Sunday, June 25, 2017

Cool Air is Starting to Move In

Today broke several daily temperature records,  with temperature climbing into the mid nineties around Seattle and upper 90s to the east.  The interior of SW WA and the Portland area jumped to 100F and more, as did the Tri-Cities.

Here in Seattle, temperature were quite pleasant on Puget Sound, but jumped into the mid-90s over NE Seattle.   Even hotter over Bellevue and Redmond.


But as forecast, everything is changing now.  The trough of low pressure (the thermal trough) has jumped over the Cascades and an onshore pressure gradient has developed (see pressure difference table below). The Hoquiam minus Seattle pressure difference jumped to 3.5 hPa...guaranteeing the inland movement of cool air.

The winds  and temperatures above Seattle Tacoma Airport show the incipient changes,  with hot SE winds replaced by cooling southwesterlies aloft.  And temperatures aloft are falling.
Coastal clouds have moving northward and thickening during the day (see satellite image from an hour ago) and those clouds will move in overnight.


I look forward to hearing the tinkling of my wind chimes around midnight, a sign of the influx of welcome marine air.  Our regional AC has been turned on....now it is only a matter of time.

The Hot One Today

Temperatures on Saturday were toasty around the region (see below), with upper 80s reaching into Puget Sound, near 100F in Portland, and over 100F in portions of the torrid Willamette Valley.   As predicted, temperatures surged into the low 90s along the WA coast due to offshore (easterly flow).


Temperatures are warmer this (Sunday) morning over much of the region by roughly 5F, and a key parameter (the Seattle-Yakima pressure difference) suggested a large offshore pressure gradient (that helps warming)...see the table below.  The pressure differences between Seattle and the coast are still negative (higher pressure in Seattle), which suggests no push of marine air during the day today.
A really useful tool for short term forecasts of temperature is to look at time-height cross sections of temperatures and winds from aircraft coming in to Seattle and Portland.   Here is the latest from Seattle (red is temperature, the vertical axis is height in pressure, with 850 being around 5000ft.  Time increases to the left and is in UTC/GMT).   850 hPa temperatures are around 22C (which are very warm) and could support surface temperatures as high as 37C (upper 90s), where there is no marine influence.

In fact, the 850 hPa (about 5000 ft) temperature at Quillayute, on the WA coast, is at record high levels for the date (see climatology at the radiosonde site there, with red being record highs, the dot is the temperature at 5 PM yesterday).

Consistent with this, here is the latest high resolution UW WRF forecast for 5 PM.  Mid to upper 90s away from the water (eastern Seattle suburbs and lower western Cascade foothills). You don't want to know about Portland and the Willamette Valley, where 100F+ will be widespread.

So today is going to be very warm... so be prepared.   I close my shades and fill my house with cool morning air with fans.  But it will be the last day of the uber-heat and there is already a sign of change....low cloud are starting to move up the Oregon coast.  An indication that an onshore push of marine air may be in store for tomorrow.



Friday, June 23, 2017

Weekend Heat Wave

The warmest days of the year so far  over the Northwest are coming up this weekend and some folks in western Washington will be sweating with temperatures exceeding 90F.  Today got to 81F at SeaTac...as perfect a day as one can imagine.

The Weather Channel revs up Seattle's temperature to 86F on Saturday and 89F on Sunday, before cooling down on Monday.  I suspect temperatures will be considerably warmer east and south of Seattle this weekend.



To get the big picture, let's start by looking at a sequence of forecasts of sea level pressure (solid lines), surface winds, and lower-atmosphere temperatures (cold shading).

At 5 PM today, one notes low pressure over the CA interior and western Oregon that is coincident with warm temperatures (hence the name, thermal trough).  This thermal trough is associated with offshore (easterly) flow forced by building pressure east of the Cascades.  Today, with the thermal trough south of western Washington,  there are cool northerly winds over Puget Sound.


Tomorrow at 5 PM is much warmer over western WA and Oregon, as the easterly flow moves northward.

 By 5 PM on Sunday, major changes are occurring.  Temperatures peak over western WA and the thermal trough has just "jumped" over the Cascades into eastern WA.  The warmest day for Seattle, but cooling starting on the coast.

 The effects of the thermal trough moving east of the Cascades is really obvious at 5 PM Monday.  Marine air and a large pressure difference has moved into western Oregon and Washington.
Taking a look at the surface (2-meter) temperature forecasts from the super high resolution UW WRF forecast model, today at 5 PM shows low 80s into SW Washington and southern Puget Sound.

