November 28, 2021

Forecast: November 28th, 2021

By Preston Donion

Hello Huskies and happy Sunday!

I hope you had a wonderful Thanksgiving and long weekend. As we enter the tenth week of the quarter, we also enter December, and both offer some chaos and excitement! I can’t speak for what week ten holds for anyone else in an academic sense, so let’s focus on the weather that the final month of the year has on tap for us (it’s a nice distraction from that homework anyways)!

Today started quite warm, with temperatures climbing all the way to the upper 50s in the early hours of the morning thanks to our frequent visitor, the atmospheric river. Carrying tropical warmth and moisture all the way to the Pacific Northwest, the river is responsible for our temperatures running about 8° above normal for this time of year, and of course those gray skies! Expect showery conditions to continue throughout today and into tomorrow.

The first half of the week looks to be driven by the atmospheric river, with temperatures reaching into the mid to upper 50s every day through Wednesday. As Prince would have wanted, we may be partying like it’s 1999; the record highs for November 28th and 29th sit at 59° and we have a chance to tie that with our pipeline from the tropical Pacific in town! Rain will also be making an appearance at some point and to some extent each day. I suppose we weren’t satisfied just breaking the record for wettest fall, and we’ll build on that record to try and put it out of reach for future years! That being said, any rain over the next few days should mainly be in the form of showers rather than any really impactful downpours at least in the South/Central Sound.  

As we reach December, we’ll begin a noticeable descent into more seasonal temperatures and even dip below average after this decidedly warm stretch. This change is a result of the shifting winds; our current setup brings the warm and wet air from the ocean onshore (westerly winds), whereas the end of the week sees our winds bringing air in from the northeast. This typically carries colder air, as it is pulling from the Cascades and Canada, and is known as “offshore flow”. The rain will subside, and we’ll get a dry and cool Thursday and Friday before Saturday provides one of my least favorite combinations of conditions we see in the winter: cold and rainy! With a high in the low 40s and plenty of moisture, it feels like we’re being taunted with what could have been. Have no fear though, because there is some indication that this colder pattern will take hold for a while and thus may provide another opportunity for snow. Models disagree significantly at this point, so there is no solid answer on what we may see heading into week eleven.

In the meantime, here is an excellent look at cold air near the surface and how that new pattern could change the conversation from rain to a wintry one. The first image highlights the extremely warm conditions permeating the whole state today; freezing level is well above 1000 feet above ground level even in the mountains. Thus, the result is rain for everyone rather than snow.

The next image shows the same time next Sunday, and cooler conditions have brought that level down significantly! In some places around the South Sound, this indicates freezing temperatures at ground level. That’s an important ingredient for snowfall and accumulation, but it is just one of several that we need to see a winter wonderland in Western Washington.

It is pretty rare for us to get everything we need all at once, but we are entering the time of year where it is possible, so we can’t rule anything out yet. If you’re a snow fan like me, perhaps you’ll have to come back to the blog each day this week and watch as we get more clarity on if we can put it all together this time around! Have a fantastic Sunday and we’ll be back with more tomorrow!

Reach forecaster Preston Donion at theuwdawgcast@uw.edu, or on Twitter @PrestonDonion