Tuesday, October 6, 2015

Apple Computer Could Revolutionize Weather Forecasting: Will It Take the Challenge?

A number of popular smartphones have atmospheric pressure sensors; in fact, there may be a billion smartphones with highly capable atmospheric pressure sensors by the end of 2016. 

Pressure is the most valuable surface observation for weather prediction since it provides information about the the deep atmosphere above.  With pressure alone, meteorologists can determine the three-dimensional structures of the atmosphere.  And pressure does not have exposure problems like wind or temperature...in a building, in a pocket, inside or outside, in the sun or not....it doesn't make much of a difference where the smartphone is located.  It is the golden parameter.  And meteorologists can make use of both pressure and pressure change to help start (or initialize) our weather forecasting models.

Imagine a world with a billion barometers

So we should get ready for a weather prediction revolution?  Perhaps, but there is a major hurdle that must be crossed first:

The infrastructure for collecting this hugely promising weather data does not exist. 

But at least one company has the potential to radically improve the situation: Apple Computer.

The question is whether Apple will help.

The iPhone 6 series (iPhone 6, 6+, 6S) have now sold over 150 million units around the world and remains the most popular smartphone in many markets.  All have atmospheric pressure sensors.
 By next year, 250 million iPhone 6's will be in use around the world.

To be useful, the pressure from the smartphone must be accompanied by position data from the unit's GPS.  The history of movement of the phone would be help, as would its speed, which would tell us if it were in a moving vehicle.

Apple could assist in a number of ways in the collecting smartphone pressure data.  Obviously, the best approach would be to build pressure collection into the operating system (iOS, which Apple control).  Or pressure collection could be an option in the weather app that Apple preinstalls on every iPhone.

Want to see a shadow of what is possible?  The Weather Channel app allows the collection of smartphone pressure and we were able to get a sample of their data---perhaps we are getting data from 1/1000 of the iPhone6s out there.  Want to see what it gives us?

Let's start with a data rich country...the U.S.  On the left are the convention observation locations over the Oklahoma area, on the right, from smartphones.   Big enhancements You can even get pressures from smartphones on roads.

But the biggest advances might be in second and third world countries without a lot of weather data, such a India.  Below is an image with conventional data on the left and smartphones on the right. Big enhancement.  Many folks have smartphones in developing countries.

Smartphone pressures are also available from some Android phones (e.g., Samsung Galaxy series)--still waiting for a positive response from Google on my inquiries for help in pressure collection.

I have two graduate students working on the use of smartphone pressures for improvement of numerical weather prediction.  We have some initially favorable results with a low density of pressure available from two small companies (Cumulunimbus Inc. and OpenSignal), but we really need more density to prove the value of the technology.

Where might dense pressures really help?   We believe that large numbers of pressure might help forecast the initiation of thunderstorms.   Or provide better short-term forecasts for wind turbines. Situations in which defining small scale weather features are important.  And those are only a few of the potential weather features situation where smartphone pressures might help.

So Apple computer, please give me a call or email.  Or leave a comment on this blog.   You could potentially change the world of weather forecasting at little cost.

Sunday, October 4, 2015

Puget Sound Winter Air Quality Has Greatly Improved

These days there is a lot of talk about environmental problems, but there is one great success story we should not forgot: the substantial improvement in air quality around the nation, and specifically here in the Puget Sound region.

Here is a plot of the levels of small particles (PM2.5, smaller than 2.5 microns), capable of moving deep into the lungs, at Kent, Washington (provided to me by Nick Bond, state climatologist) from 1990 to now during the winter.  You will note a big drop during the 1990s, with levels now a quarter of what they had been.
What about larger particles at Kent (PM 10)?  Major decreases!

Want to know about Seattle?  Huge drops in PM10 (see below).  The red lines shows the warming level of the national air quality standards.   Seattle exceeded in in the late 80s and early 90s.  Now we are well below.

Live in Tacoma?  Big improvements there as well.

