The Stratosphere Plummets over Seattle....and Huge Precipitation Contrasts

Today, the stratosphere was much, much closer to you than normal, and we all lived to tell the tale.

As many of you know, the lowest layer of the atmosphere is the troposphere, where nearly all the weather occurs (see below).  Temperature generally decreases with height in the troposphere (red line)

Above the troposphere, there is the stratosphere, where the temperature increases with height...first slowly, then rapidly.

Temperatures are warm near the surface due to the heating of the surface by the Sun, while aloft the heating is due to the absorption of ultraviolet radiation by the ozone layer.

Over our region, the boundary between the troposphere and stratosphere (the tropopause) is typically around 35,000 ft... just a little above the typical cruising altitude of jet aircraft.

You can often see the boundary from your aircraft window.   Clouds and haze in the troposphere, clear air and blue skies in the stratosphere (see below)

Something dramatic happened this morning to the boundary between the two layers (again, the tropopause).

It plummeted from roughly 35,000 ft to around 23,000 ft.  

If you were flying above western Washington this morning at typical cruise altitude, you were deep into the stratosphere, with lots of ozone being ingested into the aircraft.

How do I know the stratosphere was that low?   

Because there was an ascent of a National Weather Service radiosonde (balloon-lifted weather instrument) that showed the situation clearly.

Here is the plot, with red being temperature and blue dew point.  Temperature stopped cooling, and air became very dry (indicated by the dew point declining rapidly) around 400 hPa pressure, which is found around 23,000 ft.

Weather forecast models create a map of the height of the tropopause, and one was shown before 5 AM this morning.    

It is very high over the warm tropics and lower near the poles.  

But there are also complex distortions in the height of the stratosphere over the midlatitudes and polar regions, and one such structure was over our coast, with the blue color indicating a downward distortion of the tropopause.

Weather balloon went right into this.

This local distortion of the tropopause was due to a well-defined upper-level trough this morning, indicated by the blue colors and the low "L" in the figure below

How unusual was the descent of the stratosphere to 23,000 ft this morning?   I checked the radioaodne data for the last 50 years.   

It was the tenth-lowest excursion in October on record.

Impressive.

Finally, since I am talking about impressive things, how about the total precipitation around the Olympics over the past 48 hours (below)?

Nearly five inches on the southwest side and 0.17 inches on the northern flank near Port Angeles. 

We are talking about a factor of over 25 times!  

Why did this occur?  

With the low offshore, strong moist winds approached the Olympics from the southwest and were forced to rise, releasing a large amount of moisture as rain.  

On the northern side, the air sank, was warmed by compression, and the relative humidity dropped, killing any precipitation.

You got to love living here... 👴