Not All Temperature Records Are Equal

Some records are more significant than others.  

And some records are being used to hype normal temperature variability in unfortunate ways.

Consider yesterday (Sunday).   SeaTac Airport beat its daily record (77F0 for that specific date, reaching 81°F.   

The Seattle Times puts the 81°F day on the FRONT PAGE!  Must be a slow news day.

The Seattle Times story was heavy on hype, with several unfounded statements (see below).

Temperatures scorched past their record high.

Foreshadowing the inevitable summer of drought.  (This is total nonsense, by the way).

Should you worry about the RECORD high temperature yesterday?    Read on.

Why Monday's record did not mean much.

Monday's record high was a daily record.   

Daily records are frequently broken because there are so many opportunities to do so (365 chances each year!).    Breaking an annual record (the warmest day of the year) is much more significant.

Breaking the daily high-temperature record yesterday was particularly lame.  

Why?  Because the previous high temperature on that date (77F) was particularly low.  

You can see this by looking at the plot  (at SeaTac) of observed temperatures (blue lines) and record highs (red shading).   The previous record high temperature on that day (77F) was anomalously COLD.  The coldest daily high for ANY DAY IN MAY.    Even the end of April had warmer record highs. 

By the luck of the draw, May 3 never got above 77°F, and thus this was a record ready to be broken.  Low-hanging meteorological fruit.

The 81F record is still a low record high in May at SeaTac, cooler than ALL the other record highs for the month.

Breaking this wimply record has little meaning and does not foretell an inevitable summer drought as stated by the Seattle Times reporter (Conrad Swanson).

The latest forecasts are emphatic that there will be a cool down, with light precipitation returning.

The latest European Center Forecast has  SeaTac temperatures dropping to normal  (highs in the 60s).

Showers will return on Friday and Saturday (see below).

The kind of hype and exaggeration of heat and drought found in the Seattle Times and several amateur YouTube channels is unfortunate.

People are being misinformed and made to worry without cause.  Hyping climate change and exaggerating normal climate variability may get more clicks and revenue, but the costs of such misinformation are substantial.

There Is No Drought Emergency in Washington State

On April 8, Washington State declared a DROUGHT EMERGENCY for Washington State. 

 In fact, this is the fourth year in a row that the Washington State Department of Ecology has done so.

As described below, these drought emergency declarations are unwarranted and are contradictory to meteorological facts and the actual impacts.

Let me remind you about the definitions of emergency and drought.

An emergency must be sudden and unexpected, requiring immediate action to prevent imminent danger.  It is a crisis.   As I will prove below, this does not characterize what has happened in Washington this year or the past few years.

The term "drought"  means both MUCH drier than normal conditions and significant negative impacts of the dryness.

Half the years have below-normal precipitation.  Half the years have below-normal snowpack.  All these below-normal years are not drought years.

Let us consider the water situation this year.

The major reservoirs of our state are full or WAY above normal in water storage. Some examples"

Seattle:  much above normal.

Everett:  much above normal

The critically important Yakima River reservoir system:  FULL and much above normal.  

The Columbia River water levels are above normal, and predictions are for plenty of water for both irrigation and power. The Columbia is the most important source of irrigation water in eastern Washington.  It irrigates TEN TIMES the number of acres as the Yakima River. 

River levels in the state are all close to normal.

Precipitation over the State for the water year (October 1 to now)?

Above normal for most of the state,  and MUCH above normal in the mountains (that is why all the reservoirs are so full!)

Soil moisture?  Above normal!

Crop moisture?    Above normal in much of the state, nowhere below normal.

Current status of crops?    They are in excellent shape with extremely high yields for winter wheat. Apples look good as well

So with all this good water news, why is the Washington State Department of Ecology calling a drought emergency?

They claim it is because the state snowpack is below normal:  about half of average (see below).  This snowpack normally melts in May and June, helping to top off the reservoirs and support streamflow during the early to mid-summer.

Don't get me wrong.  It would be better if the snowpack were normal.  But there really is no water problem this summer with the current snowpack and certainly no drought.

First, 50% snowpack is not zero, and there will be substantial snowmelt water available during the next few months.   

Second, reservoir managers were very wise and used the above-normal precipitation of the past winter to fill all the reservoirs.  Better weather prediction supports this, since they can fill the reservoirs, knowing they would have time to partially drain them if a major storm approaches.

Third, and this is not advertised by the water fear mongers, Washington State gets much more precipitation (including snow water) than it needs, and much of the snowmelt moves down the rivers into the sea.

Fourth, Washington State agriculture can do quite well with below normal precipitation.   This is true of the Yakima basin farmers when they don't get their full allotment.  

