On August 25th, an outflow boundary produced from afternoon convection in southwestern Kansas moved northward. Thunderstorms developed along this boundary in northwestern Kansas during the evening hours.
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.
On August 25th, an outflow boundary produced from afternoon convection in southwestern Kansas moved northward. Thunderstorms developed along this boundary in northwestern Kansas during the evening hours. These thunderstorms yielded hail up to golf balls in size and wind gusts up to 75 mph. The winds from the thunderstorm also produced a localized dust storm in eastern Greeley county.
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 Aug 25, 2:02 PM MST, 2 hours 17 minutes earlier.
Area Forecast Discussion National Weather Service Goodland KS 302 PM MDT Wed Aug 25 2021 .SHORT TERM...(This evening through Thursday night) Issued at 300 PM MDT Wed Aug 25 2021 Overview: An expansive upper level ridge will persist over the Southern Plains and southern MS River Valley.. downstream of persistent troughing aloft along the Pacific Coast. The Tri-State area will remain situated on the N-NW periphery of the ridge.. at the far southern fringe of the mid-latitude westerlies. In the lower levels.. a weak/broad thermal low will persist in the lee of the central Rockies. In a rather stagnant synoptic pattern one would generally expect little change in sensible weather conditions, however.. in such close proximity to the mid-latitude westerlies, the Tri-State area will, nevertheless, remain within the 'sphere of influence' of small amplitude waves progressing northeastward from the Intermountain West into the Northern Plains -- whether that influence be direct or indirect. In general, well-above normal temperatures and dry conditions are anticipated to persist. Isolated afternoon and evening are possible during the aft/eve hours Today and Thursday.. generally in northeast Colorado and southwest Nebraska (in closer proximity to the mid-latitude westerlies). Convection Today: At 20Z, isolated diurnal convection was developing invof a weak sfc cyclone /thermal low/ in far southwest KS and far southeast CO.. as simulated reflectivity forecasts via the HRRR and NAM NEST have suggested. Recent HRRR/ NAM NEST runs have backed off on isolated development along the CO Front Range and/or Palmer Divide late this afternoon.. perhaps due to considerable convective inhibition assoc/w persistent stratus in northeast CO. While effective deep layer shear is on the order of 35-40 knots invof the NE/KS border.. values sharply decrease with southern extent into KS.. closer to the ridge aloft. Assuming isold development does not occur in northern CO, organized convection appears unlikely. South of I-70 -- mainly in Greeley/Wichita counties -- strong insolation, near dry-adiabatic SFC-H5 lapse rates, moderate instability, and extreme DCAPE suggest that any high-based updrafts (short-lived, as they may be) will be capable of producing brief severe downbursts. Convection Thursday: Southwest flow aloft will modestly strengthen over the central Rockies as cyclonic flow aloft broadens/expands eastward from the Pacific Coast to the Intermountain West.. yielding a somewhat deeper lee cyclone in eastern CO.. and noticeably breezy south winds in western KS. Expect a greater potential for convection (compared to today).. with activity most likely emanating from the CO Front Range during peak heating. With strong insolation, steep low-level/mid-level lapse rates, moderate instability, and extreme DCAPE, any high- based updrafts will be capable of producing damaging winds. At this time, the greatest potential for organized severe weather appears to be further north.. in central/northern Nebraska.. an area more firmly entrenched in the mid-latitude westerlies. .LONG TERM...(Friday through Wednesday) Issued at 238 PM MDT Wed Aug 25 2021 At the start of the extended period, the CWA lies underneath a trough yielding a mostly southwesterly flow during the Friday. Models show redevelopment of the trough occurring near the far western U.S./Canada border throughout Friday. On Saturday, the southwesterly flow looks to continue as the redeveloped trough progresses eastward into the Northern Plains region. A shortwave disturbance appears to pass over the CWA during Saturday evening as well. On Sunday, models depict the trough moving into the Great Lakes region with a trailing ridge moving over the western CONUS giving the CWA a westerly flow aloft. Another shortwave disturbance is seen moving over the CWA on Sunday evening. Going into Monday, the ridge continues to be the dominating feature over the central CONUS with another trough building in the Pacific Northwest. On Tuesday, forecast guidance shows the flow aloft turning northwesterly as the upper air ridge in the central CONUS becomes sandwiched between two upper air troughs. This pattern looks to continue going into Wednesday with the GFS showing an upper air high possibly forming over the CWA while the ECMWF does not currently have this feature. At the surface, the CWA looks to have some precipitation chances during the long term period. While Friday looks to stay dry in the CWA, the first chance for showers and thunderstorms appears to be around Saturday afternoon and evening for the eastern half of the CWA as a surface trough sets up in eastern CO. Sunday sees a slight chance for showers and thunderstorms mostly for areas along and east of KS-25 ahead of an approaching cold front that passes through the CWA during the day though the timing of the frontal passage still has some model uncertainty. Monday and Tuesday look to have minimal precipitation chances being due to the upper air pattern. Wednesday evening sees a possible return for showers and thunderstorms as models show a possible surface low setting up in northeastern CO. Elevated fire weather concerns are possible for