POLSON, Mont. -

The name of a missing kayaker has just been released, Robert W. McDonald from Polson. He went missing on Flathead Lake and a massive search effort has been put on hold until the morning.

The search started late last night near Bear Harbor Condo, in Polson Bay, when 43-year old McDonald did not return home from an afternoon kayaking trip.

Rescue crews have searched certain areas of Flathead Lake and then searched them again looking for Robert McDonald.

"They searched Polson bay, all of Polson Bay at Flathead Lake, Skidoo Bay and they searched this entire river down to the dam," said Karen Sargeant, Lake County Sheriff Information Officer.

After no sign of the missing kayaker, two helicopters and a search and rescue unit from the Swan Valley were called off Sunday afternoon, but Lake County search and rescue boats continued their grid pattern search through the early evening, aided by two search dogs.

Sargeant explained that weather conditions may have lead to McDonald going missing.

"All yesterday, I'd say from about 11 on, the lake was very, very choppy, very rough. And in the photo he texted, you could see white caps on the lake," explained Sargeant.

Sargeant says McDonald wasn't wearing a lifejacket and that the type of kayak he was in, a yellow 12 foot eclipse, can sink if it takes on too much water.

"The lake is very, very cold still and without a personal floatation device to help you stay out on the surface, your body temperature will drop rapidly and hypothermia will set in rapidly," said Sargeant.

Crews aren't giving up. The Flathead County Sheriff's Department will begin tomorrow morning at 9am.

They are bringing in more watercraft and personnel to conduct a specialized sonar unit search which will search areas underwater.

Search crews are also asking people on the lake to keep an eye out for any signs of the missing kayaker.

Anyone with information is asked to call the Lake County Sheriff's Department at 883-7301.