The Day of No Weather and SuperBlue Skies

When I get up in the morning, one of the first things I do is check the latest satellite image.

Today's imagery (below) was stunning: not a single cloud in the sky

Nearly all my blogs are about some interesting weather feature...the more severe the better.  

But what to talk about on the most boring weather day in years?

When I got to the UW this morning, I took pictures of the sky ..the most perfect blue skies I could remember.

Viewed from the Seattle PanoCam this am, the light from the blue sky on Puget Sound gave the water a super-blue tint.

So why was the sky so clear?

The upper-level (500 hPa, about 18,000 ft) weather map at 11 AM  explaines a lot.   There was a strong ridge or high offshore, and such features have powerful downward motion on their eastern side...which prevents cloud formation.

Sinking air causes warming by compression and relative humidity to drop (since warm air can "hold" more water vapor than cooler air).  This prevents cloud formation.

The predicted relative humidity at around 10,000 ft (700 hPa pressure) was extraordinarily dry, with dark blue colors indicating relative humidities below 30%.

The solar radiation today was unimpeded, resulting in the variation over the day being almost a perfect cosine shape (the values at Snohomish are shown below).

Why is the sky blue on clear days?

Light from the sun has all wavelengths of visible light.   Atmospheric molecules scatter short wavelengths (like blue) more than longer wavelengths (like orange and red).  As shown in the image below, this preferential scattering of blue light makes the sky look blue.

Water droplets and particles (such as from wildfire smoke) scatter all wavelengths similarly, giving the sky a whitest cast.

As you can imagine, small particle concentrations were very low today, as shown by the PM2.5 numbers (concentrations of particles of 2.5 microns or less) around Seattle (below).  With clear skies, low relative humidity, and clean air, no wonder our skies were amazingly blue.

Enjoy the blue skies....clouds move in over the weekend.

Potential Aurora Tonight

 I have held off mentioning this because I did not want to "cry wolf", but there is an increasing chance that some of you might see some auroral activity tonight.

The latest guidance from the NOAA Space Weather Center (YES,  NOAA!!) indicates the critical index of potential auroral activity (Kp) has now reached 6, which I have found to be the minimum required for even a minor light show around here (see plot below).

The updated Kp forecast takes the index to nearly 7 between 8 and 11 PM tonight...see below.

The graphic from the Space Weather Center shows potential coverage reaching at least northern Washington.

The big question is clouds.   Right now, there are some high clouds overhead (see image around 6 PM), which would be fatal for good viewing, but the latest animation suggests the clouds will be through in 3 hours.

We have a chance!   I will certainly be going outside for a look around 10-11PM tonight.  Good aurora hunting!

Why The "Emergency Drought" is No Emergency

Aesop's Fable "The Boy Who Cried Wolf" talks about the danger of exaggerating a threat to the point that no one believes you.

The Department of Ecology and the Seattle Times would be well advised to read this ancient story, because they are misleading the people of our state with their claims of a "drought emergency."

The truth is clear:  such "emergency" claims are contradicted by the facts.

Crying wolf about a non-existent drought not only lessens public confidence in such warnings but wastes money and can lead to a lack of public response when the situation becomes truly serious.

Remember the definition of an emergency (Cambridge Dictionary):

A dangerous or serious situation, such as an accident, that happens suddenly or unexpectedly and needs immediate action

As described in this and my previous blog, the current precipitation situation is not dangerous, did not develop suddenly, and does not require immediate action.

The claims of a drought emergency, centered on Kittitas and Yakima counties (see map), are very weak for many reasons. 

Consider the situation for the reservoirs serving this area.  Water levels are rapidly rising and will soon exceed last year's level.  Currently, the Yakima region reservoirs are at 67% of normal capacity and most of the snowmelt is in the future.  Thus, the storage levels will improve further.  By a lot.

One reason we can be sure of this is the predicted stream flows (by the Portland River Forecast Center).  The predicted river levels by late summer should be 87% to 105% of normal.   Healthy river levels like this are good for irrigation and for filling reservoirs.

The snowpack is not in an "emergency" state, with relevant basin being 86% of normal (see below from USDA)

The situation this year will be far better (moister) than last year.  But even with drier conditions than this year, agricultural productivity in Washington State was quite good in 2024 (see below), with the greatest weather problem for 2024 being the cold wave last spring (not drought).

Good news on the temperature front this year: no freezing cold wave predicted by the very skillful ECMWF ensemble of many forecasts through the end of the month.  Once in May the threat is over.

