Alert archive / Wyoming / Severe Thunderstorm Warnings in 2000

Severe Thunderstorm Warning 21, NWS Riverton, WY

July 20, 2000Johnson County, Wyoming

NWS Riverton, WY issued this severe thunderstorm warning at Jul 20, 2000, 9:15 PM MDT for Johnson County, Wyoming. It was in force for 30 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: Jul 20, 2000, 9:15 PM MDT (03:15 UTC)
Expired: Jul 20, 2000, 9:45 PM MDT
In force: 30 min
Issued by: NWS Riverton, WY
Area: Whole counties; the outline is the Mesonet’s reconstruction

County Johnson County, WY

The radar

The Riverton/Lander radar (KRIW), 198 km from the middle of the area, began a volume at 03:18 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

Riverton, WY (KRIW), launched 00:00Z, 3.3 hours before the alert went out and 192 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-p

Temperature in red, dew point in green, the mixed-layer parcel dashed.

Hodograph

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: 37 J/kg
Mixed-layer CIN: -40 J/kg
Mixed-layer LCL: 3130 m above ground
0-6 km bulk shear: 23 kt
0-1 km storm-relative helicity: 21 m²/s²
0-3 km storm-relative helicity: -42 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.1

Open this sounding in Storm Lab

The text

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

568 
WUUS55 KRIW 210317
SVRRIW
WYC019-210345-

BULLETIN - EAS ACTIVATION REQUESTED
SEVERE THUNDERSTORM WARNING
NATIONAL WEATHER SERVICE RIVERTON WY
915 PM MDT THU JUL 20 2000

THE NATIONAL WEATHER SERVICE IN RIVERTON HAS ISSUED A

* SEVERE THUNDERSTORM WARNING FOR...
  EXTREME SOUTHEASTERN JOHNSON COUNTY IN NORTH CENTRAL WYOMING

* UNTIL 945 PM MDT

* AT 906 PM MDT...LOCAL LAW ENFORCEMENT REPORTED A SEVERE
  THUNDERSTORM PRODUCING GOLF BALL SIZED HAIL OVER EXTREME
  NORTHEASTERN NATRONA COUNTY AT THE TOWNS OF MIDWEST AND EDGERTON.
  DOPPLER RADAR INDICATED THE STORM MOVING NORTHEAST AT 20
  MPH.

* THE SEVERE THUNDERSTORM WILL BE...
  OVER RURAL SOUTHEASTERN JOHNSON COUNTY BY 925 PM MDT

THE SEVERE THUNDERSTORM IS CAPABLE OF PRODUCING...
 DAMAGING HAIL UP TO THE SIZE OF GOLFBALLS
 WINDS UP TO 60 MILES AN HOUR

THIS IS A DANGEROUS STORM. IF YOU ARE IN ITS PATH YOU SHOULD PREPARE
FOR DAMAGING WINDS IN EXCESS OF 55 MPH...LARGE HAIL...AND DEADLY
LIGHTNING. PEOPLE OUTSIDE SHOULD MOVE TO A SHELTER...PREFERABLY
INSIDE A STRONG BUILDING BUT AWAY FROM WINDOWS.

REPORT SEVERE WEATHER TO THE NEAREST LAW ENFORCEMENT AGENCY. THEY
WILL RELAY YOUR REPORT TO THE NATIONAL WEATHER SERVICE FORECAST
OFFICE IN RIVERTON.

LAT...LON 4357 10617 4350 10620 4351 10603 4364 10604
WCJIN-WYNE
RWM
NNNN

The office that day

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

Issued	Product	Office	Counties	Lasted
Jul 20, 8:28 PM MDT	Severe Thunderstorm Warning	RIW	Natrona	47 min

Nearby

Severe Thunderstorm Warnings in Wyoming, 2000 Every severe thunderstorm warning in 2000

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.