September 28, 2011

Virgin Pacific Front

The fronts we experience in the interior of western Washington and Oregon, or east of the Cascades are generally pretty wimpy affairs, having been highly modified and weakened by the coastal mountains (including the Olympics) and then the higher Cascades.   Wind shifts are generally weak, precipitation intensity moderate, and the structures torn apart by the terrain.

But out over the Pacific, men are men, women are women, and fronts can be well-defined and far stronger.  Until the Langley Hill radar was installed, our knowledge of Pacific frontal features were mainly based on research work done by aircraft and coastal radars completed over relatively short periods during field experiments--Peter Hobb's group at the UW did the classic work on such systems.

Well now we have a wonderful operational radar looking offshore and we had a view of a beauty of a front.

Now we start with a visible satellite picture at 12:45 PM on Monday as the front approached the coast:

Nice looking frontal band, but exactly where is the front? How strong is it?   Well, we don't have to worry anymore folks...we have the Langley Hill radar.  You can see it offshore (below) --a band extending SSW to NNE crossing the NW tip of the Olympic Peninsula.  Notice the corrugations in the front?   Classic...there are cores of heavy precipitation and gaps between them.

Take a look at the observations at Destruction Island (just off the central WA coast) for the last few days--and take a special look on the 26th (times are in UTC-- 12 is 5 AM, 0 is 5 PM).  You can see the trough of low pressure with the front and winds gusting to 60 knots.

Impressive....and stronger than any of the winds that hit Long Island during Irene. 

The strength of such Pacific fronts are not uniform...they are much stronger in the core areas of heavy precipitation than the gaps in between.  Sometimes the frontal characteristics are INTENSE in the cores.  During the 90s we have field experiment called COAST in which we flew the NOAA P3 Hurricane Hunter aircraft into a Pacific front.  The scientists wanted to go out and cross one of the cores to see what it was like.  The NOAA P3 pilots agreed...they had been through many hurricanes, so they were not concerned.   Well, the passage through the core was very, very intense--with several g's up and down and even the coffee pot broke off in the rear of the aircraft.   Several scientist thought they were going to die. The pilots were more flights through cores at low levels--this was a lot worse than going through hurricane eyewalls!

DOG Alert

We had a solid spotter report of my lost cockapoo in Mountlake Terrace near Terrace Creek Park...if any of you live or work up there can you keep an eye out?  For a picture of her, check the link on the right.  Thank you so much.
Here is where she was seen:

Friday, September 30th 6-8pm
West Seattle Meet & Greet Happy Hour with Candidates Marty McLaren & Sharon Peaslee (and I will be there too!).   Refreshments, of course.
TOPIC: Improving Math, Science and STEM in SPS
7020 18th SW (north of SW Myrtle)
Donations appreciated. - all are welcome

September 25, 2011

The New Radar Documents A Frontal Passage

Monday Morning Update:

Here is the storm total precipitation ending 10:30 AM on Monday from the new radar....notice the enhanced precipitation on the windward (SW) slopes of the Olympics:

In science, major advances in understanding often come with a new instrument, one that casts light on a previously unobserved phenomena.  Certainly, that is true of meteorology; through new understanding and additional data from new sensors, the skill of prediction increases.

The frontal system that passed through during last night and today was observed from beginning to end by the new Langley Hill radar---lets take a look at only one viewpoint:  the reflectivity at the lowest elevation angle (.5 degrees).   As we have talked about many times in this blog, such reflectivity is closely related to precipitation intensity.

First, consider the image at 5:34 PM yesterday.  Note the precipitation intensity (reflectivity) is given in dbz and yellow is very heavy stuff, green a lot lighter, etc.  Looking offshore we could see the approach of the Pacific frontal system (something we could not do before).   During the day yesterday (Saturday) the skies over Puget Sound clouded up and some light showers formed as the air over the western interior destabilized at midlevels--producing lots of altocumulus castelanus.   You can see the light showers in the radar, indicated by the north-south linear features.   Not forecast well.   This was not frontal precipitation, but rather the instability was initiated by the approach of the upper level trough associated with the front.

Four hours later around 8 PM the offshore precipitation was approaching rapidly and some light showers remained over the western slopes of the Cascades,

As the evening progressed the band reached the coast, as shown by this image at 1:44 AM.  Look how nicely the radar shows the band from Vancouver Island to south of Tillamook, Oregon.  The location of this radar was chosen very, very carefully to allow such a comprehensive view.  Behind the band the precipitation is spottier and more intense, indicative of convective precipitation.

