO 
PRODUCE STRAIGHT LINE WINDS TO 60 MPH...HAIL AND DEADLY LIGHTNING. 

BAKER

LAT...LON 4088 10436 4072 10408 4095\ 10395 4100 10422

The office that day

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

IssuedProductOfficeCountiesLasted
Jul 15, 6:16 PM MDTSevere Thunderstorm WarningBOUAdams, Morgan29 min
Jul 15, 6:47 PM MDTSevere Thunderstorm WarningBOUAdams, Arapahoe, Washington28 min
Jul 15, 6:55 PM MDTSevere Thunderstorm WarningBOUMorgan, Weld60 min
Jul 15, 7:22 PM MDTTornado WarningBOUMorgan33 min
Jul 15, 8:10 PM MDTSevere Thunderstorm WarningBOULincoln, Washington35 min

Nearby

Tornado Warnings in Colorado, 1998Every tornado warning in 1998Tornadoes 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.