If you’ve been outside at all over the past couple weeks then you know it’s definitely that time of year again. Time to take a peak into what our winter weather season might have in store for us. My “forecast” for this coming winter is more of a statistics based outlook than an actual forecast. I looked at and reviewed past years which had similar sea surface temperatures and similar weather patterns to make my prediction. Years with similarities are called analog years. Based off of analog years (years with similar conditions), current forecasts, and recent sea surface temperature trends, it seems clear we will experience a La Nina this winter.

What is La Nina, and what are the effects here in Oregon? In short, La Nina is a cooling of the sea surface temperatures in the Pacific Ocean off the coast of South America. I used arrows in the the image below to highlight that cooling. I also pointed out the cooling south of Alaska as this too can directly effect our weather.

Basically you can count on a La Nina winter being active with more weather action taking place than in a typical winter. The primary impacts being wetter than normal, cooler than normal, a good mountain snowpack, higher chance for major flooding, and increased chances for valley snow. Let’s break those down in detail.

1.) WETTER THAN NORMAL Perhaps the number one thing which stands out to me is how wet La Nina winters typically are in the valley. All 9 analog years I reviewed in detail gave Salem either near average or above average precip. This lends pretty solid confidence we will end up with a fairly wet/rainy winter with plenty of rain and mountain snow which is great news for our ground water and drought conditions. As is the case every winter, Salem should still see a number of dry days mixed in. The key thing to remember is that overall between now and March we have a higher chance of ending up wetter than average.

2.) SOLID MOUNTAIN SNOWPACK Odds significantly favor an above normal mountain snowpack this year which is great news for skiers/snowboarders and very good for our water supply with a solid above average snowpack occurring in all 9 analog years! One caveat is a few of these analog years got off to a slow start in the snow department meaning Nov and Dec weren’t necessarily real good in terms of mountain snow; however, all of the years analyzed ended up with an excellent second half of the ski season as snow ramped up nicely in Jan and Feb. Bottom line is whether it starts early or takes its time, a good mountain snowpack this winter is a safe bet. This image from Mark Nelson over at Fox 12 Oregon does not include last winter’s La Nina; however, the point seems clear that La Nina winters tend to bring really good snowfall totals to our mountains which is why I’m feeling confident we see a good mountain snow season this year.

3.) FLOODING  This next one is not good news. Keep in mind I’m strictly talking odds here by looking at what happened in past La Nina winters, but for this one the odds are not in our favor. Of the 9 years surveyed, 5 saw a notable (either moderate or major) valley flooding event. The percentage of La Nina years with significant flooding events is high when compared to non La Nina winters. Below is a list of historic flood events on the Willamette River in Salem. This list only contains floods occurring since flood control dams were built in the 50s. It’s no coincidence 10 of Salem’s 13 worse floods occurred in La Nina winters, and it makes sense. It’s a natural consequence of having lots of mountain snow and more rain than normal. So while it’s far from certain, one would be wise to keep this in the back of their mind as the odds of seeing some sort of flooding event this year are higher than normal.

4.) COOLER THAN NORMAL 8 of the analog years ended up as either average or cooler than average. Basically don’t expect a “mild” winter.

5.) VALLEY SNOW  Perhaps the most anticipated question is whether or not it’s going to snow here in the valley. Well, all 9 analog winters produced at least some snow here in Salem. 😉 Breaking it down further this is where it gets tricky. 5 of the 9 analog winters I reviewed in detail gave Salem a legit snowstorm with several inches of snow. The other 4 only saw minor accumulations of a slushy inch or so which is not really enough to enjoy in my humble opinion. So take it for what you want, but odds are quite high we at least get a dusting of snow at some point this year, and more importantly, odds are somewhat higher than normal we see a respectable sized snowstorm this winter bringing us several inches of snow. Far from a slam dunk as I like to say, and we are talking statistics, but it does provide some extra hope for us snow lovers.

So yes, may the odds be ever in our favor. Here’s a quick recap for you:

1.) Odds favor a wetter and stormier than normal winter overall.

2.) Odds favor a good mountain snowpack and good year for ski resorts.

3.) Increased odds for a significant valley flooding event.

4.)  Cooler than normal weather (overall) is likely.

5.) Higher than normal odds for a more significant snow event here in the valley.

The odds definitely favor a more active winter, but only time will tell, so be ready for anything. If you have been reading my posts over the past year then you know I’ve really hit hard the idea of having supplies on hand at home for when a disaster strikes. Look at the severe impact Covid-19, last year’s wildfires, and the major ice storm all had on our community. You want to be prepared. For example, even if you don’t live in a flood plain it’s still a good idea to be ready for a major flood as such an event would likely effect the supply chains to our local stores. Something to think about.

Okay, I’ve laid it all out there. I really hope you all have a nice fall and winter season. I personally really enjoy the extra time with family and friends fall and winter brings along with the holidays and festive activities which accompany this time of year. Focus this season on what is important in your life and enjoy the people around you God has placed in your life. Regardless of what happens weather wise I enjoy being your forecaster and and I hope it’s a safe, enjoyable, and fun season for you all!!