July 31, 2011

Saving Seattle's Schools Requires New School Board Members

This year we can take a huge step in turning around the troubled Seattle School District, but to do so will require replacing the current board members that are up for election.

The multitude of problems in this poorly run and poorly performing district are manifest, and ultimately the origin of these deficiencies can be traced to a lack of leadership, energy and curiosity among several of  the school district's directors.  It seems that local newspapers run another depressing story every few weeks about a major Seattle School failure or scandal.  A few examples include:

(1)  Multiple reports of financial irregularities, including an out of control Small Business Development Program that wasted 1.8 million dollars.

(2) Poor administrative control and lack of transparency by superintendent Marie Goldloe Johnson that resulted in her firing

(3)  Lack of progress on student achievement, particularly by minority and low-income students.

(4)  Firing of a highly competent and beloved principal of Ingraham High School and an unwillingness to admit error over the incident.

(5) Selling Martin Luther King Elementary to a group with inside connections, for a loss of near 7 million from what could have been secured from the Bush School.

(6)  Selection of a high school math curriculum found to be mathematically unsound by the State Board of education.

(7) Deliberate deception about the college readiness of Seattle students.

(8)  Acceptance of an influx of untrained "Teach for America" "teachers" when a large pool of experienced or properly trained teachers are available

(9)  The State Board of Auditors 2010 audit produced a highly damning audit of district finances, citing mismanagement of district resources and noted that the school board failed to properly oversee the superintendent.
I could go on and on..but you get the message--poor student performance, poor administrative structures and oversight, cronyism, corruption, and much more.

Ultimately, the Seattle School Board is responsible for the school district and it is clear they have not done a very good job.   Many of them have been content with rubber-stamping the Superintendent's recommendations, have shown little curiosity about  obvious failures, have provided minimal oversight,  and have shown little interest in taking strong steps to turn around a sinking district.

But the waterfall of failures have gotten the community's attention and the worst school directors are now up for reelection.  Retiring the current incumbent directors up for reelection and replacing them with active, questioning individuals could have a huge impact. particularly since the remainder of the board is much stronger (DeBell, Patu, Kay Smith Blum) .  If you are a Seattle voter, this year you can have a major impact for good--here are my suggestions.

District 1:   Sharon Peaslee over the incumbent Peter Maier.  Maier is one of the worst of the current board members, and it is has been reported that he knew about some of the financial shenanigans early and chose not to act.  He also voted for the terrible Discovering Math series, even after he was told it was unsound (I was there...he really didn't care).   Sharon Peaslee has substantial teaching education and experience, was a key player in saving Ingrahm HS principle Martin Floe, and has been a real activist for better math and other issues.

District 2:  Kate Martin or Jack Whelan over the incumbent Sherry Carr.   Sherry Carr has a lot in common with Peter Maier--lack of curiosity, lack of vision, stay the course, support the superintendent.   Kate Martin has great vision, amazing knowledge about education, is willing to ask hard questions, and has the experience in management to back it up.  And extraordinarily articulate.  Jack Whelan, a member of the the Foster School of Business at the UW, is the poet of the campaign, writing cogently and insightfully about the districts problems.  He will not rubber stamp.

District 6:  Marty McLaren over the incumbent Steve Sundquist. Steve was supporting Goodloe Johnson to the end and rarely questioned the Superintendent's direction.  He STILL believes that the selection of poor Discovery math books was a good idea and has pushed the idea of bringing  barely qualified Teach for America recruits into our classrooms.  Amazing.  Marty McClaren is an extraordinary individual, with substantial teaching experience and was the force behind the initially successful math textbook lawsuit, for which she took personal financial responsibility (one of the most selfless acts I have seen in a while).  She is the kind of person that will ask questions...a lot of them.

Folks...elect 2 or 3 of the above and the majority of the board will change from stay-the-course rubber stamp types to inquisitive, intelligent individuals ready to show considerable leadership.

Announcement:  There will be a candidate forum for Seattle Public Schools, District 1 on August 10th at Enlighten Cafe and Art Gallery at 5424 Ballard Avenue NW. Time- 8pm

July 30, 2011

Dry Time and Low Clouds

We are now in the driest time of the year climatologically (see graph below of climatological probability of rain, click to enlarge)--in fact, the driest day of the year on average was yesterday July 29th, when .005 inches of rain has fallen on average at Seattle-Tacoma Airport over roughly the last half-century.  We think of ourselves as being a wet place, but during the magical last week of July and first week of August we are one of the driest places in the U.S., with a climatological probability of rain of around 10%. 

