Major Snow Event in Montana and Alberta, With Light Snow in Our Mountains

Getting some light snow in September over the higher elevations of the Northwest is quite normal, but what is about to happen over western Montana and southwestern Alberta, will be unusual--with several feet falling at some locations on the eastern side of the Rockies during the next week. 

And here in western Washington we will get a taste of much cooler temperatures and a dusting over our high terrain.

Regarding the first date of snow, here is a wonderful graphic from NOAA/NWS (link ) providing the earliest first date of snow.   Lots of locations with September and even late August dates in western Montana, eastern Oregon, the high terrain of Idaho, and the spine of the Cascades.

So now that the shock of potential snow is over, let's take a look at the latest forecasts for total snowfall over the next week--examining the forecasts of the European Center model and the UW WRF modeling system (below).

They are very similar...HUGE snow dump of 2-3 feet on the eastern sides of the Rockies.  And a few inches to a half foot over the higher elevations of the Cascades.  Eastern Oregon will get a thin veneer of snow.

The forecast temperatures at Seattle from the European Model show the abrupt change ahead.  Mid-60s for a few days, but then highs of only around 55F on Saturday and Sunday, with a slow warm up after that.   Rain late Thursday and more on Saturday.   No snow for us!

But the story in Spokane is different.  The bottom drops out there. A 20 degree drop in the high temperatures, with minima declining to below freezing.  And snow is forecast there.

Missoula is something else.  25-30F drop, 9 inches of snow, minima below 20F. 

The cause of all this?  An usually deep upper level trough that will move into our region from the Northwest (see 500 hPa upper level map below).  Wow.  I get shivers looking at it.