Alert archive / Wyoming / Severe Thunderstorm Warnings in 1998

Severe Thunderstorm Warning 131, NWS Cheyenne, WY

July 21, 1998Laramie County, Wyoming

NWS Cheyenne, WY issued this severe thunderstorm warning at Jul 21, 1998, 4:49 PM MDT for Laramie County, Wyoming. It was in force for 31 min. No storm report in the archive falls inside the area while it was in force.

The area

The counties it named.

The facts

Issued
Jul 21, 1998, 4:49 PM MDT (22:49 UTC)
Expired
Jul 21, 1998, 5:20 PM MDT
In force
31 min
Issued by
NWS Cheyenne, WY
Area
Whole counties

County Laramie County, WY

The radar

The Cheyenne radar (KCYS), 20 km from the middle of the area, began a volume at 22:51 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

Rapid City, SD (KUNR), launched 12:00Z, 10.8 hours before the alert went out and 341 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, Rapid City, SD at 12:00Z on 1998-07-21Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 0 joules per kilogram.LCL10008507005003002001001 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, Rapid City, SD at 12:00Z on 1998-07-21The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 49 square meters per square second.19395878Sfc1 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
0 J/kg
Mixed-layer CIN
No buoyant parcel
Mixed-layer LCL
1942 m above ground
0-6 km bulk shear
41 kt
0-1 km storm-relative helicity
49 m²/s²
0-3 km storm-relative helicity
274 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0

Open this sounding in Storm Lab

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.

NWS Cheyenne, WY wrote its last area forecast discussion before this severe thunderstorm warning went out at Jul 21, 2:10 AM MDT, 14 hours 39 minutes earlier.

Area forecast discussion, Jul 21, 2:10 AM MDT, 14 hours 39 minutes before
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RIVERTON WY
210 AM MDT TUE JUL 21 1998

IR LOOP INDICATING COLD TOPS OVER N UTAH ASCT WITH SHORT WAVE THAT WAS
OVER CENTRAL MT...W WY AND N UTAH AT 00Z. UNABLE TO GET SLC RADAR AND
UNABLE TO OBSERVE LDS VIA AFOS AS WELL AS BLM LTG DATA FROM INTERNET.
WILL JUST GO AHEAD AND MENTION TSRA FOR SW WY THIS MORNING AS WAVE
MOVES EAST. MEANWHILE THE SFC COLD FRONT WILL CONT TO PUSH SW ACROSS
WY THIS MORNING AND SHOULD BE THROUGH ALL OF WY EXCEPT THE SW BY THIS
AFT PUTTING AN END TO THE RECORD BREAKING HEAT WAVE ALONG WITH THE
INFLUX OF MORE CLOUDS AND COOLER TEMPS. 70 RH AT LOWER LEVELS INCR
FROM THE NE AND SHOULD ENVELOPE THE NE CWFA BY WED AFT. 400MB MSTR
ACTUALLY GETS SHUNTED JUST S OF WY TONIGHT AND RETURNS N WED. BEHIND
FRONT UPSLOPE FLOW BECOMES ESTABLISHED UP TO H7 THUS RAISING THE SFC
DEW PNTS. AREA OF WEAK PVA TRACKS E ACROSS WY TODAY PROVIDING SOME
LIFT. WOULD GO WITH 30 POPS FOR SW AND S CENTRAL ZONES OF CWFA WHERE
BETTER UPPER LEVEL MSTR AND OVER NE ZONES WHERE MOIST UPSLOPE FLOW
BEST ESTABLISHED. 20 POPS ELSEWHERE TODAY. ANY TSRA THAT FORM WILL BE
BETTER RAIN PRODUCERS THAN THOSE OF LAST COUPLE OF DAYS.  WITH INCR
MSTR AT ALL LEVELS AND UPSLOPE BECOME BETTER ESTABLISHED WED WOULD GO
30-40 POPS MOST AREAS FOR WED AFT TSRA. SPC HAS OUR NE ZONES IN SLGT
RISK FOR WED. PREFER COOLER FWC TEMPS FOR TUE AND WED AS CLOUDINESS
WILL INCREASE AND CAA TAKES PLACE AT ALL LEVELS EXCE0PT WOULD STICK
WITH WARMER FAN TEMPS FOR RKS TODAY.

LIPSON

The office that day

Everything else NWS Cheyenne, WY issued on the same UTC day.

IssuedProductOfficeCountiesLasted
Jul 21, 4:28 AM MDTSevere Thunderstorm WarningCYSKimball32 min
Jul 21, 2:43 PM MDTSevere Thunderstorm WarningCYSScotts Bluff12 min
Jul 21, 2:48 PM MDTSevere Thunderstorm WarningCYSScotts Bluff32 min
Jul 21, 3:53 PM MDTSevere Thunderstorm WarningCYSBanner32 min
Jul 21, 4:00 PM MDTSevere Thunderstorm WarningCYSKimball30 min
Jul 21, 4:28 PM MDTSevere Thunderstorm WarningCYSKimball32 min
Jul 21, 4:39 PM MDTSevere Thunderstorm WarningCYSCheyenne31 min
Jul 21, 4:52 PM MDTTornado WarningCYSCheyenne, Kimball33 min
Jul 21, 5:01 PM MDTSevere Thunderstorm WarningCYSKimball29 min
Jul 21, 5:10 PM MDTSevere Thunderstorm WarningCYSCheyenne50 min
Jul 21, 5:28 PM MDTTornado WarningCYSCheyenne32 min
Jul 21, 2:14 PM MDTSevere Thunderstorm WarningCYSGoshen31 min
Jul 21, 2:50 PM MDTSevere Thunderstorm WarningCYSGoshen35 min
Jul 21, 3:27 PM MDTSevere Thunderstorm WarningCYSLaramie33 min
Jul 21, 4:18 PM MDTSevere Thunderstorm WarningCYSLaramie32 min
Jul 21, 5:20 PM MDTSevere Thunderstorm WarningCYSLaramie45 min

Nearby

Severe Thunderstorm Warnings in Wyoming, 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.