On September 12th, a cold front moved through east-central Colorado allowing for evening thunderstorms to develop in the area. These thunderstorms produced wind gusts up to 60 mph as well as with pea sized 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 GLD wrote it up.
On September 12th, a cold front moved through east-central Colorado allowing for evening thunderstorms to develop in the area. These thunderstorms produced wind gusts up to 60 mph as well as with pea sized hail.
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 Sep 12, 1:50 PM MST, 2 hours 7 minutes earlier.
Area Forecast Discussion National Weather Service Goodland KS 250 PM MDT Sun Sep 12 2021 .SHORT TERM...(This evening through Wednesday) Issued at 250 PM MDT Sun Sep 12 2021 Tonight...a weather disturbance moves off the Colorado front range along the Palmer Divide late this afternoon entering far eastern Colorado around 6 PM MDT then into parts of western Kansas and extreme southwest Nebraska around 8 PM MDT (9 PM CDT). Activity should diminish late this evening and end around or shortly after midnight. The threat for severe weather exists generally along and west of Highway 83. Low temperatures are expected to be in the mid 50s to around 60. Monday...the forecast area will be under zonal flow aloft. Another weather system per 700-500mb relative humidity moves into the area west of Highway 83 toward late afternoon, continuing east after midnight. Given the better 700-500mb moisture and upper jet support the current forecast pops favoring areas along and north of the interstate looks good. High temperatures are expected to be in the mid 80s to mid 90s. Low temperatures are expected to be in the low 50s to low 60s. Tuesday...the upper flow shifts slightly to the northwest as an upper trough moves into the area late in the day and out of the area during the evening. Slight chance and chance pops continue along and north of the interstate in the morning with increasing chances for showers and thunderstorms moving into the northwest half of the area in the afternoon associated with the upper trough. Precipitation chances decrease quickly from northwest to southeast in the evening with dry conditions after midnight as the upper trough exits and moisture availability decreases. Blending the better performing temperature guidance from the past 5 days yields afternoon temperatures in the low 70s to low 80s, very similar to the NBM guidance. Low temperatures are expected to fall into the upper 40s to mid 50s as a 1015mb surface high noses into the area from the northeast. Wednesday...dry conditions are expected. Blending the handful of temperatures that have performed the best over the past several days supports the NBM forecast highs in the low to mid 80s. .LONG TERM...(Wednesday night through Sunday) Issued at 230 PM MDT Sun Sep 12 2021 At the start of the long term period, model guidance shows a north- northwesterly flow over the CWA as the CWA is underneath the backside of a weak subtropical trough on Wednesday night. On Thursday, the CWA sees the flow aloft turn more westerly as a ridge moves into the southwestern CONUS with the aforementioned trough moving eastward. Going into Friday, long term models start to show a stronger ridge developing in the northwestern CONUS though the GFS shows a slower and more suppressed trough development compared to the ECMWF. By Saturday, the CWA looks to be underneath the ridge as it advances eastward. Going into Sunday, a trough starts to move into the Pacific Northwest with ECMWF having a quicker progression than the GFS. By Sunday night, the ECMWF shows the trough base north of the CWA while the GFS shows the CWA underneath the front portion of the trough off to the west. As there is some uncertainty here between long term models, this situation will be monitored to see if there is better agreement in future runs. At the surface, the CWA looks to stay mostly dry during the long term period as minimal precipitation chances are seen especially underneath the ridge. Elevated fire weather conditions could potentially be a concern for the far western portions of the CWA on Thursday and Friday with forecasted minimum RH values near or just below 20%. Near critical fire weather conditions are possible on Saturday and Sunday for the western half of the CWA as forecasted minimum RH values look to be as low as 13-14% in this area. The limiting factor currently for fire weather is found in the maximum wind gusts as they look to come close, but not not quite meet fire weather criteria at a little above 20 mph each day. This situation will be monitored in case these conditions change. The Tri-State area expects daytime highs on Thursday and Friday in the upper 80s to lower 90s range followed by highs on Saturday in the upper 80s to middle 90s. Sunday's daytime highs look to be in the lower to middle 90s. The Tri-State area sees overnight lows on Wednesday between the lower 50s and lower 60s with the remainder of the long term period seeing overnight lows in the middle 50s to middle 60s range. && .AVIATION...