Today will remain dry, but there is a good chance it will rain tomorrow (Sunday)!--more on that later.

Before I talk about tomorrow, I wanted to show another fascinating figure on our cloudiness issue this year, produced by Dr. Jim Johnstone (Dr. Fog), who I mentioned in my last blog.  Beware!  This is one hell of a depressing figure.

The grey bars show the average number of hours of cloudiness at Sea-Tac Airport per month (1=January, 12=December).  18-19 hours a day in midwinter, with a gradual reduction to about 15 in June.  Then a HUGE decrease to around 11 in July, a graduate increase through September, and a jump up in October.  All locals know about this pattern--we have three months of relatively bountiful sun: July through September.

But now the depressing part.  The black line shows this year. You will notice that we have maintained wintertime cloud levels through June.  And I guarantee you that when July numbers get plotted in a few days, we will be way above normal (probably 15-16).  This figure, more than any other, expresses the unhappy moods of so many.

But yesterday was simply spectacular and today will be the same.  I was on the East Coast last week and experienced 103F with dew points in the mid to upper 70s.  Personally, I would rather have the cooler, milder weather. 

This morning some low clouds along the coast pushed in through the Strait and Chehalis Gap...but are rapidly burning off as I write this (see image).

Tomorrow, a weak front will move in--pushing a surge of marine air into the west and to the Cascade crest.  Here is the predicted 24-h precipitation ending 5 PM tomorrow.

The windward side of the Cascades will be a soggy place to hike and conditions will deteriorate rapidly going into BC.  So go south and east for better conditions.  Low clouds will spread over the west.   But improvement beckons on Monday...

July 28, 2011

The Cold Truth

Several of you have note 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 scientists who has spend a 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.  Now you will hate me for telling you this... but I have a project with Dr. Eric Salathe to simulate Northwest weather under global warming. 

Guess what.  These high-resolution simulations suggest more low clouds west of the Cascades as the interior heats up.  More interior heat causes the pressure to fall to the east and global warming seems to be associated with a stronger East Pacific High--the result:  more low clouds offshore and more onshore flow.

 And what about his results for temperature?  Here are the April-June temperatures for the entire state.  I bet you know which year was the coolest.  This year.  It is in a class of its own.

Or how about a plot of where the daily maximum temperature records (both record high maximum and record low maximum temperature)  have occurred this year during April-June?  The big concentration of record low maxima (blue symbols) is over the Northwest, while record high daily maxima were found over the southeast.

But if you really want to get into the murk, take a look at the amount of radiation measured at the top of the atmospheric science building at the UW.  On July 25th  the UW's sensor's measured  4.51 megajoule (unit of energy) per square meter,  the darkest day in almost 4 months.  On a bright sunny day we would be up in the low 30s.  Not since 4 April 2011 with 3.47 MJ/m2 have we seen a darker day in Seattle as measured at the U of WA.

This weekend....below normal temps but perhaps acceptable.  A disturbance approach from the north will get mighty close on Sunday, so go south and east for better weather.

July 25, 2011

Heavy Showers and Thunderstorms

I wasn't going to blog today...but had to mention the convection--heavy showers and thunder--that rolled through on both sides of the Cascades.  The radar showed it nicely---here are a few samples.

And all of this during one of the climatologically driest weeks of the year.  A number of locations along the eastern slopes of Cascades, around the Tri-Cities, and over the south Sound got .15 to .20 inches in the downpours.

And I hate to admit it, but the forecasts were not good regarding these thunderstorms--both the human predictions and computer models.   The NWS forecast yesterday was correct about a major cool down today as the upper trough pushed in, but pretty much missed the heavy showers.  The models also did not do well.  At least we have plenty to work on!

Now this was a classic convective pattern, with a sharp trough moving in:

But clearly some ingredient was missing in the models--either how the models were initialized or their descriptions of the physical processes.

