Cliff Mass

Cliff Mass: Cloudy weather is at its worst in 60 years

Several of you have noted that it is not the cool temperatures or even the rain that bothered you this last few months, but the lack of sunlight–sort of like a summer version of seasonal affective disorder (SAD).   So what is the truth about clouds this spring and summer?In such situations there is ONE expert on our local murk that I trust, a local scientist who has spent  great time looking a the climatology and trends of local clouds.  I have mentioned him before—Dr. Jim Johnstone, AKA Dr. Fog, a researcher here at the UW.

Here are some of his depressing results–the average number of hours a day with clouds at Sea-Tac for April through June 2010 and 2011 have simply been the worst over the past 60 years. We are talking about 18-19 hrs a day of cloud on average.  And the general trend the last few decades is for more clouds.


Cliff Mass: East Coast versus West Coast. The continental weather seesaw…

It often seems that the U.S. east and west coasts are on some kind of weather seesaw.   Recently westerners have been complaining that the East Coast is warm and the West is cool, but sometimes it goes the other way.  Quite frequently, warm records are found on one coast when cool records are occurring on the other.   The coastal weather seesaw some people call it.   And now,  a new index reveals its intimate details.   In this blog you will view the Coastal Contrast Index (CCI), an advanced new diagnostic tool never shown before in public.   

The CCI is based on the difference between the temperatures of major cites on both coasts.  Specifically, the mean temperatures of eastern cities (TE) minus the mean temperatures of western cities (TW).


For TE we use Boston, New York, Washington DC and Atlanta.  For TW we use Seattle, Portland, San Francisco, and Los Angeles.  The selection of these particular cities is based on arcane scientific principles that are too complicated to explain in this blog.  Yes, the latitudes don’t match exactly, but that is where the people are.  And I should note that the data analysis for the CCI was done by data analyst extraordinaire of the UW:  Neal Johnson.

Ready to see it?  Take a look at this graph… (more)

Cliff Mass: Why the Northwest is nearly heat wave proof

As we complain about our cool summer, we should not forget that the central and eastern portions of the U.S. has been experiencing major drought and heat waves (as noted in my previous blog there is an intimate condition between our coolness and their heat).  It turns out that when one does a careful accounting of the meteorological causes of death, heat waves far exceed tornadoes, hurricanes, lightning, and floods in causing deaths and injury.   Only one other meteorological parameter is in the same league:  roadway icing–which injuries and kills thousands of people per year around the U.S.  Consider a few examples of heat wave losses:  the U.S. heat wave in 1980 killed more than 1250, while the famous Chicago heat wave killed 700.  And of course the 2003 European heat wave brought an extraordinary toll of roughly 50,000.

Of course, the key reason we don’t have many heat waves is the Pacific Ocean… (more)



Did Sea-Tac’s third runway change our climate?

This is getting bizarre

Cliff Mass weather: Why do we suffer?

It is reminiscent of the Book of Job.
We look to the heavens and ask:  Why do we suffer?  Why is the warmth of summer denied us?

… In fact, the atmosphere has been “frozen” in a certain configuration since late winter, causing the heavy snowpack in the mountains as well as cooler than normal and cloudier than normal conditions. 

Now one reason that we have had this pattern is because of the La Nina of last year, which is associated with colder than normal temperatures over the tropical waters of the central and eastern Pacific.  La Ninas cause tropical convection (thunderstorms) to shift eastward and the easterly trade winds to strengthen.  Why do we care about this?  Because the shift of the convection perturbs the entire atmosphere– think of a pond and you throw in a rock…there are waves in the pond.  Our pond is the earth’s atmosphere and the rock is the thunderstorms; shifting where the rock hits (which the big thunderstorms are) changes the waves that are moving out into the entire atmosphere. 




Did Sea-Tac’s third runway change our climate?

This is getting bizarre

Cliff Mass: Did Sea-Tac’s third runway change our climate?

Last week the Seattle Times had a front page story about the Northwest becoming warmer and wetter  based on recently updated climate statistics at Seattle-Tacoma Airport.  But can we use one observing site to reliably determine region climate trends?  In my previous blog I noted that this is a real problem:  one site is not necessarily representative of a region and besides it might have observing issues.  And Sea Tac has such issues in spades:  changes in the local environment, changes in sensors, and changing positions of the sensors.

But there is a related issue: although I believe that the threat of anthropogenic global warming forced mainly by CO2 and other greenhouse gases is extraordinarily serious and –quite frankly– inevitable, I also worry about the integrity of our surface observations.  I don’t believe my field has given sufficient attention to the impact of development around our weather stations, or of poor placement of our thermometers near concrete, buildings, or other generators of heat.

Between 2004 and 2008 there was a huge change at the airport, one of the largest construction/earth moving projects in the region in years–the building of a third runway.  In this blog I will ask the question: did the construction of the third runway have an impact on summer temperatures reported from the airport?   My conclusion and that of my colleague Mark Albright is: 

it sure looks like it.


Cliff Mass’ weather forecast: This is getting bizarre

I think we communally must have sinned.  I have followed the weather around here for a long time and I can’t remember such sustained cool, cloudy weather during the middle to end of July (including what is going to occur).  The latest round of model runs–including the ensemble forecasts–suggest this situation is not going to end during the next week.    In fact, some days will be worse.

The latest Climate Prediction Center forecasts for the next 6 to 10 days are pretty emphatic:  a greater probability of cooler and wetter conditions than normal–here are the graphics (click to enlarge):

And for those of you  ready to make a crack about the fallacy of global warming, note that the eastern U.S. is experiencing a heat wave.  Average the whole country and we are above normal!



Cliff Mass’ weather report: The big chill

During the past two weeks we have enjoy fairly nice weather over the region, a break from the cooler and wetter-than-normal conditions this spring.  I got some bad news for you…amazingly, the cool pattern is back and it isn’t going away soon.  And it will rain–today.

Here is the latest visible satellite picture.  It looks like winter, with clouds over the entire region and a very solid mass of clouds moving in from the southeast.

Why is this happening during a period in which the weather is usually fine?


Cliff Mass: Northwest getting warmer and wetter? Not really

On Thursday the Seattle Times had a banner headline: “Our new “normal” weather:  wetter and warmer”

It turns out there are a lot of issues with this claim if you really examine the facts.  Let’s do it!



Cliff Mass: Fireworks-induced air pollution

Wake up with a little cough Tuesday morning?  Did the air in your neighborhood Monday night seem more like Beijing than the pristine Northwest? It is not your imagination. Blame FIAP-  Fireworks Induced Air Pollution.

There was a decided degradation in our air quality late yesterday– in fact, at some locations it was downright unhealthy for those of you with respiratory problems. (more)



Cliff Mass: Fourth of July weather — the facts

There is a lot of weather mythology about the Fourth of July in the Northwest.  Some believe it always rains or that the weather is worse than other nearby days.  Or that the fireworks “seed” the atmosphere for more clouds for particularly poor weather late on the fourth.

There ARE some interesting climatological aspects of this weekend…so let’s check it out. Here is a plot of the climatological probability of measure precipitation at Sea-Tac Airport.

You  can see that during the latter part of June we are locked into roughly a 27% chance of rain and that this value holds into the July 4th weekend.   But then the Northwest magic occurs. (more)