And now the great disappearing trick!  The Camano Island radar had a blind spot west and south of the Olympics.  Of course, our new radar has a blind spot too--NW of the Olympics!   Here is a view of few hours later that shows this.  Believe me, the band extended north of Everett.  And look can see instability showers over the Pacific, with some with red colors---very, very heavy rain.  Interestingly the surface front (with the lowest pressure and windshift) was NOT with the continuous precipitation band over Puget Sound, but was still offshore at this time.

In fact, there was another band of precipitation, fairly convective looking, that come in with the front around 9 AM Sunday (see below).

 Around 12:38 PM there were lots of showers over the western slopes of the Olympics and coastal mountains.   You see the regular streakiness in the convection?  That is associated with convective roll circulations.  And see the bluish colors just off of Gray's Harbor?  That is the radar seeing the surface of the ocean.

And finally the situation after the front around 5 PM on Sunday...a few convective showers over the Pacific.  Showers and sunbreaks.

This radar is going to teach us a great deal about Northwest meteorology.  Knowledge that will both aid my colleagues in the National Weather Service and help us gain a better understanding of the interactions of incoming weather systems with our coastal terrain.

 Seattle School Board Candidate Events

There are two important gatherings to listen and talk to Seattle School Board candidates:

Wednesday, Sept 28th-7:30pm
The Stranger's School Board Candidate Debate
Town Hall - 1119 8th Avenue, Seattle
NOTE:  The event is FREE but tickets are required.
Click here for ticket information.

Friday, September 30th 6-8pm
West Seattle Meet & Greet Happy Hour with Candidates Marty McLaren & Sharon Peaslee (and I will be there too!).   Refreshments, of course.
TOPIC: Improving Math, Science and STEM in SPS
7020 18th SW (north of SW Myrtle)
Donations appreciated. - all are welcome

September 23, 2011

Sweating in the Pacific Northwest

 Note:  I made some changes to the html code that should make the blog work far better for IE9 browsers.  Let me know if anyone is having problems with performance of this blog on any browser...cliff

Bicycling to work today, I found myself wiping the sweat from my brow as I entered my building.  It really felt like the East Coast during summer out there. In fact, the last few days we have had some unusually humid air over the region, with nighttime minimum temperatures far higher than we are accustomed to.    The dewpoints were quite high this morning...rising into the mid-60s in some locations.   In fact, during the past day we have had the most humid air of the summer invading our region.  What is going on?

During the past several days we have had a pattern with unusually high pressure to our southeast and low pressure to our northwest (see graphic at roughly 18,000 ft--500 hPA pressure).   The result is a strong current in the lower to middle atmosphere from the southwest extended well back into the subtropics.  A flow that effectively transports moisture into our region.

 Here is a graphic showing the total water vapor in a column of air over the NE Pacific this morning--you see the current of high water vapor values heading our way from north of Hawaii?   This is often called an atmospheric river.

This river of moisture has been mainly directed into Vancouver Island and central BC and they have had very large amounts of rain this week.   You can also see the current of moisture--at least the part associated with clouds--in the visible satellite image this afternoon:

We have been just on the southern side of most of the clouds and rain, but within the current of higher than normal moisture.

With a current of warm, moist air coming towards us, our temps have been above normal and with the humidity our low temps have been WAY above normal.   Water vapor is very active in the infrared--in fact water vapor is the most important greenhouse gas in the atmosphere.  Such gases tend to warm us up at night--- they intercept the infrared radiation leaving the earth and reemit some back down to the surface, thus lessening cooling.  There is a reason deserts are cool at night--not much moisture.

Take a look at the temperature plot for the last week:
 See how high our minima have been the last three days? 10-15F above normal!

In short, we have been in the sweet spot--on the southern edge of a plume of warm, moist air.

Tomorrow will be the last day of the semi-tropical warmth, with temps getting into the lower 80s in places.  And the pattern shifts and we will have rain on Sunday and clouds/rain for much of the next five days.....

well...autumn did begin today.

Dog Update
   Still looking for my little cockapoo Leah.   My family is convinced that someone has picked her up in the area near the intersection of  105 N St., Holman Rd, and Greenwood Ave N.  Here is the area:

If any of you live in this area, please keep your eyes out for her (see link on right for pics). Let me know if you see anything.

