June 07, 2023

The Worst Air Quality in New York History?

A historic meteorological/air quality event is now occurring over the New York metropolitan area.

And as far as I can determine, this is the worst air quality event ever recorded there over the past 70 years, the result of smoke from large wildfires in northern Quebec.  

Certainly, the worse air quality ever observed during the warm season in the region.

The real-time cam image of New York City around 1 PM PDT is stunning (see below)

And the high-resolution MODIS imagery reveals the area of dense smoke over the Big Apple:

When I checked the small particulate levels (PM2.5, the concentration of particles smaller than 2.5 microns--millionth of a meter), using the PurpleAir network, I could not believe my eye..values of 300-450 micrograms per cubic meter.

And a plot of PM2.5 from an official site in Queens, NYC shows levels getting to around 800 micrograms per cubic meter...just unheard of.

The weather situation has been perfect to pull the Quebec smoke into the New York area.  Why?   Because of a strong low-pressure area just off the NE coast (see map below at around 5000 ft).  I have added a red arrow to show the low-level wind flow.

The NOAA HRRR Smoke model clearly shows the circulation of the smoke around the low:

So why have we gotten into the early season wildfire situation in northern Canada?

Because the atmosphere over North America has been in an unusual, persistent configuration, with a ridge of high pressure over Canada and a trough of low pressure over California (the figure below shows the situation around 18000 ft for the past month).  Red indicates much higher than normal heights, which are associated with warmer temperatures at low levels, blue indicates lower-than-normal pressure (troughing).

A similar pattern has been in place over the last 90 days (see below).

The high pressure resulted in unusual warmth and drying of the surface fuels.

Is there any reason to think that this configuration is the result of global warming/climate change?  Current research suggests no.

How Unusual Is the Recent Dry Period?

I have gotten several nervous emails from folks concerned with the relatively dry period of the past month over the Pacific Northwest.

Are such dry conditions unprecedented?

Are late springs getting drier?

Is global warming behind it?  Or El Nino?

I will try to answer the questions below.

Let's check the numbers, starting with Seattle.  Below I have plotted the total precipitation for May 1 through June 5 for SeaTac Airport and added a best-fit trend line as well.

You will note that our recent period was dry, but not the driest by far.

In fact, a list of the driest May 1-June 5 periods shows that this last month was the 11th driest since the late 1940s.

Now check out the trend line.  There is NO indication that the May 1-June 5 period is getting drier.  In fact, the long-term trend is towards wetter conditions.  This suggests that progressive global warming was not the origin of our lack of rain.

What about the other side of the Cascades?  Let's consider the long-period observation location at Kennewick in the Tri-Cities.

Similar story to Seattle.  We have had a dry period, but it has happened before many times, and the trend is towards a WETTER late spring.

According to the records, this recent period was the 10th driest on record at Kenniwick.

The bottom line is that we had a dry period, but such dryness in late spring is not that unusual and there is no trend towards drier conditions in May and earlier June.   No suggestion that global warming/climate change is the cause.

What about El Nino?   

El Nino conditions in the tropical Pacific have only really developed during the past month, but let's check out the NOAA Climate Prediction Center historical precipitation anomaly from normal for April to June during El Nino years (below).  A very mixed bag over Washington State.  Wetter than normal over the Southwest.

Now if I blog about the lack of precipitation,  you KNOW what is going to happen in the future.  

Below is the latest total precipitation forecast through Friday at 5 PM.  Lots of precipitation (many from thunderstorms) east of the Cascade crest, with perhaps a few errant showers getting into western Washington.  Bountiful precipitation in northern California.

June 05, 2023

Cold Water Along the West Coast and Unusually Cold Over Southern California

 If you want sun and warmth, don't travel to southern California during the next week.   

Stay in the sunny Pacific Northwest, where the weather will be as close to perfect as one might imagine.

Much colder than normal water is found off the West Coast from Oregon to Baja, and southern California is cold and enshrouded with clouds (see visible satellite image a day ago).  June Gloom+

Sea Surface Temperatures

Here is the latest plot of sea surface temperatures along the West Coast, with large stretches below 50F (purple colors, below 10C).  Too cold to swim in!

Much of the offshore waters are well below normal, as indicated by the blue colors below.

Why are the coastal waters so cool?   Probably, two reasons.

First, there have been persistent, unseasonable low-pressure areas that have repeatedly formed off southern California.  

To illustrate,  the upper-level heights at 500 hPa (think pressure around 18,000 ft) this morning are shown below.  A low with a nice counterclockwise circulation is just offshore of southern California.  Such lows are associated with stronger winds and atmospheric disturbances that stir up the upper ocean, mixing cooler water from below up to the surface.

And then there have been periods when high-pressure builds offshore and northerly winds develop over the waters of northern CA and Oregon.  This pattern results in coastal upwelling of cold water within 100 miles or so from the coast (see a schematic of coastal upwelling below).

