Europe Model: One Last Storm and Snow Fest In the Mountains

Saturday, December 12, 2015

One Last Storm and Snow Fest In the Mountains

Even native Northwesterners are getting a bit storm weary, but there is one more storm to deal with before the weather cools and calms down. A sea level pressure forecast (solid lines are isobars, lines of constant pressure) show a deep (975 hPa central pressure) low center off northern Vancouver Island at 4 PM. Temperature is shown by the colored shading. Not super warm. That is good for snow.

This afternoon you can expect very strong winds over NW Washington and along the coast, with gusts to 40-60 mph (see the forecast of sustained winds at 1 PM from the UW WRF model).

Wind gusts at Smith Island over the eastern part of the Strait of Juan de Fuca are already (11 AM) reaching 50 knots....and they are still increasing (see below)! These are southeasterly winds, resulting from the interaction of strong southerly winds with the Olympics.

That low center will move eastward across southern BC, weakening as it does so, but still producing a large difference in pressure (pressure gradient) over western WA and the coastal waters. The forecast below at 4 AM illustrates this.

Winds could gust to 40-50 mph around Seattle, particularly near the water. You might want to go to sleep with a flashlight handy.

The freezing level is relatively low right now (about 3000 ft) and with plenty of precipitation from this system, there will be substantial snow today, certainly above 3500 ft. Then the temperatures cool behind the low (northwesterly flow follows) and we will move into a cool, showery regime with moderate snow in the mountains.

Here is the forecast 72-hr snow total for the next three days. We are talking of several feet of snow in the Cascades and Olympics. Very good for skiers. This period will guarantee skiing over the holiday break. And really good in increasing the snowpack for water resources next year.