Historic flooding, range fires, tornadoes, blizzards, and severe thunderstorms impacted Western and North Central Nebraska over the past 12 months. Below is a summary of the 5 most significant weather events from 2011 as selected by the staff at the North Platte National Weather Service office.
2011 North Platte River Flooding
Record snowfall fell across the mountains of the Upper North Platte and Lower North Platte River Basins of Wyoming and Colorado during the 2010-2011 winter season. By May 1st, the basin average snow water equivalent reached near 175 percent of normal. This was about 25 percent above the historic maximum. The record snowfall resulted in significant challenges in managing snowmelt runoff for reservoirs in Wyoming and Nebraska. Releases were increased in early February for some Wyoming reservoirs, and in early March from Kingsley Dam in Nebraska.

The increased releases resulted in flooding along the North Platte River in Nebraska by mid March. Flooding would continue to worsen with record flooding occurring in June at both Lewellen and North Platte.

The first press conference concerning flood planning for the city of North Platte was held on April 6th. Discussed during the press conference was in a best case scenario, the river stage at North Platte would remain above flood stage through July. Lake McConaughy was also projected to become nearly full sometime in June and that releases from the lake may need to match inflows which could force record stages at North Platte.

Another press conference was held May 12th in North Platte where a detailed plan of releases from Lake McConaughy was discussed. The river stages were projected to exceed record stages and the impacts from this were detailed in a press release issued after the meeting.

A meeting was held May 23rd in North Platte consisting of local, state, and federal partners including the Army Corps of Engineers. This meeting focused on how to best plan for flooding along the North Platte and Platte Rivers. Predictions on infrastructure and buildings that may be affected from the high flows was discussed in detail.

The Army Corps of Engineers created flood elevation maps for the city of North Platte and nearby areas in late May. As a result, a series of dikes were built beginning in early June to protect the city of North Platte, with airlifted sandbags placed along the east bank of the river east of North Platte to protect residents and the airport from major flooding.

Major and significant flooding occurred from the North Platte River by mid May. Water flooding from the east bank of the North Platte River ran into White Horse Creek and flooded some residential properties and threatened the North Platte Automated Surface Observing Systems. Highway 30 near the airport also was
closed from May 26 until June 22nd as flood waters prompted the highway to be cut to allow flood waters to pass. Residents living north of the North Platte River along Highway 83 and along and south of North River Road, experienced worsening flood problems. Although many residents sandbagged their properties, a few however were unable to protect their properties and were forced to evacuate from their homes.

River flooding along the North Platte River upstream of Lake McConaughy is infrequent with a return interval every 10 to 15 years. Downstream of Lake McConaughy, river flooding is very infrequent. In fact, direct flooding from the river in 2011 only occurred once since 1941. In 1971, a large amount of water was released from Kingsley Dam to prevent potential dam failure from high winds on the lake. This caused flooding near North
 Platte, although much less significant than what occurred in 2011.

The river stage at North Platte reached a new record stage near 7.69 feet on June 3rd and June 22nd. The river stage at Lewellen also reached a new record stage near 8.63 feet on June 21st. What proved significant about the record stages was the long duration of flooding observed. At North Platte, the river went above flood stage on March 9th and remained above major flood stage beginning May 8th through October 4th. The most significant flooding occurred from May 21st through July 3rd when the stage remained above 7 feet and damage to properties was most significant. At Lewellen, the river stage remained above 8 feet from May 8th through June, with a bridge destroyed and flooding to residential properties on the south edge of Lewellen.

Southwestern Nebraska Blizzard of April 15th
While blizzards in April may not be common, when they do happen they are usually quite memorable. In this case, low pressure tracked across the central plains through the day Thursday April 14th, eventually stalling across north central Kansas for a time Thursday night, then moved into western Missouri by Friday morning April 15th. Ahead of this low pressure system, moisture streamed northward and combined with cold air coming south to produce heavy snow across Western and Central Nebraska. Heavy snow continued to fall Thursday night and early Friday with as much as a foot of snow or more from Grant and Arthur counties into eastern Keith county. In addition, wind gusts over 50 mph were common and produced blizzard conditions over much of Western and North Central Nebraska, which contributed to the closure of many highways across the area including Interstate 80 over the western half of the state...with drifts over 6 feet reported in many places. This storm was also a rarity because since this was a strong spring storm, thunderstorms were also reported across the plains. In some areas of southwest Nebraska thunder and lightning were reported at the same time heavy snow was occurring which makes this storm one that will be remembered for years to come.

