Weather prediction technology has evolved tremendously over the past decades, and yesterday’s local snow event was a great example of how far we’ve come.
The most difficult Northwest forecasting problem is predicting snow.
And there is no snow problem more difficult than a situation where there is snowfall and where there are very localized weather effects.
Yesterday (Tuesday) it snowed very hard and the high resolution models worked very well.
forecast
As I described in this blog, cold air has entered and an approaching frontal system brings in generally very light snow, with heavier snow in North Seattle and Snohomish counties. Models also predict heavy snow in the Cascades, including its lower western slopes.
Below is a high-resolution WRF model predicting snowfall until 4 a.m. today (Wednesday) taken at 4 p.m. Monday.
Light snow falls from downtown to Tacoma (about 3/4 inch), heavier snowfall (5-7 inches high) from Lynwood to Everett. Heavy snow on the mountain.
Large spatial variations. The NWS takes off the map with snow reports (see below–with some additions I’ve included). The forecast is very, very good.
We simply couldn’t do anything like this 20 years ago. And this success was not a one-time thing. Remember the big heat wave in June 2021? We accurately forecast the record breaking temperature the day before. I could give you dozens of other examples of great success.
Improved weather prediction enables society to deal with extreme and unusual weather in a way that was not possible just a few years ago.
Problem
Society needs to recognize and use these improved projections. Case in point: Seattle Tacoma Airport yesterday. To put it mildly, it’s bedlam. Less than an inch of snow caused dozens of flights to be canceled and flights delayed for 1-3 hours. The situation is particularly dire for Alaska Airlines, which cannot afford to defrost.
A slight chance of snow was forecast and temperatures were not too cold (just barely freezing) that morning. Snow arrived at the airport around 7:45 am. Someone from Alaska Airlines told me that the problem is that a lot of planes are parked on the runway overnight and they don’t have the hangar capacity to keep them under the roof.
How about this offer? Placing large tarps on all the wings and surfaces important to the plane on the ground in such rare situations? Tarps are cheap.
And then there was the widespread blackout due to wet snow on tree branches. Local utility companies need to put much more emphasis on managing the vegetation around their power lines. The major Seattle City Light outage occurred in the (snowy) north side of the city (see below)
Next event
More snow and cold are coming to our area, and the snow distribution will be very different. Much of the lowland snow activity will be in the south.
Below is the total snowfall for the 24 hours ending at 4pm on Thursday. Snow from Olympia or Tacoma to the south. Snow fell in southwestern Washington and the southern Cascades as well as a large swath of eastern Western Australia.
There is some uncertainty about the northern edge of the ice sheet…keep that in mind
But WAIT! The snow possibilities don’t end there! Another low will move offshore Friday afternoon with another front closing Friday night (see sea level pressure forecast, with low temperatures, for 4pm Friday.
.gif)
This could bring some light snowfall for the Puget Sound country overnight (Friday/Saturday), with more snow in the mountains (see 24-hour snowfall ending at 4am on Saturday)
Someone should drop some big tarps at SeaTac Airport for our friends at Alaska Airlines.
