The discussion came up in the newsroom for the first time today…why is it so nice outside? What they really mean is, “I thought it was going to be a rough winter!”. First, I never said it was going to be a rough winter. We have said that La Nina winters tend to be cooler and wetter than average.
Do you realize that other than a few interesting days last week, and a few days before Thanksgiving, the weather has been totally uneventful this winter? By the way, when I say “winter” I should really say our stormy season. November-February is when we get most of our rain, gusty south and east wind, and all of our arctic blasts. So we are in the 2nd half of “prime time” now. Most important, I see nothing of interest in the next 10+ days; much drier than average weather continues with very little snow in the mountains. That’s going to move us into mid-January with dead weather. That’ll only leave about a 4 week period in which we could get a major snow or ice storm, or days-long blast of cold air.
Yes, over the past 5 days or so we’ve seen hints of a major pattern change, first around the 10th of January, now even later, maybe the 15th. If that occurs, then there’s no reason we couldn’t see a totally different 2nd half of winter. It’s something to keep an eye on. I refuse to put any emotional energy into a possible pattern change until I see more consistency with models.
Here’s the big question: Could we have a boring La Nina winter with well below average snowpack and drier/milder than average lowlands? Check out this chart from the Ski Mountaineering Website:
Yes, it has happened before; just very rarely. Remember 2000-2001? That was the 3rd year of La Nina conditions, and it was a weak La Nina, a bit weaker than this year’s event. I clearly remember almost nothing of interest occurring that winter. We had a brief little ice storm event in mid-December, but that was it. There were no arctic blasts, the low at PDX was only 24, and no southerly windstorms. No flooding either. Snowfall in the mountains just sort of limped along gradually increasing. Timberline (62″ base today) stayed in the 80-90″ base range all the way through January and February. Cascade skiing wasn’t very good with long periods of dry weather.
So keep in mind that it’s POSSIBLE to have a slow, boring, eventless La Nina winter, but just very unlikely.
In the short term, tomorrow’s temperature forecast is interesting. Today PDX only hit 50 with a light (and cool) easterly wind. The southern and western metro area was well into the 50s, Salem and Eugene hit 57. Tomorrow we get sunshine through midday with southerly breezes picking up ahead of a cold front. So all areas should see the warmer air above mix down nicely. 850mb temps surge up to +8 to +9 C tomorrow morning too. Add those three factors up and we could get surprisingly warm…assuming the clouds hold off until at least 2-3pm. If so, I could see some 60 degree highs here and there. The record for tomorrow is 59 at PDX. We’re going 57 to be safe, but that’s still 12 degrees above average.
Chief Meteorologist Mark Nelsen