Perhaps a hint of the origin of the failure can be found from the infrared satellite sequence today.  Here are images from last night through this afternoon.  My eye sees two features:  one associated with the trough moving in from offshore and another feature initially over Oregon.  It is when they join that the convection blew up in a way that Friday's computer runs missed.  My own examination of the model output suggests that the eastern convection was associated with a weak upper trough over land that the models underplayed....but I only looked at the situation briefly.  It takes some detective work to conclusively discover what is behind such forecast failures.

July 24, 2011

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 (click to enlarge) for January 1 through July 21st.

The blue line shows the daily climatological values based on long-term average temperatures for those dates and cities. 
Notice that from January 1 through roughly 10 April, the West Coast is generally WARMER than the East Coast by about 10F.   And then in late spring and summer the East Coast becomes warmer by roughly 10F again.  The seasonal seesaw...its real.  And the reasons are clear:  the West Coast has the relatively mild Pacific to its west, which keeps us warm in winter and cool in summer.  The East Coast has a large continental area to its west (weather generally comes from the west in the midlatitudes as you know), which is cold in winter and warm in the summer.

But this graph doesn't stop there!  The red line shows the index for THIS YEAR and the information is sobering.  And very different than normal. 

During the winter, the East Coast was WAY cooler than normal compared to the West Coast .  We are talking 20-25F cooler than the West.  You remember that--snowstorm after snowstorm, frigid day after frigid day for the forlorn easterners.  Some folks even blamed than on global warming.

And then in roughly mid-February an atmospheric switch was flipped and on most days the East Coast was warmer than the West--much warmer than it should be.  On many days, particularly this summer,  the East was 15-20F warmer than the West.   And if we included the last few few days, there would be a spike to 25 or more.

The reason for this anomalous behavior has been discussed in the blog several times:  the establishment of a persistent mean trough over the West Coast and a ridge over the central and eastern U.S. during February, a pattern that has just not gone away.

Finally, you will notice several big swings of the index and there is a reason.  Although there has been ON AVERAGE a trough over the west and a ridge over the east, on a daily basis sometimes there are brief excursions to the opposite situation, occasions when there is a ridge over the west and a trough over the east.  Then the seesaw goes the other way.  And westerners love it!

Why is the east and west coasts so frequently out of phase?  The reason is that the flow aloft is usually very wave like and the wavelength of the typical wave is frequently just about right to give us the out-of-phase coasts (see graphic).
The upper level flow pattern is very wave-like and has typical wavelengths.

This wavelength is set by a number of things, such as  the rotation rate of the earth and the typical temperature variations of the planet.    Why did we get this anomalous wave pattern this year?  La Nina is partially to blame, but there is probably more.   Is this a sign of global warming?  I don't anyone can answer this question at this point and keep in mind that while some places are warmer than normal, others are cooler.

One incident says little about long-term climate change, but some in the media are already saying that this incident is "consistent with" or "the kind of events we will experience under" global warming.  Want to see an egregious example of this--check out the NY Times.

July 22, 2011

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.
     Definitions of heat waves vary, but the National Weather Service likes to use the heat index, which combines temperature and humidity.  Humidity reduces our ability evaporate water from our skin--a very potent cooling mechanism (take a look at dog or cat in hot situation--they can't sweat and suffer for it!).  Here is a table for that index:

In essence, it tells you what the air feels like, or in other words how effectively you can get rid of body heat.  Generally, the NWS puts out warnings when the heat index gets to roughly 105F. In the Northwest we rarely get such values--not only because we are generally cool, but because when we get hot, the air is very dry and so the relative humidity is low.  Today over the northeast U.S. some locations had heat indices over 120F!!  For example Warrenton, VA had a heat index of 133F at 3 PM.  That is truly dangerous.   Washington National hit 120F.

Only once in recent years did we get into serious heat index values, and that was the heat wave of July 28-29, 2009 when we got to 103F in Seattle.   We had unusually high humidity values during much of that heat wave because the air reaching western Washington originated over the moist western slopes of the British Columbia Cascades:  a relatively unusual trajectory the low-level flow during our heat waves.

Eastern Washington can get over 100F pretty easily during the summer, but that heat is relatively dry.  And dry heat has another advantage--the air temperatures often cool substantially at night.  Why?
Humidity acts as a blanket.  Water vapor is a potent greenhouse gas the is very active in the infrared part of the spectrum.  It absorbs IR radiation emitted by the surface and re-emits IR radiation back to the ground...thus contributing to warming at the surface.