I talked to a reporter from WA Ag Information Network today and he had talked to several growers.  They are optimistic about the current season.

So should you.

In summary, the "drought emergency" talk is highly irresponsible and in contradiction to observed facts on the ground.  It is used as a tool to scare people, often with unsupported attempts to connect the fictitious "drought" to climate change.  

Finally, it is interesting to check Google Trends for how many searches have included "drought emergency...see below.  

This term has become more trendy during recent years, with Washington State being the number one place in the nation for using it.  The state with the most reliable and bountiful precipitation in the nation.   That tells you something....

If only Aesop were alive today....

A Sky Full of Lines

When the conditions are just right, the Northwest sky can be streaked by dozens, if not hundreds, of cloud lines called contrails.

Consider a view from the NOAA GOES geostationary satellite this afternoon (below).  The linear features are contrails.   A lot of north-south lines over western Washington (aircraft going up and down the coast), while over the ocean, there is a mixture:  some planes from Hawaii and others from CA heading north and west.

A lower polar-orbiting satellite got a closer-in view a few hours before, and if you look closely, you can see the shadows of the contrails on the ocean.

Contrails are associated with a layer aloft that is at or near saturation (100% relative humidity).  In fact, the UW WRF model showed high relative humidity air (lighter colors) moving in around 2 PM (below).

The balloon-launched weather instrument (radiosonde) at Forks, on the NW Washington Coast, at 5 PM shows temperature and dew point with height.  Between 300 and 400 hPa (7340 to 9331 meters, 24000 to 31000 ft above sea level), the air was nearly saturated, and close to saturation just above and below.

Excellent conditions for contrail production.  

Why?  Because jet engines inject extra water vapor into the atmosphere, plus lots of particulates that can serve as condensation or freezing nuclei that enhance to cloud formation process.

A potent sign of the potential for contrail formation is the development of a thin cirrostratus cloud layer, a high-level cloud made of ice crystals.   You can see this with your own eyes.

At 9 AM this morning, the skies over Seattle were essentially clear.

By 1:20 PM, a thin haze of cirrostratus clouds was evident.

At 2 PM, there were contrails, in this case an "x" of crossing contrails above Mount Rainier.   A bit over the top, perhaps, but that was reality.😃

I am taking a chance blogging about this.   I can guarantee some folks will be upset at me for writing this blog.  

Why?  Because some people think that these lines in the skies are not the result of combustion in aircraft engines ejecting water vapor and particles, but a secret, nefarious government project to fight climate change.  Instead of calling the lines contrails, they term them CHEMTRAILS.  

Beautiful Satellite Imagery

 If you want to know one of many reasons that NOAA and federal investments in weather technology are important, consider some of the weather satellite and radar imagery available during the past few days.

Below is a visible satellite image from one of NOAA's GOES Geostationary weather satellites.   Such satellites are parked over the equator around 36,000 km above the Earth's surface.

The star indicates Seattle, and you can see a potent frontal band of clouds offshore (blue arrow).  When that front moved in, we had some rain.  This front was shearing apart at this time, with the lower portion lagging behind, as indicated by a thin line of clouds (red arrow).  

This feature is called a narrow cold frontal rainband and was discovered by UW researchers.

Behind the front, there was cold, unstable air that produced fields of cumulus clouds with clear areas in between (noted as well).   When such cumulus activity moves in, we receive our famous showers and sunbreaks.

Another valued piece of NOAA weather hardware is the weather radar network, with several radars in our area.

As the frontal bands moved over land yesterday, you could see the broad band of precipitation with the primary frontal band (red arrow) and s narrow one with the surface front.  Look closely, and you can view showers on the windward (western) side of the Olympics.   Marvelous, but expensive technology.

Friday afternoon, a much weaker front was offshore (see below) and will move in overnight.

In addition to the geostationary satellites and weather radars, NOAA and NASA have some low-flying (about 800 km above the surface) polar orbiting weather satellites.  Such satellites give a much higher resolution view of the clouds and the Earth's surface.

Here is the view of Western WA today from the MODIS satellite.

While the image of the Columbia Basin can even identify individual irrigated fields.

The U.S. has built a marvelous and expensive weather observing system, and I suspect that no one, of either party, wants it to go away.

Is There Really A Drought Emergency in Washington State?

 The Washington State Department of Ecology has declared a drought emergency for large areas of Washington State, with particular emphasis on the Yakima watershed of south-central Washington.