areas along and west of the CO border on Friday and Wednesday with minimum RH values around or just below 20%. Near critical fire weather may be possible for the same area on Tuesday with forecasted minimum RH values as low as 15% are seen. Maximum wind gust speed may be the limiting factor for fire weather conditions on these days, but the situation will be monitored for changes in future model runs. The Tri-State area should see high temperatures on Friday and Saturday between the lower and upper 90s. On Sunday, daytime highs cool to the lower to upper 80s with a cold front passage followed by Monday's highs being in the lower to middle 90s. Tuesday's highs expect to be in the middle to upper 90s while Wednesday's highs stay in the lower to middle 90s. Tri-State area overnight lows for Friday expect to be between the lower 60s and lower 70s with Saturday seeing overnight lows in the middle 50s to the middle 60s. Overnight lows for remainder of the long term period look to be in the upper 50s to middle 60s range. && .AVIATION...(For the 18Z TAFS through 18Z Thursday afternoon) Issued at 1200 PM MDT Wed Aug 25 2021 While MVFR ceilings may linger through late afternoon at both terminals, VFR conditions are anticipated by sunset. However, redevelopment of MVFR-IFR ceilings cannot be ruled out late this evening and early Thu morning. 10-15 knot NE-ENE winds will veer to the E late this afternoon, further veering to the S late this evening and overnight. Southerly winds will strengthen to 15-25 knots late Thu morning.. near the end of the TAF period. && .GLD WATCHES/WARNINGS/ADVISORIES... KS...NONE. CO...NONE. NE...NONE. && SHORT TERM...VINCENT LONG TERM...076 AVIATION...VINCENT
Hazardous Weather Outlook National Weather Service Goodland KS 829 AM MDT Wed Aug 25 2021 COZ090>092-KSZ001>004-013>016-027>029-041-042-NEZ079>081-261430- Yuma-Kit Carson-Cheyenne-Rawlins-Decatur-Norton-Sherman-Thomas- Sheridan-Graham-Wallace-Logan-Gove-Greeley-Wichita-Dundy-Hitchcock- Red Willow- 829 AM MDT Wed Aug 25 2021 /929 AM CDT Wed Aug 25 2021/ This hazardous weather outlook is for extreme southwest Nebraska... northwest Kansas and east central Colorado. .DAY ONE...TODAY AND TONIGHT... Scattered thunderstorms may develop across portions of the area late this afternoon and evening, mainly in northeast Colorado and areas south of Interstate 70 in northwest Kansas. Isolated severe storms are possible, mainly between 4 PM and 10 PM MDT. Damaging winds are the primary hazard. An isolated instance of large hail cannot be ruled out, mainly in northeast Colorado. .DAYS TWO THROUGH SEVEN...THURSDAY THROUGH TUESDAY... Elevated fire weather conditions are possible during the afternoon hours on Thursday, Friday and Saturday, mainly in eastern Colorado. .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
Special Weather Statement
National Weather Service Goodland KS
558 PM CDT Wed Aug 25 2021
KSZ042-252330-
Wichita KS-
558 PM CDT Wed Aug 25 2021
...A strong thunderstorm will impact portions of southeastern Wichita
County through 630 PM CDT...
At 557 PM CDT, Doppler radar was tracking a strong thunderstorm 8
miles southeast of Leoti, moving north at 10 mph.
HAZARD...Winds in excess of 40 mph and nickel 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 southeastern
Wichita County, including the following locations... Marienthal.
PRECAUTIONARY/PREPAREDNESS ACTIONS...
If outdoors, consider seeking shelter inside a building.
&&
LAT...LON 3837 10135 3860 10131 3855 10113 3831 10113
TIME...MOT...LOC 2257Z 198DEG 7KT 3841 10122
MAX HAIL SIZE...0.88 IN
MAX WIND GUST...40 MPH
024Special Weather Statement
National Weather Service Goodland KS
501 PM MDT Wed Aug 25 2021
KSZ041-042-252330-
Wichita KS-Greeley KS-
501 PM MDT Wed Aug 25 2021
...A strong thunderstorm will impact portions of southwestern Wichita
and southeastern Greeley Counties through 530 PM MDT/630 PM CDT/...
At 501 PM MDT/601 PM CDT/, Doppler radar was tracking a strong
thunderstorm 12 miles southeast of Tribune, moving north at 10 mph.
HAZARD...Wind gusts up to 50 mph and nickel 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 southwestern
Wichita and southeastern Greeley Counties, including the following
locations... Selkirk.
PRECAUTIONARY/PREPAREDNESS ACTIONS...
If outdoors, consider seeking shelter inside a building.
&&
LAT...LON 3827 10177 3851 10176 3846 10139 3826 10152
3826 10174
TIME...MOT...LOC 2301Z 198DEG 7KT 3832 10164
MAX HAIL SIZE...0.88 IN
MAX WIND GUST...50 MPH
024The Goodland radar (KGLD), 101 km away, was scanning. The volume nearest the first event began at 23:17 UTC.
6 thunderstorm wind, 6 hail. Local standard time, as filed.
Report received of visibility reduced to one-quarter mile or less at location due to blowing dust associated with outflow from nearby thunderstorms. Wind gust speed estimated based on nearest Mesonet station.
Report received of golf ball sized hail at location.
Report received of half inch to penny sized hail at location.
Report received of an estimated 75 mph thunderstorm wind gust at location.
Report received of an estimated 60 to 70 mph thunderstorm wind gust at location.
Report received of pea to quarter sized hail at location.
Report received of an estimated 60 to 70 mph thunderstorm wind gust at location. Time is radar-estimated.
Report received of quarter sized hail at location. Time is radar-estimated.
Mesonet station reported a thunderstorm wind gust of 59 mph at location.
Report received of hail up to penny sized at location.
Off-duty NWS employee reported quarter sized hail at location.
Mesonet station KKSCOLBY28 reported a 58 mph thunderstorm wind gust at location.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Kansas in 2021Every state in 2021This day in weather historyWarnings in Kansas, August 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: 982499, 978758, 978760, 978761, 978762, 978764, 978765, 978766, 978768, 978770, 978771, 978772.