Thunderstorms developed on the afternoon of August 22nd and brought local severe weather. In eastern Johnson County, the public reported quarter size hail.
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Deaths and injuries are direct and indirect together, as the offices filed them. Damage is property and crops in the dollars of the year, not adjusted for inflation, and only where an office estimated it.
The episode as NWS RIW wrote it up.
Thunderstorms developed on the afternoon of August 22nd and brought local severe weather. In eastern Johnson County, the public reported quarter size hail. At the Greybull airport, an outflow boundary from distant thunderstorms brought a 65 mph wind gust.
The local office's own words before the first event, as it sent them, from the Iowa Environmental Mesonet's archive of National Weather Service text.
NWS Riverton, WY wrote its last area forecast discussion before the first event at Aug 22, 3:58 PM MST, 46 minutes earlier.
Area Forecast Discussion National Weather Service Riverton WY 458 PM MDT Thu Aug 22 2019 .SHORT TERM...(This evening through Friday) Showers and isolated thunderstorms have developed across northern WY this afternoon. The western half of the state has been cloudy for much of the day and, as previously thought, eastern areas have the best shot of strong storms due to longer heating and greater instability. However, the far north will also have a chance for a few stronger storms with increased vorticity associated with the low pressure center approaching. The low pressure center is currently making it's way from Idaho into southern Montana. The cold front should pass through WY overnight tonight and keep activity lingering on the eastern side of the Divide. Otherwise, the southwest has been warm and dry, and breezy winds have begun to pick up with the increased pressure gradient. On Friday, the trough axis finally pushes through WY, creating enough lift for isolated to scattered showers to redevelop. Most of the activity will be around the northern mountains, but lower elevations in central and northern areas will have a chance as well. The southwest will be mainly dry and see breezy winds again, but a few isolated showers may form as well. .LONG TERM...(Friday night through Thursday) Friday night appears to be our transition away from a typical summer pattern to something which may resemble more like a pattern representative of early fall. Once the well defined shortwave exits the area Saturday night, we will be under a fast west northwest flow pattern. Meanwhile, As the shortwave slowly exits the area Friday evening, evening thunderstorms will continue to erupt over our eastern zones across Natrona and Johnson Counties where the lifted indices will still be -5 along with decent capes. Then on Saturday, a jet max noses in from the west northwest, placing our northern zones under the left front quad of the jet max and the southern zones under the right front quad. Therefore, some shower activity is expected to develop in our northern zones late Saturday and should continue into the evening with the help of some Q vector forcing in that region. The RFQ of the jet should keep some of our southern zones somewhat breezy. Saturday should be significantly warmer, especially over our northeast zones after a sharp cool down Friday. Sunday should stand out as a critical fire weather day as the west northwest flow continues to increase as 40 knot winds at 700mb mix down under the influence of the right front quad dynamics. The MEX guidance is indicating 30 knot winds for KRKS for Sunday and Sunday night with KJAC showing 22 knots. These winds should max out late in the day ahead of the associated shortwave embedded in the flow followed by a related cold front that will push south across the area Sunday night. This front may spark off some convection in our north and northeast zones Sunday evening. Monday is shaping up to be a bit cooler behind the front under a mainly dry northwest flow., Then warmer conditions on Tuesday before the jet stream briefly takes a dip south and pushes a backdoor cold front through, cooling off places like BYG where temps could be 13 degrees cooler Wednesday over what they will be Tuesday. This front will spark off a few thunderstorms mainly in Johnson County late Tuesday. Then the next shortwave which was due in around the middle of next week, which the models were having a difficult time resolving, should remain well to our northeast as agreed upon by the latest model runs, so will keep daily convection east of the Divide to a minimum for Wed/Thu. && .AVIATION...