Never Too Late To Snow

Monday, April 29, 2013
10:52 P.M.

First off, let my apologize for my lack of punctuality when it comes to posting these blogs as of late. I’ve been very busy recording an album for a funk band I am in, and I have had a string of seizures to boot. Thankfully, the album is almost done, and I’ll be going into the Swedish Neuroscience Institute on Thursday to get some brain tests done and see if we can get the seizures under control. If anybody knows how to fix the human body, it’s those Swedes. I’ve also been in the process of writing a more in-depth post about a climate talk I went to, but when the Snoqualmie Pass WSDOT cams took my breath away today, I knew that the Weather Gods were calling upon me to write a quick blog in the immediate future.
In any event, I hadn’t been following the weather closely, so I was extremely surprised when I saw a layer of white covering I-90 from Denny Creek to Easton. I’ve seen Snoqualmie Pass covered in snow in mid-June, so it wasn’t the time of year that had me trippin’. What really struck me was that most regions in the sound reached the mid-to-upper 50s today, which meant that for there to be sticking snow at Denny Creek (I think Denny Creek is at approximately 2,000 feet), there must have been an incredibly steep environmental lapse rate (decrease in temperature with height). This would imply that the atmosphere was very unstable, but I don’t recall seeing any massive cumulonimbus popping up over the area this afternoon. 
I tried to get the Sand Point profiling data which would give me an estimation of how the temperature varied with height, but I was having problems opening the .gif files from the profiler. Instead, I decided to look at the radiosonde soundings from the 00z Quillayute weather balloon launch. The plot below shows the temperature and winds as a function of increasing elevation (and hence decreasing pressure), and it also gives the statistics for things like CAPE (Convective Available Potential Energy) and other acronyms that are Greek to me.
This plot is called a “Skew-T” plot because the axes for temperature are angled and have a positive slope instead of simply being vertically oriented parallel to the y-axis. At first glance, it would look like the temperature more or less remains the same before increasing in the upper levels up the atmosphere, but once you know that this t-plot is skewed, you know that the temperature decreases until it more-or-less flattens out above 200mb. We are concerned with the air near the surface, and you can see that there is an extremely rapid decline in temperature with height between the 1000-900mb levels.
Here are the current conditions along I-90. Seattle has cooled down to 46 degrees, but it is still snowing well below the pass. This snow will continue throughout the night before dying down tomorrow morning.
The Summit at Snoqualmie is technically still open for the season, and they claim that the last day they will be open is May 5th for Cinco de Mayo. I hope to be up there listening to Jimmy Buffett with the best of ’em, but even if that doesn’t end up happening, I would not be surprised in the least if they extended the season for another week. This is what happened during the massive snow year of 2007-2008, and I skied the Alpental Backcountry on Memorial Day of that year, which was officially the last day any part of the Summit was open. Don’t count on them keeping it open much longer though… even if there is enough snow, they still gotta find a way to make a profit. And if only season’s pass holders are coming up to the slopes, Boyne is losing money.
Thanks for reading! My brain is still a little scrambled for a seizure I had Sunday night, so if you come across any awkward phrasing, cut me a little slack. I’ll get my other post-in-progress up soon.
Charlie
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