Cold Wave Arrives Northwest With Snow Falling On The Mountain. There may be snow in the lowlands.

We enjoyed an unusually dry, mild weather in mid-November, and Thanksgiving Day was a delight, but now the dangerous signs of La Nina winter are about to emerge.

The air is cold and freezes hard will hit the entire state next week, with heavy snowfalls in the mountains that will delight the ski community.

We should all take steps to deal with the coming cold, from removing outdoor faucets and protecting pets, to ensuring that the large number of homeless people in the area are brought inside. in or protected.

The upcoming situation is typical for a La Nina winter, in which the central and eastern tropical Pacific Ocean is colder than usual. During such winters, we often observe a large band of high pressure developing over the northeast Pacific, with cool, northerly (from the north) currents to its east (see illustration). higher level map graphics for Saturday at 10pm).

If there’s a disturbance in that northerly stream, moving south of Alaska, we could have mountain snowfalls, and if these trenches are positioned just right, there could be lowland snow. .

As in any good play, the action can be divided into several acts.

Stage 1: Initial cooldown and Snow on the Mountain.

Today (Friday) a cold front is moving through bringing more rain to the area and snowfall at higher altitudes. On Saturday and Sunday night, a low pressure trough will enter, causing further colder temperatures and more snow in the mountains. Take a look at the totals through Monday at 4pm. Some feet in the mountain!

By Tuesday morning, the cool air mass behind the high-rise trench will move into this area (see map forecast at 4 a.m. Tuesday). The color indicates an air temperature of approximately 2500 ft. Blue indicates the air is cold enough to have snow, and purple indicates icy, icy air. This arctic air is associated with high pressure, resulting in low-level northeasterly winds in the Fraser River valley that will begin to move into Bellingham and vicinity.

Act 2: Second trough, colder air and possibility of snow in the lowlands

On Wednesday, the second trough will move south out of Southeast Alaska (see the higher (500hPa pressure level) forecast below at 10 a.m. Wednesday). Not perfect for snow in the lowlands west of the Cascades, but close.

This higher trough creates upward motion and precipitation, and will align with a low center of the surface that will move over the central coast of Western Australia on Wednesday afternoon (see sea level pressure forecast, with low temperatures below).

This model will also suck cold air into northwest Western Australia.

This cold front will then move south and by Friday morning, the whole area will turn cold. VERY cold east of the Cascades. RADIATION on the east side of the Rockies of Montana.

The question would be about precipitation, and therefore snow. The UW WRF latest forecast is producing some snow in the lowlands. To illustrate here is the total snowfall for the 24 hours ending at 4 a.m. Thursday. Most lowlands get several inches.

What about Central Europe’s high resolution snow forecasting model? It snowed in the lowlands, but about 12 hours earlier and further north.

For an extended forecast with uncertainty, you should consider a set of multiple forecast runs. Here is the full European Center forecast for snow at SeaTac Airport. The top panel shows the snow forecast for each of the 51 different model runs, while the bottom panel shows the high-resolution forecast snow forecast (blue line) and the group average .

Both high resolution and set prediction are for several inches. But beware of a problem of such populations: the model’s resolution is low, which tends to increase snow near sea level (because you’re smearing predictions of higher snow at higher altitudes on lowlands).

Key point: you can be sure of lots of snow in the mountains and a big cold snap next week. There is a high chance of snowfall in the lowlands west of Washington but significant uncertainty at this time. By Monday, we should have a very good idea of ​​what’s going to happen.

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No Podcasts Today…Thanksgiving Holiday!