Sunday, October 30, 2011

Nor'Easters versus Northwest Windstorms

During the last day, a strong Nor'easter (also called Northeasters by some) struck the northeast U.S. with strong winds, rain in the coastal areas, and snow inland.

What made this storm so remarkable was the snow.   Rarely do such storms bring this much snow so early.  Usually the first snow of the season hits the coastal northeast U.S. in mid-December.  From this events, some locations are breaking long term records--such as the earliest 1-inch snow for over a century at New York City.  This storm is NOT a record for earliest snow over the region---historically, most northeast snow have had some snow as early as mid-October. Snow on trees that are still leafed is a major issue, resulting in lots of downed trees and power outages.

 The weekend event is an example of a a Nor'easter--a strong, midlatitude cyclone (low pressure center) that moves up the east coast from the southwest to the northeast over the nearshore waters, roughly paralleling the coast. The winds move around such lows in a counterclockwise way, with the strongest winds generally from northeast over the north and western quadrants of the storm.  Here is a National Weather Service surface chart at 10 PM PST on Saturday night as an example (solid lines are isobars--lines of constant pressure....the closer together they are, the generally the stronger the winds).  Winds are shown by wind pennants at various stations.

Nor'easters are cousins to the big northwest windstorms (e.g., the Inauguration Day Windstorm, Chanukah Eve Windstorm, Columbus Day Storm).    Both get most of their energy from horizontal variations in temperature--thus they are midlatitude cyclones.  This is very different from tropical cyclones, such as hurricanes and typhoons, that derive their power from the warm temperatures and moisture of tropical oceans.

Both Northwest major cyclones and Nor'Easters have impressive satellite signatures, with characteristic cloud swirls and frontal cloud bands.   Want to see?  Here is an enhanced infrared image of the December 12, 1995 storm that hit us hard


and here is the latest east coast storm in the visible:


Large, impressive systems. For the Nor'eastern event...do you see that lines of clouds extending NW to SE from the coast---that is caused by cold air going over warm water.   In general, the very strongest Northwest cyclones are stronger than the top Nor'easters, with our 1962 Columbus Day storm probably being the most powerful non-tropical coastal storm to hit the U.S. in a century. (Beware--those wily east coasters like to call their storms "Perfect" or "Storm of the Century" and get books and movies made about them.  Don't believe their propaganda--ours are bigger and more powerful).

Before roughly 1990, few of these big storms--on either coast--were well forecast by our numerical models.  The 1962 Columbus Day storm came as a big surprise, and the President's Day Snowstorm of 1979 brought unforecast snow to D.C.  (very bad place for forecast failures!).   But by the early 1990s something had changed.  Our models now had sufficient resolution and physics, and satellite information was improving our description of the atmosphere to a point that we began to get these storms right.   For example, both the West Coast Inauguration Day Storm (January 1993) and the East Coast "Storm of the Century" (March 1993--I hate that name), were correctly predicted days before.  And we have only gotten better in time.

Lets see how we did for the current storm.   Here is the model analysis at 5 PM on Saturday.

Nice low off the coast, large coast pressure variations.  The dashed lines indicate lower atmosphere temperature, with the first blue one indication conditions cold enough for snow.  The forecast by the National Weather Service GFS model initialized 36 hr before is shown below...as well as the precipitation forecast (light blue is the heaviest).  Not bad!


Or how about 60hr before? Still quite good, but displaced a big too far offshore.


Keep in mind that some of these strong midlatitude cyclone can have hurricane force winds over water and are the equivalent of category 1-2 hurricanes.  And  midlatitude cyclones are much larger than tropical systems and do not weaken as quickly when they pass over land.

If a big midlatitude cyclone hits the Northwest this year we will have a magnificent view of the details using the new coastal radar.  And if our models are wrong about intensity or position, the new radar will enable us to get out timely warnings in time to save property and lives.  We have finally caught up to the east coast, where they have had radars looking offshore for decades.

Announcement:  The Puget Sound Chapter of the American Meteorological Society will be meeting on Wednesday, November 2 at the Northeast Branch of the Seattle Public Library at 6:30 PM.   UW Graduate Student Luke Madaus will describe the new dual-polarization products available from the newly upgraded National Weather Service radars.  All welcome.   Location: 6801 35th Ave. N.E.  More directions at: http://www.spl.org/locations/northeast-branch/net-getting-to-the-branch

Thursday, October 27, 2011

The Most Dangerous Weather Phenomenon in the Northwest

If you live in the Northwest, what weather phenomenon is the worst threat to your life?   What type of weather has the greatest chance of causing you bodily harm?

Floods?  No way...although they cause the greatest economic damage to the region.

Windstorms?  Not even close..although most major windstorms do cause a few fatalities and injuries.

Thunderstorm winds or lightning?  Nope--a minor issue around here.

 Give up?   I think the clear cut winner is ice on the roadway, often known as BLACK ICE, even though it does have to be black or invisible.

Pay attention to this blog--it could well save your life.