What happened during the 2025 Drought Emergency?

The Washington State Department of Ecology is undermining its credibility with these inflammatory and unscientific drought emergencies.   

They would be wise to read some classical literature, such as The Boy Who Cried Wolf and Chicken Little (The Sky Is Falling).    One loses credibility when exaggerating threats.  Eventually, others don't take you seriously.

The Sky is Falling!

Warm But Not Hot

 During the first two weeks of May, there is often a short warm period that surges to 80°F or more, followed by a serious cool down.

This year will be no different.

Below are the forecast temperatures for Seattle.  Warming to 80F on Monday, followed by cooling into the upper 60s, with no major heat through May 11.

To illustrate this typical temperature pattern, below is a plot of temperatures in Seattle for April 1- May 31, 2024.  Observed temperatures are in blue and record highs in red.  Record lows in blue.

A major warm-up around May 9, followed by cooler temperatures the rest of the month.  Classic.  

You will notice that May brings the end of any frost threat.....good for gardeners to keep in mind.

So why do we often see a spike in temperatures in early May followed by cooling?

First, the sun has become strong in May, as strong as it will be in August.  Solar radiation at noon is summer-like, and days have become longer.  

Below is the solar radiation reaching Seattle since January 2025.  By May 1, we are really cooking.

To get warm temperatures, even in summer, we need a period of offshore flow, since onshore flow off the chilly Pacific will not allow us to get out of the 60s.

To produce the upcoming warming, this weekend will bring offshore-directed (easterly) winds, as illustrated by the winds, temperatures, and heights (pressures) around 5000 ft (850 hPa pressure) on Saturday morning (below).

Why do we typically have fewer really warm days later in the month?  

Because later in May brings extensive low-cloud areas over the eastern Pacific as high-pressure builds offshore.  This high pressure pushes the cloudy/cool air into western Washington. 

We call this "June Gloom," but it typically starts to move in during mid-May.

Here is an example of June Gloom cloudiness from last May.  Enough to make me want to grab a sweater.

Contrail Fest over Eastern Washington

The satellite imagery over eastern Washington this morning looked like someone had gone crazy with a white crayon,  drawing many white lines, most extending roughly east-west.

Here is a closer view.   The white lines are contrails created by aircraft.

Look very closely, and you will see some black lines as well:  the shadows are produced by the contrails stopping the sun's light from reaching the surface.

Contrails are formed by the combustion of jet fuel in aircraft engines.  This combustion produces water vapor that condenses into water droplets, which eventually freeze into crystals in the cold temperatures aloft.   Combustion particles aid the condensation.

Contrails are thicker when the air is already close to saturation.  Thus, contrails are particularly obvious when the air aloft is already moist.   

Look closely at the satellite imagery above, and you will see a thin veil of cirrostratus clouds, indicating air already at saturation.  Adding more water from the jet engines simply makes the clouds thicker.

Or we can look at the temperatures (red lines) and dew points (green lines) from the radiosonde (balloon-born weather observations) at Forks, on the Washington Coast (below).  Near the level at aircraft fly (marked trop on the figure), temperature and dew point are nearly the same, indicating a moist atmosphere near saturation! (the Y-axis is height in terms of pressure; 500 is about 18,000 ft, 250 is about 35,000 ft).

Temperature (°C)

Climate Change and Contrails

Contrails both cool that atmosphere (by reflecting solar radiation to space) and warm it (by emitting infrared radiation down to the ground).   

A number of careful studies have found that the warming is dominant.  

Thus, contrails contribute to global warming.  Much, much less than CO2, but still a contribution.

One way to reduce this warming by contrails is to alter flight paths to avoid cirrostratus clouds or regions where the upper troposphere (where planes fly) is near saturation with water vapor.   Some folks have suggested this be done.

In any case, the effects of contrails are relatively small, much, much smaller than the aggregate effects of global CO2 increases.

A Strong Morning Inversion Undermines Air Quality and Messes Up the Coastal Radar

This morning, a strong low-level temperature inversion caused the air quality to decline over western Washington and created false radar echoes on local weather radar.

Reminder:  an inversion occurs when temperature increases with height, a reversal (inversion) of the normal situation in which temperature decreases with height. 

Let me show what lower atmospheric temperatures looked like this morning.

At 5 AM at Forks, on the northwest Washington coast, temperatures increased by about 10°C (roughly 18°F) in the lower few thousand feet (red line is temperature).  Above the inversion, the temperature declined with height

An inversion was also present at Seattle-Tacoma Airport at 6 AM this morning, with about a 6°F warming between 400 ft and 1800 ft (see below)

Inversions create zones of strong vertical stability, inhibiting the vertical mixing of pollutants, allowing concentrations to increase near the surface.

