Wind, rain wreak havoc over Memorial Day weekend

by nathan oster

Mother Nature clearly wasn’t in a cooperative mood this year with folks who had plans for the long Memorial Day weekend.

The weather was the dominant story, as high winds that toppled trees and power lines and cut the power to homes across south Big Horn County on Sunday afternoon were followed for an encore by a steady rainfall on Monday that hastened mountain snowmelt and threatened homes along Shell Creek.

While Saturday was nearly ideal, the pivot point of the long weekend came late Sunday afternoon. By the end of day, reports were numerous and coming in from across south Big Horn County of downed and uprooted trees, toppled power poles and damaged or missing rooftops and structures.

Basin suffered the most direct hit, but damage reports also came in from as far north as Greybull and as far south as Manderson, according to Tim Troutman, a warning coordination meteorologist with the National Weather Service.

Troutman visited Basin after the storm to document the damage and file a report.

Because the NWS has no weather equipment in either Basin or Greybull, only official readings from Sunday afternoon’s storm came from the South Big Horn County Airport. A gust from the southwest of 78 mph was documented there at 5:41 p.m.

“What occurred to cause all the wind damage, we had a line of thunderstorms moving from south to north on Sunday, and as the winds approached the Basin area, some higher gusts developed along the leading edge of the thunderstorm, producing a decent amount of damage across the southern part of town.”

Troutman said he documented for his report a roof being blown off the J&E Irrigation building, large limbs on a camper on South Fifth Street, a snapped power pole on South Ninth Street, and a total of 15 to 20 downed or uprooted trees, just in Basin.

“We’re estimating maximum winds speeds, in the Basin area, at around 75 miles per hour,” he said.

Troutman ruled out a tornado, citing the lack of “twisting” or “snapping” that was evident along the path of the storm. “Looking back at the radar and after observing the damage, we’re calling it ‘straight line wind damage,'” said Troutman. You get that, he said, “when you have high winds along a line of thunderstorms pushing down to the surface and producing outflow winds that blow everything in one direction.”

 

‘A loud boom’

The most significant damage in Greybull might have been to the home of Shanna Flath in the 400 block of Seventh Avenue North. Shanna and her daughter Kaitlyn, 14, were inside when the storm blew in.

“She was taking a nap on the couch in the living room and I was sitting on the floor in front of the window,” she said. “It happened really fast. I heard a loud boom. Immediately I woke her up said, ‘We have to get out of here.'”

Flath said her living room curtains had been drawn to about 6 inches and that she didn’t realize that a fully matured tree had fallen on her home until she went outside. Bob Leach, her next-door neighbor, was there to meet her.

“He gave me a hug, asked me if I was OK and gave me advice on what to do,” she said. Her first call was to her parents. Emergency responders advised against staying in the home, so she spent Monday and Tuesday night at her parents’ house.

When the tree was removed on Tuesday, some structural damage to her home was discovered.

Shanna said her daughter was initially shaken up, but is now anxious to get home again.

“I’m just thankful that we didn’t get hurt,” she said. “For a wind to come out of the south like that … it was unusual. Now we’re just waiting for the insurance adjustor. Hopefully things will start coming together for us.”

A tree was also uprooted at the Antler Motel on North Sixth Street.

 

Then the rains came…

In the aftermath of the windstorm came a steady rain that continued throughout the day on Monday. The official 24-hour precipitation total recorded the airport was 67 hundredths of an inch, although some rain gauges around town registered more than that.

Members of the Shell Fire Department responded to the Kedesh Ranch property at the base of the Big Horn Mountains early Monday to begin filling sandbags in anticipation of a swelling of Shell Creek.

Mike Nelson, the fire chief in Shell, said firefighters and a dozen or so volunteers from the community filled about 4,000 sandbags. When the level of the creek rose, the nearly 3-foot wall of sandbags that was built was instrumental in preventing widespread property damage.

Water “got up around” two houses on the west side of the creek, but not inside, said Nelson.

On its website, the NWS tracks current and historical SNOWTELs and river stages by basin. Included on the site is information about Shell Creek, taken from weather equipment found near the community of Shell.

The record flood stage at that location is 7.5 feet. Between 6 a.m. and noon on Monday, the creek rose from about 5 feet and a flow of 1,500 cubic feet per second to a reading of 6.42 feet and a flow of nearly 3,500 cfs.

By Tuesday morning, it was back down to a more normal level of 4.67 feet.

Nelson said he and others are keeping a close watch on the gauges as the mountain snowpack continues to melt.

 

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