WeatherWatcher: September, La Niña, Weekly forecast

 

Photo by Carl Dinse

Fall arrived in what seems like overnight with a lot of rain, colder than normal temperatures, and everything changing color. 

September clocked in at 2°F below normal and with 4.27 inches of rain, well above the normal of 2.2 inches of rain. That rainfall amount of 4 inches is more usual for October.

Daily high and low temperatures compared to average in October for Shoreline.

The colder and wetter conditions we've experienced seem to be making up for our very dry and warm summer. 

There is a reason behind the sudden cooler and wetter pattern. La Niña is returning and is expected to persist through most of fall and all of winter. Our weather these past couple weeks is a textbook La Niña weather pattern for the Pacific Northwest.

Seasonal Outlook: For Shoreline and Lake Forest Park, our fall and winter season will be colder and wetter than normal with an earlier start to the cold and wet than last year. Rainfall will likely be above average through most of the fall and winter. Windstorms will probably be close to average, with a few events breaking 50mph and maybe one event over the 60mph mark. 

I think there is a slightly higher chance of a late November to early December snow event due to the early onset of La Niña-like weather patterns. Late December and January are open windows for a larger snow event like the one we had last February, where we got 10+ inches of snow accumulation. 

It's important to note that these weather events are just a little bit more likely. There is also a chance we will see little or no snow, or little or no windstorms, or something much more severe. La Niña years, especially back-to-back ones, generally favor more rain, colder, and potentially more snow.

Weekly Forecast: This weekend and next week temperatures are expected to remain colder than normal. We are even looking at lows dipping into the 30's early next week. Highs are expected to be in the upper 50's and low 60's for both Saturday and Sunday. 

Saturday is a transition day, with mostly cloudy skies and some fog possible in the morning hours. Rain moves in late in the afternoon with steady rain Saturday evening turning over to showers going into Sunday morning. Sunday afternoon and evening look to be cloudy, and showers likely with a slight chance of a thunderstorm.

Monday and Tuesday look sunny, with highs in the low to mid 50's and lows near 40 Monday night into Tuesday morning, possibly 37-39°F away from the water. Tuesday through Friday chances of rain return for each day, with temperatures ranging in the low to mid 40's for lows, and low to mid 50's for highs.

For current weather conditions visit www.shorelineweather.com