February 18, 2014

Some weather tidbits

I had to scrape the rust off this blog this morning – has it really been more than six months? Anyways, here is an olio of weather-related things that popped up this morning.

Mount Rainier in the snow

Today Cliff Mass of the University of Washington wrote on his meteorology blog about the big snows that are hitting the Cascades this week and included this picture of the Jackson Visitor Center at  Mount Rainier National Park:

Jackson Visitor Center yesterday (2/17/2014)

Jackson Visitor Center yesterday (2/17/2014)

For those of you who have not seen this splendid new building and might be deceived by the scale of the photo into thinking you are looking at something the size of an outhouse, here is a shot I took on our visit last July. It’s a big building!

Jackson Visitor Center, July 2013

Jackson Visitor Center, July 2013

MF Snow Depth

Cascades Snowpack

Up here in the North Cascades the mountain snowfall has been below average so far this winter, but not nearly the sort of drought you’ve been reading about down in California, Oregon and even southern Washington. (Down here in the NW lowlands we’ve had modest rainfall and snow has been nearly absent.)

Dangnabbit!! I just lost half of this post! I made an accidental click on a bookmark and the browser left the page without warning. I thought WordPress did some auto-saving but I guess not. Here we go again…

To document the situation, here is a graph that I’ve concocted out of data from a remote monitoring station belonging to the Soil Conservation Service and located at about 5000′ elevation on Lookout Mountain. (No, not that Lookout Mountain! And not that one either! It seems there are as many Lookout Mountains and there are Mud Lakes and Boulder Creeks.) This one is a few miles WNW of Mount Baker near the Heliotrope Ridge trailhead. The graph shows the water equivalent of the snow on the ground – essentially a measure of the weight or mass of the snow. This gives the best estimate of the meltwater that is going to be available to water crops the following summer, which is what the SCS is interested in.

The squiggly red, orange and green curves are for 2011, 2012 and 2013, respectively; the smoother purple line is an average for most of the 15 years or so that the station has existed.

For us hikers, the most pertinent thing is the point where the curve drops back to the axis, indicating that most of the high country hiking trails will be snow-free. Recall that 2011 (red) was the year that the DOT (Department O’Truckin’) could not open the road to Artist Point. And last year (green) there was above average snowfall but it melted so quickly that the hiking trails were available a bit early.

You have to look closely (or expand the picture) to see this year’s dark blue curve – it has been below but very close to the average for the water year so far – you can see a little uptick in response to the recent storms.

The thing that always strikes me first about this graph is the way the curves are clumped pretty close to average until about this time of year. The high snow years didn’t really start moving off average until February or, in the case of 2011, even March or April.

So the upshot is that we are having a fairly average year.  And what does that tell us about next summer hiking?

Nothing. Or maybe less. But talk to me again in April.

WunderMap radar image of NW Washington & SW BC

WunderMap radar image of NW Washington & SW BC

Rain Shadow

I close with a screenshot from this morning of the weather radar over NW Washington – it gives a vivid picture of the Olympic Rain Shadow. The precipitation pattern looks like a doughnut with a big hole over Whidbey Island and the eastern end of the Strait of Juan de Fuca. The story here is that storms, like this one, tend to come in from the southwest, riding the prevailing winds. The first terrestrial obstruction they encounter is the massif of the Olympic Mountains, which drives the air up and wrings the moisture out if it. Places on the windward flank like Aberdeen and Forks will get massive amounts of rain (100″ per year or more) while spots in the lee, such as Sequim and Port Townsend, receive Arizona-like rainfalls of 10″ or less.

There is another gap in the rainfall pattern directly over the Olympics, but I’m going to put that down to the fact that the radars, being located down near sea level, do not do a good job of seeing rain in high mountains. The main radar station in this area is located on Camano Island and has a clear view out over the water but not up into the Olympics.

BTW this image is from the “WunderMap” produced the weather site called Weather Underground. The name is kind of a snarky reference to the radical 60s group but it’s the best weather site I’ve found. I especially use their link to the Scientific Discussion to get a behind-the-scenes look at the forecast.

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