Here is an example of the large daily (diurnal) range of temperature at Pasco the last few weeks:

Eastern Washington has had a delightful climate this summer, but notice the big changes in temperature..particularly when they get warm.  Highs mid-80s and lows around 50-55F.  I hope it is warm enough for the grapes, which I believe like warm days and cool nights.

Of course, the key reason we don't have many heat waves is the Pacific Ocean, which keeps us cool and dry (see sea surface temperature map below).
While cold water is found west of the Northwest, the eastern U.S. gets air moving northward off the steamy Gulf of Mexico (temps in C, 30C is 86F)

No that last word is not a typo.   The ocean temperatures only rise into the low 50s during the summer at best, and with the East Pacific high offshore, we generally have onshore flow, bringing the cooling effect of the ocean.  Cool air can not pick up much water vapor so air off the ocean is relatively dry (low dewpoints).  To get really warm, we need offshore flow, but that air is generally dry too.  And offshore flow generally doesn't last very long around here.

And there's more!  When the west side heats up the pressure generally falls over the region (warm air is less dense and thus pressure declines).  We call that low pressure the thermal trough (or more accurately, the thermally induced trough).   So we have high pressure and oool air offshore and lower pressure/warm air over us.  Well, air wants to go from high to low pressure...it is just hankering to move in in this situation!  The warmer we get, the lower the pressure, the more than cool air wants to move in.  When large scale offshore flow weakens, the cool air surges in...giving us an onshore or marine push.

The bottom line:  when the Northwest was designed, natural air conditioning and protection against heat waves was a built-in feature. Even under global warming, this natural cooling system should still keep our summers tolerable.  In fact, if the interior of the continent heats up sufficiently, producing lower inland pressure, our local AC might get stronger!

Now it doesn't seem so bad to be in the cool Northwest anymore....

July 20, 2011

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?

Is this a great test of a stormy Satan?  If we accept the coolness and clouds without complaint, will the warmth of a true summer be restored, as Job was restored when he accepted God's will without complaint?

Verily, we have not acted like Job.  We torture ourselves counting the minutes of warmth (Sistek blog here).  Headlines in our papers promise greenhouse-induced heat(Seattle Times) and its manifestation is like a ghost.  National Weather Service forecasts suggest coolness will end next week, but the heat disappears like the water-on-the-road mirage on a heated road.  Blogs, comments, and articles in all sorts of media complain and protest.  Cold-hearted Satan is smiling. 

But redemption is possible.   Perhaps, armed with a better understanding of what is occurring, we can accept our fate, and with our complaints silenced, warm weather will be our just reward.

So why have we been stuck in such a cold pattern?  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.  Here is a classic example from last weekend:

This figure shows the heights of the 500 mb pressure surface...roughly half way up in the atmosphere. Where the lines extend northward there is a ridge, southward, a trough.  Red and yellow colors indicate low heights.
You notice a big ridge over the eastern Pacific, a trough over the northwest and adjacent coastal waters, and a ridge over the central U.S.  The atmospheric circulations are wave-like with typical wavelengths of several thousand km, so a ridge over the eastern Pacific is often associated with a rough over the West Coast, and a ridge over the central/eastern U.S.   So our cool weather and their heat wave/droughts are intimately connected.
    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.

Anyway, a number of research studies and lots of experience has shown that the La Nina shifting of the thunderstorms sets up the upper level pattern shown above, with the cold trough over us.  Here is an example:

The La Nina has weakened during the past few months, with the sea surface temperatures in the tropical Pacific nearly normal (a "neutral" situation).  But the thunderstorms and the trade winds are still in a La Nina-like configuration and this may be keeping the midlatitude pattern we so hate in place.  But what is causing the thunderstorms and trade winds to stay in the La Ninaesque pattern?   And could other factors be keeping us in this particular configuration.   We do not know.  At least I don't know!

Right now the computer models suggest a partial break over the weekend and back into the murk next week, but it is too soon to be sure about any of it.

Perhaps knowing a little more of what is happening will give us the patience of Job.

July 17, 2011

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.

So let us consider Seattle-Tacoma Airport, clearly the most reported station in western Washington and one frequently cited as a harbinger of climate change (such as in the Seattle Times).

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.

 But first a few pictures.  Here is a picture of  Sea-Tac before the third runway was installed. I have also indicated the position of the National Weather Service/FAA temperature sensors (their ASOS system) by a blue circle (just to the west of the second runway).

