We will nonetheless count on to see lowland snow tomorrow, and being nearer in time, I’ve highly effective further forecasting instruments to use.
However earlier than I achieve this, let me notice that there was an impressive auroral show final night time, principally behind the clouds, and through some openings, the sky was aflame.
Right here is a picture from North Kitsap, supplied by climate cam maestro Greg Johnson of Skunk Bay Climate. Beautiful.
Again to snow.
That is late season for western Washington/Oregon snow and temperatures are marginal. However with adequate precipitation depth, melting and evaporation can drive the snow stage right down to the floor. The end result: moist snow.
The most recent forecasts are converging on round 2 inches close to sea stage, however as we’ll see, there can be appreciable variability.
The function of curiosity is a low middle (and related fronts) that’s centered off the Oregon/Washington coast proper now (see picture). Proper now some weak bands of precipitation are over land. Some gentle drizzle and snow showers.
That low middle will drift to the northwest in the course of the subsequent 24 hr, related to an approaching upper-level trough of low strain. The ocean stage strain map at 4 AM tomorrow (Tuesday) is proven as an example.
Now, let’s study the forecast mannequin output.
The entire snowfall (not snow depth) by way of 4 PM Tuesday from the uber-resolution UW mannequin is proven beneath. Maybe 2 inches within the central Sound, with much less over the hotter water. Comparable quantities over Bellingham and the San Juans. Much less south of Seattle.
The European Heart mannequin, with far much less decision, has a fuzzier however comparable forecast.
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If I’ve tried to speak one thought on this weblog, it’s that forecasts have uncertainty and meteorologists should outline this uncertainty and talk it.
If solely politicians, Covid-forecasters, and a few native newspapers did the identical.😆
A key instrument for outlining forecast uncertainty makes use of an ensemble of many, however believable forecast simulations. The UW runs among the best such ensembles within the nation and you’ll benefit from the fruits of this expertise.
For instance, right here is the ensemble snow forecast for Seattle. Strains present totally different forecasts, with the black line being the common of all of them.
The snow revs up after 10 PM tonight (06/28), with appreciable uncertainty. The typical whole snowfall is about 2 inches.
Olympia? Some snow this AM they usually find yourself with about 3 inches by tomorrow afternoon.
Portland ought to get about 1.5 inches.
The European Heart has a lower-resolution ensemble. For Seattle, it suggests about 3-4 inches.
So plan for snow in a single day into tomorrow morning. And with above-freezing temperatures, no ice ought to bond to the floor. And it’ll heat up tomorrow afternoon with onshore move behind the low.
