The combination of a stationary front over the area, a shortwave moving across the area and strong jet dynamics brought rounds of severe thunderstorms over northern and central Wyoming. The hardest hit town this day was Lovell where a combination of 70 mph winds and golf ball size hail produced widespread damage with hundreds of broken windows and many houses with damaged siding.
Every event with a place to put it. Tap one for its entry below.
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.
The combination of a stationary front over the area, a shortwave moving across the area and strong jet dynamics brought rounds of severe thunderstorms over northern and central Wyoming. The hardest hit town this day was Lovell where a combination of 70 mph winds and golf ball size hail produced widespread damage with hundreds of broken windows and many houses with damaged siding. Strong winds also downed many trees and limbs. The same storm produced 79 mph winds at the Greybull airport. Elsewhere, severe thunderstorms moved through Johnson and Natrona Counties. There were numerous reports of quarter to golf ball size hail from west of Buffalo through Midwest and into Casper. A weak landspout tornado also touched down north of Casper. Another storm produced quarter size hail in Thermopolis.
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 Jul 26, 10:39 AM MST, 1 hour 11 minutes earlier.
Area Forecast Discussion National Weather Service Riverton WY 1139 AM MDT Thu Jul 26 2018 .SHORT TERM...(Today through Saturday night) Issued at 215 AM MDT Thu Jul 26 2018 The pattern we are currently in now will more or less remain the same through Saturday night. The long wave trough will remain over the Eastern United States and the long wave ridge in the west with the bubble of high pressure remaining in the American Southwest. This will keep us under an unstable west northwest flow with a surface boundary wedged along the Continental Divide with higher dew points pooling in areas of the CWA east of the divide and drier and warm air over areas west of the divide corresponding with the aforementioned Southwestern high. With higher dew points/more moisture east of the divide, higher capes will be common east of the divide with scattered late day thunderstorms more prominent in this area over the next several days with lower cloud bases. West of the divide, one can look forward to mainly higher based thunderstorms with not as much rain but as much wind as the heavier storms will have east of the divide. There will be a few subtle weather features sliding on by in the upper levels from the west northwest from time to time along with additional reinforcing weak sfc boundaries moving in from the north. The next such boundary will be kicked off by a weak shortwave moving through the area Friday, and the next one will likely approach later Saturday night. Also, weak mid level circulations will wobble on through for the next several days as well. We will get some added lift from some right rear quad dynamics on Saturday night as well. SPC has a large area east of the divide under marginal risk for the next few days but gradually takes this area slightly to the northeast with time over the next few days. Overall, temperatures will be relatively unchanged through Saturday. .LONG TERM...(Sunday through Thursday) Issued at 215 AM MDT Thu Jul 26 2018 A weather system moves through the region Sunday into Sunday night. This will produce showers and thunderstorms from the Bighorn mountains and Johnson county southward to Casper mountain during the day into the evening hours. Showers and storms will be more isolated over the rest of the region Sunday into Sunday evening. High temps Sunday will be in the 70s to near 80 east of the continental divide, with mid 70s to mid 80s west of the divide where more sunshine will occur. Showers and storms end late Sunday night. Monday will be dry over the region with high temps back into the 80s for most places. Tuesday will be warmer with mostly dry weather. Isolated showers and storms will occur over and near the mountains Tue afternoon and evening. Wednesday and Thursday will be very warm to hot with isolated afternoon and evening thunderstorms. Expect highs in the 80s to lower 90s. && .AVIATION...For the 18Z TAFS through 18Z Friday afternoon Issued at 1132 AM MDT Thu Jul 26 2018 An unsettled northwest flow will bring a round of scattered showers and thunderstorms along and east of the Continental Divide this afternoon and evening, with storms initiating off the high terrain through 20z and moving out into the basins through the rest of the afternoon. A few storms will be likely be strong, isolated severe, with hail and heavy rain; possible brief IFR/MVFR conditions. Drier air west of the Divide will result in much more isolated activity (KJAC-KPNA-KBPI-KRKS). A thunderstorm complex may move out of central Montana into north central and northeast Wyoming late this evening into early Friday morning, mainly along and east of Interstate 25. Strong northerly outflow winds may precede this line of storms. The storms should track east of Casper early Friday morning. && .FIRE WEATHER... Issued AT 215 AM MDT Thu Jul 26 2018 The same general pattern will hold for the next few days with the best chance of late day thunderstorms east of the divide along with higher humidity and a few strong thunderstorms and isolated severe thunderstorms. West of the divide, only isolated high based thunderstorms are expected that will mainly produce strong wind gusts and some lightning. The minimum relative humidity will be in the mid teens in zones 277 and 279 as well as southern zone 278. && .RIW WATCHES/WARNINGS/ADVISORIES... Red Flag Warning until 8 PM MDT this evening for WYZ277-279. && SHORT TERM...Lipson LONG TERM...AR AVIATION...LaVoie FIRE WEATHER...Lipson
Hazardous Weather Outlook National Weather Service Riverton WY 203 AM MDT Thu Jul 26 2018 WYZ001>020-022>030-271100- 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- 203 AM MDT Thu Jul 26 2018 This Hazardous Weather Outlook is for Western and Central Wyoming. .DAY ONE...Today and Tonight Scattered thunderstorms, especially along and east of the Continental Divide. Some of these storms will likely produce small hail, locally heavy rainfall, frequent lightning, and strong gusty winds. There will be a few strong thunderstorms and even isolated severe thunderstorms are possible. .DAYS TWO THROUGH SEVEN...Friday through Wednesday Friday afternoon through Saturday night...Scattered thunderstorms, especially along and east of the Continental Divide. Sunday...Isolated afternoon and evening thunderstorms along and east of the divide. Tuesday...Isolated afternoon and evening thunderstorms. .SPOTTER INFORMATION STATEMENT... Spotters urged to report wind gusts past 45 mph, hail size, and rainfall amounts. Thank you.
