Record setting precipitation and snowfall fell in the latter half of January across western Oregon and Washington state, with the inland northwest seeing a comeback of sorts to the water year. Significant snowfall was observed across the central and northern portion of the inland northwest with back-to-back 5-8″ snowfall events resulted in the closure of WSU and UI on the 19th. Lewiston, Idaho saw it’s heaviest 24-hr snowfall since 1950, and LaCrosse, WA it’s greatest single day snowfall total on record. Collectively, the comeback over the last half of the month resulted in respectable monthly accumulated precipitation numbers, with places like Spokane making a dent in their water year deficit, some spots getting back to normal with significant precipitation across the Snake River Plain as Boise reported over 2 inches of precipitation in a 3-day period!
Overall, most locations west of the Northern Rockies that receive a majority of their precipitation from November-March are still 5-30% below climatological normals. Moreover, while mountain snowpack improved somewhat across the western US over the last two weeks, most watersheds are still playing catchup with the clock running.
Temperatures last month were generally warmer than normal for daytime highs and near normal, or slightly below normal for overnight lows, in part a function of the benign fair-weather the first half of the month. This of course is nowhere near as interesting as the very mild temperatures last month across the upper-midwest and the downright frigid temperatures across central and western Alaska including the all-time coldest Januaries in Nome and Bettles.
The next two weeks look rather dry and mild for much of the inland northwest. And by mild, I’m talking in relative terms, of course. A blocking pattern is being set up in the eastern Pacific that should direct the jet stream into Canada and south-central Alaska (I’m sure they’re please by that idea). This regime is strongly mapped onto the Pacific North American (PNA) pattern which is a teleconnection of sorts that controls the longwave pattern over the Pacific and North American sectors (creative name huh?). During the next couple weeks, we’ll be in the positive phase of the PNA whereby a ridge parks over western North America ushering in mild air and directing the storm track up and over the western US, with a compensating trough over the eastern and specifically southeastern US.
Whereas La Nina winters typically increase the potential for wetter than normal late winters/early springs across much of the wetter locations of the Pacific Northwest, the outlook doesn’t look that optimistic for the water-year comeback. The CPC Climate Forecast System is predicting near normal precipitation for the northern tier of the inland NW the next three months and subpar conditions across Oregon and the southern half of Idaho in addition to much of the southwestern US. Then again, a couple significant precipitation events can overcome the deficit we’ve gotten ourself into this year. We’ll have to wait for the all-knowing groundhog’s prediction tomorrow…aka meteorologist unappreciation day.