 Seattle School Board Candidate Events

There are two important gatherings to listen and talk to Seattle School Board candidates:

Wednesday, Sept 28th-7:30pm
The Stranger's School Board Candidate Debate
Town Hall - 1119 8th Avenue, Seattle
NOTE:  The event is FREE but tickets are required.
Click here for ticket information.

Friday, September 30th 6-8pm
West Seattle Meet & Greet Happy Hour with Candidates Marty McLaren & Sharon Peaslee (and I will be there too!).   Refreshments, of course.
TOPIC: Improving Math, Science and STEM in SPS
7020 18th SW (north of SW Myrtle)
Donations appreciated. - all are welcome

September 21, 2011

The Big Day Arrives. The Washington Coastal Radar is Operational!

Today I received a wonderful email from Brad Colman, head of the Seattle National Weather Service Forecast Office:   the new coastal radar, located just north of Hoquiam, is now fully operational and the data is flowing to the outside world.

This radar, on top of Langley Hill, has been updated to include dual-polarization, which will allow a whole new collection of valuable products.

Enough talk, here are some examples.  Today there is a band of precipitation offshore that is slamming into Vancouver Island.   Want to see?   Check below.  Pretty impressive...and you will notice the precipitation band stretches south to offshore of northern Oregon.

 Here is what the Seattle radar shows--virtually nothing over the offshore waters south of Forks.

Here is a long range view of precipitation from the new radar.   This is amazing!  We can see another band two-thirds up Vancouver Island--some of it 400 km (250 miles) away.

All this stuff is online for your viewing pleasure (click on links)

National Weather Service site
UW Radar Site
and many others will be available soon.

For the first time, residents of the Washington coast now have what many of us have enjoyed for years---real time radar coverage.  And just as important, we can finally see the details of storms approaching our coast.   There is only one thing left to do on the radar--to turn on the zero-degree elevation angle scanning that will greatly increase its offshore range and low-level coverage.  This crucial enhancement is scheduled to be initiated during the next two months.

For more background information check out the radar website:

September 20, 2011


When nights are longer, winds are light, and the skies are clear we often see larger local differences of temperatures at night, and particularly at daybreak when temperatures are coldest.    Consider the temperatures around Puget Sound this morning at 7 AM (sunrise was 6:53 AM):

Click to make bigger!
Quite a range!  Temperatures varied from 37F at Shelton to 52F near the water in Seattle--15F!.   Clearly, being near the water helped keep you warm (temps of Puget Sound were in the lower 50s) and there was substantial cooling as you moved inland.  And remember these are air temperatures at roughly 5-6 feet--the temperatures of some of the ground surfaces could have been lower.   Perhaps even some frost near Shelton!

During the late fall, when the water is still near 50F and the interior drops into the teens, we can have far larger temperature differences.

But proximity to water is only one cause of temperature variations.   The urban centers tend to be warmer (the heat island effect) due to the release of heat by concrete and the multitude of heat sources in a city.

And then there are terrain effects.  Cool air tends to flow into valleys and low spots, and thus they are cooler...sometimes by 5-8 F compared to surround hills or ridges.  If you have a car thermometer you can see this effect as you drive.   Or if you are crazy like me, you might walk around a hilly neighborhood with a digital thermometer.

You see why TV weathercasters show multiple temperatures on the news--they have to---temperatures are too variable around here.

What about daytime high temperatures?  Here are the temps at 3 PM this afternoon.
click to expand
Mid-50s near the water to mid 70s inland...even as high as 81F at Kent.  Roughly 25F variation.  Temperatures of course decline if you go high enough, since in generally temperature decreases with elevation:  thus, temperatures are less in the Cascades.

You got to love living in an area whether you can choose your climate with a few mile drive. 

Of course, there are even smaller-scale microclimates:  the differences between an eastward or westward facing slope, north or south side of your home, shady versus sunny plots, and more.  I learned from experience where I should not plant my tomatoes.

Friday, September 30th, I will participate in a meet-and-greet with two excellent Seattle School board candidates: Marty McLaren and Sharon Peaslee at Puget Ridge Cohousing Assn, 7020 18th SW (north of SW Myrtle) from 6-8 p.m.  Refreshments of course.

Dog Update:  My little cockapoo is still on the loose...if you are in Seattle and see her (see below), let me know...thanks...cliff

September 18, 2011

Seattle Lags Behind In Math and This Can Be Fixed!

