FAIRBANKS - Meteorologists described Monday's widespread rainfall as an "epoch winter rain event" and it's not over yet.
Two-tenths of an inch of rain had fallen at Fairbanks International Airport by noon Monday and forecasters at the National Weather Service said more than an inch of rain could fall by the time it stops, which is expected to be sometime Wednesday.
"We haven't ever seen anything like this in the Interior," hydrologist Ed Plumb at the National Weather Service in Fairbanks said Monday as the rain continued to fall.
An extremely warm and moist airmass moving around a large high pressure system over the North Pacific pumped warm, moist air into the Interior and much of the rest of the state early Monday morning, resulting in widespread rain from Anchorage to Barrow, said meteorologist Brad Sipperley.
"It started raining at 5:30 a.m. and it's been raining ever since," he said just before noon. "We've had freezing rain from Anchorage to Barrow."
The heaviest rain fell in the Central Interior. In the Yukon River village of Galena, about 270 miles west of Fairbanks, six-tenths of an inch of rain fell from 6 p.m. Sunday to 10 a.m. Monday, Sipperley said.
In Fairbanks, about two-tenths of an inch of rain fell at the airport between 6 a.m. and noon on Monday.
Rain was expected to continue most of Monday and much of Tuesday before cooler air begins moving into the area, Sipperley said.
"We could surpass the record (winter) rainfall we had in 1937," Plumb said, referring to the 0.99 inches of rain that fell on Jan. 20, 1937.
Rain during the winter in Fairbanks is unusual and rainfall amounts over one-quarter of an inch anytime between mid-November and early April are extremely rare, according to the weather service.
The last time that happened in Fairbanks February 2003 when 0.29 inches of rain fell between Feb. 8-10.
It marked only the second time in more than 100 years that measurable rainfall was recorded in Fairbanks in the second half of November, according to weather service records. The only other November rainfall on record was Nov. 24, 1936 when 0.42 inches of rain fell.
"It is quite the blast of warm, moist air," Sipperley said.
The warm, moist air broke down a high-pressure ridge that was centered over the Interior, Sipperley said. He called it a "tropical moisture train."
"There's a large trough of low pressure aloft that came over from Siberia," he said. "It's pushing on top of the ridge and flattening it out. As it flattens out the top of the ridge it allows that moisture and warm air in the door.
"We're receiving every bit of moisture and warm air that is available," Sipperley said.
Freezing levels were all the way up to 6,000 feet, Sipperley said. Temperatures are expected to hover in the low 30s today and most of tomorrow in Fairbanks. Rain is forecast all the way through 9 a.m. Wednesday
"Colder air doesn't start pushing into here until Wednesday night," Sipperley said.