Northwest Mountain Snow in June: A Cold/Wet Period for the Northwest

The images from the Mount Rainier Lodge area during the last day were winterlike, with several inches of snow on the ground

The Crystal Mountain ski area was similarly snow-covered.

And Whister Peak appeared more like March than June 

Thunderstorms, with small hail, hit both sides of the Cascades, with substantial precipitation totals yesterday (Saturday); many mountain locations received over an inch of liquid water.

This situation has brought much colder than normal temperatures to the region, with many locations 10-20 F below climatology ( see below).   Many higher terrain locations did not get out of the 30s!

But even colder and wetter weather is in the forecast, with major positive implications for water resources this summer.

The forecast temperature anomaly (difference from normal) for the region for Tuesday to Wednesday morning (below) is for 5-15F below-normal temperatures, with the coldest temperatures over the Cascades and eastern Washington and Oregon.

Wet conditions will dominate from late Monday into Tuesday morning, with some locations in the Cascades receiving 1-3 inches.    Very favorable for water resources this time of the year: moistening the soil, filling reservoirs and rivers, and reducing water demand.

The origin of this cold/wet period is anomalous low pressure (roughing aloft in meteorological parlance), as shown by the upper-level  (500hPa, roughly 18,000 ft) forecast map for Monday at 5 PM.  Blue indicates the low/pressure/troughing

Temperatures should recover a bit by the end of the week (see forecast through Friday for Seattle, shown below), but we will have to endure a cool/wet period first.

Wet, Cool Winter-Like Weather in June

During the next week or so, the weather will be more reminiscent of February than June, with lots of rain and MUCH colder than normal temperatures.  

Reservoirs, already above normal, will be topped off, streamflows will be substantially enhanced, and soils moistened.

Let's begin by looking at the predicted precipitation totals (by the European Center Model).

Through Friday, some regional light rain (see below)

The totals through Tuesday morning are getting serious, with windward (western) slopes and higher terran of the region wetted by as much as 2-3 inches.

Values of cumulative precipitation over the next 15 days are quite extraordinary, with substantial rain even falling over eastern Washington.

Now I will show you something hard to believe.  

A very, very strong atmospheric river will be aimed right at us on Sunday evening (a measure of the amount of water moved by the atmospheric river is shown). 

Just stunning.

Not only will it be wet, but much colder than normal, which reduces evaporation considerably and encourages water to percolate into the soil.  

Below is the forecast difference of temperature from normal for the next five days.  

Brrr! The whole region is 3-6F colder than normal,

Next five days?   Double Brrr!   The entire region remains cold!

The NOAA Climate Prediction Center is going for wetter than normal for their 5-10 day forecast:

And the NOAA Northwest River Forecast Center predicts that local rivers will rise substantially.  For example, consider the Yakima River, which is of prime interest these days.  Big jump upwards.

Having an extended cool, wet period at this time of the year is extremely favorable for both water supply and agriculture.   

Hopefully, the "extreme drought" hype will fade now.

Dramatic Mirage Over Puget Sound and a Super Sea Breeze

Today was the warmest day of the year so far, with some western Washington locations reaching the mid-80s, bringing some strange and remarkable weather features to our area.

First, there were some dramatic mirages for locations near Puget Sound.  Sandy beaches became sand cliffs, mountains were thrust high with strange valleys, and houses were displaced into the sky (see sample below off of Whidbey Island)

Picture courtesy of Greg Johnson 

 Want to be really impressed?  Play the video below, provided by Greg Johnson of Skunk Bay Weather.

So what is going on?  

Superior mirages produced by the intense inversion (temperature warming with height) in the lowest few hundred feet of the atmosphere.  

Why such a strong inversion?  Because we had very warm air above our cold (about 50F) water.

To illustrate, below is the temperature variation with height (red line shows temperature) at Forks, near the NW Washington Coast.  Temperature is in C (x-axis), and height is in pressure ( hPa, 850 is about 5000 ft).

An intense 15 °C low-level inversion (again, temperature warming with height) near the surface.

Such inversions act as a lens that bends light, making objects look higher than they really are.  Superior in this case means higher.

But not only did we have crazy optical effects, but we had a super sea breeze on the coasts.

So strong that its leading edge was apparent in the weather radar around 1 PM  today (dark blue line):

At Hoquium, near the Washington Coast, the sea breeze front produced a rapid wind shift from easterly to northwesterly around 1 PM, accompanied by a substantial acceleration of the wind speed.

Temperature peaked around 80°F before the sea breeze hit, and then dropped into the 60s by late afternoon.

Our short heatwave is over, and western Washington should remain below 70F for the next week.  Plus, lots of rain over the weekend.