In the late afternoon of the 20th, a cluster of storms began to from in north central Colorado and moved east. As the evening progressed, this cluster grew into more of a line.
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 GLD wrote it up.
In the late afternoon of the 20th, a cluster of storms began to from in north central Colorado and moved east. As the evening progressed, this cluster grew into more of a line. This line of storms produced up to four inch diameter hail, accumulating hail up to a foot deep, 75 MPH wind gusts, and heavy rain. The combined effect of accumulating hail and heavy rainfall led to street and basement flooding in Yuma.
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 May 20, 5:26 PM MST, 2 hours 26 minutes earlier. Its key messages:
Area Forecast Discussion National Weather Service Goodland KS 626 PM MDT Mon May 20 2024 .KEY MESSAGES... - A Tornado Watch is in effect until 11 PM MDT this evening for Yuma County in Colorado, Dundy County in Nebraska and Cheyenne County in Kansas. East of the watch area, along the Kansas and Nebraska border, severe thunderstorms capable of producing very large hail, damaging winds and torrential rainfall are possible late this evening into tonight. - A Flood Watch remains in effect until sunrise Tuesday morning for Dundy, Hitchcock and Red Willow counties in southwest Nebraska (where 1 to 3 inches of rain fell over the weekend). - Potential for patchy frost in northeast Colorado early Wednesday morning. Very low confidence. && .SHORT TERM /THROUGH TUESDAY NIGHT/... Issued at 250 PM MDT Mon May 20 2024 Across the region this afternoon, with a low/front sitting over west central Kansas, skies are mixed with sunny conditions west, and partly sunny east due to a persistent veil of low cloud associated with the vicinity of the low/front. Winds have shifted easterly from the mornings northerly fetch, and temperatures as of 200 PM MDT are ranging mainly in the 70s with some 60s due to extensive clouds. Looking aloft, the latest RAP40 500mb analysis is showing broad SW flow over the region, with a elongated trough pushing through the north central Rockies. It will be this trough, via current guidance, that swings off the Rockies and east-northeast into the north central Plains this evening. This will be followed by a weaker system on Tuesday with a more easterly track along the northern fringe of the cwa. For the short term period, the latest wx concerns continue to focus on the threat for severe wx this afternoon/evening, flooding chances later tonight into Tuesday morning. There are also chances Tuesday/Tuesday night for another round of rain/thunder. Currently, with a frontal boundary extending west from the central Kansas area into central Colorado, this will be the focus for storm initiation as the upper trough moves off the Rockies. Current CAMs(HRRR, RAP and NamNest) show development around 00z Tuesday, moving east through northeast Colorado, before shifting into SW Nebraska this evening. Some differences as to the placement/movement of the convection as it moves out of Colorado, but the overall trend does impact SW Nebraska at the minimum. Threats do diminish as your push southward through the cwa. Best chances look to occur along and north of highway 36. SPC does continue to carry an Enhanced Risk for Nebraska, tapering to a Slight Risk for severe for areas south of this to Interstate 70, then Marginal concerns thereafter. Model soundings show decent instability from 00z-06z Tuesday across the Enhanced Risk area as SBCape/MUCape all reach into the 2000- 3000j/kg range. Hodographs do support tornado potential, but large hail up to baseballs and winds up to 70-80 mph are possible, especially north of the Interstate. Things do taper sharply the further south you go away from the shortwave vicinity. Other concerns through tonight will be the threat for flooding due to heavy rainfall as the storms pass. We do have the Enhanced Risk area under a Marginal for excessive rainfall. This will all depend on storm speed through the area tonight. PW values do approach the 1- 1.3 inch range this evening as east-southeast flow persists. Have continued the Flood Watch with the addition of Dundy county through 12z Tuesday. Another round of rain is expected on Tuesday/Tuesday evening, with the passage of another shortwave. Surface low south of the cwa will help funnel moisture into the area, with the focus along and north of the