OREM — Severe afternoon thunderstorms halted the efforts of rescuers at Utah Lake just before 6 p.m. Thursday.

Rescuers said bad weather forced them to call off the search for the day, but if storms do not get in their path Friday morning they will continue looking for Lon Thongthipvoravong of Orem. Rescue crews were able to find the boat that capsized Monday evening, spilling six men into the choppy waters, but there were still no signs of the lost boater Thursday.

Crews located the upside-down, submerged boat about a mile west of the Links at Sleepy Ridge golf course about 12:30 p.m. Thursday and had divers retrieve personal items to verify it was the boat in question, said Utah County Sheriff's Lt. Dave Bennett.

"That helps us a lot," Bennett said. "Now we can reference where the boat went down and where we're finding other debris."

Lon Thongthipvoravong, a 32-year-old Laos native, is the only man who has not been found after he and his five friends were tossed into the water when waves sunk their tri-hull boat Monday evening. Crews have been searching for Thongthipvoravong since then.

Bennett said the temperature of the water has risen into the 70s, which may make it easier for rescue crews to locate Thongthipvoravong's body, which will hopefully rise to the surface.

"We're scaling back," he said, "just waiting for nature to take its course."

But even a scaled-back effort still means more than a dozen officials and Utah County Search and Rescue volunteers will conduct surface searches, use a side-scan sonar boat and dive to investigate any sonar findings, Bennett said.

It was the sonar equipment that helped find the sunken boat, and it will continue to be used in the search for Thongthipvoravong's body.

Crews aren't going to spend time and energy pulling the boat from the water at this point, Bennett said, but instead focus on locating the man. Some of Thongthipvoravong's family members were also out on boats with officials to help with the search.

The search is still focused two to four miles north of the state park and west of the golf course, where other debris from the boat had been found along the marshy edges. On Wednesday, searchers found Thongthipvoravong's fishing bag and his sandal; however, the pack was not on the man when the boat capsized, officials said.

E-MAIL: sisraelsen@desnews.com

Contributing: Cimaron Neugebauer