I got sensitized to the threat of roadway ice in the first years after I started at the UW.   On occasion I would do legal (forensic) consulting and I was surprised that most of the cases were associated with lawsuits dealing with roadway icing.  I was stunned by how many people were getting killed and injured....the WA State Patrol statistics were depressing--a dozen or so were losing their lives each year on State Highways due to icing, and hundreds, if not thousands were being injured.  The whole situation was made worse by the lack of knowledge by highway maintenance folks regarding the causes of icing and the primitive state of pretreatment of highways to prevent icing.  I decided to make a study of the subject and began working closely with Washington State DOT to improve the situation (and they have made a huge effort that has paid off in reduced deaths and injuries).

But State DOT folks are not everywhere at all times and many icing deaths and injuries occur each year on our roads (17 deaths in 2009 in WA aline from Federal online stats).  So let me explain how you can protect yourself and your family.

Roadway icing has two major causes:  frost and freezing fog, and the fog is the worse threat.   Frost occurs generally on cold, clear nights--the earth radiates heat to space and the earth cools to the dewpoint..and if the dewpoint is at 32F or less you get frost.  Frost can make the road slippery, but it produces a relatively thin layer, which allows the roughness of the road to still supply some traction.  Yes, you can be killed by frost, but you got to be driving really fast or make a big error.

The big threat is freezing fog.  Classic situation around here:  clear, cold night....the roadway temperature drops below freezing..perhaps a little frost... but nothing bad.  Near the road, there is a boggy or wet area over which fog forms.   The fog then drifts over the roadway and lots of the fog droplets freeze on the roadway, leaving a thick ice deposit.  Very dangerous.  If you are driving on a cold night when temperatures are in the 30s or below and fog is around..SLOW DOWN IMMEDIATELY.


Now lets talk temperature!  On cold, clear nights the road surface is often colder than the air above.   Official temperatures are measured at around 6 ft, and the road surface can be 2-5F colder than that on such nights.  You have a temperature sensor on your car?  That sensor is a few feet off the ground and could well be warmer than the road.  BOTTOM LINE?  If you car thermometer or reported temperatures reach the mid-30s, icing is quite possible on the roads.  Slow down.

Another major piece of advice--bridges and elevated roadways ice up first.  Why?  The ground conducts heat into the  roadway, especially early in the season.  Bridges and elevated roadways don't have this heat source and thus cool down faster than roads in contact with the soil.  Half the cases I have consulted on have been on bridges and elevated sections.

Bottom line--if weather is going to kill or seriously injure you, chances are it will be from roadway icing.  Slow down when the warning signs noted above occur.  Be sure to purchase a car with Vehicle Stability Control (many new cars have this now), which lessens, but DOES NOT ELIMINATE, skidding on icy roads.

If you want to learn more about this topic , check the webpage I have created here.

Seattle School Board Race News

The Seattle times published ANOTHER story today  about crimes and scandals in the school district: one of the individuals involved in ripping off the district had an escort service as well. 

Another Times story revealed that outside individuals...many connected with high tech and Microsoft...are sending large amounts of money to the incumbents because the incumbents are on board with "school reform." (mainly blame the teachers and judge their performance based on "objective" student evaluations, hire Teach for America applicants, etc.)  The great irony is these high tech folks are supporting the wrong people...school board members that have contributed to the degradation of math education in the district.  All the challengers want first-class math instruction with curriculum and books similar to those used in countries where the kids do well in math.  The incumbent school board folks have supported fuzzy math, with lots of calculators and group work, with very poor content.  The Gates Foundation, Microsoft millionaires and other supporting the incumbents are contributing to folks that are cutting off the supply of math capability students to the high tech industries of the area.

Most local community groups (e.g, Democratic party), unions, and local math-education groups (e.g., wheresthemath.com) support the challengers. So does the Stranger.  Pathetically, the Seattle Times supports the incumbents.  Here is what the Times editorial board said today:

"Board members and district officials also cannot escape blame for the thefts in the district's Regional Small Business Development Program....Blame must be shared again by the board and district leaders for allowing, tolerating, inviting — pick your verb — a district culture of indifference and dishonesty. Board members showed too much confidence, or a stunning lack of curiosity, about the superintendent's management." ...
 
In the upcoming School Board election, this page endorsed the incumbents...The Times believed the incumbents are most knowledgeable about the inner workings of the district and best able to repair the damage"

Can you believe this?  The school board incumbents have been entirely incompetent in running the district, but they should be retained, because they know how they screwed up and thus can fix the problems they created?  The Seattle Times editorial staff is very disappointing--such sloppy work is not what you would expect from the main newspaper in such a major city.

Support the challengers if you want improvements in the Seattle School District.

Monday, October 24, 2011

The Truth About Wind Chill

How many times have you heard it on a TV weathercast?   "The temperature is 35F, but with the stiff winds today, the wind chill temperature is 24F, so bundle up!"

 TV folks sometimes refer to the wind chill temperature as the apparent or equivalent temperature, the temperature it would feel like if the wind was calm.

Now if the temperature is 35F and the wind chill temperature is 24F, will water freeze? (Answer: No)

Will your car battery have a harder time starting your car if the wind chill is lower, but the temperature is the same? (No)

What exactly is this wind chill business?

