During the late afternoon and through the evening a group of thunderstorms moved in from the northwest behind a cold front.  Storm activity increased in coverage as the storms moved southeast, transitioning from producing mainly hail in Eastern Colorado to straight-line winds and flash flooding.  The straight-line winds blew down power lines in western Sherman County and blew down or damaged multiple trees at the travel center on I-70.  Multiple trees were uprooted in Tribune from the straight-line winds as well.  The largest hail size reported was quarter size south of Ruleton.  This line of storms also produced torrential rainfall over the western part of Sherman County, causing some county roads to be closed.
Meanwhile to the west a second group of thunderstorms had formed behind the cold front.  The strength of these storms was less, however thunderstorm winds caused major damage to a barn northwest of Norcatur.

Thunderstorm Wind in WALLACE, KANSAS
From 26-JUL-18 18:04:00 to 26-JUL-18 18:04:00 (MST-7)
Location: SHARON SPGS ARPT
Magnitude: 61.00 EG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Wind gusts of 70 MPH were reported.

Thunderstorm Wind in GREELEY, KANSAS
From 26-JUL-18 18:36:00 to 26-JUL-18 18:36:00 (MST-7)
Location: HORACE
Magnitude: 52.00 MG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Mesonet

Hail in WALLACE, KANSAS
From 26-JUL-18 18:05:00 to 26-JUL-18 18:05:00 (MST-7)
Location: SHARON SPGS ARPT
Magnitude: 0.75 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Thunderstorm Wind in GREELEY, KANSAS
From 26-JUL-18 18:50:00 to 26-JUL-18 18:50:00 (MST-7)
Location: TRIBUNE ARPT
Magnitude: 59.00 MG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Mesonet

Thunderstorm Wind in WICHITA, KANSAS
From 26-JUL-18 20:04:00 to 26-JUL-18 20:04:00 (CST-6)
Location: LEOTI ARPT
Magnitude: 60.00 MG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Mesonet

Flash Flood in SHERMAN, KANSAS
From 26-JUL-18 17:00:00 to 26-JUL-18 20:00:00 (MST-7)
Location: RULETON
Flood cause: Heavy Rain
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Other Federal Agency

Multiple county roads either washed out or underwater.  Barricades have been setup across some of these roads.

Hail in SHERMAN, KANSAS
From 26-JUL-18 17:00:00 to 26-JUL-18 17:09:00 (MST-7)
Location: RULETON
Magnitude: 1.00 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Social Media

The hail ranged from pea to quarter in size, with hail piling up in the yard.

Hail in WALLACE, KANSAS
From 26-JUL-18 17:42:00 to 26-JUL-18 17:42:00 (MST-7)
Location: SHARON SPGS ARPT
Magnitude: 0.88 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Wind gusts up to 70 MPH accompanied the hail.

Thunderstorm Wind in SHERMAN, KANSAS
From 26-JUL-18 16:38:00 to 26-JUL-18 16:38:00 (MST-7)
Location: RULETON
Magnitude: 78.00 EG
Crop damage: 0.00K
Reported by: NWS Employee

Power lines from an unknown number of poles have been blown down.  Pea size hail several inches deep is also covering the ground.

Thunderstorm Wind in SHERMAN, KANSAS
From 26-JUL-18 16:43:00 to 26-JUL-18 16:43:00 (MST-7)
Location: RULETON
Magnitude: 96.00 EG
Property damage: 60.00K
Crop damage: 0.00K
Reported by: Law Enforcement

Numerous trees of eight inches or larger snapped off at the ground between Mile Marker 8 and the Colorado border.  Four semis were blown over on I-70.  The travel center on east bound I-70 is without power.

Thunderstorm Wind in SHERMAN, KANSAS
From 26-JUL-18 16:43:00 to 26-JUL-18 16:43:00 (MST-7)
Location: KANORADO
Magnitude: 78.00 EG
Property damage: 70.00K
Crop damage: 0.00K
Reported by: Law Enforcement

Two irrigation pivots were flipped on their side on the south side of I-70 near mile marker 5.

