Thursday, May 1, 2014
I’ve actually got some free time on my hand before I get back to doing the last 3/10ths of my linear algebra assignment. So I thought I’d post a blog, because I haven’t posted for a long time. A word of advice… don’t take AMATH 352 at the UW if you don’t have to. Unless, of course, you like that kind of stuff. It’s not required for my atmospheric science major… but I’m just taking it so that I can pick up an applied math minor to add to my oceanography and music minors. I’m taking four intense science classes this quarter and one pretty disorganized one, so I hope ya’ll can empathize to at least some extent with me for my lack of posts. Actually, I have been writing posts, but I haven’t been finishing them because they’ve been too ambitious.
Today was hot. Record hot. With a high of 85, Sea-Tac absolutely obliterated its 1998 record of 81 degrees. And as of 10:38, it’s still 71, which is 9 degrees above our average high. I wonder if the May Day protests have been keeping things from cooling down. The model chart below gives an idea of what the temperature distribution was like this afternoon when temperatures were at their peak.
|Valid 05:00 pm PDT, Thu 01 May 2014 – 12hr Fcst: http://www.atmos.washington.edu/~ovens/wxloop.cgi?mm5d4_ps_slp+2014050112//84/3|
A couple interesting things on this map. First of all, notice how much “colder” Eastern Washington is. While we are basking in record warmth, many places east of the Cascade crest remained in the 70s. If I had to predict a reason for this, it would be that the interior summertime continental heat has not yet really built up yet, and that Western Washington benefited from the warming effects of downsloping air flowing off the Cascades while Eastern Washington did not have this effect. But again, this is all just conjecture.
The second point is actually directly related to the downslope warming on the west side of the Cascades. When air sinks, it compresses, and it warms at a rate of 9.8 degrees Celsius per kilometer. Snoqualmie Pass is approximately a kilometer above sea level, so when air flows down from there, it has the potential to warm the temperatures below by 18 degrees Fahrenheit. In practice, the temperature discrepancy is usually not this great because these parcels of air that sink tend to lose heat at a higher rate than the surrounding air since they are warmer, but the effect is still quite strong, especially when offshore flow is strong like today. That’s why the foothills have the highest temperatures in the above diagram even though they are at a higher elevation than places like Seattle. The air stops sinking once it gets to the foothills, and this heat is radiated back to the atmosphere before it can reach places to the west. Seattle may have reached 85, but North Bend hit 89, and Enumclaw hit 90.
While we are on the topic of downslope flow and North Bend, let’s talk about a different North Bend: North Bend, Oregon. They hit 91 degrees on Wednesday, and they are on the coast. Why? You guessed it… downslope flow off the surrounding mountains. Another fun tidbit; they were warmer than Phoenix that day! Credit to Scott Sistek of KOMO News for the interesting facts. Brookings, Oregon, which is just a bit south of North Bend, tends to experience this effect even more often, and can have freak localized warming as a result. It’s not uncommon for temperatures to be in the 50s along the coast during the winter, yet 70 in the Brookings area. Check out their and North Bend’s record high temperatures for the year.
Here’s an example of a surface observations chart I found on one of Cliff Mass’ old blog posts that shows the Brookings Effect quite well. At 80 degrees, Brookings soars above the 60s and 50s on nearly every other station. By the way, Brookings reached 86 on Wednesday.
Yikes… I’ve gotta get on my AMATH HW… it’s now 11:37 p.m. Researching this stuff takes time. But it feels good to write a blog again. Hopefully I can get back into the swing of things.