 The original wind chill index was created during the early 1940s by two polar explorers (Siple and Passel), who measured how long it took for plastic bottles of water to freeze at various wind speeds.   If the temperature was below freezing, the bottles would freeze up more quickly when the wind speed increased.  Their original index was not in terms of temperature, but rather in cooling rate.

   In the 1960s, wind chill was expressed in terms of equivalent temperatures--the still air temperature that would produce roughly the same cooling rate compared to the observed temperature and wind speed.   Finally, in 2001 the National Weather Service produced an upgraded wind chill chart that more accurately described the cooling rates at various temperatures and wind speeds (see below):


The whole idea of wind chill is based on the fact that the loss of heat on our skin is related to the difference in temperature between our skin and the cooler outside air (more cooling when the difference was larger) and the wind speed (stronger winds remove heat from our skin faster).   Under calm or near calm conditions, a veneer of "dead air" stays near our skin, and this air, warmed by our skin, act as an insulator.   If the winds pick up, this protective layer is progressively removed.

 The efficiency of batteries only depend on temperature.  If the wind is strong perhaps the battery might cool off faster if it enters an area of cooler temperatures, but the chemical reactions inside the battery only vary with temperature.  Freezing of water depends on the average speed of the water molecules (which is directly related to temperature, the average kinetic energy--energy of motion--of the molecules).  Temperature alone decides on whether water will freeze.  The winds could be blowing 500 mph, but water will not freeze at 33F!

Tonight, eastern Washington is going to be hit by some of the coldest temperatures yet this winter, and the National Weather Service has a freeze warning for the lower elevations of eastern WA.  Here is the forecast temperature for 5 AM.  Most above freezing.


And here are the wind chill temperatures at the same time (lot of them below freezing)


 Wind chill or equivalent temperatures are useful, but there are many other factors that influence cooling rate, such as the amount of solar radiation (sun) and clothing.

 Seattle School Board Information

Jack Whelan, who had run for the Seattle School Board this year, has written a wonderful piece on the current election.  If you would like to read it, do so here.

My recommendations for the Seattle School Board election is here.

And today, another State Auditor's report found that the pressure to underpay for the MLK School came from the highest levels in the School District.

Saturday, October 22, 2011

Transforming Seattle Public Schools

Every week there seems to be a new headline revealing a new scandal, a new mistake, a new problem or a new school official forced to leave at Seattle Public Schools.  Student performance lags, particularly of the least advantaged.  One of the high-tech capitals of the U.S., a city with a highly educated and progressive population, possesses a school district that is doing an incredibly poor job in preparing its students for the next century.

It doesn't have to be this way.

Enough is enough.  In this election voter Seattle voters have an opportunity to remove poorly performing incumbent school board members (a.k.a. "Directors") and replace them with individuals with a different vision;  individuals who are willing to ask hard questions and make substantial changes in the district.  And I am convinced that the election of the four challengers offers a real chance to turn this district around.

In this blog I will make the case for voting for four challengers:

 Sharon Peaslee, Marty McLaren, Kate Martin, and Michelle Buetow

What Is Wrong?

  I would need a dozen blogs to properly describe the recent troubles in the Seattle School District, including:

A rogue operation in the district administration (Pottergate) in which school employees were billing the districts for services (training small businesses to work on district projects) that were never done.  Millions wasted.  The superintendent (Maria Goodloe-Johnson, MGJ) and some of her administrators  knew about it and said nothing.   A school board member (Peter Maier) learns about this scandal and does nothing.  MGJ is fired when the media figures learns what is happening, but given a bountiful financial settlement by the school board.  A state audit detailed a rogue contracting operation within district offices, replete with overbilling, ethics violations and intimidation of critics. And the report describes a district administration without sufficient oversight from the School Board.

In fact the State Auditor found a large number of management problems with the school district, including:
  • The Seattle School District overpaid employees due to a lack of adequate
    internal controls during a payroll system conversion.
  • The School Board and District management have not implemented sufficient policies and controls to ensure the District complies with state laws, its own policies, or addresses concerns identified in prior audits.  
  • And many more items I won't list here (read the whole sordid list here).
The district sells an old elementary school school for 3 million dollars to friends of an inside administrator while a private school offers nearly 10 million dollars.  Money that is acutely needed in the classroom. The district decides to sell or re-purpose 6 schools, at substantial cost, and then finds it needs the schools a year later. The school board ignored parent testimony and other evidence that this was a mistake.  Furthermore, it did not occur to the board that their new enrollment plan, guaranteeing that children could go to local schools would encourage enrollment (surprising that parents prefer to have their kids close to home!).

The highly popular and effective principal of Ingraham High School is removed and then rehired based on a huge outpouring of support by the community and school staff.  It turns out the decision was made by a very young and inexperienced administrator (who oversees north-end principals) and the interim superintendent (Susan Enfield, whom the board should never make permanent) was unable to even admit a mistake was made.  The school board says nothing.    And why was such a inexperienced individual placed over experienced principals in the first place?   You won't find this school board asking such questions!

