May 1, 2018 Tornado Summary

Tornadoes:

Tornado #1 - Chester, NE REPUBLIC & THAYER (NE) COUNTIES Date May 1, 2018 Time (CDT) 5:44pm - 5:54pm EF Rating EF-0 Est. Peak Winds 60 mph Path Length 6.4 miles Max Width 125 yards Injuries/Deaths 0/0 Summary: This was a broad and weak tornado that developed along the leading edge of a bowing line segment. It was witnessed by multiple sources but caused no reported damage. It started in Republic County, KS and passed just south of Chester, NE before dissipating. Track Map Downloadable KMZ File

Tornado #2 - 6 mi NE of Glasco, KS CLOUD COUNTY Date May 1, 2018 Time (CDT) 6:59pm - 7:20pm EF Rating EF-1 Est. Peak Winds 95 mph Path Length 9.3 miles Max Width 225 yards Injuries/Deaths 0/0 Summary: This broad but weak tornado damaged several outbuildings and power lines along its path. End point based on an extrapolation of a video and radar data. Track Map Downloadable KMZ File

Tornado #3 - 8.5 mi SE of Concordia, KS CLOUD COUNTY Date May 1, 2018 Time (CDT) 7:15pm - 7:39pm EF Rating EF-0 Est. Peak Winds 80 mph Path Length 7.9 miles Max Width 30 yards Injuries/Deaths 0/0 Summary: This was a weak, intermittent tornado that hit few damage indicators. Path end point is estimated based on radar. Track Map Downloadable KMZ File

Tornado #4 - 4.5 mi S of Tescott, KS SALINE & OTTAWA COUNTIES Date May 1, 2018 Time (CDT) 7:41pm - 8:10pm EF Rating EF-3 Est. Peak Winds 140 mph Path Length 14.5 miles Max Width 880 yards (1/2 mi) Injuries/Deaths 0/0 Summary: The longer-tracked, strong tornado developed in far northern Saline County and tracked NE through SW Ottawa County. Multiple buildings received EF-2 damage, with the worst damage occurring near the end of the tornado's path where low-end EF-3 damage was found. This tornado was well documented by dozens of storm chasers. Track Map Downloadable KMZ File

Tornado #5 - 6.1 mi SW of Clifton, KS CLAY COUNTY Date May 1, 2018 Time (CDT) 7:49pm - 8:08pm EF Rating EF-1 Est. Peak Winds 100 mph Path Length 8.25 miles Max Width 200 yards Injuries/Deaths 0/0 Summary: This tornado developed in rural NW Clay County and tracked ENE. It damaged at least one farmstead, trees, and powerlines along its path. Beginning path segment estimated based on radar data and end point based on satellite imagery and damage reports. Track Map Downloadable KMZ File

Tornado #6 - 1 mi E of Oak Hill, KS CLAY COUNTY Date May 1, 2018 Time (CDT) 8:56pm - 9:15pm EF Rating EF-1 Est. Peak Winds 90 mph Path Length 12.0 miles Max Width 50 Injuries/Deaths 0/0 Summary: A  tornado developed just northeast of Oak Hill and traveled along rural areas that were sparsely populated, doing damage to farmstead outbuildings and trees and ending near Highway 15 where it blew down power poles. Track Map Downloadable KMZ File

The Enhanced Fujita (EF) Scale classifies tornadoes into the following categories:

EF0 Weak 65-85 mph	EF1 Moderate 86-110 mph	EF2 Significant 111-135 mph	EF3 Severe 136-165 mph	EF4 Extreme 166-200 mph	EF5 Catastrophic 200+ mph

Photos & Video:

Tornado #1: Chester, NE

Moving towards Chester (5:48pm) (courtesy of Willard Sharp)	Moving closer (5:50pm) (courtesy of Willard Sharp)	Moving across the Highway (5:52pm) (courtesy of Willard Sharp)

Tornado #2: 6 mi NE of Glasco

Tornado #3: 8.5 mi SE of Concordia

No photos or video known to exist

Tornado #4: 4.5 mi SE of Tescott

Ottawa County Tornado (courtesy of StormHour)	Ottawa County Tornado (courtesy of Daniel Shaw)	Ottawa County Tornado (courtesy of Brian Emfinger)	Ottawa County Tornado (courtesy of ClimateChaos)

Ottawa County Tornado (Courtesy of Jim Tang)	EF3 Tornado damage near Minneapolis	EF2 Tornado damage near Culver	EF2 Tornado damage near Culver

Tornado #5: 6.1 mi SW of Clifton

No photos or video known to exist

Tornado #6: 1 mi E of Oak Hill

Radar Data:

Radar Loop

Radar Loop of the Tornadic Supercells

Reflectivity/SRM image of Tornado #1 (center of the image) from the UEX radar at 5:50pm CDT.	Reflectivity/SRM image of Tornado #2 (center of the image) from the TWX radar at 7:04pm CDT.	Reflectivity/SRM image of Tornado #3 (center of the image) from the TWX radar at 7:32pm CDT.	Reflectivity/SRM image of Tornado #4 (center of the image) from the TWX radar at 7:50pm CDT.

Reflectivity/SRM image of Tornado #4 as it was occluding and producing EF3 damage (center of the image) from the TWX radar at 8:06pm CDT.	Reflectivity/SRM image of Tornado #5 (center of the image) from the TWX radar at 8:01pm CDT.	Reflectivity/SRM image of Tornado #6 (center of the image) from the TWX radar at 9:08pm CDT.

Storm Reports

Detailed Listing of Storm Reports

Environment

The synoptic environment leading up to this event featured a large upper level trough of low pressure situated across the western United States with a 100 kt jet streak ejecting northeastward ahead of the trough. Closer to the surface, strong low to mid-level flow pumped Gulf moisture northward into the region. A quasi-stationary area of low pressure was centered over north central Kansas/south central Nebraska with an attendant dryline protruding southward across central Kansas. This dryline served as the focus for thunderstorm development during the mid to late afternoon hours.

Figure 1: Upper level plot over the Central Plains, showing a trough in the west and a jet streak lifting NE and providing upper level diffluence.	Figure 2: An 850mb plot showing strong moisture advection northward into central and eastern Kansas.	Figure 3: Surface map at 7pm May 1, showing the low over north central KS and a dryline extending southward across the state.

The thermodynamic environment ahead of the dryline featured ample instability with MLCAPE values of 2000-2500 J/kg in the warm sector. Deep shear values in the warm sector were in the neighborhood of 40-50 kts and oriented orthogonal to the orientation of the dryline. The effective storm-relative helicity was around 300 to 400 m2/s2, well within the favorable zone for significant tornadoes.

Figure 4: MLCAPE values at 23Z May 1 show a narrow ribbon of instability ahead of the dryline	Figure 5: Effective shear over the region at 00Z May 2	Figure 6: Effective storm-relative helicity at 00Z May 2.

Figure 7: The 00Z sounding at Topeka shows an uncapped atmosphere with ample curvature in the 0-3 km hodograph.	Figure 8: The Significant Tornado Parameter shows a narrow ribbon of elevated values along the region where the tornadoes were observed.

Additional Information

The Forecast

SPC Day 3 Categorical Outlook	SPC Day 3 Probabilistic Outlook	SPC Day 2 Categorical Outlook	SPC Day 2 Probabilistic Outlook
SPC Day 1 Categorical Outlook	SPC Day 1 Tornado Outlook	SPC Day 1 Hail Outlook	SPC Day 1 Wind Outlook

Tornado Warning Lead Time

* Replaces Earlier Warning

Summaries from other NWS Offices

• NWS Hastings
• NWS Wichita