Interstate. Currently instability is low so not expecting severe storms at this time, but another round rain could impact already prone areas. Another Flood Watch could be needed but will be highly dependent on what is received tonight in certain areas. The final issue in the short term will be the threat for patchy frost Tuesday night. Guidance continues to show cloud cover meandering over the expected impacted areas in Colorado. With the uncertainty, have left out mention as temps into the upper 30s at worst. For temps, with a cold front moving through the region on Tuesday, a wide range in daytime highs is expected with mid 60s to mid 70s forecasted. Warmest locales will be along/south of Highway 40. Overnight lows tonight expected to range widely with mid 40s to lower 50s west, into the mid 50 through 60F east. A bit colder Tuesday night, especially west of Highway 27, with a range from the upper 30s west into the upper 40s east. The lows for tonight are highly dependent on cloud cover from remnant storms through tonight. Tuesday night, cloud cover will impact temps, especially for northeast Colorado. Current guidance keeps frost chances low at this time, but could encompass much of Kit Carson, Cheyenne and Yuma counties if cloud cover clears out. && .LONG TERM /WEDNESDAY THROUGH MONDAY/... Issued at 156 PM MDT Mon May 20 2024 From the latest GFS/ECMWF, west-southwest aloft at 500mb will persist during the long term period, supplemented by the passage of a few weak shortwaves through Friday with both models carrying a few stronger system over the region for the upcoming weekend. The timing of each system looks to occur during the evening hours at this time, but can't rule out some late afternoon development, especially this weekend. At the surface, inverted trough Wednesday evening will give way to a stronger lee-side trough Thursday. while the placement west of this system during the day will give the region decent above normal warmth, this will sink south and east of the CWA Thursday night into Friday. A low on the south side of the trough on Friday remains over the OK Panhandle region for Saturday, followed by another lee-side trough for the end of the upcoming weekend. Looking for low chances(30-40%) for rw/trw in the Wed-Fri timeframe, but it will be the weekend/early next week systems which will give a better potential for areal coverage of qpf. Of course these will be highly dependent on storm track timing through the CWA. With all the rain expected before the midweek timeframe, additional qpf could put more locales into flood prone status and will have to be monitored. For temps, daytime highs on Wednesday will range in the lower to mid 70s. Warmest day in the extended will occur on Thursday with lower to mid 80s expected. Thereafter, Friday will have another cooler day with mainly 70s, increasing to a range from the upper 70s to mid 80s by next Monday. Overnight lows will mainly range from the mid 40s west into the lower and mid 50s east. Warmest locales will be along/east of Highway 83. && .AVIATION /00Z TAFS THROUGH 00Z WEDNESDAY/... Issued at 600 PM MDT Mon May 20 2024 GLD: Expect conditions to deteriorate in assoc/w the development of low ceilings this evening and overnight.. with IFR-LIFR conditions possible after midnight (~06Z). While convection cannot be ruled out late this evening (mainly ~03-07Z).. guidance continues to suggest that activity will remain ~30-50 miles north of the GLD terminal. Ceilings are anticipated to gradually lift/improve to VFR late Tue morning and early Tue afternoon. 15-25 knot ESE winds are anticipated to become variable late this evening and overnight.. as a developing lee cyclone progresses eastward from CO into western KS. Winds will abruptly shift to the NNW-NW and strengthen to 20-30 knots an hour or two on either side of sunrise Tue morning.. as the aforementioned cyclone progresses eastward into central KS-NE. MCK: Expect conditions to deteriorate in assoc/w thunderstorms (this evening) and the development of low ceilings (overnight). Guidance suggests that the MCK terminal may be directly impacted by severe thunderstorms capable of producing very large hail and damaging winds in the 03-07Z time frame. Ceilings are anticipated to gradually lift/improve to VFR by early afternoon, though.. episodic showers and storms are possible throughout the day on Tuesday. 10-15 knot E to ESE winds may become variable late this evening and overnight.. as a developing lee cyclone progresses eastward from CO into western KS. Winds will shift to the NNW-NW and increase to 15-25 knots a few hours after sunrise (by ~15Z).. as the aforementioned cyclone progresses eastward into central KS-NE. && .GLD WATCHES/WARNINGS/ADVISORIES... KS...None. CO...None. NE...Flood Watch through late tonight for NEZ079>081. && SHORT TERM...JN LONG TERM...JN AVIATION...Vincent