 24 hour later, a MUCH warmer story, with upper 80s and lower 90s over SW Washington and 90s in the Willamette Valley.
 Sunday at 5 PM is even warmer, particularly over the western interior and the Columbia Basin.  Portland will be white hot!  And you will notice some coastal cooling.


It is, of course, dangerous to look at one forecast solution....so let's check out the latest National Weather Service higher-resolution ensemble (called SREF) for Seattle.  Most of the forecasts are for low 90s in Seattle.  Quite a bit of confidence in this forecast.


So find a fan and a cold drink...you will need them during the afternoon and early evening on Saturday and Sunday.

Wednesday, June 21, 2017

Hottest Day of the Year Map

Here is an interesting map showing the average day with the warmest temperatures around the U.S.   Amazing differences, with some places having their warmest temperatures in June (southern Arizona and New Mexico), while others having their typical high temperatures in September (coastal CA).  

A three month range!

Why do different locations have such radically different dates of warm temperatures?   Let's think about it.


On a superficial level, one might suppose that the hottest day of the year would be the day when the sun is strongest and most overhead:  the summer solstice (June 21st).

But thinking about it a bit more carefully, it is apparent that warming occurs as long as the amount coming in, i.e., the solar radiation, exceeds what is going out (infrared radiation to space).  And that might be  later than the maximum solar radiation.

Consider the daily (diurnal) temperature variation--the warmest temperatures are not at solar noon (roughly 1 PM PDT) but several hours later (around 5 PM) in summer.    Furthermore, there is thermal inertia of the atmosphere and the surface that further delays the warming (takes a while for the soils, water, and air to warm up).


So one might conclude that having the warmest day of the year in July or early August might be expected.

But why are things so different around the country, with the warmest day ranging from near the solstice (June 21st) to the equinox (Sept 21)?

I think I can offer an explanation.

First, consider the very early dates from western Texas to Arizona.  I think those are due to the North American or Southwest Monsoon, a period of clouds and thunderstorms over the interior SW U.S. that develop in late June and extends to early September.  With all the clouds and moisture moving in during late June, the high temperatures are lowered during mid to late summer, pushing the highs into June.


But why are the high temperatures so late in the summer in steamy eastern Texas, Louisiana and Arkansas?    Because they have a lot of thunderstorms and clouds during late spring and early summer, which delays the onset of high temperatures.  This precipitation characteristic is illustrated by the monthly precipitation in Houston, Texas (see below), with June being their wettest month.


Moving back to the western U.S., most of the interior has a late July maximum, which makes sense from the radiation viewpoint discussed earlier.   But what about the craziness along the thin coastal strip, where many locations don't hit their high temperatures until late August or September?

The reason has to do with the cool Pacific Ocean and the eastern Pacific high that dominates the region from late spring into mid-summer.  The Pacific Ocean is cool year around (roughly 50F near the West Coast).   During spring and most of the summer, high pressure exists offshore, with lower pressure over Arizona (see surface pressure map for June), which creates a large onshore pressure gradient along the West Coast that pushes the cool air and low clouds into

the coastal zone, keeping things cool (see satellite image for Monday afternoon).


By September, the situation changes (see below), with pressure building over the Pacific Northwest and the coastal pressure gradient weakening.
Occasionally, high pressure builds further over the inland western U.S., as cold air starts to move southward, producing offshore flow that is much warmer than the cold onshore flow off the Pacific.  Furthermore, the offshore flow can be warmed by compression as it sinks along the West Coast mountains, producing high temperatures along the coastal strip.  These situation produce the high temperatures during late summer near the coast.

In short, the variations in the dates of the high temperature days actually make sense with a little meteorological sleuthing.



Monday, June 19, 2017

Escaping the Southwest Heat

Residents of the Puget Sound region can breath a sigh of relief that they are not living farther south, since an heat wave is now frying the southwest U.S.  As shown below, high temperatures east of the California coast were generally above 100F today, with the area stretching from Palm Springs to Las Vegas soaring about 110F.  Needles, California rose to 123F.  None of these are all-time records, but several daily records have fallen.


Here in the Pacific Northwest, the temperatures aloft (say at 5000 ft)are quite warm over the entire region, but the influx of cool air and considerable low clouds kept it cool over NW Washington (mid to upper 60s).  Middle 70s over the south Sound, but near 90F in Portland.   Cross the Cascades to escape the marine influence and 90s are the rule in the Columbia Basin.



The cause of the SW heat?  A upper level ridge of high pressure that brings sinking air aloft (and sinking causes compressional heating)--see 500 hPa (around 18,000 ft) weather map for 5 AM this morning.