(For the 00Z TAFS through 00Z Friday evening) Issued at 457 PM MDT Thu Aug 22 2019 Showers with a few isolated thunderstorms are moving eastward across the state this evening. Storms have thus far been on the weaker side, but isolated higher gusts have been measured. Brief MVFR conditions could also occur with convection. Breezy winds across the area will begin to decrease through the evening, but again a higher gust associated with convection is possible. Late tonight and Friday morning ceilings will drop and MVFR conditions could be widespread. These conditions should improve by noon. Isolated showers will be possible east of the Divide and breezy winds will redevelop across southern WY. && .FIRE WEATHER... ...Multiple Red Flag Warnings are in effect across southwest Wyoming until Friday evening... Today will see a cold front push into western Wyoming. This will bring more afternoon showers and thunderstorms east of the Divide, mainly in zones 281 and 285, and increase winds in the still very dry areas west of the Divide. A Red Flag Warning has been issued for many fire zones west of the Divide for this afternoon and evening. These Red Flag conditions will extend into Friday across the southern zones 277, 278, and 279. there is a good chance that there will be continuing critical fire weather conditions west of the divide through the weekend. && .RIW WATCHES/WARNINGS/ADVISORIES... Red Flag Warning until 8 PM MDT this evening for WYZ288-289-300. Red Flag Warning until 8 PM MDT Friday for WYZ277>279. && SHORT TERM...Bourque LONG TERM...Lipson AVIATION...Bourque FIRE WEATHER...Lipson
Hazardous Weather Outlook National Weather Service Riverton WY 510 AM MDT Thu Aug 22 2019 WYZ001>020-022>030-231115- Yellowstone National Park-Absaroka Mountains-Cody Foothills- North Big Horn Basin-Southwest Big Horn Basin- Southeast Big Horn Basin-Owl Creek and Bridger Mountains- Bighorn Mountains West-Bighorn Mountains Southeast- Northeast Johnson County-Southeast Johnson County- Teton and Gros Ventre Mountains-Jackson Hole- Wind River Mountains West-Wind River Mountains East- Upper Wind River Basin-Wind River Basin-Lander Foothills- Green Mountains and Rattlesnake Range- Natrona County Lower Elevations-Casper Mountain-Star Valley- Salt River and Wyoming Ranges-Upper Green River Basin Foothills- Upper Green River Basin-South Lincoln County- Rock Springs and Green River-Flaming Gorge-East Sweetwater County- 510 AM MDT Thu Aug 22 2019 ...RED FLAG WARNING for Southwest Wyoming West of the Divide Valid from 12 Noon Today through 8 PM Friday... ...RED FLAG WARNING for Portions of Central Wyoming East of the Divide Valid from 12 Noon Today through 8 PM this Evening... This Hazardous Weather Outlook is for Western and Central Wyoming. .DAY ONE...Today and Tonight. Isolated to widely scattered thunderstorms in north and central Wyoming this afternoon. Some storms, most likely in Johnson County, could become strong with gusty winds being the main threat. Strong gusty winds and low relative humidities in southwest Wyoming as well as across portions of Central Wyoming east of the Divide is expected. A Red Flag Warning has been issued for much of the areas west of the Continental Divide, as well as portions of Central Wyoming east of the Divide. .DAYS TWO THROUGH SEVEN...Friday through Wednesday. Friday...Strong gusty winds and low relative humidities in southwest Wyoming. A Red Flag Warning has been issued for much of the areas west of the Continental Divide. Saturday through Monday...elevated to critical fire weather conditions will continue. .SPOTTER INFORMATION STATEMENT... Weather spotters are encouraged to report significant weather conditions according to standard operating procedures.
Special Weather Statement National Weather Service Riverton WY 417 PM MDT Thu Aug 22 2019 WYZ003-004-222300- North Big Horn Basin-Cody Foothills- 417 PM MDT Thu Aug 22 2019 ...SIGNIFICANT WEATHER ADVISORY FOR EAST CENTRAL PARK COUNTY UNTIL 500 PM MDT... At 414 PM MDT, Doppler radar was tracking a strong thunderstorm 8 miles southeast of Cody, moving northeast at around 5 mph. The main hazard from this thunderstorm will be very heavy rainfall and frequent cloud to ground lightning. Winds could also be around 45 mph. Although the strongest part of this thunderstorm will remain east of Cody, deadly cloud to ground lightning could impact the town of Cody. PRECAUTIONARY/PREPAREDNESS ACTIONS... Torrential rainfall is also occurring with this storm, and may lead to localized flooding. Do not drive your vehicle through flooded roadways. && LAT...LON 4435 10889 4452 10909 4462 10891 4448 10867 TIME...MOT...LOC 2214Z 228DEG 12KT 4447 10890 21
The Billings radar (KBLX), 154 km away, was scanning. The volume nearest the first event began at 23:44 UTC.
1 thunderstorm wind, 1 hail. Local standard time, as filed.
A maximum wind gust of 65 mph was reported at the Greybull, Wyoming airport from a outflow boundary from distant thunderstorms.
The public reported quarter size hail 28 miles east of Buffalo, Wyoming.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Wyoming in 2019Every state in 2019This day in weather historyWarnings in Wyoming, August 2019
NOAA National Centers for Environmental Information, Storm Events Database, compiled from the National Weather Service’s monthly Storm Data. Complete through 2026-06; NCEI adds each month about 75 days after it ends and revises past years a few times a year. Rebuilt 2026-09-24. Each event’s entry at NCEI: 849805, 849804.