Super Inversion and Record Heat

 The temperature inversion today over Seattle is one of the strongest I have ever seen.

As a reminder, an inversion is when temperature increases with height, in contrast to the normal decrease with height.  

The conditions at SeaTac Airport this morning are shown below.

42°F at the surface and 61°F at 2100 feet.    

19°F warmer.    Just amazing.

Some of the local temperature contrasts this morning were stunning, with cold air at lower elevations, and MUCH warmer temperatures on hills or downwind of hills.

To illustrate, consider the temperatures this morning near Carnation, Washington.  A range from 60 to 39F over a few miles.  60 to 42°F over a short walk.

A super-inversion was also observed on the coast at Forks (see below, temperatures in °C and height in pressure, 700 hPa is about 10,000 ft)

The UW high-resolution weather prediction for this morning had the general pattern right, with the warm temperatures associated with easterly (from the east) winds down the western slopes of local terrain.  

But it failed to get the lowest temperatures correct. Current modeling systems have too much vertical mixing and thus fail to maintain the low temperatures at the bottom of inversions.  We are working on this.

The record high for today at SeaTac is 64F (see below).   There is a good chance we will tie or beat it.

What weather pattern is producing such an extreme inversion?  As shown by the 500 hPa heights (pressure around 18,000 ft), there was a huge ridge of high pressure over the western US.  Such high pressure is associated with great warmth aloft and a lack of serious clouds.

As the sun heats the surface, it causes vertical mixing, the warm air will be brought down to the surface, and daily record high temperatures for the date are quite possible.

 Here are the predicted temperatures at 2 PM this afternoon.  Western Washington will be torrid, especially on the slopes..   Several stations will climb into the low to mid-60s today in western Washington.  Perfect for a walk, bike ride, or raking up leaves.  Much cooler in eastern Washington.  

I am planning on a long run this afternoon.😀