By every objective measure, the performance of less advantaged students (mainly in south-end schools) continue to slide against their north-end counterparts. Check out here  for some data.  And even the district's best students have faired poorly in math and science.

The incumbents voted to support Teach for America (TFA), a scheme whereby students graduating with a non-teaching degrees are put into a classroom WITH ONLY SIX WEEKS OF TRAINING.  Folks, do you want someone that casually decides to teach and then is thrown into the classroom with a a month and a half of training, while there is a huge numbers of trained teachers, who went through a college teaching program and had a year of student teaching under their belt, wanting the same jobs?  Pretty silly and this is what the incumbents are pushing for in Seattle Schools.


But let me get personal here and talk about math education. On May 6, 2009 the school board voted 4-3 to introduce the "Discovering Math" high school math textbook series into Seattle public schools, textbooks that were found "unsound" by the State Board of Education.  I and others testified in front of the board, providing strong evidence of the weaknesses in these "fuzzy math' type books (less emphasis on direct instruction and learning of key math facts, group learning, lots of calculator use, and much more).   Three of those running for election now (Maier, Carr, and Sundquist) ignored the evidence and went with these bad books (Harum Martin-Morris voted against them to his credit, as did current board member Michael DeBell).   The result was predictable:  Seattle School district 10th grade math performance on objective measures has stagnated.  As an aside, Susan Enfield, then academic officer of the district, was provided the information on Discovering Math and went ahead with her recommendation to adopt it.

The incumbents, particularly Maier, Carr, and Sunquist, have been characterized by their rubber-stamping of administration requests, a lack of curiosity, and a lack of vision.  They react to problems and never seem to get ahead of them.  If they remain in office, the depressing headlines will continue.  The challengers are a different sort--these are folks that will ask questions and not assume that the administration is giving them the straight facts.

And there is another issue...the philosophy of many of the current board members and the MGJ and Enfield administrations, one in keeping with the current "education reform" movement that blames the teachers for much of the current problems and pushes "objective" exams as measures of teacher performance.  Folks, teachers don't change demographics and they are crippled when forced to use weak textbooks and curricula as in Seattle. 

So my recommendations for each race:

Sharon Peaslee versus Peter Maier.   An easy one.   Peter is clearly the weakest of the board members and was the member who knew about the financial problems and kept quiet about it.  Didn't seem to care about math education.  Rubber-stamper.  I have known Sharon Peaslee for years.  She has a real background in education, has kids in the schools, and has worked actively for improved math education.   Sharon is strong-willed and will ask the hard questions.   She is supported by the Stranger and most of the local democratic organizations, as well as Seattle teachers.  Peter has a huge financial war chest and is running a huge number of advertisements.  Lets hope that money doesn't decide this race.

Kate Martin versus Sherry Carr.   Another clear choice.  Kate Martin is extraordinarily knowledgeable and articulate about Seattle schools. She is a fire-cracker that calls a spade a spade.  For some she is a bit sharp, but I believe Kate is EXACTLY what the district needs.   Sherry Carr has rubber-stamped virtually every administration request, is bad on math education, and failed to show leadership.

Marty McLaren versus Steve Sundquist.   Very straightforward decision for Marty.   A trained teacher that has deep experience in middle schools, Marty has a vision in which the school board actively listens to the community.  Marty has a deep commitment to improving math education and was the prime-mover and funding source of our lawsuit to stop the Discovering Math textbooks series (we initially won this case when Judge Spector found that the School Board decision was "arbitrary and capricious.").  Steve, now chairman of the school board, has been a weak leader that spends much of his time explaining away their many mistakes.  Big supporter of Teach for America. Marty has strong support and many endorsements from community organizations and teachers.

Michelle Buetow versus Harium Martin-Morris.   Michelle Buetow is energetic, asks good questions, and is a parent of two elementary school students in the district.  She would be a very good board member. Martin-Morris is a mixed bag:  one on hand he was a sustained supporter of the MGJ administration, even when it was obviously failing.  But he did vote against the Discovering math books and the selling off of the schools.  Martin-Morris has been head of the curriculum committee and all reports indicate that he has not provide energetic leadership.  For example, the allowance of waivers for individual schools to experiment with different curricula or teaching approaches has been buried.  On math Buetow is a strong supporter of direct instruction and good textbooks.  My recommendation: vote for Michelle Buetow.

What really makes change possible is that the remaining board members are far better than the incumbents up for election--Michael DeBell, Betty Patu, and Kate Smith Blum have shown independence and an inquiring mind on a number of topics.  Replace the incumbents up for election and this district will finally have a board able to move the district forward.  Leave them in place and expect more headlines.


PS:   I have some suggestions to the new board members--such as hiring more staff to serve the board--insuring that they get good information.  Interim Superintendent Enfield has proven to be a weak, ineffective administrator and has a poor track record; she should be replaced. And it is probably time for the Mayor and city leaders to get involved.  You can't have a great city, and particularly a leader in technology, and have a second class school district.  Or third-class math and science education.