A weak cold front will move through western WA tomorrow, bringing clouds and some light showers...temps only getting up into the mid-60s in western WA.   If you want to escape the cool, moist weather, you might head down to Palm Springs, where it will be a sizzling 121F tomorrow and around 115F for the rest of the week (see weather.com forecast below).


Saturday, June 17, 2017

Should Scientists and the Media Exaggerate Global Warming?

Should scientists and the media exaggerate the current and future impact of human-forced global warming to encourage people "to do the right thing"?

A number of scientists and media folks believe the answer is yes.

For me, the answer is an emphatic no, for reasons I will explain below.   Let's consider some of the arguments for and against and you can decide for yourself

Climate Exaggeration:  The End Justifies the Means

Global warming due to human-caused (anthropogenic) increases in greenhouse gases is a significant threat to mankind.  Yes, there are uncertainties, but there are potentially major, negative impacts for our species and the planet.  Most climate scientists are in agreement that there could be serious problems by the end of the century from heat waves and droughts, to heavier precipitation and more extreme hurricanes if the rise of greenhouse gases are not reduced radically.

The problem is that with all the talk, mankind is not doing enough to reduce carbon emissions into the atmosphere, and amounts of atmospheric greenhouse gases are increasing rapidly.   Concerned climate activists note that most people do not see this issue a primary concern.   And most of the impacts of increasing greenhouse gases will be in the future, and it is very difficult to get folks to sacrifice NOW to deal with a threat to future individuals mainly in other countries.

So the somewhat cynical approach used by "climate activists", some media,  and unfortunately a few scientists has been to hype and exaggerate  the impacts of increasing greenhouse gases on current weather or ecological events, even though  there is really little evidence of a anthropogenic greenhouse gas origin.   Here in the Northwest we have seen media stories stating that lone trees in the arboretum, oysters in commercial hatcheries, snowpack in the Cascades, major windstorms, and one-year droughts have been caused by increasing greenhouse gases.  But the evidence for these claims is very thin at best.


I have been struck by the persistent questions of the local media....many simply don't understand why hyping global warming is a problem.   For example, in a recent interview with KUOW, Bill Radke asked:

"What are the worst things about excessive claims?  This is our only planet so far.  Aren't we better safe than sorry?

And in a recent give and take, a writer (Charles Mudede) for the a local newspaper, the Stranger, commended past Mayor Nickels for hyping snowpack loss and explicitly state that the media needs to exaggerate enough to move the population to a state of "panic" about climate change.  You can't make up things like this.

Climate change exaggeration has also spread to the politicians and their associates.  Major Washington State officials talk frequently about the oyster factory deaths as caused by CO2 emissions, Mayor Nickels pushed snowpack loss, President Obama's science advisor claimed that eastern cold waves were caused by global warming, Governor Cuomo claimed that Hurricane Sandy was related to increasing greenhouse gases, and many more.  The list of such baseless claims is very long.  And there are cheerleaders in non-profit organizations (like Climate Central or Seattle's Climate Solutions) that not only applaud such nonsense, but take it further at times.

But perhaps the worst (and most inexcusable) examples of global warming hyping is from some activist scientists.  A primo example for our region was the attempt by some local scientists to hype the loss of Cascade snowpack, claiming it was a local example of greenhouse warming.  This led to the firing of the Associate State Climatologist by the then Washington State Climatologist.   I wrote a paper with Mark Stoelinga and Mark Albright (accepted in the peer-reviewed literature) disproving these exaggerations, by the way.  There are many more examples of scientists giving up their objectivity to become advocates.

Why Climate Exaggeration is a Bad Idea

1.  Exaggeration Threatens the Role of Science in the Nation's Political Realm

The job of science and scientists is to provide society with accurate information: about what we know, what we don't know, and information regarding the confidence in future projections. It is a not scientist's job to make society's decisions or to push folks to take certain actions--that is in the realm of the political system.

For the past half century, there has been bipartisan support of science and this will only continue as long as scientists stay objective and politically neutral.  As soon as science appears as an advocate for one party or sides with one party, it will lose the support of the other.  And nothing major can be done in this country--particularly long-term issues like climate--without having support across the aisle.


2.  Credibility of the Science Establishment

Crying wolf by hyping climate impacts will undermine confidence in Science by the general population and decision makers, because sooner or later it becomes obvious that bad information was being distributed.    Here in the Northwest, those claiming a permanent loss of snowpack in the mid-2000s, now must explain the bountiful snowpacks of the last decade.  Those suggesting the CO2 killed the oysters, now have to explain the recent excellent harvests of all kinds of shellfish.  Those claiming that the West Coast was heading for permanent drought two years ago, have to explain the turn towards wetter conditions.

