We are now in our 7th week of upper-level ridging and/or split flow giving us warmer than normal weather. In fact most of the past three months we’ve seen ridging over the West Coast or just a little bit to the east or west of us. The only significant breakdown of the ridge was around Christmas when several cold and wet storms moved through the region.
It appears that this pattern will persist another 8-10 days, but all long-range models show a change in the last few days of February. Models have been showing this for the past 4-5 days too. To highlight:
- Mild and dry weather continues for about one more week across the Pacific Northwest
- Wetter and cooler weather arrives the last couple of days of February…plan to finish dry weather projects by that time.
- Ski areas may see their best snow conditions since Christmas NEXT weekend (Feb 28/Mar 1). But nothing will change for this coming weekend; lots of thin spots down low still.
- It’s possible some closed ski areas could open up again by the first full weekend of March
Today was great, tomorrow looks the same, and then a mix of clouds and sun coming up the last few days of this week as the ridge breaks down a little. Then the ridge pops back up quite strong to our west over the weekend. Look at Sunday:
With the ridge slightly to our west, we get a cooler push of air out of southwest Canada Sunday and Monday. Not an arctic blast by any means, but we likely won’t see 60 degree days. More typical low-mid 50s instead with the gusty east wind. I noticed both the GEM and ECMWF (12z runs) had a very strong pressure gradient on Sunday, but the 00z GFS does not. The 00z GEM on the other hand has a significantly colder push of air, one that would give us high temps in the 40s with more of a winter feel Sunday/Monday.
They are all in almost perfect agreement by Tuesday, March 3rd…two weeks from now. At least the ensemble averages are…this leads to high confidence of a pattern change towards colder and somewhat wetter as we head into March. The first significant rain and mountain snow arrives a week from Thursday, the 26th.
A huge question is whether it’s a temporary change…like back at Christmas. Or is it the classic switch to wet/cool as meteorological spring arrives? Good question. The monthly run of the ECMWF from last night implies it’s going to last longer than a week. Here is the map for week 3, March 1st-8th…pattern is the same.
Then week 4 which takes us into mid-March:
Still the same pattern with the upper level high out over the Aleutian islands.
Chief Meteorologist Mark Nelsen