Friday, October 21, 2011

Jet Stream Weather

As many of you know, the jet stream is a current of strong winds---much narrower than its length--that is often found in the upper troposphere--typically between 25,000 and 35,000 ft--in the midlatitudes (generally 35-50N).  The jet stream (a.k.a, the jet) is associated with major weather systems-- the wind and rain storms that strike the region-- particularly in the winter.  Jet stream winds can reach over 200 mph, and can greatly accelerate or retard the motion of jet aircraft, depending whether they are heading east (fast trip) or west (long trip).   Midlatitude jet streams can meander north and south in a wavelike manner. 

The jet stream was first described by German meteorologists in the 1930s and this feature become very obvious to pilots on bombing missions during World War II.   The jet stream is generally strongest in the mid-Pacific and some missions directed at Japan found themselves making little headway to the west at times.

During a typical year the jet stream core is north of the Northwest in late summer and then slides down into our area in late October and November.   Think of the jet stream as an atmospheric hose and we are on the receiving end during November through January. When is the hose most predictably and intensely over us?  The last week of November.  The wettest and stormiest week of the year climatologically.  In December the jet actually heads south of us more frequently and the weather actually improves in our area...believe it or not.

Today and Saturday the jet stream will dip down close to us... let me show you.  The following charts present the wind speed (in meters per second, roughly double for knots or mph, by colors) at a pressure level of 300 mb (roughly 30,000 ft).  Here is a forecast for  today at 2 PM.   Strong jet over the Pacific that is approaching northern Washington, with values well over 100 kts.

Tomorrow the jet pushes in just to our north

This weekend we will be hit by some disturbances riding on the jet, particularly on Saturday.
Here is the 24-h predicted rainfall charts end Saturday, Sunday, and Monday at 5 AM.
Ending 5 AM, we see modest amounts over western Washington reaching 1-2 inches on the western slopes of the northern part of the State.
 A second system gets here Saturday morning and as you will see, the rainfall, particularly in the mountains is far more serious (1-2 inches being widespread)--see map below for 24-h rainfall ending Sunday at 5 AM.  Bad for hiking!  But you can escape the rain on Saturday by heading to eastern Washington or by positioning yourself in the rainshadow to the NE of the Olympics.

Finally the 24-h rain ending 5 AM on Monday is unimpressive...some light showers, with much of the western lowlands and eastern WA being dry.  Sunday is the better day for outdoor activities.


Dawg Dash Forecast

And talking about outdoor activities, the annual Dawg Dash will take place on Sunday at the University of Washington at 9:30 AM (http://www.promotionevents.com/dawgdash/).  It will probably be cloudy with a few sprinkles, but nothing compared to the deluge of last year!

Seattle School Board Race
My next blog will discuss in detail, but I believe that supporting the challengers is critical for turning around this district. 

Tuesday, October 18, 2011

Winning Meteorological Roulette

 If you live or work in Mountlake Terrace please click here.

What is it like to win the jackpot in a meteorological roulette game?   It is having a radiosonde float into your yard after flying miles high in the atmosphere and being lauched many miles away.  David Stroble of Mt. Vernon found a parachute, a shredded balloon, and a radiosonde (they call it a microsonde) in his backyard on October 15th. You can see the proof in pictures below:


 Radiosondes are meteorological packages that report temperature, humidity, pressure and wind as they are lifted high in the atmosphere by a weather balloon.  According to the National Weather Service radiosondes can ascend to over 35 km (about 115,000 ft--23 miles) and can drift hundreds of km.  Temperatures can drop to as cold as -130F and flights can last two hours or more.  The balloon is about 6 ft in diameter when it starts, but expands to 20-25 ft before it bursts.

This radiosonde started at Quillayute on the WA coast around 3 AM on October 14th (it was the 12 GMT radiosonde).  As shown on this map, the route covered about 180 miles:


And here is a plot of the observations from the unit....check out the winds...they are consistent with the route--very strong from the westsouthwest aloft.

Each radiosonde unit comes with a prepaid mailer to send it back for refurbishment and release.  My colleagues in the NWS tell me only a small proportion of the 75000 units launched each year get returned (around 15%)...but the U.S. government saves money on every unit that gets mailed back.

So keep a good luck out for used radiosondes...I am told that finding one is more lucky than finding a four-leaf clover.

Holiday Gift News for Weather Lovers

Need a perfect holiday gift for the weather inclined?   Sure, you could get my Northwest weather book, but I have an even better idea--a Washington weather calendar!  This is a fund-raiser for the Seattle Student Chapter of the American Meteorological Society and all the profits support this good cause (KCPQ is a sponsor that is not getting any of the proceeds).  Cost:  $13.99.



Lots of nice pictures and packed with weather info.  To order try your local bookstore or calendar shops (including the UW Bookstore) or secure it online at http://weather-calendar.com/washington/

Heat Surge

Today is going to be a MUCH warmer day than yesterday and far warmer than the National Weather Service is forecasting.   The NWS is going for 66 at Seattle---mid 60s are their forecast for the Puget Sound region and they are going 67-69 on the eastside.   Folks...I am convinced we are going to see 70s today at many locations away from cool water and mid-70s at some spots on the eastside.

