A particularly dangerous thunderstorm moved south across Eastern Colorado during the evening near a stationary front. As the thunderstorm moved through Kit Carson and Cheyenne counties it produced a swath of damage from the combined effects of baseball size hail and thunderstorm wind gusts.
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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 GLD wrote it up.
A particularly dangerous thunderstorm moved south across Eastern Colorado during the evening near a stationary front. As the thunderstorm moved through Kit Carson and Cheyenne counties it produced a swath of damage from the combined effects of baseball size hail and thunderstorm wind gusts. The highest wind gust reported was 83 MPH in the northwest part of Kit Carson County. Aside from the structural damage, many animals in the path of this storm were killed, including nine antelope south of Seibert.
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 Goodland, KS wrote its last area forecast discussion before the first event at Jul 29, 4:57 PM MST, 5 minutes earlier.
Area Forecast Discussion National Weather Service Goodland KS 557 PM MDT Sun Jul 29 2018 .UPDATE... Issued at 546 PM MDT Sun Jul 29 2018 Just completed an update. Main change was for the pops and qpf this evening. This mainly done for ongoing severe cluster moving into our western portion of our area. Previous grids had highest pops and qpf further west. Nothing else done for now. && .SHORT TERM...(This evening through Monday) Issued at 201 PM MDT Sun Jul 29 2018 Latest upper air analysis shows high pressure over the Desert Southwest beginning to extend northward. Moving around the high pressure is an upper level short wave trough, currently over Southeast Wyoming. East of the Rockies, widespread cloud cover was seen on satellite. At the surface a stationary front extended south- southeast from Wyoming toward Southeast Colorado. For the rest of the afternoon the severe thunderstorms in Wyoming will spread southeast, and additional storms will move east off the Rockies, toward the High Plains. The stationary front will serve as a focus for convection as well. Am expecting the strongest storms to be located near this front. Am expecting storm activity to be moving into northwest Yuma County before the afternoon is over. This evening storm activity will continue spreading southeast across the forecast area. The storm activity should spread southeast fairly quickly in the early evening. Storms should have a peak intensity from roughly 5-9 PM local time. Of concern is the lower 700-500mb lapse rates as the upper level short wave trough moves through. This may indicate the severe activity will only last a couple hours into the event, by the time storms move into the forecast area, before storm intensity declines. Storm activity will end from northwest to southeast late in the evening, possibly lasting an hour or two after midnight. Threats: Hail up to golf ball size, possibly up to hen egg in the tornado watch area. Wind gusts up to 70 MPH. This will mainly be a threat south of Highway 36. Flash flooding. This is more favored south of Highway 36 where repeated rounds of heavy rainfall are more likely to occur. Am on the fence regarding issuing a watch at this point. If WPC issues an MCD for flash flooding, will be much more in favor of issuing a watch. Tornadoes. This will be more likely further west toward the stationary front. Low level helicity is very supportive of tornado genesis over Kit Carson, Cheyenne, and souther Yuma County, with the eastern fringe of the helicity extending just across the state line into Kansas in counties in the tornado watch. Confidence concerns: The widespread cloud cover is very concerning for severe weather generation. Severe weather has not lived up to what the environment could generate the last couple of days, so the added cooling effect of the cloud cover lowers confidence of severe weather occurring. Also, the models seem to have slightly slowed down the arrival of the severe weather. The later in the day storms move in, the less likely they will be of producing severe weather. In general am expecting severe weather to occur, the question is what will the areal coverage be. At this point confidence is low that the severe threat will be of the magnitude that we typically would see for an enhanced risk day. Due to the complexities of the weather today, have not had a chance to analyze weather for Monday. A quick looks shows a possibility for storms in the morning, which seems reasonable given what has happened the last two days. During the afternoon the upper level trough axis moves through bringing any storm activity to an end. .LONG TERM...