One of the most frustrating aspects of working on the improvement of math education is dealing with an educational establishment that makes decisions based on fads and opinions rather than empirical facts.

Now, let us accept that there are different approaches to teaching mathematics, with a major divide between the "reform, discovery approaches" and the more "traditional, direct instruction" approaches.  Reform/discovery approaches became the rage among the educational community in the 1990s and I believe it is a major, but not sole, reason that math performance has lagged.

As a scientist, it would seem to me that the next step is clear:  test a variety of curriculum approaches in the classroom, insuring the class demographics are similar, and find out what works best.  In short, do a carefully controlled experiment with proper statistics and find the truth in an empirical way.  But what frustrates me is that such experimentation is virtually never done by the educational bureaucracy.  They seem to go from fad to fad and student progress suffers.  Reform math, Integrated Math, Teach for America, Whole Language, and many more.

Last Friday I and some other interested parties met with the head of curriculum and head of science/math for the Seattle Public Schools.  I do appreciate the fact that there were willing to hear us out.  But when we asked them about what plan they had for testing various math curricula and then proceeding with the most effective approaches, you would think we were from a different planet.   No plans to do such testing and a dedication to the "system approach", which appears to be arranging lots of tutoring and alternative classes when students run into trouble.  I would suggest it is better to stop them from getting into trouble in the first place.

Just maddening!  But the interesting thing is that some unofficial experiments with the use of more traditional approaches to teaching, ones based on direct instruction, learning of foundational concepts, and practice to mastery ARE occurring and the results are stunning.

Some examples:

The Seattle Public Schools use reform/discovery math at all levels (my opinion...a disaster).  Schmitz Park Elementary got permission to  try Singapore Math textbooks in 2007 (traditional direct instruction).  Its students’ math scores soared; in 2010 the 5th graders had the third highest passing rate in the state on the state test, even though the school has no gifted magnet program.  North Beach Elementary began using Saxon Math in 2001.  Their scores rose dramatically and stayed high for years, until a new principal, who opposed Saxon, took over; then the scores plummeted.  That principal was replaced, and the scores are back up.  At Ballard High, teacher Ted Nutting's students' scores on the AP calculus test have for several years averaged far higher than those of any other school in the district--guess what he and the Ballard precalculus teacher doesn't use?  Discovery/reform math.

Or how about Seattle high schools?  Here are the scores from the Algebra I end of course (EOC) assessments in order of % of students getting free lunch (a proxy for economic status of students).   Now you might expect student scores to scale with the socioeconomic status of the students, assuming everyone got the same curricula right?  And that is generally true except for two schools: Franklin and Cleveland.  Franklin is the largest anomaly.  Well folks, a little research has found that teachers at Franklin have generally put the district-provided reform math books away and have taught the students using more traditional/direct instruction approaches...and the results are obvious.  Cleveland has double-length math classes.   Can you imagine if we had double-length math classes plus good curricula in all Seattle schools? 

What  about in other districts?  Consider Gildo Ray Elementary in Auburn, which switched to Singapore Math -- Math in Focus (traditional texts) for the last two years from Everyday Math (which Seattle uses).  The pass rates on the MSP Math Exam in 2011 for grade 5 jumped to astounding levels:

Low Income : Black : Limited English Pass Rates in the 3 Columns
47.2% : 39.3% : 23.2% : State
44.8% : 33.8% : 26.0% : Seattle
88.5% : ..n/a… : 85.0% : Gildo Rey elementary in Auburn
I could give you many more examples. But the bottom line is clear:  a large number of informal experiments have shown that direct instruction approaches with an emphasis on mastering basic facts and practice to mastery produce widely better outcomes for our students, and the educational bureaucracy doesn't seem to care.  Why?  Because the educational business is far more interested in theoretical ideas and "social justice" than empirical proof.  And Schools of Education are more a part of the problem than the solution.

It is really so sad.  Replacing the curriculum and books is relatively inexpensive and easy compared to most other changes and could be done quickly.  Don't get me wrong, poor student performance has a multiplicity of causes, from too large classes, overworked teachers, teachers without sufficient subject mastery, student poverty, lack of home support, and many more.  But curriculum improvement is a low-hanging fruit that we should grab. The money could be found for new books.  How many parents would be willing to contribute for a new textbook to insure their child had a chance for a future?  Or might the Gates Foundation contribute to textbooks instead of the valueless Teach for American boondoggle?   God knows the huge sums wasted by the Gates Foundation and Microsoft on ill-considered experiments that have generally done more harm than good.