 Although it is hard to see, just to the west of the weather sensors the ground sloped down a hill (Sea-Tac is on a high spot), a hill that had lots of vegetation.  During the summer, particularly during the afternoons, the winds are from the northwest, and thus the air reaching that sensor was from above that vegetated hill.  Vegetation keeps daily temperatures down (mainly from evaporation of water--transpiration) and the higher you are above the surface in summer, the cooler the air.

In 2004 construction began on the third runway--a huge task.  Massive amounts of fill were brought in to the west side of the airport--just where that vegetated hill was located.  And a huge new concrete runway, with all kinds of taxiways and ancillary roads, were built.  A massive change of the surface west of the sensor.

Here are two recent pictures of the current runway situation (with the blue circle showing the sensor position).  Quite a change.

Here is a close of view of the sensors based from an image available on Google maps:

Now I did quite a lot of research to determine whether there were any temperature sensor changes recently (position, type, etc) at the airport and have reached lots of assistance from the folks at Sea Tac Airport and the National Weather Service.  Based on their help, and the documentation available from the National Climatic Data Center, I think we can say, quite authoritatively, that the temperature sensor has has not been moved since 2002 ( it had been shifted a bit then in consideration of the third-runway construction, and there had been major moves/sensor changes in previous years).
OK, now lets answer the question.  Did the runway change the summer climate at the airport?  My colleague, Mark Albright, calculated the difference in summer temperatures (June, July, August) between Sea-Tac and an average of four nearby official reporting locations (Olympia, McMillan Reservoir near Tacoma, Kent, and Buckley).
Negative means that the neighbors are warmer than Sea-Tac, which you would expect since they are farther inland and generally south of Sea-Tac (which has some cooling influence from the Sound).  You will see that Sea-Tac was generally cooler than those surrounding station (by roughly 1.5F) early in the period. And the slight shift in 2002 had little impact.   But after construction began in 2004 (particularly in 2005 to 2006 when the heavy earth moving occurred) things changed: Sea-Tac temperatures warmed up by roughly 2F so it was the same or warmer than the surrounding, more inland, stations.   I strongly suspect we are seeing the influence of the third runway.

The impact of development at the runway is also suggested by looking at recent temperatures at truly neighboring observing locations (not all official).  For example, here is a plot of temperatures during the afternoon of July 15th in the Sea-Tac neighborhood at 4 PM (click to enlarge).   Sea-Tac is the warmest of the bunch at 74F!
Bottom line:  It really looks that the third runway has significantly warmed summer temperatures at the airport.  Thus, one must be really careful in assuming that any warming there is the result of some kind of greenhouse gas influence.

Now this is not the only site with problems, a very significant percentage of our observing sites have moved, had sensor changes, are in areas in which urbanization have occurred, or other issues.  This makes it very difficult to use surface data to secure reliable information on regional temperature trends.  It is possible, but one has to spend considerable time to remove the bad stations or make reasonable adjustments.  Much more work needs to be done in this area.

July 14, 2011

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!

The causes of our cool, cloudy weather and their heat wave are the same: a persistent upper level flow pattern with a trough over the eastern Pacific and a ridge over the central U.S.  I can't tell you why it has been so persistent.  It could be random chance...like getting five heads in a row.  Or perhaps it is forced by some slowly changing sea surface temperature anomaly.  There are several possibilities.

The forecasts maintain this pattern for the next, with occasional strengthening of the trough leading to rain here on the western side of the Cascades.  Take a look:





You see the troughing along the West Coast in all of them? It is hard to tell them apart. 

And the ensemble prediction system, which averages many forecasts to give us the best possible prediction, provides the same answer.  In two weeks we will be in the middle of the meteorological summer--climatologically the driest and warmest time of the year.

Regarding the weekend, plan outside activities on Sunday...Saturday, particularly the morning, looks like a rain-out.  On the good side, you will save money on watering your garden.

July 12, 2011

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.

But first a recap to make you feel better.  Here are the temperatures at Sea-Tac Airport versus the normal high (red line) and normal low (blue) line for the past two weeks.
 You will notice that most days we either just reached normal or exceeded it, plus a few days below normal, which  is...well..normal.    Most days are not normal!   Amazingly we have been drier than normal this month...a few hundredths of an inch when we usually have .3-4 inches by this time.