(Monday night through Sunday) Issued at 117 PM MDT Sun Jul 29 2018 On Monday night, an upper trough exits the High Plains from west to east and northwest flow redevelops aloft, with upper ridging across the west coast. Surface high pressure moves into the region behind the departing wave, resulting in dry weather through Wednesday night. Thursday through Saturday, the western upper ridge expands east and flattens as a disturbance travels east along the Canadian border. The ridge quickly redevelops and amplifies on Sunday. Predominantly dry conditions are forecast to persist during this timeframe. However, some spotty slight chances of showers and thunderstorms cannot be ruled out during the evening hours as weak waves rotate through the the northwest flow. High temperatures gradually warm from the 80s on Tuesday to the low 90s on Friday. Temperatures in the 90s continue over the weekend as well. Low temperatures follow suit and steadily warm, ranging from the low 50s to the low 70s throughout the long term period. && .AVIATION...(For the 00Z TAFS through 00Z Monday evening) Issued at 546 PM MDT Sun Jul 29 2018 For Kgld, expect thunderstorms to affect the site in the 01z to 03z time frame. Although believe the strongest part of this thunderstorm complex will be west of the site, site should see variable wind direction gusts up to 45 knots with mvfr conditions expected through 02z to 04z. After 04z vfr conditions are expected with north to northeast winds near 7 knots for the rest of the period. It is possible between 15z to 18z, thunderstorms may affect the site. For Kmck, vfr conditions are expected through the period. Weak thunderstorms may be near the site this evening. However I am not optimistic about that though. Also some thunderstorms may be near the site between 15z and 18z. Winds will vary from north to east at 8 knots or less. && .GLD WATCHES/WARNINGS/ADVISORIES... KS...NONE. CO...NONE. NE...NONE. && UPDATE...BULLER SHORT TERM...JTL LONG TERM...JBH AVIATION...BULLER
Hazardous Weather Outlook National Weather Service Goodland KS 239 PM MDT Sun Jul 29 2018 COZ090>092-KSZ001>004-013>016-027>029-041-042-NEZ079>081-302045- Yuma County-Kit Carson County-Cheyenne County-Cheyenne-Rawlins- Decatur-Norton-Sherman-Thomas-Sheridan-Graham-Wallace-Logan-Gove- Greeley-Wichita-Dundy-Hitchcock-Red Willow- 239 PM MDT Sun Jul 29 2018 /339 PM CDT Sun Jul 29 2018/ This hazardous weather outlook is for extreme southwest Nebraska... northwest Kansas and east central Colorado. .DAY ONE...THIS AFTERNOON AND TONIGHT... A Tornado Watch is currently in effect until 9 PM MDT for Colorado counties, Cheyenne, Kit Carson, and Yuma. It is also in effect for the following Kansas counties, Sherman, Greeley, and Wallace until 9 PM MDT. A Severe Thunderstorm Watch is in effect until 9 PM MDT 10 PM CDT for Nebraska counties Dundy and Hitchcock, and Kansas counties, Cheyenne, Rawlins, Thomas, Sheridan, Logan, Gove, and Wichita. Severe thunderstorms will be capable of producing hail up to golf ball or even hen egg size. Wind gusts up to 70 mph may occur south of Highway 36. Tornadoes may occur in the tornado watch area, with the threat increasing to the west. The potential for severe weather will be greatest in eastern Colorado and extreme western Kansas between 6 PM and 9 PM MDT. Flash flooding will remain possible, particularly in areas repeatedly affected by thunderstorms during the past 48 hours and for locations south of Highway 36. .DAYS TWO THROUGH SEVEN...MONDAY THROUGH SUNDAY... Hazardous weather is not expected at this time. .SPOTTER INFORMATION STATEMENT... Spotter activation may be needed this afternoon and evening. Any severe weather reports are greatly appreciated. JTL
The Goodland radar (KGLD), 115 km away, was scanning. The volume nearest the first event began at 00:03 UTC.
7 hail, 2 thunderstorm wind. Local standard time, as filed.
Gusts of 58-83 MPH occurred as the storm moved through.
The hail was at least golf ball size.
The hail started out as baseball size then declined to quarter size. The hail was accompanied with wind gusts of an unknown magnitude due to the hail damaging the anemometer. The combined effect did significant damage to buildings, trees and vehicles.
The hail was at least two inches in diameter.
A number of buildings in Seibert sustained damage. The post office roof had roughly half the shingles blown off. One machine shed was completely destroyed, with the foundation blown clean. A second machine shed, that was built using concrete blocks, only had a third of the roof blown off. A building in town had the entire roof blown off. A pine tree was uprooted and resting on the house next to it. A small machine shed was flipped over and blown onto a road in town. There were also many homes with vinyl siding destroyed on the windward side of the home from the hail and wind.
Three pigs, an unknown number of cattle and antelope were killed as the storm moved through.
At least one vehicle window was broken by the hail.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Colorado in 2018Every state in 2018This day in weather historyWarnings in Colorado, 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: 775388, 775369, 775372, 775376, 775379, 775392, 775382, 775384, 775385.