Or consider the number of days of moderate or worse air quality over King County:  a big decline in the 1990s

I could show you many more statistics, but you get the picture: the concentration of small particles has radically lessened in our region.  A boon to the health of Puget Sound residents, particularly those that are sensitive to poor air quality.

So why has air quality gotten better?  There are many reasons.

Probably the most important is the reduction in wood burning by our local residents and better wood stoves.   We are simply burning less wood and fireplaces and wood stoves have been a huge source of particles and toxics.

Back in the 80s, the Seattle Times was FULL of ads for wood stoves.   Many new homes had wood fireplaces.   The situation is very different today.  The ads are gone.  Wood burning is less popular, and many homes have gas fireplaces.   Just as important, Federal and local regulations have required that new wood stoves are far less polluting.

A lot of credit should be given to local  and Federal air quality agencies such as Puget Sound Clean Air Agency (PSCAA), the State Dept. of Ecology, and EPA, who have worked aggressively to reduce emissions.   Only low-emission wood stoves are now sold as result of their actions.  When the meteorology is poor for dispersion of pollutants (weak winds, strong and low level inversion), agencies such as PSCAA call burn bans that restrict burning wood other than for primary heating.

Local, state, and Federal  agencies have also worked to reduce emissions from cars, trucks, and large vessels, in addition to lessening emissions from industrial sources.

Getting back to wood.  In general, it is a very dirty and polluting way to heat a home (see graphic from PSCAA).   Natural gas is hugely better and inexpensive natural gas has encouraged folks to use this fuel.

Meteorologically, we are now moving into the worst air quality season for home fireplace/stove smoke.   Nights are getting longer and cooler, so folks want to get the wood burning.  But this is also the season of strongest, low-level inversions, as relatively clear skies allow the surface to radiate heat to space, producing an inversion---warming of air with height.   Inversions are very stable and tend to act as atmospheric caps that keep pollutants, like smoke, near the surface.  Winds are also relative light this time of year, before the big storms approach.

Want a good example of a low-level inversion?   Consider this morning!  Here is the temperature plots with height at the Sand Point (Seattle) vertical profiler, run by the Puget Sound Clean Air Agency.  Large increase in temperature with height in the lowest several hundred meters of the atmosphere.  Pollutants will be trapped near the surface.  And air quality has declined at some locations around the Puget Sound region.
Some folks in rural neighborhoods love burning wood.   But during inversion situations, they end of seriously polluting their own air and that of their neighbors.  I can't tell you how many times I have seen situations like this, with dense smoke coming out of a fireplace that does not loft because of an inversion.  Not good.

The worst wood smoke air quality tends to be in valleys, where the smoke and low-level cool air below the inversion tends to pool.   Some of the low areas of Lake Forest Park, north of Seattle, are notorious.  What is happening there this morning with the strong inversion?  (see graphic of small particle levels).  Oh oh....bad news.  A spike in particle concentrations.

So the bottom line is that regional air quality has greatly improved, particularly in reducing small particle pollution.   But wood smoke is still a serious issue, particularly during inversion conditions and in valley areas.

Friday, October 2, 2015

Extraordinary Flooding Possible In South Carolina

Although I generally keep my view on Pacific Northwest weather, the forecasts for South Carolina and vicinity are so unusual and threatening that I wanted to mention it. And because of Boeing, there are concerns about what happens around Charleston, SC.

Huge rainfall totals are forecast to hit that region, with 10-20 inches being expected in some locations.  Flooding should be expected.

This flooding is NOT directly associated with Hurricane Joaquin, but with the confluence of tropical moisture streams.

Let me begin by showing you the cumulative rainfall totals from the National Weather Service GFS model for the next 66 hours. Over Washington State, some very light precipitation (mainly tonight), but over the eastern U.S. it is the end of the world.   You can see one area of heavy precipitation offshore, with values between 5 and 10 inches....that is the precipitation accompanying Joaquin.   But there is another, even HEAVIER precipitation region with values getting to 15-20 inches stretching from South Carolina and into western North Carolina.  That is what I am talking about.   And this is from a relatively coarse global model--local rainfall could be much heavier.

