WeatherWatcher: Winter outlook and this week's forecast

Sunday, October 20, 2019

Winter day on NE 185th St I-5 overpass
Photo by Carl Dinse

I've been seeing a lot of headlines and getting a lot of questions about what this winter might hold in store for us. So it's that time again when I tell everyone what I think might happen this winter, and scare you with all the possibilities.

Today, we seem to be lining up pretty close to the 1967-68 winter. The mid season snowfall last February and coming off an El Niño winter with a near neutral PDO index (Pacific Decadal Oscillation) lines right up with the 1967-68 time frame. That winter had a couple of snow events, around 3-4" in December and about 8" of snow in January. 

The Pacific Decadal Oscillation (PDO) index is near neutral, slightly in the cool phase. We had a warm blob off the west coast that has been dissipating, and the Pacific ocean seems to be configuring itself for a cool phase. The PDO is a fairly recently discovered oscillation and a method of forecasting it is not well developed. So right now it's hard to say if the PDO is going to go into a full cold phase, or remain neutral or otherwise. Cool phases of the PDO typically, but not always, have influenced more lowland snow events and arctic outbreaks for the area.

The El Niño Southern Oscillation is in a neutral phase, and expected to remain that way through the 2019-2020 winter. That means, no El Niño, and no La Niña, so there's no cooler and wetter or warmer and drier influence there. Neutral years tend to be more stormy and more variable than an El Niño or La Niña.

The upper atmosphere jet stream has been favoring the same patterns as last February, which is why we've been cooler than normal much of the last 45 days. I think we should expect to see this intermittent blocking and trough pattern throughout the winter season.

What does this mean for our winter? Stormy periods, warm periods, cool periods, a couple of lowland snow events, and a fair share of windstorms. It's likely we will see our first taste of lowland snow near Thanksgiving. I'm feeling we have a solid 50% chance of another prolonged arctic outbreak sometime this winter as well, complete with a solid snow cover. I also think we could see a couple atmospheric river events, with more rainfall than the ones we've been seeing the past 5 years or so.

So, a lot of this:

A few of these:

One or two of these:

Finally a 50% chance of this:

Between now and the first week of November is probably a good time to get yourself prepared for winter storms. 

Bottom line: We are not likely to have a mild or calm winter.

This week's Forecast: We have a stormy start, but a calm ending to this week's weather forecast. 

Monday is going to likely be another breezy and wet day. Monday evening may see some pretty good wind gusts up to 35mph, not quite strong enough to reach high wind criteria. Rainfall amounts for Monday could be significant; up to 1-2 inches of rain is possible. High near 57°F, a low near 50°F.

Temperatures Tuesday through the weekend vary between the upper 50's to right around 60°F. Lows in the mid to upper 40's to around 50°F. Showers Tuesday, Thursday night, Friday, and Saturday. Partly to mostly sunny skies Wednesday-Sunday. Yes, the forecast calls for partly sunny skies, and a chance of showers on some of these days later in the week.


For current weather conditions visit www.shorelineweather.com




2 comments:

Unknown October 21, 2019 at 9:30 AM  

Thanks so much Carl!! I was wondering because it seemed it is a bit stormy early this year! Bobby's Mom

Nanook October 23, 2019 at 4:56 PM  

Just to add to the fun, this is one of the deeper solar minimums we have on record, periods of low solar activity tend to bring the jet stream further south and that tends to bring arctic air down and storms. So this is
further indication this winter is not going to be mild.

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