Compare the temperatures aloft of today versus previous days from the Seattle profiler at 6 AM. HUGE warming above 400 meters--we are talking 10C (18F)--warmer at 600 meters.  Yesterday hit 61F at Sea-Tac:  you do the math (no, it probably won't get as high as 79F--but it will surge)

There is a thin veneer of cool air near the surface, chilled by infrared cooling to space under nearly clear skies. Above that cool air there is a strong inversion in which temperature warms with height.

Easterly flow aloft has really started cranking up as shown by the profiler winds and temperatures shown in this figure (y axis is height in meters, x axis is time in GMT--later to the left):
 20 knot easterly winds above 400 meters!

Here is the pattern of surface (2-meter) temperatures from our super-high resolution numerical weather prediction model for 2 PM today, clearly showing some 70s near Seattle and lots of 70s to the southwest:
But most important, there is probcast....our ensemble-based statistical forecasting tool that is very good in warm-up situations--it is showing mid 70s on the eastside and torrid conditions in the Willamette Valley.


 The only subtleties to this forecast is how high the air will mix vertically under the modest sun of this time of the year and how well the easterlies will mix downward.  In the summer, when the sun is strong, this would be an easy forecast.

Well, it is going to be fun (and very pleasant) to watch the day evolve....I am betting that many of you will experience 70s today.  If all of you stay in the mid-60s, it will be back to the drawing board for me.

Sunday, October 16, 2011

Is Sequim the Sunniest Place in Western Washington?

There is no more important question for sun-starved residents of western Washington.

Where can one go on a day trip and experience a lot more sun?   And particularly more sun during mid-winter when eastern Washington descends into its low-cloud enshrouded gloom and cold temperatures.

This blog will reveal new information and a web site dedicated to this issue.

Most of you might be suspect the answer is the Sequim area, since it well known that Sequim and adjacent locations are in the famous Olympic rainshadow, with far lower amounts of precipitation than anywhere else west of the Cascades; typical values are around 15 inches a year compared to 37-38 inches in Seattle.  And satellite imagery often shows a hole in the clouds around Sequim, particularly when the flow approaching the Olympics is from the approximately the south-southwest to southwest.   Here an example from this week (Oct 10, 11 AM):


You can imagine those self-satisfied Sequim types, playing golf on one of the many local courses, smiling in satisfaction in their wise decision to move there.  But is there better evidence that Sequim is a sunny place on regular basis?  Perhaps sea fog sneaks in there from the Strait or something else is occurring!   Well, we don't have to speculate anymore.  A series of solar radiation measuring devices have now been put in around the state and today I will discuss an analysis by rainshadow enthusiast David Britton, who has created a website DEDICATED to the local rainshadow phenomenon (my kind of person!):  http://www.olympicrainshadow.com/

Mr. Britton compared the solar radiation reaching three stations:  Lincoln High School in Port Angeles, his home in Sequim adjacent to the Strait, and on top of the atmospheric sciences building at the UW in Seattle.  He has carefully calibrated the sensors using clear days--when solar radiation should be nearly identical at these sites.  Here is an example of some of his findings--comparing the number of "Mostly Sunny" skies--check his website for this definition--from September 2010 to August 2011.




 Sequim has more sunny days than Seattle for all recent months except July and August.  Some months, such as December 2010 and April 2011, the difference is huge (8 more days of sun per month).  He also has a seasonal table that is interesting:
For mid-winter (Nov, Dec, Jan) there were 20 mostly sunny days in Sequim and 4 in Seattle, but the number of cloudy days were the same.  His number of "dreary" days (very low amount of solar radiation) is far higher in Seattle (19) than Sequim (5).  His web site also reveals that Port Angeles is nearly as sunny as Sequim.

If there were more solar radiation measurements on the Puget Sound eastside I suspect that Issaquah and North Bend would be pretty dark places.  Perhaps we better not find out...

 The rainshadow over Sequim is driven by southwesterly or south-southwesterly flow at and near crest level of the Olympics--since that direction produces downslope over Sequim and vicinity.   I took a look at the upper level flow approaching the Olympics at roughly crest level (5500 ft, 850 mb) and found that there was strong SW flow during the months when Sequim was much sunnier and a lack of such flow on months in which Sequim and Seattle are about the same.  During the summer, winds aloft are more northerly and thus there is little rainshadow activity at all...consistent with the above results.

Right now the Washington State Agrimet network has dozens of sites with solar radiation measurements and we should be able to create good solar radiation maps for the region.  Anyway, I am going to have a student do an extensive analysis of the region radiation measurements...but I am betting Sequim holds the records for west of the Cascades

Finally, need a perfect holiday gift for the weather inclined?   Sure, you could get my Northwest weather book, but I have an even better idea--a Washington weather calendar!  This is a fund-raiser for the Seattle Student Chapter of the American Meteorological Society and all the profits support this good cause (KCPQ is a sponsor that is not getting any of the proceeds).  Cost:  $13.99.