In short, there is very strong evidence that a change of curriculum from reform/discovery/fuzzy math to direct instruction approaches with an emphasis on basic facts/mastery could greatly improve the math performance of all students.  I challenge the educational establishment to do the robust experiments that will prove or disprove this statement. Sadly, I suspect they won't.  That is why we need new school board members in Seattle and in other districts that will ask for a more rational approach to curriculum acquisition.

September 17, 2011

The End of NW Drought

The second half of summer has been really dry over the Northwest.  Take a look at the plot of actual versus normal precipitation at Spokane and Sea-Tac Airport for the last 12 weeks: we have had little rain the last month and are down 1-2 inches for the period compared to normal.  Not a serious issue since we are usually dry this time of the year.  And it is going to change!

Here is the lastest infrared satellite picture (Sat morning).  There is considerable cloudiness over us right now from a weak frontal disturbance and even some light showers are occurring), but the main action will be Sunday AM as a strong system reaches western WA. Let me remind you that the whiter the pixel in an infrared image the cooler and thus higher the clouds.

Here is the forecast 24 hr precipitation ending 5 PM on Sunday.  Pretty impressive precipitation after our drought...with .5 to 1 inches forecast over the mountains and windward slopes, and several tenths of an inch over portions of the lowlands.  Even eastern WA gets some scattered precipitation, a fact that is of importance to agricultural interests there.   Want to be dry?...go south of Portland or head to eastern Oregon.

There has been some talk about snow in the mountains, but until you are hiking about 7000 ft I don't think you have to worry about that...but it WILL be wet and windy.  In fact, the winds will also pick up noticeably over the lowlands as well.

Several of you have asked for the latest situation regarding the coastal radar.  The unit is now down for a retrofit for the new dual-polarization option--an enhancement that every NWS radar in the country will receive during the next year.  It is hoped that the radar will come back on line during the next week and the data should be flowing for public use soon after that.  A dedication is planned for later this month at the radar site.   But the radar will still be missing a critical option...the zero degree elevation angle...which will allow the radar to see much farther and better, particularly at lower levels.  Our radar will be the first in the nation to have this option and the NWS promises it will be operational by Nov 1.

Finally, any of you living in Seattle please take a look at the picture and info to the right regarding my lost dog. We took her to local dog sitter who lost the dog over NW keep your eyes out and let me know if you see her.  Thanks.

Reminder:  I am teaching atmospheric sciences 101--Weather--this fall at the UW if anyone is interested in taking it.  Retired folks can do it through the Access program (something like $5) and others can take the course as a non-matriculated student (but they do charge)

September 14, 2011


 Numerical weather prediction models are generally solved on a three-dimensional grid, with the distance between the points--the grid spacing-- a measure of the resolution of the model.

We often talk about the horizontal resolution of a weather forecasting model ... the horizontal distance between the grid points.   This resolution has greatly improved over the years as greater computer power has become available--from roughly 600 km in the earlier 50s to 12 to 4 km resolution today.

Let me shown you the implications of resolution using the WRF model used at the UW.

Here is 36-km resolution--representative of the best we had roughly in the late 1990s--for surface air temperature.
Really just the major features:  no hint of valleys, Puget Sound is not apparent. No volcanic peaks.

Here is 12-km, the main resolution run by the National Weather Service today.  A bit better, with more definition.  No Puget Sound really.

 Next 4-km.  Far more structure and the valleys are much better defined.

 And finally, the best--4/3 km.  Run here at the UW  for Washington and nearby states, the detail is extraordinary.  Much of Puget Sound is defined.  Individual river drainages are clearly resolved.  You need this resolution to get realistic flow in the Columbia Gorge.

Mount Rainier and other volcanic peaks are clearly evident.  In five years or so such resolution will be operational throughout the nation.  This image is really beautiful could hang it on the wall as art.

Right now the National Weather Service runs a global model at roughly 25-km resolution, and regionally at 4-km grid spacing. To be able to explicitly simulate thunderstorms one needs to do better than 4-km resolution, with more being better.

In the vertical, the resolution is dependent on the number of layers we have.   For our local WRF model we used 37, with more layers near the surface where we really need the detail.

