Several severe weather events including thunderstorms with large hail, damaging winds and tornadoes have had local impacts on flora and fauna in the sandhills of northern Nebraska.
There has been one or more storm each month during June through August.
At Valentine NWR south of Valentine in Cherry county, "We have now had three hailstorms in this area for the summer that lasted long enough/had large enough hail to cause damage," said Mel Nenneman, a Fish and Wildlife Service biologist at the refuge.
After the June 13th storm, he observed some dead birds, including the Mourning Dove, Barn Swallow and Eastern Kingbird, all in the vicinity of the refuge headquarters. "No surveys were conducted after the storms went through, and there were no dead waterbirds observed, but we didn't have time to go look everywhere.
"I have not observed any dead birds from the most recent storm (August 9th), but the worst of the hail did not hit the refuge," Nenneman said. "Our maintenance man indicated that the area just west of the refuge was hit hard enough that all the vegetation is beat down, broken off, or stripped of leaves. This damage is similar to damage observed after the 13 June hailstorm that hit the refuge in a couple of places.
"While I don't have a widespread survey or good numbers on bird mortalities from these storms, the observations of dead birds after the June storm would suggest that there was very likely some bird mortality from this most recent storm, especially in the area west of the refuge. Given the nature of the damage to vegetation (west of here in the most recent storm, two areas on the refuge in the June storm), any bird caught in the path of the severe hail would be very lucky to survive, unless they were able to hunker down in a plum thicket or cedar tree."
The North Platte office of the National Weather Service typically prepares a summary report following severe weather. They include known instances of precipitation amounts, wind and hail. If tornado damage is reported, office staff may visit the affected area to investigate further, and may include pictures of the damage.
"We’ve had a lot of severe weather this summer," said Debra Blondin, a meteorologist in the North Platte office. "It is relatively unusual to have the severe weather continue to occur at this frequency for this long into the summer season. Part of the reason for this is that a very strong upper level low pressure remained stationary over the Great Lakes region keeping western Nebraska under a northwest to southeast oriented jet stream. This ‘northwesterly flow’ is usually a very active pattern for us. It is also a ‘cooler’ pattern because it allows the cooler air from Canada to filter into the area. Normally by late June and early July, the jet stream is into North Dakota and southern Canada leaving western Nebraska in hot and dry conditions."
June Storm Reports
Severe weather on June 13 including extensive rain, strong winds, hail and a tornado. Rainfall amounts varied from one to three inches in the Cherry county area. Winds reached 30 mph.
Hail varied from pea-sized at south of Valentine and north of Elsmere; marble-sized south of Cody; quarter-sized southwest of Valentine, in the refuge area; and one-inch diameter in the same vicinity. A tornado was report south of Merritt Reservoir.
A graphic map of this information shows the areas of the severe weather.
Image of the Crookston supercell, as shown at the National Weather Service web site.
On July 16, an EF2 tornado with winds reaching 118 m.p.h. was reported south of Crookston. "Numerous large tree limbs were snapped off throughout" the Robert Kruger ranch, the weather service reported. Building damage was also noted.
Southern Cherry county and Hooker County had a severe storm on July 23rd, with a second storm in the eastern sandhills..
The weather service reported: "STORMS INITIALLY FORMED OVER SOUTHEASTERN CHERRY COUNTY AND NORTHERN HOOKER COUNTY...WHERE SEVERAL REPORTS OF HAIL...SOME AS LARGE AS TENNIS BALLS IN SIZE WERE OBSERVED. THE STORMS CONTINUED TO THE SOUTH...WHERE CONTINUED REPORTS OF LARGE HAIL WAS RECEIVED BY THE NATIONAL WEATHER SERVICE. ALSO...A FUNNEL CLOUD WAS OBSERVED 11 SOUTHWEST OF MULLEN FROM THIS STORM. THE STORM CONTINUED SOUTH INTO PORTIONS OF KEITH...MCPHERSON AND LINCOLN COUNTIES AND EXHIBITED STRONG ROTATION ON RADAR...WHILE NO TORNADOES WERE REPORTED...ONCE AGAIN VERY LARGE HAIL WAS OBSERVED," according to meteorologist Shawn Jacobs.
In the Mullen vicinity, hail measuring from 1 inch to 1.75 inch were reported at different localities. Hail reaching an inch in size was also reported in central Brown county, eastward to south of Bassett and into western Holt county, near Amelia.
Reports of this storm can be visually noted on a map of the local storm reports.
A severe storm also occurred in the Valentine NWR area on July 28th, Nenneman said. Details of this storm are not available.
A severe storm of long duration occurred from central Cherry county eastward to northern Holt county on August 8th. Hail that measured 1.5 inches in diameter were reported by the public in the Valentine area. A wind gust at nearby Merritt Reservoir reached 60 m.p.h., with hail to the westward measuring from pea-sized to an estimated 1.5 inch diameter. Southeast of the refuge, in the immediate vicinity of the refuge, the public reported "golf ball sized hail accompanied by damaging winds estimated to be in excess of 60 m.p.h.," according to the weather service report.
Although there is very little direct evidence of bird mortality from this weather, the information from the June storm at the refuge, indicates that hail did cause bird deaths. Similar mortality could be expected from the other severe storms mentioned that had large hail, so there likely has been ongoing and repeated instances of bird deaths occurring throughout the summer breeding season.