Lots of nice pictures and packed with weather info.  To order try your local bookstore or calendar shops (including the UW Bookstore) or secure it online at http://weather-calendar.com/washington/

Dog Report

Thanks for those who came out to Mountlake Terrace to search for my dog....no luck.  But she is someplace...so if anyone in the area sees her (see website link on right and here)...let me know....thanks, cliff

Friday, October 14, 2011

Indian Summer

In much of the U.S. it is called Indian Summer.  In France the term is St. Martin's Summer, while in eastern Europe Old Ladies Summer and Gypsy Summer are often used.  All of these names describe a warm period in the autumn that follows a period of cool weather-- in fact, some demand a killing frost before the warmth.   Well, we don't get too many killing frosts west of the Cascades in autumn, so the term Indian Summer here is usually reserved for periods in mid-fall when the temperature rise to summer-like levels*.  And we have real shot of this on Tuesday of next week.


Well, let me first document that we have had some cool weather--in fact the last two weeks have generally been cooler than normal, and last night there was a real chill in the air (I know about this personally, I was out searching for my lost dog in Mountlake Terrace).  Here are the temps at Sea-Tac airport compared to the normal highs and lows:
 During the last two weeks only one day had max temps above normal and most were far below.  Today will be another cool one.   But this will change in a big way.

Today (Friday) there will be considerable clouds and some light sprinkles, particularly in the central Cascades.
Saturday will be sunny and warmer...very nice...but you won't mistake it for summer--Indian or otherwise.
Sunday a weak trough will bring cooling and lots of clouds (maybe a bit of sun)

But Monday starts the warm-up and Tuesday it will be in full bloom. Want to see some weather maps? (of course you do!)  Here is the upper level (500 mb) chart for Tuesday morning at 5 AM.  Wow...big ridge over us...and a trough over CA that is working its way north.


Here is the sea level pressure, surface winds, and lower atmosphere temperatures at the same time. Good offshore flow with higher pressure east of the Cascades and lower pressure west of the mountains.  You will notice a low pressure area near the Oregon/CA border.


With offshore flow, there will be virtually no clouds and air will be compressed as it sinks from higher elevations.  Here are the predicted surface (really 2-meter) air temperatures at 2 PM on Tuesday.  Temperatures above 70F over land, particularly on the eastside of western Washington and along the coast, downstream of the Olympics. Expect the warmest temperatures in the foothills...like North Bend and Issaquah. 

Western Washington is warmer than eastern Washington in such situations.

So get your bathing suit ready, Tuesday will be your day.  I suspect this will be our last excursion into the 70s this year...better enjoy it.

* Sequim dropped below freezing on Wednesday night.

Tuesday, October 11, 2011

Tale of Two Radars: Rainshadow and Windward Enhancement

 Dog Alert!  See Message at the Bottom---Particularly If You Live in Mountlake Terrace.

With weather radars on both sides of the Olympics now, we can do something we have never done before:  examine simultaneously both the enhancement of precipitation on the windward side of the mountains and rain shadowing on the other.

Here is the storm-total precipitation from the new Langley Hill radar for the past two days.

I know it is hard to see the geography well.... but if you examine this closely you see values of over 2.5 inches on the southwest side of the Olympic, with lighter amounts offshore.  This is a good example of orographic enhancement, with the showers coming off the Pacific being enhanced from uplift on the western and southwestern slopes of the mountains as the air is forced to rise by the terrain.  The sharp cut-off of precipitation over the mountains is not real...it is due to mountain blockage effects.

What about the other side?   Here is the view from the Camano Island radar:

A complex pattern, but with a big hole of light precipitation to the northeast of the Olympics--this is the rainshadow, which extended from the north Sound to Bellingham. Rainshadows are caused by air descending and warming down mountain slopes on the lee side of a barrier.  The rainshadow was shifted away from Sequim and Victoria because the coastal winds have been more west-southwest than southwest or south-southwest.  And you will notice the precipitation really picked up over the western slopes of the Cascades as the air was forced to rise again--some amounts exceeded four inches.   Now these values are not well-calibrated, but the qualitative picture is certainly realistic.

For comparison, take a look at the visible satellite image this morning at 10:45 AM.  You can see the convective showers approaching the coast, the enhancement on the windward (western) side of the mountains, and if you look carefully you can spot some rainshadowing (really cloudshadowing here!) over northeastern Puget Sound.  Of course, the big kahuna rainshadow is to the east of the Cascades, where you could have escaped all the showers today.   And then air rises over the western side of the Rockies and clouds return from Spokane westward. 
 

At the UW we have software that combines the National Weather Service and Canadian radars--here is a view at 4:20 PM:

Really nice.  You can see the showers offshore, how they become more intense over land, how they die just east of the Cascade crest, are absent over eastern Washington, and start again...in a wimpy way... over Idaho.  And I haven't even mentioned the blustery winds of 20-35 mph all around the region today.

You got to love the weather around here...lots of variability!  Don't you feel sorry for people back east where the weather is so uniform and boring?

My Dog (see picture to the right) was seen today (10/12) near the intersection of 236th St SW and Cedar Way.  If you see her please call immediately (206 719 5603) 

Sunday, October 9, 2011

Its All in the Timing

How many times does this happen?  The National Weather Service forecasts rain coming in at a certain time and the forecast is off by a few hours, either early or late.  The truth is that this happens all the time and such timing error increase with the length of a forecast.  And variations in timing of consecutive forecasts provide valuable information on forecast uncertainty.  Consider the rain over Saturday night.

