Kotzebue’s July was one for the record books, with the highest monthly precipitation on record. The previous rainfall record for the midsummer month was set more than two decades ago.
To understand what led to Kotzebue’s heavy rainfall in July, it helps to look at weather systems in the Northern hemisphere.
This summer saw two instances of high pressure systems near Alaska. One was in eastern Siberia and the other was in Western Canada and Eastern Alaska. Both led to dry weather and numerous wildfires in the area.
“Western Alaska has just been stuck between those two high pressure systems,” said Rick Thoman, a climatologist with the International Arctic Research Center in Fairbanks. “In the atmosphere between two high pressure systems, you have low pressure. That’s how the atmosphere works. And so we’ve had multiple storms moving through the area, bringing not just one round of rain, but repeated rounds of rain.”
In total, Kotzebue saw 5.31 inches of total precipitation in July. That beat out the previous record of 5.26 inches set in August 1998. And when meteorologists measure precipitation, that includes snowfall in the winter months.
“You take the snow, and melt that down to get how much water’s in it,” Thoman explained. “So when we talk about precipitation, it is a fair comparison between what falls in January and what falls in July.”
Looking at the rainfall trend in Kotzebue, July was bookended with two heavy rain events. The first came on July 6 and 7, when Kotzebue saw the highest single-day rainfall amount on record.
“(We) had the all-time 24-hour record and then the repeated rain the last week of the month,” Thoman said. “Yet in between, from the 11th until the 23rd, there was some rain but not a lot of rain.”
Thoman says it’s not unusual for Kotzebue to see a lot of rain in the summer, but it normally comes towards the end of the season.
“Lots of folks have been remarking how July seemed like a fall month with all the rain,” Thoman said. “And certainly when we get these heavy type rain events like this, they are much more likely to occur in August than in July.”
Kotzebue wasn’t the only community in Western Alaska that saw heavy rainfall in July. Red Dog Mine saw over 7 inches of rain. Nome saw its second wettest July on record and Bethel saw the wettest July in more than 90 years.
Thoman said as the Arctic gets warmer, more extreme weather patterns will become more likely.
“With earlier ice loss, with warmer ocean temperatures, we can anticipate that when Northwest Alaska gets in between these high pressure systems at the hemispheric level — so we’re in the low pressure point — the threat of heavy rain will be higher than it was in decades past,” Thoman said.
Thoman said these days in the Arctic, weather is always extreme somewhere. It’s just a matter of where.