The NWS Storm Prediction Center three-day forecast totals parallel the GFS runs, giving a conservative total of 13.2 inches.

What I showed you  above was the precipitation totals over several days.   The area of heavy rainfall is associated with a narrow band of precipitation that is forecast to be  extraordinarily persistent and nearly stationary, as illustrated by the precipitation forecast for a 3-h period ending 5 PM PDT tomorrow (Saturday).  You can see the hurricane offshore.

So why does this narrow feature exist?   Substantial insights can be derived from looking at the winds near 10,000 ft (700 hPa), relative humidity, and upward motion at the same time (see map).  There is an area of high pressure to the north (H shown in red) and a low to the south (L in red).  Between them there is a region of strong easterly winds that are bringing moisture into the region.  Moisture that is forced to rise by the nearby Appalachians and their eastern foothills.   But there is more.

Some flow is circling around the low and converging into the easterly flow--right over south Carolina.  Converging air flows cause upward motion that produces precipitation.  But there is still more.  This converging flow is forced to rise by the mountains. The red lines shows upward motion (very subtle but look close and you will see it over S. Carolina).  That upward motion in the presence of tropical moisture is producing intense precipitation.

The latest (9 PM PDT) NWS radar image shows heavy precipitation moving into the area.

The National Weather Service has flood watches, flood warnings, flash flood warnings, and more posted right now (see graphic), and some areas are being evacuated. This is a serious, unusual, and life-threatening event, one that our models have been warning about for several days.  I hope the Charleston Boeing facility is ready for intense rainfall...they are going to get it.

Wednesday, September 30, 2015

Will Hurricane Joaquin Be This Year's Superstorm Sandy?

Superstorm Sandy struck the NY metropolitan area during the last week of October 2012, result in 233 deaths and 75 billion dollars in damage.

The forecast problem today regarding Hurricane Joaquin is extraordinarily similar to the one faced by meteorologists during the week before Sandy made landfall.  Amazingly similar but with an interesting twist.  

Hurricane Joaquin at 8 PM Wednesday

Just as with Sandy, one major forecast model is bringing the hurricane inland with a "left hook" while the other is taking the storm out to sea.  But in this case, the situation is reversed....the  latest (Wed evening) U.S. GFS model is taking the storm inland over New York with heavy precipitation and strong winds.  In contrast, the usually (but not always) superior ECMWF model is pushing the storm out to sea.

Let's look at the latest forecast, starting with the U.S. GFS model (lines are isobars of constant pressure and shading is precipitation).   One can hardly believe one's eyes:  New York/New Jersey is in the crosshairs.  

But before New Yorkers panic, I should note there is a great deal of uncertainty in this forecast.  The previous runs of the GFS model took the storm into North Carolina and Virgina, so the modeling system has not stabilized on a solution.  Furthermore, the GFS model ensemble system (GEFS), in which the model is run many times with different initial conditions, is producing a wide variety of tracks and intensities.   Here is the 90h forecast of GEFS (previous run at 1800 UTC today), presented with what is known as a spaghetti diagram, with each lines representing the 984 hPa isobar (line of constant pressure).  You see the circles all over the place and of different sizes?  That means a lot of uncertainty.

The GFS and GEFS are run at relatively coarse resolution (13 km and 50 km grid spacing, respectively).  The National Weather Service has its high-resolution HWRF model (4km grid spacing) that cost tens of millions of dollars to develop....what does it show? (see below).  Interesting, HWRF is going further south of the main GFS model.

Now lets turn to the supposed Gold Standard weather forecast model, the European Center Model (ECMWF).  The European Center model takes the storm northward and then out to sea towards the northeast, as shown by the following forecasts initialized at 1200 UTC today (Sept 30th).

Saturday at 5 PM PDT
 Monday at 8 PM
 Tuesday at 11 AM PDT

There is substantial uncertainty with the ECMWF forecast, something we can explore by looking at the output of their ensemble system.  Here is their high-resolution forecast (solid lines, isobars of constant pressure) and variability in their ensemble (shaded colors) for 1200 UTC on Monday (5 AM PDT).  The shading to the left of the high resolution low center suggests that some of the forecast took the low farther to the west.