This was quite apparent this morning as air quality declined to the moderate level (yellow colors) in the graphic from the  EPA AirNow website.

Low-level haze was apparent on the Seattle PanoCam this morning around sunrise.

Strong-level inversions can also mess up local weather radar, acting as an atmospheric lens that bends the radar beam down.  As a result, the radar beam reflects off the surface and is reflected back as a false echo, indicating precipitation where none is occurring.

Such a false echo was clearly apparent on our local coastal radar (Langley Hill, near Hoquium) at 7:21 AM.  It was not raining offshore!

Over land, spring temperature inversions weaken rapidly during the day as the land surface warms,  as illustrated by the temperatures over SeaTac at 4 PM (below).  No more inversion as temperatures at the surface warmed into the lower 70s!

So, take a deep breath...air quality is quite good now over western Washington...and I am going to go for a few-mile run knowing that bad air quality won't be a problem.

Fog In the Wrong Season

This morning, fog was widespread over the lowlands of western Washington, with many of the river valleys in the murk (see visible image below around 7 AM)

Several local weather cams showed the fog.  Olympia had almost no visibility.

And it wasn't much better on the Chehalis River Bridge.

All this foggy action is a bit unusual in late April, which is close to the time of minimum frequency of dense fog for most locations in our region. (see below)

Why is dense fog unusual in April and May?

Because days are much longer and the sun is getting quite strong.  Thus, the surface is getting warmer. But the air is still relatively cold aloft.  

That leads to a rapid decrease in temperature with height, which results in instability and vertical mixing.

Vertical mixing is the enemy of fog, which generally forms when cold, dense air is near the surface, and warmer air is aloft.

Exactly, the situation that was occurring this morning (see the temperature above SeaTac Airport this morning below).

So why the fog this morning?  

A strong high-pressure area aloft developed to our northwest (highs of the 500 hPa pressure surface are shown below...think of pressure around 18,000 ft).  Red indicates the high pressure.

Such an offshore high-pressure aloft causes sinking, which warms the middle atmosphere.  Furthermore, high pressure causes clear skies aloft, which allows the lower layers to cool by emitting infrared radiation.

Warming above and cooling below is perfect for fog formation and the development of a low-level inversion.

California and Oregon Are Getting Our Rain: But That is OK

 There is always a yin and a yang in the weather.

Because of the structure and limited extent of weather systems, one area's precipitation bounty inevitably means less precipitation than normal for an adjacent region.

This is often true on the U.S. West Coast.  When California is wet, we tend to be dry and vice versa.

In April, such a reversal of fortune is occurring, with northern California and Oregon receiving above-normal amounts, and less than normal precipitation over Washington State.

Let's start with the current water year (October 1 to now) precipitation totals (the percentage of normal is shown).

Western Washington and the Cascades are in good shape, which is why our reservoirs are full.  Southern California has been wet.  But Northern California and much of Oregon have been drier than normal.

Climatologically, precipitation tends to shift north in the spring as the moisture-transporting jet stream moves northward, leading to a drying of California, while maintaining substantial precipitation in Washington State and British Columbia.

You can see this effect in the climatological precipitation maps for the region (below).

For January, substantial precipitation (dark blue color) extends from Washington State to Northern California and down the Sierra Nevada. Even Southern California gets a piece of the wet action.

But April is different, with far more precipitation falling over the Northwest than California, with profound drying over the southern portion of the state (see below).  In May, the California lack of precipitation is even more profound

But this year, something different is happening. 

The total precipitation forecast for the next 15 days (below) is for heavier-than-normal precipitation in California, with southern Oregon getting a substantial wet bounty as well.    Washington State will get some welcome precipitation as well, but the real action will be south of us.

The folks in LA and San Diego will be startled by all the rain, but the thorough wetting of California will greatly benefit the huge agriculture industry of the Golden State.  

What is going on?  

This is not climate change, but rather the development of anomalous upper-level lows that are heading into California.  

Below are predicted upper-level (500 hPa pressure, about 18,000 ft) maps, with blue showing troughs of low pressure (which are associated with precipitation).

11 AM Monday....a deep trough over northern California.

5 PM Saturday... another CA trough

Monday, May 4?   Another low-pressure area is heading to California.

Finally, although Washington State has a dry period ahead, we received substantial precipitation last night from a wet system that dropped very heavy precipitation exactly where we needed it:   on the eastern side of the Cascades and over the mountain barrier (see 24 hr below).   

Perfect for supporting agricultural needs over the Yakima Valley region.  

The weather gods are taking care of both California and our region.😊