SIOUX FALLS, S.D. (KELO) — Weather that happens near Summit, doesn’t exactly happen in the rest of South Dakota.

Thick fog that mysteriously appears or high winds that seem to come from nowhere are all part of the weather saga of Summit. The small city on Interstate 29, about 33 miles north of Watertown and about 29 miles south of Sisseton has welcomed many travelers who are stranded because of the mysterious weather.

But there isn’t some science fiction phenomena that causes the weather changes at Summit, it’s just science.

Summit sits on the highest part of the Coteau des Prairies or Prairie des Coteau in eastern South Dakota. The coteau is a plateau that is about 200 miles long and 100 miles wide. It stretches from eastern South Dakota into northwestern Iowa and Southwestern Minnesota.

“Downslope winds via the Prairie Coteau can play a factor in wind speeds since that kind of wind gets forced down the slope from higher elevations due to gravity,” said KELOLAND Meteorologist Adam Rutt.

Aaron Dorn, a meteorologist with the National Weather Service in Aberdeen is also familiar with those downslope winds. The elevation near Summit is about 1,000 feet higher than the surrounding area, he said.

Dorn used a southwest wind to describe what can happen at Summit.

“Summit is at the top of the ridge and gets blasted hard. The wind travels down the lee side of the coteau…,” Dorn said. The wind hits the lower ground and is then propelled back up at a high speed and travels east.

While there is a scientific reason for what can be dramatic shifts in weather such as wind speeds and fog, Dorn acknowledges that the Summit area has earned a reputation.

“It’s the Bermuda Triangle of our region,” Dorn said.

This graph shows how wind responds when it hits high elevation at Summit. The lower part of the graph shows Summit in the highest brown elevation reading. The wind hits the high part and hits the downslope and then rises again in speed. Wheaton is to the east in Minnesota. National Weather Service office in Aberdeen graph.

These two graphs combine the wind speed and downslope and compare speeds in the region. National Weather Service in Aberdeen graphs.

Stranded in the Bermuda Triangle of the state

Val Nelson is the manager of the Coffee Cup Travel Plaza and TA Express at Summit.

She works in the “Bermuda Triangle of South Dakota.”

“Seriously, you can go five miles in whatever direction and it’s totally night and day difference,” Nelson said.

The shifts in weather or a predicted winter storm or fog can cause problems for travelers on I-29.

During the latest winter storm, the South Dakota Department of Transportation closed I-29 from Watertown to the North Dakota border at 6 p.m. on Feb. 21

“We have a few families that were here last night,” Coffee Cup employee Jennifer Lewandowski said on the morning of Feb. 22.

Stranded travelers may grab a pillow and blanket from a vehicle and hunker down in a booth or aisle.

“It was blowing all day but then it started snowing and that’s when it got bad,” Lewandowski said of the weather conditions.

The wind frequently blows at Summit but “last night it was horrible,” Lewandowski said.

The Coffee Cup travel plaza at Summit on Feb. 22. Coffee Cup photo.

The SDDOT opened I-29 north from Watertown at 10 a.m. today (Feb. 22).

Rutt said at about 12:45 p.m. the area was still in 20 to 30 mph winds with gusts up to 40 mph. The SDDOT was still advising no travel in northeastern South Dakota.

The Coffee Cup in Summit is one of several owned by a company based in Sioux Falls. Tom Heinz built the travel plaza in Summit 41 years ago.

“We’ve had a lot of people stranded. We’ve had a lot of accidents. Unfortunately, we’ve had some fatalities,” Heinz said of traveling near Summit.

“Due to the elevation, weather and road conditions can change quickly,” Heinz said.

Heinz said he’s grateful the business has been a storm shelter for travelers in need over the years and grateful for his employees who are there to help.

“We welcome them,” Heinz said of stranded visitors.

Nelson said the business bought a generator several years ago that better allows it to be open during storms or foggy conditions, even if the power is out.

Several years ago, the travel plaza stayed open even without power because travelers and others may have needed it, Nelson said.

Travelers have been stranded for multiple days. There were storms so bad only the hoods of vehicles parked in the lot could be seen when the storm ended.

The DOT and weird conditions at Summit

Mark Peterson, an engineer for the South Dakota Department of Transportation, said DOT employees are aware conditions can change near Summit and along the couteau ridge.

“Even going into yesterday (Feb. 21) our conditions weren’t bad right at Watertown. Once you got to Summit and then north, conditions were terrible,” Peterson said. The SDDOT decided to close the I-29 north and southbound lanes from Watertown to the North Dakota border.

A photo from the SDDOT camera at Summit on Feb. 22. The photo is from 1:53 p.m. Feb. 22.

Plow drivers may be headed toward Summit from the west, east, north or south and will say that conditions significantly change as they get closer to Summit and the couteau, Peterson said.

The SDDOT has a salt storage facility at Summit which means trucks from all four directions likely reach Summit during their maintenance routes, Peterson said.

Heinz would like the SDDOT to have a manned facility in Summit because of the area’s changing weather conditions. The SDDOT does a good job of keeping the roads safe in bad weather but a manned facility would help if a traveler does get stranded in the area, he said.

Peterson said the Summit facility has not been staffed during his 22 years with the SDDOT. Trucks come in from those four directions and the site is about 30 miles from a SDDOT site in any of those directions, he said.

Driver awareness of conditions, closing

Nelson said there are fewer stranded travelers in the past few years than before. People seem to be paying attention to social media weather condition alerts and road closing alerts, she said.

Peterson agreed that people are paying closer attention to the weather and driving condition reports and alerts.

The SDDOT’s 511 app has improved how travelers get information on weather and road conditions, Peterson said.

The NWS has also ramped up local effect over the past five to 10 years, Dorn said. That effort includes consistent communication with emergency management staff in counties in the region to discuss the forecast and possible weather complications, he said.

“Still, there are people who are going to defy all the odds…,” Nelson said.

And sometimes, travelers may be caught unaware.

A thick spring or fall go can roll in around Summit. “That gets people in trouble quickly,” Heinz said. “It can be clear 10 miles in any direction.”

And “people absolutely stay here because of fog,” Heinz said.

The Coffee Cup in Summit on a brighter day. Coffee Cup photo.

Whether it’s a blizzard or the fog when the so-named “Bermuda Triangle of weather” strands travelers, they can gather at the Coffee Cup travel plaza.

“You realize that when people hunker down, everybody is pretty much the same,” Heinz said. “Everybody is pretty much equal, doctors and truck drivers…they treat each other with respect. They are all in the same boat trying to stay safe and sound.”