It takes a lot more computer power to make even modest improvements in resolution--every time you double horizontal resolution you need roughly 8 times more computer power.   It is not surprising that weather forecasting uses some of the most powerful computers in the world.

Here in the Pacific Northwest we run 36, 12, 4 and 4/3 km resolution forecasts twice a day on clusters of commodity-off the shelf--processors (Intel Nehalem cores).   This activity is sponsored by the Northwest Modeling Consortium, a group of Federal, State, and Local Agencies and some private sector firms.  

September 12, 2011

When is a record not really a record?

Today the Seattle Times has an article noting that Seattle (Seattle Tacoma Airport) has beat the all-time record for the number of consecutive days of 80F and higher in September.  Today (Monday) should be much cooler since marine air has pushed into western Washington overnight, with low clouds extending to the Cascades.  The heat wave is over.

Here is the plot of the temperatures the last few days.
You will note that on two of the days the temperatures only got to 82F.   Now here is the question.  As I documented in an earlier blog (click here to see it), the third runway has clearly warmed up the temperature sensor at Seattle by roughly 2F.      On the two days SeaTac reached 82 of the now 9 day streak above 80 the neighborhood surrounding SeaTac had highs of 78 and 79, averaged over 4 schools.  That leaves the obvious question:  would Seattle have reached this record if the third runway was not built?  We cannot be sure.

As I have discussed in this blog a number of times, the implications of human-emitted greenhouse gases are profound and substantial warming is pretty much inevitable.  But there IS an issue of our temperature sensors being in places in which development has occurred, as well as sensors that are simply poorly placed.  I don't think we have a clear understanding of the impact of these sensor problems, even though some research has been done on it.

Just to show you the problem, here are pictures of the temperature sensors at three official climatological observing stations in Washington State.  Remember sensors should be over natural vegetated surfaces, away from buildings and concrete/asphalt, and not near heat sources.

Here is Wilbur, Washington.   Breaks every rule....even near the exhaust of an AC unit!  (The temperature unit looks like a set of stacked plates---that is the temperature enclosure)

 Or Dayton, Washington.  Being above gravel is a no-no, and it is close to a building and concrete.

Or Conconully, Washington.  Above rocks and concrete steps.

The problem folks is I could show you dozens more of these for the Northwest and hundreds for the U.S.  Poor siting, not above natural vegetation, too close to buildings, and more.  And it gets worse---there is development/urbanization going in the neighborhoods of many sensors.  Some of the worse problems are at rural sites, so studies that have tried to determine the "true" temperature signal by separating rural from urban sites have often been flawed.

We have a problem.   The U.S. is now establishing a set of primo instruments in virgin locations, but that doesn't help much in documenting past trends.  TThere is little doubt that some records have been influenced by these siting issues.

Now for those global warming skeptics who are smirking about all this, let us make it clear--poor siting does not mean global warming induced by humans is nonsense.  It means we have to be more careful in separating out sensor issues from the real signal.  The real signal is going to get a lot larger,

Finally, any of you living in North Seattle, please keep your eyes out for my lost dog:  more information here

September 10, 2011

Smoke Signals and Lost Dog

Before I deal with the main blog topic, I would like to ask those of you in North Seattle to be on the look out for a lost black/while cockapoo:   information is here.  Thanks for any help.

During warm days there is a profound change in winds up and down the Olympics that is normally invisible, but become apparent when there is a wildfire on the Olympic slopes.

Dale Ireland has a wonderful permanent cam facing the Olympics and has been recording the smoke from the Big Hump fire the last few days.

Here is a video for a few days ago:

This one is also good: 

During the day, as the slopes are heated there is upslope flow moving towards higher elevations--this upslope flow and the destabilization of the atmosphere as the mountains heat up produces convection and enhanced upward flow.   Sometimes this convection is accompanied by a cumulus cloud as well as smoke (called pyrocumulus).   The rising air cools due to the expansion of the upward-moving air and eventually the initially warm air is no longer buoyant (becomes the same temperature as the environmental air at that level) and no longer rises.  You see this all the time from smoke from smokestacks hitting a level through which it can pass and then spreads mainly horizontally--check out this picture:

During the evening, the surface of the mountains cools as the infrared radiation loss to space exceeds the incoming energy from the sun.  The daytime convective/smoke plume dies (since it depends on the surface being sufficiently warmer than the air above), and air starts moving down the mountain....known as downslope flow.  The smoke is entrained in this  flow and heads down the slope.  That is what you are seeing.

