Cause Of Late-Season Interior Rain Remains A Mystery
Rain in Interior Alaska is rare, or so it might seem, but the region has seen rain fall in November in seven of the last 12 winters. An explanation remains a mystery.
Rick Thoman is the Climate Science and Services Manager for the National Weather Service in Alaska. After a fierce winter storm brought freezing rain to the Fairbanks area this month, Thoman decided to do some detective work.
“This is part of Forensic climatology,” Thoman said.
While Forensic Climatology isn’t actually a science, Thoman has spent the last few weeks combing through more than a century’s worth of climate data for the region. He says winter-time rain has pelted the Interior before.
“We can see that both in the 1960’s and in the 1920’s and 30’s there was even more winter rains than we’ve had lately,” Thoman said.
Those periods were separated by decades with few if any rain events. Thoman says there isn’t a distinct pattern to rain-laden storms, so he doesn’t really have an explanation.
“Well, we actually have not been able to find the smoking gun in this case,” Thoman said. “It does not appear to be well correlated with the usually things we look at for driving winter climate in Interior Alaska.”
Those are things like sea surfaces temperatures in the North Pacific.
“That perhaps is less surprising than we might think, because these are very specific weather events and those kind of climate drivers like sea surface temperature anomalies tend to operate over longer time scales, whereas these are just one or two or three-day type events,” Thoman said.
So even if his investigation is inconclusive, Thoman say it might be a god idea to keep an umbrella nearby.
“The periods in the 1920’s and 30’s and the 1960’s lasted longer than we’ve had so far, so based on that past record, so we might expect more of these in the relatively near future, but we have to remember that these don’t all have the same mechanisms behind us and it’s certainly a good example of how the past may not be a guide to the future,” Thoman said.
The forecast for this the last week of November calls for clouds over the Interior and maybe a few snowflakes, but no mention of rain.