Yesterday, some pretty strong storms rolled through areas of Western Washington, bringing vivid lightning, torrential downpours, and even funnel clouds to multiple locations throughout the state. With cool air aloft and high sun angles warming the air at the surface, the atmosphere quickly became very unstable, and vigorous thunderstorms quickly developed.
In order to show you how unstable the atmosphere was, I’ll show you a sounding of the atmosphere, which is a trace of the temperature, dewpoint, and wind velocity (and other associated parameters) from ground level to nearly 100,000 thousand feet as measured by a radiosonde, which is a package of instruments that is launched by a balloon and floats well into the stratosphere before the ballon pops and the instrument package parachutes safely back to Earth.
Today’s radiosondes can measure temperature, humidity, solar insolation, and pressure, and they have a GPS sensor so that they can calculate their precise location throughout the atmosphere and therefore calculate windspeed and direction as well. As they rise throughout the atmosphere and take measurements, they send their measurements back down to earth via radio transfer, generally at a frequency of either 403 MHz or 1680 MHz.
Credit: Plymouth State University
Here’s a picture of a guy launching a radiosonde. Although it looks easy in this picture, it can be quite difficult in inclement weather! I’ve seen some videos of some UW graduate students trying to launch one in a windstorm, and they were entertaining to say the least.
Credit: NOAA
Anyway, the left diagram in the picture below is yesterday’s 5pm sounding from Quillayute on the Washington Coast. The red line marks the temperature and the green line marks the dew point. Also, keep in mind that this is a “skew-T” chart, meaning that the temperature contours are diagonally skewed and not vertically parallel. The dotted pale yellow and two blue diagonal lines delineate constant temperature markings, meaning that the temperature from 300 mb up to 100 mb is more-or-less constant at -50 degrees C. Brr!!! The picture on the right is a hodograph, and I’ll go into that in more detail on a later blog.
There are a lot of variables to explain here, but the main thing that this Skew-T sounding shows is that the lower atmosphere is moist and unstable, meaning that there is a large decrease in temperature with height and that warmer, less dense air from the surface has a tendency to rise and create clouds/precipitation. From the surface to 3,000 feet, the temperature decreases at a rate of 8 degrees C per kilometer, which, although not otherworldly, is nevertheless impressive for our region, especially for mid June.
Regardless of what the temperature and humidity soundings were like, some places got absolutely walloped with rain. Tacoma was one of those places. Take a look at this radar image showing a powerful thundershower entering the region around 1 pm. Reds equal very intense rain. Be sure to check out this video that “Kalieh” sent to King 5 showing substantial urban flooding in Tacoma. It’s pretty amazing stuff!
Additionally, there was a TON of lightning around the region yesterday, especially in Oregon and off the coast. It’s very rare that we see that many strikes west of the Cascades!
And now for the grand finale – there were FOUR separate funnel cloud reports that viewers sent into KOMO alone! Check them out on Scott Sistek’s blog here. In the public domain, the United States Coast Guard spotted a waterspout off Cape Disappointment. I wouldn’t want to get caught fishing in one of those!
Happy Father’s Day to all you dads in the house, and thanks for reading the blog!
Charlie