September 09, 2011

Latest on La Nina

A number of you have asked about La Nina and the upcoming winter.  It is always prudent to wait until mid-September before making the call, a call that in any case has considerable uncertainty.  The U.S. Climate Prediction Center has just upgraded the status from a La Nina Watch to a La Nina Advisory--they are basically committing to a forecast of a La Nina winter.  It is not unusual for two La Nina years to occur in a row, although the second one is generally weaker.

I don't have to tell you the implications of La Nina for the Northwest--AFTER January 1 it is generally associated with cooler/wetter conditions that produce more snowpack than normal in the mountains and a higher probability of lowland snow.   So local departments of transportation should stock up on road deicer!

So what are some of the signs of an upcoming La Nina?  First and foremost, colder than normal sea surface temperatures (SST) in the tropical Pacific.    Here are the SST anomalies (differences from normal) for the last year.  Take a particular look at the Nino 3.4 values.  The cold anomalies have increased.

We have also seen that cold anomalies have increased substantially BELOW the is the proof:
And the wind field (stronger trade winds) have not abated since the last La Nina.

Until recently, the NWS was undecided whether the coming winter would be a neutral (La Nada!) year (when tropical SSTs are near normal) or a La Nina year.   The trends now point to the latter, although there is still some uncertainty.   The latest computer predictions (see graphic below) are mixed between La Nina and Neutral, although the NWS coupled forecast model (which is a coupled ocean-atmosphere prediction system that is run out for months) is going for La Nina--and this model has been skillful lately.
One thing for does not look like an El Nino year! 

And here is the latest winter predictions from the Climatic Prediction Center:

Wetter and colder for us, warmer and drier for the SE.  Does this look familar?

So it might be a good winter to get that annual ski pass.  Probably lots of snowpack for next summer's water supply.  And local global warming skeptics will make the usual remarks.

September 07, 2011

Large Diurnal Temperature Range

An interesting aspect of the current weather regime is the large diurnal (daily) temperature range--the difference in temperature between the daily highs and lows.  At a number of Northwest locations we have seen highs in the 80s and 90s, while temperature have plummeted at night into the lower 50s and even some 40s, with some dropping into the 30s.   I am talking about surface air temperatures here, measured at roughly 2 meters. Some good examples:

Baker, Oregon--high of 90 and a low of 39F:  a diurnal range of 51F!
Olympia,WA--high of 85 and low of 44:  range of 41F

Or consider the Turnbull climate reference network site near Spokane that had  a 51 deg temperature range today with a low of  36 and a high of 87 on Tuesday.  What is really amazing is the range of surface (ground) temperature that on Tuesday jumped from 32 F to 114 F (82F!!) on Tuesday.  You read that right....from frost on the ground to 114F in one day.   That will crack some rocks!

 Here are graphs of temperature for the last two weeks--all of which show the huge range.  First, Sea-Tac, then Pasco, and finally Spokane.  All have a much greater range than normal.
So why such a big range?  Hint:  we often observe such big daily swings during late summer and early fall.

We start with fairly warm aloft and the sun being still fairly strong....that allows warming.
We have weak offshore flow aloft...that keeps the low clouds and marine influence at bay.
We have clear or nearly clear skies...that allows good infrared radiational cooling to space--and thus good temperature falls at night.
And nights are getting longer--that gives more time for nighttime cooling.  And the relatively equal time for heating and cooling at this time of the year is helpful

Put this all together and you get one big temperature range.  During the winter the range is far less in general, particularly because the cloud cover reduces heating during the day and infrared cooling at night.

Now for the controversial part of this blog.   There seems to be some difference in opinion whether a large temperature range is good for viniculture.   Does a big range help or hurt the quality of grapes used in wine-making?  Some online sources claim that such a range is good since it has the effect of producing high acid and high sugar content as the grapes' exposure to sunlight increases the ripening qualities while the sudden drop in temperature at night preserves the balance of natural acids in the grape.  Others, like the book by Gladstone, claims that a narrow temperature range is good.  Any wine experts read this blog?  What is the correct story?  I have always found the meteorology of wine making fascinating...and will climate change make eastern Washington wines even better?  Perhaps in another blog.

More Rain for the Northwest is Good News for Wildfires

After a very pleasant dry spell, another rainy period is ahead for the western side of the region and the Cascades on Friday and Saturday.  ...