The National Hurricane Center puts out a subjective forecast based on looking at all the models, tempered by human experience.  Their solution?  Take the hurricane up the coast over DC.  This would shake things loose in the nation's capital....maybe encourage the purchase of a better weather supercomputer!

And one thing that is pretty sure-- no matter what happens:  the East Coast will be hit by heavy rain.   Here is the cumulative precipitation through Tuesday at 5 PM.  Five to 15 inches along the coast.

So what should you take away from all this?

A dangerous hurricane is moving northward but the track of the storm is still highly uncertain.  Major international modeling systems disagree.  Their ensemble systems (many forecasts run with slightly different initial states) disagree.  Consider the trending of the GFS model farther northward each run and the stability of the EC solution, I suspect the storm will track into New England or just offshore, but it is impossible to be sure at this point.  HWRF seems to be going the wrong way (too far south).

Folks should not panic, but those from Cape Hatteras to Boston should watch the forecasts carefully and begin preparations.  Hopefully, the models will converge during the next day to a robust solution.

Monday, September 28, 2015

A Perfect Autumn Week

I know many of you are looking forward to rain and clouds, but they will come soon enough.

In the meantime, enjoy an extraordinary fall week, with temperatures getting around 70F, no rain, and lots of sun.  And the bite of crisp temperatures in the morning to ensure you feel invigorated and alive.

The temperatures during the past four weeks have been very close to normal, as shown by the plot below (red and blue lines are average highs and lows)
Precipitation has been a bit below normal during the same period (blue is normal, red observed), by roughly .7 inches.
Want to see something amazing?  Here is the total precipitation predicted though Saturday at 5 AM (from the GFS model)  Nothing along the U.S. West Coast-:  WA is entirely dry.   But the  East Coast gets washed away.  SE Alaska gets torrential rain as well.

The pattern producing this weather is really not exceptional (see upper level map below for tomorrow afternoon).  A deep trough over the Gulf of Alaska is trenching Alaska, while a weak ridge is stationed over the western U.S. and Canada.  A weak trough is off of our coast.

The National Weather Service forecast for the next four days is  as close to ideal as imaginable (see below), with highs around 70 and lows near 50 (colder away from water). Sun.  No rain.

Last night some of the cooler suburbs southeast of Seattle dropped into the mid-30s...and that was at 2-m above the surface.  Some folks surely had frost.  In contrast, the temperatures only dropped to the mid-50s at some locations near the water. (the 92 was probably a thermometer near someones grill).  I am always amazed by our local contrast on cold, clear nights.  20F differences is not unusual...can get to 30-35F in the right situations.

This good weather won't last forever.  The latest NAEFS North American ensemble forecast of many model predictions indicates more clouds and some rain by the second week of October (see below).   So enjoy this pattern while you can.

Saturday, September 26, 2015

Perfect Sky Conditions Tomorrow for Supermoon Eclipse

Tomorrow (Sunday) night around sunset, Northwesterners will be able to enjoy a rare supermoon total eclipse with no clouds impeding the view.

We start with supermoon, a full moon that is unusually large and bright because of the moon's unusual proximity to the earth. Specifically, that moon will appear 14% larger and 33% brighter than normal. The moon's orbit around the earth is an ellipse, with the distance between the two varying between 222,000 and 252,000 miles.

Then. on top of that we will have an eclipse, with the earth lined up with the sun to eclipse the moon.  The combination of supermoon and a total eclipse is relative rare, with the last one occurring in 1982

 and the next one in 2033.  Even more impressive and unusual, this lunar eclipse is the last of a series of four, called a tetrad.

Supermoon events are often called blood moons, because the moon can have a reddish hue from light scattering off the Earth's atmosphere.  Here in the northwest, the eclipse will start at 6:07 PM and totality will last from 7:11 to 8:23 PM, when the sky will be quite dark.