Special Weather Statement National Weather Service Riverton WY 808 AM MDT THU JUL 26 2018 WYZ011-020-261445- Southeast Johnson County-Natrona County Lower Elevations- 808 AM MDT THU JUL 26 2018 ...SIGNIFICANT WEATHER ADVISORY FOR SOUTH CENTRAL JOHNSON AND NORTH CENTRAL NATRONA COUNTIES UNTIL 845 AM MDT... At 808 AM MDT, Doppler radar was tracking a strong thunderstorm over Hole In The Wall, or 12 miles southwest of Kaycee, moving southeast at 45 mph. Dime size hail and winds in excess of 40 mph will be possible with this storm. This storm will remain over mainly rural areas of south central Johnson and north central Natrona Counties, including the following locations... Willow Creek School. This includes Interstate 25 between mile markers 220 and 228. PRECAUTIONARY/PREPAREDNESS ACTIONS... Frequent cloud to ground lightning is occurring with this storm. Lightning can strike 10 miles away from a thunderstorm. Seek a safe shelter inside a building or vehicle. && LAT...LON 4319 10657 4363 10694 4371 10683 4336 10629 TIME...MOT...LOC 1408Z 319DEG 40KT 4357 10679 Baker
Special Weather Statement National Weather Service Riverton WY 1213 PM MDT THU JUL 26 2018 WYZ009>011-261900- Southeast Johnson County-Northeast Johnson County-Bighorn Mountains Southeast- 1213 PM MDT THU JUL 26 2018 ...SIGNIFICANT WEATHER ADVISORY FOR NORTH CENTRAL JOHNSON COUNTY UNTIL 100 PM MDT... At 1213 PM MDT, Doppler radar was tracking a strong thunderstorm over Saddlestring, or 13 miles northwest of Buffalo, moving southeast at 40 mph. Half inch hail and winds in excess of 40 mph will be possible with this storm. This strong thunderstorm will be near... Buffalo around 1230 PM MDT. Other locations impacted by this storm include Buffalo Johnson County Airport and Johnson County Fairgrounds. This includes the following highways... Interstate 25 between mile markers 283 and 299. Interstate 90 between mile markers 54 and 57, and between mile markers 63 and 65. PRECAUTIONARY/PREPAREDNESS ACTIONS... Frequent cloud to ground lightning is occurring with this storm. Lightning can strike 10 miles away from a thunderstorm. Seek a safe shelter inside a building or vehicle. && LAT...LON 4445 10710 4455 10690 4418 10645 4408 10676 TIME...MOT...LOC 1813Z 324DEG 37KT 4444 10695 Baker
The Riverton/Lander radar (KRIW), 182 km away, was scanning. The volume nearest the first event began at 18:49 UTC.
6 hail, 1 tornado, 1 thunderstorm wind. Local standard time, as filed.
A thunderstorm developed over the Bighorn Mountains and became severe as it moved south-southeast across Johnson County. There were multiple reports of quarter to golf ball size hail along the path by spotters and on social media.
Trained spotters and a Natrona County Sheriff's Deputy reported quarter to golf ball size hail in Midwest and Edgerton.
Trained spotters reported hail ranging from quarter to ping pong ball size from Bar Nunn into the east side of Casper. Some of larger hail damaged a carport in Casper.
Two trained spotters photographed a landspout tornado to the north of Casper. The tornado remained over open county and caused no damage.
Trained spotters reported up to quarter size hail around Thermopolis.
A severe thunderstorm crossed the border from Montana and brought up to golf ball size hail across much of northern Big Horn County. Lovell was the hardest hit community where there was widespread damage. One official estimated that over 60 percent of the homes had damage, mainly from damaged siding and broken windows from the hail bring driven by winds over 70 mph. Large hail was also occurred in Frannie and Cowley.
A severe thunderstorm brought high winds through much of northern Big Horn County. The strongest wind gust recorded was 79 mph at the Greybull Airport. Other notable gusts included 62 mph at Cowley and 59 mph at Frannie and Lovell. The strong wind combined with golf ball size hail to produce widespread damage across the city of Lovell.
Trained spotters reported nickel to ping pong ball size hail in the vicinity of Kaycee.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Wyoming in 2018Every state in 2018This day in weather historyThe tornado archive for Wyoming, 2018Warnings in Wyoming, July 2018
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: 765555, 765556, 765557, 765558, 765560, 765567, 765573, 765559.