Today generally worked out about as expected; no snow in the lowlands. There was plenty of “chunky rain” on my drive to work at 1-2pm. Models did well showing temperatures holding steady or even dropping as the day wore on.
Sticking snow level was all over the place. From around 200-300′ way out westside near Banks
to 2,000′ or a bit higher east of Rhododendron at mid-afternoon
This really points out how important precipitation intensity can be to snow level forecasts in these marginal snow setups.
Steady precipitation has ended for most of the area, and now it’s on to very spotty showers tonight through Monday in the post-frontal cool airmass. GRAF model says less than .10″ for most of us along I-5 through sunset Monday. There’s not going to be much of anything falling out of the sky tonight and Monday
Since temperatures are just a few degrees above freezing and wind is light, any clearing could lead to icy roads. This is far more common than snow in our climate. So keep a close eye on your car thermometer tomorrow morning as you head out and of course Andy & Tony have you covered on FOX12 OREGON. Of course if skies don’t clear much, we won’t have to worry about icy roads. I think it’ll be real spotty. A summary of the next 24 hours…
TUESDAY & BEYOND
An active weather pattern continues through the end of the month, and at least into the first days of February. But it’s not a strong westerly jet stream running right into the Pacific Northwest. Rather a series of cold upper-level troughs that drop down along the coastline, or into the Eastern Pacific. #1 is approaching now; will be right over us Monday
That one heads down through the Desert Southwest Tuesday/Wednesday while #2 settles in just offshore
Then by Saturday/Sunday, #2 has moved east of us and a larger/deeper low (#3) is plopped down in the Gulf of Alaska. This wouldn’t be quite as chilly for us since the cold air is dumping out over the northeast Pacific. It’s a long path over the mild ocean from Alaska to the Pacific Northwest!
This doesn’t tend to be a HUGE snow producer for the Cascades (until next weekend) since a lot of the energy is headed to our south. The Sierra Nevada pick up many feet more snow than the Cascades this week.
So the big question is…could we see another close call for lowland snow? Possibly, but it’s a stretch just like today.
One thing we know isn’t in play; there’s no source of cold air to the east. I don’t see a setup this week that would bring in 20-30 degree air through the Gorge with moisture riding over the top for a widespread snow event. What I DO see is another “close call” Tuesday afternoon/evening. As a Pacific frontal system moves toward the West Coast (2nd jet stream image above), most energy heads south. But we get the leftovers as a band of precipitation swings north over us. There will be a relatively strong surface low well offshore too. The GRAF model shows the precipitation moving over the Willamette Valley Tuesday afternoon/evening with heaviest precipitation from Salem south and west. That’s because the precipitation band is moving away from the main storm center and weakening. There are hints that MAYBE the west side of the Willamette Valley up against the Coast Range could score snow to relatively low elevations…maybe.
This model and the ECMWF produce about .20-.30″ liquid precipitation. But temperatures remain above freezing through the Valley on both. GRAF gives hints the far westside of Willamette Valley might get something. But nothing for most of us…like today
The WRF-GFS says forget it as well; all the sticking snow is right up against the east side of the Coast Range. Total snow ending at 4pm Tuesday…It could be quite a snow dump up in the Coast Range!
ECMWF tries a little harder, but temperatures are 33-38 degrees through the entire “event”.
Luckily we’ve got another day to see if models warm up a few degrees as they did this time around. There WILL be an gusty east wind blowing through the Gorge, but there’s no cold air source eastside as I mentioned. So that doesn’t help us. Models are insisting dewpoints drop down into the 20s Tuesday just ahead of the precipitation too; allowing the 40-42 degree midday temps to drop down close to freezing a few hours later with evaporative cooling. I’m a bit skeptical.
Beyond Tuesday, snow levels lift a bit. It appears Wednesday through next weekend they will be in the 1,500′-3,000′ range. No sign of rain in the Cascades and it’s going to stay cool in the valleys.
I will have some time to blog again tomorrow evening, sometime after 5-6pm. Hopefully things become a bit more clear at that time. That should allow us to either swing toward NO SNOW in the valley (most likely) or SOME OF US WILL GET A LITTLE TUESDAY P.M.
Chief Meteorologist Mark Nelsen