Tuesday: watching for low elevation snow

Out The Door Tuesday: Out the door Tuesday, we’ll see morning lows of 27-30 degrees in the Willamette Valley. It should be mostly dry.

By about mid-day: Moisture from an incoming Pacific storm system rolls inland. And this is where it gets tricky. Some of our forecast tools insist on south wind (including the forecast ‘model’ we use at KOIN Local 6) that makes it breezy and in the 40s in the Willamette Valley. If that’s true, this would be mainly a rain event. But other forecast tools suggest parts of the Portland-Vancouver metro could hang on to an east wind for a bit (or have little wind at all), giving us some snow either at the start or shortly after rain starts…changing it back to snow in the metro area.

There’s one other thing to consider: the timing of the incoming system. To me, it looks like it’s ahead of schedule. If it shows up in the morning (after a cold night!) the air should be cold enough to start as snow. If a south wind develops, we switch to rain. If that wind is not strong enough, the metro could stay as snow until the main storm front passes. So you see what I mean, right? This is a tricky forecast.

Tuesday Evening – Into Wednesday Morning: Colder air streams in behind the main storm system. This creates some pretty strong showers and falling snow levels. The sticking snow level is between 500’ and 1,000’ during this time with some light accumulations certainly possible. Like this past Saturday morning, many places on the Valley floor can see snow during heavier showers and a dusting is possible about anywhere Wednesday morning if your house gets hit by snow showers overnight.

So, a lot of weather drama ahead—and much still to be decided. Here are some other specifics:

Coast: High Wind Warning Tuesday for south wind gusts of 65-70mph. A Winter Weather Advisory for the Coast Range. Anywhere from 1-6” of snow is possible by Wednesday night depending on where showers hit hardest. Highs: 40-43.

I-5 Corridor/Willamette Valley:  See above for the metro area…the central & southern Willamette Valley will see rain developing Tuesday afternoon along with breezy south winds. Sticking snow levels close reach 500’ to 1,000’ Tuesday night & Wednesday AM. Highs: 40-44.

Gorge: Mainly afternoon snow developing. Watch for accumulations Tuesday night into Wednesday morning—possibly down to near I-84 and SR-14. Highs: 40-44.

Cascades: Winter weather advisory. Snow level about 1,500’ early, below 1,000’ late. Heavy snow of 10-20” Tuesday night into Wednesday night. Highs: 20-30.

Central/Eastern Oregon: Winter Storm Watch for Central Oregon including Bend, Redmond & Sun River on Tuesday night. Snow
developing and increasing during the evening. Highs: 32-42.