National Weather Service United States Department of Commerce

Overview

Heavy rain from slow-moving thunderstorms produced significant flash-flooding across Niobrara County June 3-4, 2015. An over active and unusually moist spring weather pattern, typical during a developing El Nino, was the primary contributing factor in producing the antecedent conditions as well as the slow-moving and heavy rain producing thunderstorms that impacted Niobrara County. During the month of May precipitation over Niobrara County ranged from 4.69" to 7.11" across the northern part of the county. The approach of an upper level weather disturbance combined with the ground moisture already in place set the stage for a series of training, slow-moving thunderstorms that moved between Manville and Lusk during the late evening on June 3rd. Rainfall rates from these storms were 2-3" per hour. These extreme rainfall amounts caused flash flooding during the early morning hours of June 4th. According to radar and ground estimates, 3-6" of rain fell.

Flooding
Flooding near Lusk. Water reaching heights over 3-4 feet.

Source: Niobrara County Library

Timeline

June 3rd

20:30 - Rain began in the Flash Flood impacted areas.

20:43 - Severe Thunderstorm Warning issued for areas SW of Lusk until 21:30

21:34 - Severe Thuderstorm Warning issued for much of SW Niobrara County including Lusk & Manville until 22:12

22:15 - Flash Flood Warning issued for areas west of Lusk including Manville until (6/4) 02:15

22:16 - Severe Thunderstorm Warning issued for much of southern Niobrara County until 23:00

22:59 - Severe Thunderstorm Warning issued for southern Niobrara County until 23:45

June 4th

00:05 - Flash Flood Warning issued for Niobrara River Basin including Lusk until 03:00

00:15 - Rain intensity significantly diminished in and around Lusk

02:16 - Flash Flood Warning issued for SW Niobrara county until 05:15

03:00 - Flash Flood Warning issued for Niobrara River Basin including Lusk until 06:00

05:21 - Areal Flood Warning issued for SW Niobrara County until 11:15

05:55 - Flash Flood Warning/Emergency issued for the Niobrara River Basin including Lusk until 09:00

08:59 - Flash Flood Warning/Emergency issued for the Niobrara River Basin including Lusk until 12:00


Photos & Video:

Lusk hwy18 lusk hwy 85 bridge collapse hwy 85
Flooding west of Lusk
Source: Unknown
Highway 18 near Manville
Source: Wydot
Highway 85 partial road collapse
Source: David Mayberry
Bridge collapse on highway 85
Source: WY State Police
Photo flooding window damage lusk Depot
Flooding in Lusk during the early morning hours 
Source: Niobrara County Library
Flooding of roadways in downtown Lusk
Source: Niobrara County Library
Damage to a business in Lusk
Source: Niobrara County Library
Depot in Lusk underwater
Source: Niobrara County Library

Radar:

Radar Image
Radar loop outlining the 3 storm cells that impacted southern Niobrara County.
The first radar image is from 8:39 PM showing the 1st cell just SW of Lusk, and the 2nd stronger cell to the south. The 1st cell moves off the the northeast and at 9:39 PM the 3rd storm is beginning to develop. At 10:19 PM the 3rd cell merges with the 2nd and remains almost stationary at 11:32 PM the storms are now exiting the area.

Storm Reports

departure from normal precip Storm Total Precip
Departure from normal precipitation in May 2015. Storm Total Precipitation

nws logo Media use of NWS Web News Stories is encouraged!
Please acknowledge the NWS as the source of any news information accessed from this site.
nws logo