But something has changed--something that is obvious by scanning the sky.  Yesterday some showers moved through and today (Tuesday) we are certain to get more.  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?  The reason:  an anomalous upper level low has moved in just offshore.  Here is the upper level chart for this morning for the UW WRF forecasting system:

The chart shows the height of the 500 mb pressure surface (roughly 18000 ft) and you can see a deep low centered a few hundred miles off of Washington.  And upper level troughing just hangs out along the West Coast this week.  Here is Wednesday afternoon:

Saturday during the day:

And Sunday late afternoon 

 You get the picture...this pattern is not going anywhere according to this forecast model solution.  Last night's run had a major warm up on Monday...no longer.

One tool meteorologists use to estimate our confidence in theforecasts is from ensembles--running the models many times with slightly different starting points or physics.   The average or mean of the ensembles tends to be more skillful than any individual forecast and spread of the forecasts give you a measure of uncertainty.

Here is the ensemble-mean anomaly (difference from normal) for upper level heights (same field as above) from the National Weather Service operational ensemble system.  Blue indicates that the mean of the ensemble is lower than normal and there is a lot of blue along the west coast.  And we are not talking just about the Northwest--the entire West Coast will be cooler and cloudier than normal. 

And the spread or variation among the ensembles is relatively low (see graphic below)--thus the confidence in this cool solution is relatively high.

The ensembles do have a lot of disagreements next week---so don't sell your swim trunks yet.  But in the near term, don't plan on typical warm, sunny weather.  And keep in mind this upper level pattern is making the eastern U.S. unbearably warm...with upper 90s in New York today.

July 10, 2011

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.  Lets do it!

The story was based on the fact that the National Weather Service has just changed the period used to calculate our climate--what they call the "normals."   A thirty year period is used and each decade they shift it forward to cover the last thirty years. The official climate normals were 1970-2000 and are now 1980-2010.

 The folks at the Seattle Times presented and discussed the results from Seattle (t is important to note is only ONE location in the region and might well not be representative!).  Here are their results, showing the normals from the last three versions of the climate normals  (1961-1990, 1971-2000, 1981-2010).

 Lets look at precipitation first.  Precipitation at Seattle dropped from the first normal to the second, and then increased for the new one.  Seattle is getting wetter?  Not so fast.  First consider the differences between these values--only a few tenths of inch separate them and I am pretty sure these differences would not be statistically significant.

But there is something else.  It is well-known fact among local meteorologists that something was wrong with the Sea-Tac rain gauge during the 80s and early 90s--the "SeaTac anomaly" in which the gauge reported too low, compared to gauges in the neighborhood.  Recently it was fixed.   This anomaly would clearly contribute to the trend.

Now if we can't be sure about Sea-Tac, what about the new normals for the other climatological stations in the region?  Here are the annual normals for the last three versions for Hoquiam (hqm), Olympia (olm),Bellingham (bli), and Spokane (geg).

(thanks to Neal Johnson of the UW atmospheric sciences department for crunching these numbers)

Completely different story!  The annual precipitation has gone down! Stop the presses!  New headline---the Northwest is getting drier!  But I wouldn't say that either...these differences are surely not statistically significant, meaning they are small enough that they could be due to random variations that are not connected with any true trend.

    What about the warming?  Could there be a problem with that too?  It turns out that if you look at other stations, one gets a mixed bag, some are cooling--like Hoquiam(hqm) and Bellingham(bli)-- and others show slight warming--like Spokane (geg).  Here are some samples.
 This makes a lot of sense to those of us who are working on the regional implications of global warming---the eastern Pacific has not warmed--in fact it has cooled.

So what about the rising temperatures at Sea-Tac Airport?  I suspect it is probably bogus due to sensor issues, the development around the airport, and the addition of the third runway.  A careful comparison high temperatures at Sea-Tac and the temperatures of surrounding stations indicated a several warm degree anomaly at the airport (done by Mark Albright, past state climatologist). For example, the first 8 days of July, Sea-Tac was 2.3F warmer than two nearby stations.


 The bottom line:  be very skeptical about dramatic headlines about climate change--when you dig a bit, you may find the truth is more complicated.

The Weather Regimes of Summer

 Weather patterns tend to get "stuck" for extended periods and we have certainly seen such persistent conditions this summer.    W...