(For the 18Z TAFS through 18Z Monday afternoon) Issued at 1100 AM MDT Sun Sep 12 2021 KGLD...VFR conditions are currently expected through the period. North winds around 12kts at taf issuance will continue through about 19z before veering to the northeast then east this afternoon and speeds around 10kts. For this evening winds remain from the northeast and east at speeds up to 10kts then become light and variable after midnight. There is enough confidence to introduce a chance of thunderstorms impacting the terminal in the 02z-04z timeframe. Primary hazards are outflow wind gusts up to 45kts, possibly higher given a favorable environment for even stronger gusts. Stratus and sub VFR cigs may develop in the 11z-16z timeframe. KMCK...VFR conditions are currently expected through the period. A northeast wind around 10kts at taf issuance will veer to the east at similar speeds this afternoon and continue for the overnight hours before becoming light and variable. Showers and thunderstorms cant be ruled out and should they occur happen in the 05z-08z timeframe. At this time given the low confidence they will not be included in the forecast. Stratus and sub VFR cigs may develop in the 09z-16z timeframe. && .GLD WATCHES/WARNINGS/ADVISORIES... KS...NONE. CO...NONE. NE...NONE. && SHORT TERM...99 LONG TERM...076 AVIATION...99
Hazardous Weather Outlook National Weather Service Goodland KS 300 PM MDT Sun Sep 12 2021 COZ090>092-KSZ001>004-013>016-027>029-041-042-NEZ079>081-131300- Yuma-Kit Carson-Cheyenne-Rawlins-Decatur-Norton-Sherman-Thomas- Sheridan-Graham-Wallace-Logan-Gove-Greeley-Wichita-Dundy-Hitchcock- Red Willow- 300 PM MDT Sun Sep 12 2021 /400 PM CDT Sun Sep 12 2021/ This hazardous weather outlook is for extreme southwest Nebraska... northwest Kansas and east central Colorado. .DAY ONE...THIS AFTERNOON AND TONIGHT... There are Marginal and Slight risk areas for potential severe thunderstorms from 5 PM MDT (6 PM CDT) to 10 PM MDT (11 PM CDT). The area of focus will be mainly along and west of Highway 83. The primary hazards are wind gusts up to 70 mph and hail up to one inch in diameter. The strong wind gusts may produce some blowing dust and reduced visibilities. .DAYS TWO THROUGH SEVEN...MONDAY THROUGH SUNDAY... There is a Marginal risk for severe thunderstorms Monday afternoon and evening for areas mainly along and north of Interstate 70 and west of Highway 83. Elevated fire weather conditions are possible Thursday afternoon across far eastern Colorado. Elevated fire weather conditions are possible Friday, Saturday and Sunday afternoons along and west of Highway 83. .SPOTTER INFORMATION STATEMENT... Spotter activation will be needed from 5 PM MDT (6 PM CDT) to 10 PM MDT (11 PM CDT) for those along and west of Highway 83.
Special Weather Statement
National Weather Service Goodland KS
435 PM MDT Sun Sep 12 2021
COZ091-122300-
Kit Carson County CO-
435 PM MDT Sun Sep 12 2021
...A strong thunderstorm will impact portions of northwestern Kit
Carson County through 500 PM MDT...
At 434 PM MDT, Doppler radar was tracking a strong thunderstorm 10
miles north of Arriba, or 12 miles northwest of Flagler, moving east
at 35 mph.
HAZARD...Wind gusts of 50 to 55 mph and pea size hail.
SOURCE...Radar indicated.
IMPACT...Gusty winds could knock down tree limbs and blow around
unsecured objects. Minor damage to outdoor objects is
possible.
This storm will remain over mainly rural areas of northwestern Kit
Carson County.
This includes Interstate 70 in Colorado between mile markers 391 and
410.
PRECAUTIONARY/PREPAREDNESS ACTIONS...
If outdoors, consider seeking shelter inside a building.
Torrential rainfall is also occurring with this storm and may lead to
localized flooding. Do not drive your vehicle through flooded
roadways.
This storm may intensify, so be certain to monitor local radio
stations and available television stations for additional information
and possible warnings from the National Weather Service.
To report severe weather, contact your nearest law enforcement
agency. They will relay your report to the National Weather Service
office in Goodland.
&&
LAT...LON 3957 10315 3957 10280 3921 10277 3922 10315
TIME...MOT...LOC 2234Z 276DEG 29KT 3943 10323
MAX HAIL SIZE...0.25 IN
MAX WIND GUST...55 MPH
TTThe Goodland radar (KGLD), 115 km away, was scanning. The volume nearest the first event began at 22:55 UTC.
2 thunderstorm wind. Local standard time, as filed.
Mesonet station reported a 59 mph thunderstorm wind gust at location.
Report received of an estimated 50 to 60 mph thunderstorm wind gust at location.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Colorado in 2021Every state in 2021This day in weather historyWarnings in Colorado, September 2021
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: 985277, 985283.