No wonder the Weather Channel is avoiding us.
The visible satellite imagery at 7:15 PM Tuesday shows some offshore clouds and a few convective showers over the eastern Cascade slopes and southeastern BC.
But boring can also be revealing, exposing weather phenomena normally obscured by active weather.
Let me prove this to you. Question. If the large scale weather pattern is static with no storms or weather features approaching or leaving, will surface pressure change?
The answer is yes. Lets take a look at the surface pressure variations at Seattle Tacoma Airport for the last three days (the top panel is sea level pressure, next precipitation, and then solar radiation). The precipitation was obviously flat-lined, but look at pressure--you see those wiggles?
On each day, pressure tends to be highest around 18Z (Zulu or Greenwich Mean Time), which is 11 AM PDT. Pressure tends to be lowest around 00 Z (5 PM).
I did a paper on this subject once and here are the average pressures through the day for various locations around the world. You see the semidiurnal pressure variation? They are bigger in Miami than Seattle (Denver is large because of mountain effects I won't get into here).
So you ask, why is pressure varying during the day? Is is heating at the surface during the day and cooling at night?
It turns out the answer is no...most of the pressure variations is due to an atmospheric tide in the upper atmosphere.
You know about tides. They occur because of the attraction of the moon and there are two highs and lows. Here is an example for Milford, CT for one day. Two highs and two lows.
Seattle School Board Race
I strongly support Sue Peters for school board and I hope you will too. She has been a strong advocate of better math in Seattle Public Schools and I have been extraordinarily impressed during my interactions with her. She has a very impressive educational resume, including serving on a number of district committees and task forces, has a respected education blog, has been an active volunteer in local schools, and was a founding member of the Seattle Math Coalition. Sue is supported by FOUR of the current school board members and has a long list of endorsements by local organizations. The Seattle Times, the supporter of corporate education philosophy, endorsed her opponent...another sign that Sue is on the right track.
Check out her web site at: http://suepeters4schoolboard.org/http://suepeters4schoolboard.org/
Please vote for her in the primary and support her campaign.