3.   Making Decisions for Infrastructure and Public Policy

Those pushing for exaggerating climate change forgot a very important issue:  that realistic and accurate predictions are required by society to adapt to expected changes.   Any climate scientist will tell you that a certain amount of future climate change is guaranteed due to the current level of greenhouse gases in the atmosphere (which the atmosphere hasn't caught up with) and the fact that we aren't going to zero emissions in the near future.   To protect lives and property, substantial adaptation efforts will be be needed, such as infrastructure improvements.  For example,  more dams and reservoirs may be needed to deal with reduced snowpack.   Some folks will have to move away from locations near river banks, as maximum flows are enhanced by warming.    You can't build infrastructure with hyped and exaggerated projections:  the costs could be hugely increased or the designs would be improper for the actual future environment.

Adaptation and resilience to climate change will demand the best projections science can determine, including full information about uncertainties.   Politically useful exaggerations today will not be adequate.


4.  Psychological Stress on the Population

By hyping and exaggerating the current and near-term impacts of global warming, climate exaggerators are putting substantial stress on on the general population, and particularly the most psychologically vulnerable.   The constant headlines and apocalyptic warnings are making people feel vulnerable, uncertain, powerless and under duress, particularly since most don't possess a lot of options for moving or changing their lifestyles.   The media is making thing worst by talking about climate psychological stress, with some even suggesting the existence of pre-traumatic climate stress disorder.


I have gotten dozens of emails from folks acutely worried about climate change, including those ready to move to our region to escape disaster in their current locals.  Particularly poignant was a woman that was afraid to move to San Diego to aid her aging father, because she feared that imminent climate disasters in southern CA would endanger her teen-aged children.  Hype and exaggeration can push folks to turn away from the unpleasant stressor, making productive action less, not more, likely

5.  Exaggeration and Hype can be Counterproductive

 Folks have a good intuition about when they are being played or lied to.  When someone is exaggerating and distorting the truth.   When global warming is used as an explanation for nearly any type of natural (or unnatural) disaster, folks start doubting.  Heat waves? Global warming. Cold Waves? Global warming?  Floods?  Global warming.  Drought? Global warming.  Dead trees?  Global warming.  Too much vegetation growth that cause fires?   Global warming.

Such hype is particularly obvious when it gets combined with the social goals of a particular party.

And in this environment of hype, they see climate scientists, climate activists, and vocal politicians not "walking the talk" in their own lives, such as enjoying extensive domestic and foreign travel on carbon-emitting aircraft.    Climate exaggeration, and the doubts it engenders, make it less likely that folks will try to reduce carbon emissions or support policies that do.


6.  Truth Telling Opens Hearts

When scientists work to provide objective truth about climate change, moderate and conservative folks are much more likely to listen.  I have learned this first hand:  since I am known as someone that rejects hype, I have been invited to talk to conservative groups about climate change.   I was surprised that many of such groups are concerned about long term impacts (such as agriculture interests in eastern WA) and are ready to work on adaptation efforts.

7.  Exaggeration of Impacts Can Undermine Important Environmental Efforts

Global warming is not the only environmental issue or challenge.  But hyper-attention to increasing greenhouse gases can undermine key environmental efforts that enhance our sustainability with our planet.   Consider large wildfires over eastern Washington.   Some folks, including major WA State politicians, keep on talking about the role of global warming.   But talk to folks who really understand the problem (such as faculty in UW's Forest Resources College) and they discuss ill-conceived fire control and poor forest practices that have led to an unnatural and dangerously flammable forest environment.  And key steps to fixing our forests were stopped or slowed by those pushing a global warming agenda (e.g., prescribed burns, thinning and removal of slash).   Commercial oyster growers clothed themselves in greenhouse gas environmentalism, distracting politicians in our state from dealing with the oyster-growers anti-environmental actions, like widely spraying toxic herbicides and pesticides over Washington State waterways.



The History of Deceiving the Public to Get Them to "Do the Right Thing"

Throughout our nation's history there have been those who have attempted to deceive the public to get them "to do the right thing."    Lies encouraging people to support supposedly great goals have generally produced public disasters.  Consider a few:

1.   Lying to the public about weapons of mass destruction prior to the second Gulf War by President Bush and associates.  That led to an unnecessary war, the deaths of hundreds of thousands of people, and the destabilization of the Middle East.

2.  Exaggeration of the threat of the "domino effect" led to the Vietnam War.

3.   Exaggeration of the threat of marijuana, led to nutty drug laws that resulted in enriched drug lords and the preferential imprisonment of minorities.

