Eatonville Heat Wave

This morning, one area of western Washington warmed into the lower 60s, with brisk southerly winds--more like Hawaii with strong trade winds than western Washington in midwinter.

The location? The area around Eatonville (near the SW entrance to Mt. Rainier).  Here is plot of the weather conditions there (time is in GMT, so 1256 is 4:56 AM).  Temperatures were in the 50s overnight and rose to 60F at 5:55AM!  Temperatures help up until 1855 GMT (10:55 AM), after which cooling occurred.  Why so warm?   Hint:  look a the winds.  Winds turned southerly and were strong at the temps rose.

 Take a look at a plot of the observations around 10AM.  There was a whole region of warmth around Eatonville that extended toward Enumclaw and southwestern Tacoma.  At the same time that Eatonville luxuriated at 60F it was only 42F at Renton.  I could make a Renton joke here but will fight the urge.

We can get an idea of the type of air moving into the region by looking at the radiosonde upper air observations at Salem, Oregon--see below.  Strong winds from the southwest and quite warm air aloft (12C,54F) above colder air near the surface.

And what is immediately upstream of Eatonville?  Substantial terrain, reaching 3-4 thousand feet, as show below:

Now we can put it all together.  Strong, warm flow approached the terrain south of Eatonville and then descended toward the town.  Cool air near the surface was swept away and the downsloping air warmed by compression (adiabatic warming is the term in the weather biz).   Turns out that our high resolution models had a good idea of this...here is the 12hr forecast from the super high resolution (4/3 km) UW WRF model:

Theorange/ reddish colors are the warmest.

I should note that both sides of the Cascades have been far warmer than normal lately--with low temperatures close to the usual highs.  Here is the proof for Sea Tac and Spokane:

Temperatures should cool down later this week.  And keep in mind that last January was also mild, but was followed by super cold air in February.

Tonight's Political Commentary

 Senator Rick Santorum, who is now so much in the news for surging in Iowa, is well known to the meteorological community, and not in a good way.  In 2005 he introduced the National Weather Service Duties Act that would have prevented the NWS from providing the public with any weather information when private-sector entities perform the same function commercially.  It appeared he was trying to help a business in his district, Accuweather, gain a huge market.   In September 2005, Santorum criticized the National Weather Service for its evacuation warnings given for Hurricane Katrina, saying they were "insufficient" and said the public suffered "serious consequences" when they fall short of "getting it right.  Just nonsense...the Katrina warnings were the strongest I have ever seen. 

Dog News

My little Cockapoo was AGAIN seen in Mountlake Terrace near an apartment complex (Markland Woods Appt) in the vicinity of 236th SW and Cedar Way.  If you live in the area, keep an look out!

Virga!

Tonight the wind is blowing outside as another trough passes by...in fact, wind gusted above 50 mph at some exposed locations near water.   But in this blog, lets talk about something much more benign...

On New Year's Eve lots of folks were at the Space Needle to watch the fireworks display and it was precipitating....but not at the ground.  At ground level it was completely dry at midnight, but precipitation was falling from the clouds above and evaporating before it reached the ground--that's virga.

We had a few ways to tell that precipitation was falling...the Camano Island radar--whose lowest beam is about 2000 ft above the city--showed the precipitation  at midnight (see image):

The vertically pointing Seattle profiler also showed precipitation falling from above and evaporating.   But at the surface there was nothing until 1 AM.  Here is the observations at Seattle-Tacoma Airport:

L- at 0853 UTC (12:53 AM PST) was the first precipitation report--even though the radar had showed precipitation for a few hours.  Earlier in the evening there was a large difference between the temperature (lower 40s) and the dewpoint (mid 20s) at this location, indicated low relative humidities.  In fact, here is the plot at the UW...the air got drier and drier during the period before midnight (the RH is found in the fouth panel down).

During the day you can see virga...here is an example:

Virga is often noted around here during the beginning stages of precipitation events.  And having dry air at low levels helps insure precipitation evaporates before reaching the surface.   The deeper the dry air the better.  West of the Cascades a situation with easterly flow at low levels with moist, southwesterly air aloft is a good virga producer, and is one that often occurs as storms approach us from the west.

From below, the clouds lose their hard edges and there is a "softness" to the underside of the clouds during virga periods.   Sometimes you can fell a cool chill at the ground as the air, cooled by evaporation, reaches the ground.

Anyway, virga might be a .5 on the meteorological Richter scale, but still is worthy of note.