Photo by Dean Cosgrove

Photo by Dean Cosgrove

Rangeland Fire Prompts the Evacuation of Stapleton
Tuesday, October 4, saw high temperatures soar to around 90 degrees and combine with dry air resulting in relative humidity values dropping to around 10 percent. A tight pressure gradient across the region produced south winds 25 to 35 mph with gusts up to 45 mph. This combination created critical fire weather conditions. Reports of several fires occurred this day. The largest and most destructive fire started in extreme north central Lincoln county around 3 pm CDT. The fire then spread north into Logan county. The fire destroyed 2 homes and prompted the evacuation of residents near the town of Stapleton.

Below is a list of the highest temperatures, lowest relative humidity values, and peak wind gusts from October 4.

Tuesday (October 4)
Location High Temp (F) Low RH (%) Max Wind Gusts (mph)
North Platte 91 10 41
Valentine 92 10 44
Broken Bow 90 10 44
Imperial 89 9 47
Ainsworth 90 9 36
Oneill 90 15 35
Ogallala 90 9 39
Thedford 90 10 43

Several Tornadoes Hit North Central Nebraska in August
While August is typically a quiet month in terms of severe weather and tornadoes. August 2011 saw abnormally active weather with several rounds of severe storms impacting the area. The majority of the tornadoes reported during the month were brief touchdowns and caused little or no damage. However, one tornado near Wood Lake was classified as a strong tornado and caused extensive damage in areas it struck.

On August 11th, severe thunderstorms developed over North Central Nebraska from northeast Cherry county through Boyd county. Storms initiated along a warm frontal boundary which was draped across southwestern South Dakota into northeastern Nebraska. Storms then merged into a line of severe storms which moved from southern South Dakota into northern Nebraska. As the evening progressed, several storms began to exhibit strong rotation, and at 749 pm CDT, the first tornado touched down just to the northwest of Wood Lake in Cherry county. A second tornado touched down in the same location then the storm moved southeast and produced a third tornado approximately 5 miles south of Wood Lake. The first tornado was a brief touchdown and was rated EF0 with no damage reported. The second tornado occurred northwest of Wood Lake and was rated EF1. This tornado damaged some outbuildings and caused damage to a home. The third confirmed tornado was on the ground for 20 minutes from 805 to 825 pm CDT. This tornado was rated EF3 with maximum wind speeds of 140 mph. Damage occurred to tree groves, windmills, fencing as well as to a steel culvert which had been previously washed out.

Another storm to the northeast produced several funnel clouds and three confirmed brief tornado touchdowns in the Johnstown area in Brown county between 758 pm and 902 pm CDT. These tornadoes all touched down in open fields with no damage reported, so they were all rated EF0.

Later yet, another storm developed over southeast Cherry county and moved across Thomas and Blaine counties. A brief tornado touched down at 953 pm CDT one mile west of Purdum in Thomas county. Damage occurred to trees and power lines and was rated an EF0.

On August 18th, severe thunderstorms produced tennis ball sized hail and several tornadoes north and east of Ewing in Holt county between 523 pm and 549 pm CDT. Two tornadoes were reported and were brief touchdowns with no damage reported. Later that evening a storm over southern Cherry county produced an EF0 tornado which briefly touched down in an open pasture.

Photo by Ron Brawner

Photo by Ron Brawner


Severe Thunderstorms with Large Hail and Damaging Winds
Roll Across Northern Nebraska on August 7
Strong thunderstorms developed over southern South Dakota during the late afternoon hours and crossed into northern Cherry county around 7 pm CDT. The storms quickly became severe with baseball sized hail reported in Kilgore around 715 pm CDT. In addition to large hail, strong straight line winds downed power lines and uprooted trees south of Kilgore. One tree landed on a house 5 miles south of Kilgore, producing significant structural damage to the house. The storms tracked east southeast, impacting Valentine around 8 pm CDT. Wind gusts up to 77 mph were reported at the Valentine airport and lasted approximately 20 minutes.

The storms accelerated as they moved east. By 845 pm CDT, 71 mph wind gusts were reported at the Ainsworth airport. By 930 pm CDT, trained spotters reported 70 mph winds at Atkinson and 60 mph wind gusts were reported at O`neill.

In addition to numerous reports of structure damage from hail and straight line winds, power outages were reported in Newport, Sprinview, Long Pine and Bassett.
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