4.  Exaggeration of the threat of terrorism  resulted in a hugely expensive war on terror that undermined our civil liberties and cost trillions of dollars.


My bottom line is quite simple:  scientists and their media conduits should never hype or exaggerate the expected effects of climate change due to increasing greenhouse gases. 

Finally, I know some folks will ask me why I have mainly discussed misinformation on the "pro", generally left-leading, side, and not taken on the "skeptics"  that have certainly spread inaccurate information about the global warming threat.   My main reason is that "pro" side have generally been the dominant, controlling group.  The scientific community and most of the media (e.g., NY Times, WA Post, LA Times, Seattle Times, most networks, etc.) have been on the "pro" side, as has the Federal government for most of the past several decades.  And, being a scientist and living in Seattle, the "pro" side is around me all the time.

“The end cannot justify the means, for the simple and obvious reason that the means employed determine the nature of the ends produced.”

Aldous Huxley

Thursday, June 15, 2017

Heavy Rain and Super Rain Shadow

Announcement:  Atmospheric Sciences 101

I will be teaching Atmospheric Sciences 101 this fall if anyone is interested either as a UW student or the Access Program for those over 60.  This is a general intro to weather and weather prediction.  MTWTh 10:30-11:20, Kane Hall.
_______________________________

There was some impressive rain totals today for June, with the southwest side of the Olympics getting 2-3 inches so far, with 1-2 inches on the western side of the Cascades (see plot of 24h rain ending 7 PM Wed).   But just as impressive was the profound rain shadowing on the northeast side of the Olympics and the eastern slopes of the Cascades.   Amazingly, there were only a few hundredths of an inch of precipitation around Sequim and .02 inches at Friday Harbor in the San Juans.


Take a look at a blow-up precipitation plot for a better view. One location near Sequim had only .01 inches.  Hundreds of times that rainfall fell 50 miles away on the other side of the Olympics.


Why such a difference?   We had a very moist airflow coming into our region, driven by strong winds.   Here is plot of the winds with height at Quillayute, on the NW Washington coast. Winds near crest level were southerly to southwesterly at 30-40 knots (the heights are in pressure, 850 is about 5000 ft).  Quite unusual for this time of the year.

With such south/southwesterly winds, the moist air was forced up on the southerly/SW side of the Olympics (producing heavy precipitation) and then descended (causing drying) on the north and northeast side of the barrier.

The rain shadow was very obvious in the National Weather Service weather radars (see example below) as a "hole" in the precipitation shield.


And the rain shadow was also apparent in the visible satellite imagery this afternoon (see example below)

The heavy rain is causing some local rivers to surge to near record levels for the date--for example, the Wynoochee River near Montesano.


The situation will dry out into Saturday, but rain will return Saturday night into Sunday morning.   Nice for our plants and water bills.

Wednesday, June 14, 2017

Midwinter Moisture in June

Tomorrow is going to be an unusual June day over the Northwest.  An extraordinary plume of moisture that stretches across the the Pacific is now approaching our shores, and mid-winter amounts of rain will spread over the region.  A satellite image of the amount of water vapor in the upper atmosphere shows a "river "of moisture stretching from the southwest north Pacific to our coast.


Another satellite product of the amount of water vapor in a column of the atmosphere (for 3 AM this morning), shows large amounts of water vapor in the tropics as well as the extension of moisture heading northeastward towards the Northwest.

A forecast for this water vapor at 8 AM Thursday morning shows a very strong plume of moisture headed for the West Coast.  


This moisture plume and associated strong westerly flow will cause substantial precipitation over our region tomorrow as the moisture is forced up by our terrain.  Here are the 24h totals ending 5 AM Friday.   Really amazing amounts for mid-June, with 1-2 inches (pink colors) in many mountain areas and roughly a half-inch in Seattle.   Even eastern WA gets moistened.

To get an  idea of how unusual this moisture plume is for this time of the year, here is the standardized or normalized anomaly for the plume at 11 AM on Thursday from the European Center model (courtesy of Weatherbell, Inc.)   In this approach, the difference of the total water vapor in the column and the normal value for that date are found (the anomaly) and this is divided by a measure of the climatological variability (the standard deviation).  The plume approaching our coast has a normalized anomaly of about 4.5, which would have a return time of several years.


The implications of this event are substantial.  A major wet system in June, moistens the ground and pushes off the wildfire season.  It will also suppress water usage, which started to surge after our recent dry spell (see graphic).  Enjoy the rain....