Alert archive / Oklahoma / Severe Thunderstorm Warnings in 1998

Severe Thunderstorm Warning 430, NWS Norman, OK

June 20, 1998Grant County, Oklahoma

NWS Norman, OK issued this severe thunderstorm warning at Jun 20, 1998, 11:20 PM CDT for Grant County, Oklahoma. It was in force for 40 min. 2 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
Jun 20, 1998, 11:20 PM CDT (04:20 UTC)
Expired
Jun 21, 1998, 12:00 AM CDT
In force
40 min
Issued by
NWS Norman, OK
Area
Whole counties; the outline is the Mesonet’s reconstruction

County Grant County, OK

The radar

The Vance AFB radar (KVNX), 35 km from the middle of the area, began a volume at 04:22 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.

What was reported inside it

TimeReportWhereRemark
Jun 20, 11:40 PM CDTHail 1.75Medford, OK
Jun 21, 12:00 AM CDTHail 0.88Medford, OK

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 watch it was issued in

The SPC watch in force over the same counties when this warning went out.

IssuedProductOfficeLasted
Jun 20, 5:30 PM CDTTornado WatchSPC7 hr

The nearest sounding before it

Norman, OK (KOUN), launched 00:00Z, 4.3 hours before the alert went out and 181 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, Norman, OK at 00:00Z on 1998-06-21Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 2183 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, Norman, OK at 00:00Z on 1998-06-21The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 95 square meters per square second.193958Sfc1 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
2183 J/kg
Mixed-layer CIN
-239 J/kg
Mixed-layer LCL
2070 m above ground
0-6 km bulk shear
28 kt
0-1 km storm-relative helicity
95 m²/s²
0-3 km storm-relative helicity
194 m²/s²
Significant tornado parameter
0.0
Supercell composite
5.6

Open this sounding in Storm Lab

The text

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

000 
TTAA00 KOKC 210420 RRA
SVROKC
OKC053-210500-

BULLETIN - IMMEDIATE BROADCAST REQUESTED
SEVERE THUNDERSTORM WARNING
NATIONAL WEATHER SERVICE NORMAN OK
1120 PM CDT SAT JUN 20 1998

THE NATIONAL WEATHER SERVICE IN NORMAN HAS ISSUED A

* SEVERE THUNDERSTORM WARNING FOR...
     GRANT COUNTY IN NORTHWEST OKLAHOMA

* UNTIL MIDNIGHT CDT

* AT 1120 PM CDT DOPPLER RADAR INDICATED ADDITIONAL SEVERE 
THUNDERSTORMS DEVELOPING FROM NEAR WAKITA TO MEDFORD TO DEER 
CREEK...MOVING EAST-NORTHEAST AT 25 MPH.

* LOCATIONS IN THE WARNING INCLUDE RENFROW...NUMA...MEDFORD...
  LAMONT...JEFFERSON AND DEER CREEK

HAIL UP TO THE SIZE OF GOLFBALLS AND WIND GUSTS TO AT LEAST 65 MPH 
ARE LIKELY. SEEK SHELTER INDOORS...AWAY FROM WINDOWS...AND 
AVOID 
ELECTRICAL APPLIANCES AND TELEPHONES.

CHURCHILL

LAT...LON 3676 9799 3664 9747 3698 9747 3698 9785

The office that day

Everything else NWS Norman, OK issued on the same UTC day.

IssuedProductOfficeCountiesLasted
Jun 20, 7:02 PM CDTSevere Thunderstorm WarningOUNGarfield, Grant33 min
Jun 20, 7:20 PM CDTSevere Thunderstorm WarningOUNKay40 min
Jun 20, 7:28 PM CDTSevere Thunderstorm WarningOUNKingfisher32 min
Jun 20, 7:44 PM CDTSevere Thunderstorm WarningOUNCanadian26 min
Jun 20, 7:59 PM CDTSevere Thunderstorm WarningOUNKingfisher, Logan26 min
Jun 20, 8:07 PM CDTSevere Thunderstorm WarningOUNOklahoma23 min
Jun 20, 8:10 PM CDTSevere Thunderstorm WarningOUNCanadian20 min
Jun 20, 8:25 PM CDTSevere Thunderstorm WarningOUNLogan20 min
Jun 20, 8:30 PM CDTSevere Thunderstorm WarningOUNCanadian, Oklahoma30 min
Jun 20, 8:41 PM CDTSevere Thunderstorm WarningOUNLincoln34 min
Jun 20, 8:44 PM CDTSevere Thunderstorm WarningOUNLogan31 min
Jun 20, 8:57 PM CDTSevere Thunderstorm WarningOUNOklahoma33 min
Jun 20, 11:06 PM CDTSevere Thunderstorm WarningOUNGrant, Kay39 min
Jun 20, 11:57 PM CDTSevere Thunderstorm WarningOUNGrant, Kay48 min
Jun 21, 12:43 AM CDTSevere Thunderstorm WarningOUNGrant, Kay47 min
Jun 21, 6:20 PM CDTSevere Thunderstorm WarningOUNHarmon, Jackson40 min

Nearby

Severe Thunderstorm Warnings in Oklahoma, 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.