Hazardous Weather Outlook National Weather Service Goodland KS 809 PM MDT Mon May 20 2024 COZ090>092-KSZ001>004-013>016-027>029-041-042-NEZ079>081-220215- Yuma-Kit Carson-Cheyenne-Rawlins-Decatur-Norton-Sherman-Thomas- Sheridan-Graham-Wallace-Logan-Gove-Greeley-Wichita-Dundy-Hitchcock- Red Willow- 809 PM MDT Mon May 20 2024 /909 PM CDT Mon May 20 2024/ This hazardous weather outlook is for extreme southwest Nebraska... northwest Kansas and east central Colorado. .DAY ONE...TONIGHT... A Tornado Watch is in effect until 2 AM MDT (3 AM CDT) Tuesday morning for locations along and north of Highway 36. A Flood Watch remains in effect until sunrise Tuesday morning for Dundy, Hitchcock and Red Willow counties in southwest Nebraska. .DAYS TWO THROUGH SEVEN...TUESDAY THROUGH MONDAY... Patchy frost is possible in northeast Colorado early Wednesday morning. .SPOTTER INFORMATION STATEMENT... Spotters are encouraged to report any severe or significant weather to the National Weather Service in Goodland via social media or telephone. Vincent
The Goodland radar (KGLD), 123 km away, was scanning. The volume nearest the first event began at 02:53 UTC.
13 hail, 9 thunderstorm wind, 1 flash flood. Local standard time, as filed.
A storm survey was conducted across the town of Yuma. Multiple locations across the town suffered damage from straight line winds. Some of the damage surveyed included extensive damage to vinyl siding to a motel, suggesting 74 MPH wind gusts occurred.
Reports via social media of hail up to golf ball sized.
Emergency manager reports fire department had tennis to softball size hail about 1 mile south of Yuma.
Report and photos via social media of accumulating hail and hail drifts in Yuma. Biggest stones baseball size or larger with most stones 1 to 2.25 inch. Trained spotters in Yuma also reported hail up to around 2 inches.
Two inch hail reported on the southwest side of Yuma and lasted approximately 15 minutes.
Report and photos via social media of hail up to golf ball size but mostly smaller stones with drifts estimated from photos to be up to around 1 foot tall. Wind driven hail broke windows and damaged siding.
Trained spotter reports quarter to golf ball sized hail.
The Mesonet station yum02 reported a gust of 67 MPH.
AWOS at the Yuma airport reported a gust of 67 MPH.
Mesonet site southeast of Yuma reported a 75 MPH gust.
Report and photos via social media (X), varying hail sizes up to golf ball size. Lots of windows broke out, hail covering ground.
Report from MPing of hail from 1-2.5 inches.
Spotter reported street flooding and basements being flooded in Yuma. Pictures from other sources show hail accumulating to around a foot deep. The combined affects of deep hail and heavy rainfall likely overwhelmed the storm drains, preventing the heavy rainfall from draining away. Unclear how many basements were flooded, or how much damage was caused by the flooding.
Trained spotter reports nickel sized hail.
Trained spotter estimates 75 MPH winds with Nickel sized hail.
CoCoRAHS report of golf ball size hail. Report of shredded leaves, car dents, damaged shingles, and broken house and car windows.
Mesonet site at Welp Farms recorded a 60 MPH gust.
Multiple public reports from Wray of hail from 1-1.75 inches across a 25 minute period.
Public report of hailing for nearly 30 minutes with stones up to 1.75 inches.
AWOS at the Wray airport recorded a 63 MPH gust.
Mesonet at Osmus Farms recorded a gust of 59 MPH.
Report of estimated 70 mph wind gusts on Hwy 385 approx. 3.5 to 1.5 miles south of Hwy 34 in Wray.
Public report via social media of quarter hail 1/2 mile north of Vernon, CO.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Colorado in 2024Every state in 2024This day in weather historyWarnings in Colorado, May 2024
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: 1180215, 1177820, 1177018, 1177019, 1177020, 1177021, 1177206, 1177210, 1177022, 1177211, 1177212, 1177213, 1221317, 1177214, 1177215, 1177823, 1177216, 1177815, 1177816, 1177818, 1177819, 1177821, 1177822.