Looking at observations and predictions,  this drought declaration appears to be unwarranted and in error.

Let me provide the evidence, and you can decide.   

First, if there is a drought situation,  you might expect that precipitation would have been below normal over the "drought emergency" area, resulting in dry soils, both at the surface and below the surface.   

To evaluate this, below is the percentage of normal precipitation during the "water year" from October 1 to yesterday.  

Above normal (120-130%) precipitation at Yakima (star)!  Most of Yakima and Kittitas counties received above-normal precipitation, and only a small portion on the northeast side was below normal.

What about comparing precipitation at Yakima and Ellensburg over this water year and previous water years ending April 8?     The answer is below.

At both locations, this year was considerably wetter than normal!   Doesn't suggest much of a water emergency, does it?

What about the Vegetation Drought Response Index?   Unusually moist!

Or streamflows in the Drought Emergency area? Near normal or above normal!

The truth is that precipitation has been bountiful over the Drought Emergency area, and soils and vegetation are normally moist, if not wetter than normal.

There must be SOMETHING suggesting drought!   What is causing all this panic?   

Perhaps it is because of the snowpack?   

Below is the percent of normal for the water content of the regional snow pack this morning. 

 Northeast of Yakima, it is 97%.  Below normal by 3%!  And 105% (above normal) in Yakima and to the south.   91% for Wenatchee, but dropping to 74% to the north.

 Folks...this is not a serious situation and certainly not an emergency for Yakima and Kittitas Counties.

How can I be so sure this is no emergency?  Because the NOAA/NWS Northwest River Forecast Center considers both snowpack and precipitation to predict river levels during the next 5 months.   

River levels on the Yakima,  Columbia, and other major rivers control how much water is available for irrigation.

Below is a sample of their forecast, showing you the predicted river levels in 120 days (August)--at the end of our dry summer.  Most of the values are 80-100 % of normal.

The Columbia River will be 95-100%.

There is no water emergency, not even close.  Not even in the neighborhood.

State officials pushing this narrative are doing a profound disservice to our state.

As expected, the Seattle Times Climate Lab gave this "emergency" big play in the paper today.

The naked political advocacy and bias of the paper were pretty obvious, as suggested by all the Trump talk in the article (see sample below).

The Seattle Times is rapidly losing any credibility as a source of reliable environmental information.  Really unfortunate and very unnecessary.

April is the Month of Drying

In western Washington and Oregon, April is the month of drying.

And the same is true of much of the West Coast.

This may sound strange considering the popular mention of April showers in song and verse.

Consider the climatological probability of receiving at least 0.01 inch of precipitation at Seattle Tacoma Airport (below).  

A large drop between April 1 and May 1.  By far, this is the largest one-month decline of the year.  By the way,  .01 inch of liquid water is the criterion for measurable precipitation.

The probability of precipitation is relatively steady from mid-November to late March (50-60%), but declines to approximately 38% in late April.  

On the Washington coast (Clearwater), the situation is similar .... a big drop from the winter wet plateau to drier conditions in April (the probability of measurable rain dropping from  70% to 50%).

What about San Francisco further down the coast? 

Also a big drop in the probability of precipitation in April---but an equally large decline occurs during March.   The drying starts earlier in San Francisco.

To further illustrate the profound drying in April, below is a plot of the average precipitation along the West Coast in March and May.

Wow.   Huge decline everywhere.  Precipitation essentially goes away for Southern California during April.   LA beach season has begun!

So the question you must be asking is why?   Why is there a big drying in April over the West Coast? 

Significant changes occur in the atmosphere between the two months.  

Consider sea level pressure.  In March, there is strong low pressure over the Gulf of Alaska and high pressure west of Mexico.   This pattern is associated with strong westerly (from the west) winds in the lower atmosphere that bring storms and moisture to the West Coast.

The same map (sea-level pressure) for May is very different.  High pressure has pushed up the West Coast.  With sinking air to the east of highs, that means that much of the coastal region is under descending air...which is inherently dry.

By May, a thermal trough of low pressure has moved northward up the interior... the classic summertime pattern.    And with high pressure moving northward and low pressure to the north retreating, the jet stream is weakening and storms are deflected northward.  

Finally, a little irony.   Even though April is a drying month, this April will start with a LOT of precipitation (see the totals through Saturday morning).  Two to three inches of liquid water in some of the mountains!