Thunderstorm Wind in DECATUR, KANSAS
From 26-JUL-18 18:18:00 to 26-JUL-18 18:18:00 (CST-6)
Location: LYLE
Magnitude: 78.00 EG
Property damage: 30.00K
Crop damage: 0.00K
Reported by: Public

Major roof damage to machine shed, including part of the roof removed.  Pea size hail also occurred with the wind.

Thunderstorm Wind in WALLACE, KANSAS
From 26-JUL-18 17:44:00 to 26-JUL-18 17:44:00 (MST-7)
Location: SHARON SPGS
Magnitude: 90.00 EG
Crop damage: 0.00K
Reported by: NWS Employee

Unknown number of six to ten inch diameter tree limbs were blown down in town.

Thunderstorm Wind in GREELEY, KANSAS
From 26-JUL-18 18:50:00 to 26-JUL-18 18:50:00 (MST-7)
Location: TRIBUNE ARPT
Magnitude: 70.00 EG
Property damage: 3.00K
Crop damage: 0.00K
Reported by: Public

Thunderstorm winds blew doors off of a shed, and an entire milo field is destroyed.

Thunderstorm Wind in GREELEY, KANSAS
From 26-JUL-18 18:38:00 to 26-JUL-18 18:38:00 (MST-7)
Location: TRIBUNE
Magnitude: 78.00 EG
Crop damage: 0.00K
Reported by: Social Media

Unknown number of trees up to a foot in diameter were uprooted from straight-line winds.

Thunderstorm Wind in CHEYENNE, KANSAS
From 26-JUL-18 17:09:00 to 26-JUL-18 17:09:00 (CST-6)
Location: ST FRANCIS
Magnitude: 52.00 EG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Public

Pea size hail also occurred with the wind gusts.

Thunderstorm Wind in CHEYENNE, KANSAS
From 26-JUL-18 17:14:00 to 26-JUL-18 17:14:00 (CST-6)
Location: WHEELER
Magnitude: 54.00 MG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Mesonet

Thunderstorm Wind in CHEYENNE, KANSAS
From 26-JUL-18 17:29:00 to 26-JUL-18 17:29:00 (CST-6)
Location: BIRD CITY ARPT
Magnitude: 52.00 EG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Estimated wind gusts up to 60 MPH occurred.

Thunderstorm Wind in SHERMAN, KANSAS
From 26-JUL-18 16:43:00 to 26-JUL-18 16:43:00 (MST-7)
Location: KANORADO
Magnitude: 78.00 EG
Crop damage: 0.00K
Reported by: Trained Spotter

An unknown number of power lines have been blown down resulting in power outages.

Thunderstorm Wind in CHEYENNE, KANSAS
From 26-JUL-18 17:45:00 to 26-JUL-18 18:01:00 (CST-6)
Location: BIRD CITY
Magnitude: 61.00 EG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Law Enforcement

The gusts of 60-70 MPH continued past the top of the hour.

Thunderstorm Wind in WALLACE, KANSAS
From 26-JUL-18 17:40:00 to 26-JUL-18 18:01:00 (MST-7)
Location: SHARON SPGS
Magnitude: 64.00 MG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Storm Chaser

A second wind report, this one from law enforcement, reported the winds were still gusting to 60 MPH at the top of the hour.

Thunderstorm Wind in WALLACE, KANSAS
From 26-JUL-18 17:42:00 to 26-JUL-18 17:42:00 (MST-7)
Location: SHARON SPGS ARPT
Magnitude: 61.00 EG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Nickel size hail also occurred with the wind gusts.

Thunderstorm Wind in WALLACE, KANSAS
From 26-JUL-18 17:58:00 to 26-JUL-18 17:58:00 (MST-7)
Location: SHARON SPGS ARPT
Magnitude: 50.00 MG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Mesonet