Wednesday, February 16, 2011

Lowland Snow Chances Fading on Thursday

Forecasting snow over the western Washington and Oregon lowlands is a subtle game. To get snow, everything needs to set up right...and as I have noted before, it is easy for us to be mild and wet or cold and dry, but to be cold and wet takes some doing around here.

The models on Monday looked like we had a significant shot at lowland snow, particularly above a few hundred feet and away from the water. But the trend of the recent runs has been a westward shift of a key feature--a trough coming out of the north--which could leave us with too little moisture.

Here is the forecast from Monday

And here is the graphic from this morning's run:
Spot the differences? Much more energy offshore (stronger trough, stronger flow) in the latest run and that makes all the difference. This subtle shift results in most of the precipitation and falling pressure offshore. There could be a few showers reaching the western lowlands, but they will be scattered and only higher hills have a chance of getting some snow showers. Better chance for light snow on the coast.

As the trough moves offshore and south of us the skies will clear and the second part of Friday and Saturday should be dry. All kinds of interesting possibilities for Sunday...(yes even snow)...but that will await another blog.

We do have relatively cool air over us now and there will be some convective showers...particularly along the coast. (see satellite picture) Strong showers can bring the snow level down...even to the ground... today. In fact, Hoquiam is reporting light snow now! So don't be surprised if some locations get a snow shower today. You can see how the air became less stable during the day with from the following video. We had cold air aloft and then as the surface heated, the rate of change of temperature with height increased and the atmosphere destabilized, producing increasingly strong cumulus cells (click on picture)




By the way, here is a table showing where we are snow-wise in the mountains:


The higher volcanic peaks are doing ok (Timberline, Mt. Baker, Paradise), but the lower passes, especially in the middle Cascades are way below normal. Not the bountiful snow of a typical La Nina year...but it is not over yet. California is picking up plenty of mountain snow right now, which is very good for their water situation this summer.

PS: Just a reminder...I will be giving a dinner-time talk at Ivar's Mukilteo Landing Restaurant at 7 PM on Wednesday Feb 23rd. The subject: the strong westerly wind surges that push down the Strait with winds approaching hurricane strength. One destroyed the restaurant in 2003. Another half-destroyed the WS Ferry Elwha in 1990. Anyway, the restaurant was rebuilt with a weather theme and they just put up a cam and weather station. If interested, you should make a reservation (see information on the right side of this blog).

Newsflash: For this gathering the bartender has come up with an exciting new drink: the STRAIT SURGE. This may be the first meteorological phenomenon with its own drink. History will be made.

The destruction of the Mukileto Landing Restaurant will be the theme of this talk. Trying to get Gordon Lightfoot to pen a song.

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