Weather prediction technology has come a huge way over the past decades and yesterday's localized snow event is a great example of how far we have come.
The most difficult Northwest forecasting problem is snow prediction.
And there is no harder snow problem than a situation marginal for snow and where there are very localized weather effects.
Yesterday (Tuesday) was such a difficult snow situation and the high-resolution models did very well.
The Forecast
As I described in this blog, cold air was in place and an approaching frontal system brought general very light snow, with heavier snow over North Seattle and Snohomish counties. The models also predicted heavy snow in the Cascades, including its lower western slopes.
Below is the high-resolution WRF model forecast of snowfall through 4 AM today (Wednesday) made 4 PM Monday.
Light snow from downtown through Tacoma (about 3/4 inch), with heavier snowfall (peaking at 5-7 inches) from Lynwood to Everett. Heavy snow in the mountains.
Huge spatial variations. The NWS put out of map with snow reports (see below--with a few additions I put on). The forecast was very, very good.
We simply could not have done anything like this 20 years ago. And this success is not a one-off. Remember the big heat wave in June 2021? We correctly forecast record-breaking temperatures days before. I could give you a dozen other examples of great success.
Improved weather prediction allows society to deal with extreme and unusual weather in a way impossible only a few years ago.
The Problem
Society needs to recognize and use these improved forecasts. Case in point: Seattle Tacoma Airport yesterday. To put it mildly, it was bedlam. Less than an inch of snow resulted in dozens of cancellations and flights delayed for 1-3 hours. The situation was particularly bad for Alaska Airlines, which lacked sufficient deicing capabilities.
The potential for light snow was in the forecast and temperatures were not that cold (just near freezing) that morning. The snow reached the airport around 7:45 AM. Someone from Alaska Airlines told me the issue was that a lot of planes were sitting around on the tarmac overnight and they did not have the hanger capacity to keep them under cover.
How about this suggestion? Put large tarps over all the wings and critical surfaces for planes on the ground during such rare situations? Tarps are cheap.
And then there were the massive power outages from wet snow on branches. Local utilities need to put far more emphasis on vegetation management around their powerlines. Seattle City Light's major outages were in the northern (snowy) side of the city (see below)
The Next Event
More snow and cold are coming to our region, and the snow distribution should be very different. Most of the lowland snow action will be to the south.
Here are the 24 h snowfall totals ending 4 PM Thursday. Snow from Olympia or Tacoma south. Snow over SW Washington and the southern Cascades as well as a good swath of eastern WA.
There is some uncertainty to the northern edge of the snowband...keep that in mind
But WAIT! The snow possibilities don't end there! ANOTHER low center will move offshore Friday afternoon with another front approaching Friday night (see sea level pressure forecast, with low-level temperatures, for 4 PM Friday.
This might bring a burst of light snow to Puget Sound country overnight (Friday/Saturday), with more snow to the mountain (see 24h snowfall ending 4AM Saturday)
Someone should drop off some big tarps at SeaTac Airport for our friends at Alaska Airlines.
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