Unfortunately for the chilled residents of coastal California, powerful northerly winds will develop offshore this week as a strong high-pressure area builds over the northeast Pacific (see forecast pressure and winds for Sunday).

It will be like putting a refrigerator element along the West Coast!

San Diego and LA Chill

    To understand how bad it has been, take a look at the observed temperatures at San Diego (blue bars showing daily highs and lows), compared to the normal range (brown band),  Record highs and lows are also shown.  

All days but two did not reach the normal highs.  The lows on most days dropped below the normal lows.  NO heatwaves.

And the frigid situation (with rain by the way) is not ending.  Below is the latest extended temperature prediction for Los Angeles Airport.  Not a single day above the mid-60s.  Boring and cold.

For the same period, Seattle will be basking in temperatures from the 80s to the mid-70s, with enough variability to make it interesting.

I suspect you will see the front page of the Seattle Chamber of Commerce website reflect the new weather realities:

  Note: this is not an actual page, but a fanciful simulation of one.

June 02, 2023

Was May the Warmest in Northwest History?

During mid-May, when western Oregon and Washington were in the throes of a several day heat wave, while smoke from Alberta fires was moving in overhead, there was considerable talk about May being the warmest in the historical record for the region.

Was it a record?  Is May getting warmer in the Pacific Northwest?  Is global warming influencing May temperatures?

This will be the topic of this blog.

To begin, consider the difference (anomaly) from normal for the last 30 days for the average maximum temperatures (below).    Much warmer than normal for the northern tier of states, including Washington (as much as 6-10F in locations), but MUCH colder than normal in California and the Southwest.  

Folks I know in southern California have complained vehemently about unusual cold and wet conditions during May.

May in western Washington

    Let me begin by showing you the long-term temperature statistics for Olympia, Washington.  

Why not SeaTac?  

Because of the addition of a third runway and the substantial urbanization and development around SeaTac, its observations are NOT reliable for climate studies.  Far fewer changes and a more rural character for the area around Olympic.

First, consider the mean maximum for May at Olympia, going back to the early 1940s.  May 2023 was the third warmest on record.   But also note that May 2022 was one of the coldest and that there is no long-term trend for high temperatures at Olympia, suggesting climate change is small for that parameter.

What about the highest temperature observed in May for Olympia (see below)?  May 2023 was warm but a number of months were nearly as warm.  Importantly, there is no upward trend of extreme high temperatures in Olympia.

But the story is different for average May minimum temperature at Olympia, which has risen from roughly 41F to 43F.   

It is well known that increasing greenhouse cases have more influence on daily low temperatures than high temperatures.  Furthermore, local development (and there have been some near Olympia Airport) influence low temperatures more than highs.

May in eastern Washington

    Let's review the temperature in Kennewick, Washington in the Tri-Cities.  This station has a very long record (back to the 1890s) and far less localized development (below). 

May 2023 had warm high temperatures, which were exceeded several times druing the 1920s-1950s.  Note there is a DOWNWARD trend in the high temperatures at Kennewick.  I repeat: downward.

This plot is also a good illustration of why long records are important.  A record going back only the 1970s would suggest 2023 was the warmest ever observed, inspiring all kinds of headlines in local newspapers.  But a longer record, such as at Kennewick, shows that such temperatures were frequently observed in the past and that the long-term trend is downward.

The extreme monthly high temperatures in May for Kinnewick are DECLINING and 2023 was nothing special (below).

In contrast, the mean minimum temperature has risen by approximately 2F during the past century at Kennewick, with 2023 being the second warmest on record.

The Bottom Line

    May high temperatures on both sides of the Cascades were warm, but not record-breaking.  Importantly, there is no upward trend of the high temperatures on both sides of the Cascades, suggesting that global warming/climate change is having relatively little impact on the region's high temperatures.

In contrast, low temperatures have warmed modestly (roughly 2F) during the past century and part of that might well be due to anthropogenic warming resulting from increasing greenhouse gases (most importantly CO2 and methane) and increasing urbanization and development in the vicinity of temperature sensors.  Low temperatures are also more sensitive to wind anomalies from normal.  For example, May 2023 had far more easterly (from the east) winds, which tend to cause minimum temperatures to warm.

May 31, 2023

Wind Speed "Hot Spots' In Eastern Washington Produced by Gaps in the Cascades

This has been a very windy period over portions of eastern Washington due to a large pressure difference across the Cascades (higher pressure to the west, lower pressure to the east).

The maximum winds today since midnight  (see below) reached 51 mph near Ellensburg.  Winds were mainly strong near and downstream of Ellensburg and east of the eastern terminus of the Columbia River gorge.

A model forecast for this afternoon shows the two main wind plumes over eastern Washington.  One east of Cle Elum and Ellensburg and the other downstream of the Columbia Gorge (stronger winds shown by the blue and greenish colors).

So why are the strong winds in eastern Washington localized?