Here is a radar image from the new Langley radar at 7 PM on Saturday night. 


A frontal band is moving in, crossing the north-central WA Coast. Now here is the 74 forecast valid this time (1-h precipitation at ending 7 PM).  Got the right idea of frontal system...but too far south.

 Here is a forecast for the same time from the next cycle (62h forecast).  Whoa!  The frontal band has shifted way north...too north.

Next forecast cycle and the 50 hr forecast...the band is shifted south...not too bad.

The 38 hr forecast?  Pretty similar but a tad stronger and farther south.


The 26hr forecast? Similar, but slightly weakened.

And finally the 14h forecast. Very much the same, but perhaps a bit more diffuse.

These are very typical forecast sequences.  Go far enough out in time and the forecasts are shifting in a big way, particularly in the time that features pass a location.  As you get closer in time, the solutions tend to stabilize.  On occasions when the solution stabilizes late or not at all, forecast confidence is low, and vice versa.    But just because a solution stabilizes does not mean it HAS to be right, and sometimes the forecast models equilibrate on  a solution that is not correct.

Forecasters have a special name for the variation in forecast for the same time (e.g., 10 PM August 5) but for different forecast intervals (12, 24, 36 hr forecast, etc):  dmodel/dt.  If any of you have calculus you know why.  For those who haven't, this translates as the change in model solution over a specific time interval... a.k.a. the time  derivative.   Large dmodel/dt--low confidence in the forecast, small dmodel/dt--more confidence.

Ten years I did a paper with Brian Colle and David Ovens that showed that models  were typically fast by an hour or so.  I haven't repeated this study, but I suspect that although the errors are probably less now, errors in timing are not usual.  That is why the coastal radar is so important.  When our models are off by a few hours--too fast or slow, the radar will give us a heads up when weather systems are 6-9 hrs out.

Dog Alert
There have been repeated sightings of our dog in and near Terrace Creek Park in Mountlake Terrace.  If you are in that area, please let us know if you see her.

Friday, October 7, 2011

Is West Coast Weather Getting More Extreme?

A question that is often asked is whether Northwest or West Coast weather is getting more extreme.  More heavy rain and flooding events?  More windstorms?  Extreme losses of snowpack in the mountains?   Some groups have answered these questions in the affirmative and have stated, suggested or hinted that such extremes are connected with anthropogenic global warming.  They often provide hand-waving explanations of such extreme behavior--for example, it is accepted that the atmosphere will gain water vapor as the planet warms (by roughly 7% per degree C).  Won't that cause extreme precipitation to increase?


My students and I have looked into this issue, as have other weather/climate scientists.  As I shall discuss, this is not a simple issue and uncertainties abound, but the bottom line is that there is little evidence for area-wide increases in extreme weather due to human-induced global warming during the past several decades over our region.  That is not to say there won't be any in the future, but the impacts are anything but clear.

Lets take extreme precipitation. With UW graduate students Mike Warner and Adam Skalenakis, we looked at the trends of heavy precipitation over the past 60 years at coastal stations from southern CA to British Columbia. Specifically we looked at the trends for the top 20, 40, and 60 events of two-day precipitation.  Some of the results are shown in the figure below. Southern/central CA is a mixed bag, but northern CA and southern Oregon show a DECLINE in heavy events. On the other hand, northern Oregon and WA have seen an increase in the big rainstorms.  BC show weak upward trend.


Now heavy precipitation, of course, has a big influence on rivers...what do big river discharge events look like?  Well, we looked at the trends over the same period of maximum annual discharge of unregulated rivers (see figure below).  Importantly, we got the same pattern! Decline over southern Oregon and northern CA, increase to the north.
Up arrows indicate increasing trend, down arrows, declining trend for max annual river discharge.
So there is no uniform change in extreme precipitation along the West Coast:  some places are up and some are down.  Some nice work by members of the Climate Impact Group at the UW, looking at the output of a variety of global climate models, suggests that this pattern is the result of natural variability and not the result of any kind of global warming signal.
    What about big windstorms?  Storms such as the Inauguration Day Storm and Chanukah Eve storm?   Fascinatingly, the pattern is the same over the past half-century--- upward trend over Washington and northern Oregon and decreasing frequency of such storms to the south.  We are trying to understand exactly what is causing this configuration.
The Chanukah Eve Storm of 2006
   What about the next fifty years or so?  Will global warming change extreme weather events over our region?   The honest answer---we don't know.   The computer models do not agree.   And one can easily think of scenarios where there will be a decline of extreme precipitation and storms.   Extreme weather events are closely associated with the jet stream.  Most climate models indicate the jet stream will move northward under global warming.   Will the most extreme events gets displaced northward?

   In short, the changes in extreme weather along the West Coast has been non-uniform and don't suggest a human-induced global warming signal.  Global warming due to our greenhouse gas emissions will be very significant, but the local implications regarding extreme weather are quite uncertain.