It has to do with the variable height of the Cascades and specifically two lower areas in the north-south barrier.  Below is a terrain map for Washington and northern Oregon, with the green colors representing lower elevations.  Note there are two lower regions across the Cascades:  a near-sea-level Columbia Gorge between Oregon and Washington, and the "Stampede Gap" region of the central Cascades (with lowest elevations around 3000 ft), which also includes Snoqualmie Pass.

 Both are indicated by red arrows.

When a large pressure develops across the Cascades, with higher pressure to the west and lower pressures to the east, winds surge through these gaps, creating two major westerly wind swaths over eastern Washington.  A minor wind swath can also be produced downstream (east) of Stevens Pass.

The winds exiting these Cascade gaps strengthen during the evening after the daytime heating in eastern Washington causes the pressure to fall there (and thus increasing the pressure difference across the Cascades0. To illustrate, below are the winds forecast for this evening (in mph)...a lot more greens in eastern Washington, which means stronger winds.

With cool/high pressure to the west of the Cascade crest the last few days, the pressure pattern has been very favorable for consistent westerly winds over the wind turbines of eastern Washington, producing consistently high wind energy availability (see the Bonneville statistics below, wind plus solar shown by the green line).

As noted in my earlier blog, the total of wind and solar is roughly one-third of the demand
 (red line).  Hydro generation (blue line) has been allowed to decline because of the bountiful wind energy.

The latest forecasts suggest the west side will warm and wind energy will thus decline substantially over the next few days.

May 29, 2023

Unusually Cool Weather in the West Means Lots of Wind Energy in the East

 This is a good time to charge up your electric car...particularly during the evenings.

The reason?  

Unusually cool weather is forecast for the next few days in western Washington and Oregon.  Seattle will be firmly into cool, marine air the next few days, with highs only reaching the LOWER 60s.

In contrast, it will remain warm over the Columbia Basin, with 80s for the first part of the week, climbing into the 90s by week's end.

This pattern is very favorable for producing healthy westerly winds along the eastern slopes of the Cascades and across the wind farms east of the Cascade crest.

Taken by Jeffrey Katz

The sea level pressure (solid lines), surface winds, and low-level temperature (colors) forecast for 2 PM Tuesday (below) show the story.  High pressure and cool temperatures (green) offshore, warmer temperatures (orange and red colors) east of the Cascade Crest.  You will notice a large pressure difference across the Cascades, which will produce strong winds over the east of the barrier.

A similar, but attenuated, version of this situation was in place today (Monday) and winds were gusting to 30-40 mph around Ellenburg and other eastern slope locations (see max gusts on Monday below).

Even stronger winds will occur on Tuesday and Wednesday.    The result will be lots of wind energy generation.  The Bonneville Power summary shows increasing wind generation the past few days (green line)...getting to roughly one-third of demand (red line).   Will do even better tomorrow and Wednesday.

Wind energy generation in our region is unfortunately out of phase with demand.  When we have mild temperatures--and little need for AC-- there is lots of wind energy.  But when we really cook, wind energy is quite small since the westerly winds are absent then.

The cool temperatures in the west won't last forever.  The latest forecast suggests that we will warm up to near-perfect temperatures in western Washington by next weekend.

And relatively toasty (upper 90s) over the Columbia Basin

May 27, 2023

Rapid Snowmelt has Filled Local Reservoirs

 In mid-April, Washington State snowpack was near normal, while snowpack to the south was well above normal.

Then Washington experienced much warmer than normal temperatures in late April and May, as illustrated by the temperatures at Olympia below (normal highs are shown by the purple line)

The result of the warmth was a massive melt-off of the Cascade snowpack that has surged into local reservoirs, filling them to normal levels.

For example, consider the Yakima Reservoir system, so important for eastern Washington agriculture (see below).  Over two weeks of May, the reservoirs went from below-normal to normal levels.

Or take Seattle's situation.  Just like the Yakima reservoir system, with a very fast increase to normal levels during the past month.

Seattle's snowpack in the watershed feeding its reservoirs is shown below.  Wow.  A precipitous decline!

To really appreciate the snowpack decline, below are the last snowpack percentiles around the Northwest. Down to 35% or less in areas of eastern Washington.  But bountiful snow remains over southern Oregon and south.

The key issue has been temperature:  while Washington has been MUCH warmer than normal, California has been normal or colder than normal (see the proof below)

This pattern (warm north, cool south) has been very favorable:  it has slowed the melting of the massive snowpack over California, preventing disastrous flooding and potential damage to reservoirs/dams over the Golden State.

The forecast for the next ten days?  

You won't believe it.  More of the same (see the European Center forecast, showing the prediction temperature anomalies from normal for the next ten days).  Warm north, cool south.  Again.

California is going to be saved from major flooding, which is very good news.

The Worst Air Quality in New York History?

A historic meteorological/air quality event is now occurring over the New York metropolitan area. And as far as I can determine, this is the...