The latest weather forecast model runs indicate clear skies over the region during the eclipse.  Here is the cloud prediction from the UW WRF model for 8 PM.   No clouds over Washington and Oregon.

So head to a nice view point tomorrow and enjoy a special celestial show.

But there is more.  Some folks believe that blood moon eclipses are particularly attractive to werewolves and vampires, so you might be a bit careful, particularly if you live in or near Forks. Other believe that a supermoon eclipse ending a tetrad might signal the end of the world.  So you might want to put your affairs in order on Sunday, just in case.

Viewing Tip
     A hill looking east would be good. In Seattle, the kite hill at Magnuson Park is nearly perfect, with a view across Lake Washington.  That is where I will be tonight.

Bicycle Weather Talk

I will be giving a talk: A cyclist's guide to weather information: how to increase your chance of a dry ride
Doors open at 6:30 p.m., presentation begins at 7 p.m.
Cascade Bicycling Center
7787 62nd Ave NE, Seattle

Friday, September 25, 2015

Drought in 2016 for Washington State?

This morning the Washington State Dept of Ecology held a press conference and released a statement predicting continued drought in the our region.   They forecast a dry fall, lack of snowpack, and conditions as bad or worse than this year.  The media, of course, picked up the story and amplified it a bit.

And state officials were busy tweeting about the coming drought situation.

The media and public officials are talking about a strong El Nino, a continued blob, the effects of global warming.  Some things they are getting right, but there is a substantial amount of confusion and wrong information being given to the public.

Let's examine what we really know.   And as I will show, the odds are that next year will bring substantial IMPROVEMENT over this year regarding snowpack and drought.

The first thing to keep in mind is that the key weather feature that has kept us warm and dry, the large high pressure area over the West Coast and eastern Pacific, is no longer there.

I can prove it to you.  Here are the anomalies (difference from normal) of the heights of a mid-tropospheric level (500 hPa) first for last spring (left) and for the last three weeks (right).  Red indicates higher pressure than normal (ridging) and blue below normal (troughing)

Can you see the profound difference?  The ridge is gone and there is no hint it is coming back.  In fact, the current strong El Nino will make sure of that.

We made change to a more normal pattern during the latter part of August, resulting in the return of precipitation to our region.   In fact, here is a plot of the difference of precipitation from normal for the past month.  Precipitation has been ABOVE NORMAL over more than half of the State, with some portions (north Cascades and Olympics) being hugely above normal.  This is not a drought pattern.

The new flow pattern has also had a large impact on temperatures, greatly cooling off our state.  Here is the difference of surface air temperature from normal the last month (the anomaly).  COOLER than normal over most of the state, particularly over the wildfire areas of eastern WA.
With the lessening of the warmth and return of rain, wildland firefighters have put out or controlled most of the fires.  Fire season is essentially over now.

So the main reason that we were so dry and warm (the eastern Pacific High pressure) is now gone.  And furthermore, its direct offspring, the BLOB (the area of warm water off our coast), is rapidly weakening.  To demonstrate this, here is the change of sea surface temperatures over the past month.
Blue is cooling.   The BLOB is in its death throes.  Sad, but true.

All good news, right?  But then there is the scary El Nino threat.  A very strong El Nino (warm sea surface temperatures in the eastern tropical Pacific) is developing-- in fact, the strongest since the late 1990s.

Based on past experience, strong El Nino's have their main impact after the new year, mainly making it warmer than normal, resulting in less snow pack than normal (about a 20% reduction on average).  But this is HUGELY MORE than the snowpack we had last year (80% reduction).

NOAA and others run seasonal climate prediction models out to roughly 9 months.  What do they say?  The largest ensemble (average) of many models (IMME, International Multi Model Ensemble), shown below, prediction wetter than normal conditons on our NW coast and near normal for most of the rest of our area for October, November, and December.  In stark contrast, to the the drier than normal fall suggested in the Seattle Times headline story today.

For January, February, and March IMME is going for drier than normal over the NW and much wetter  across CA.  Classic strong El Nino pattern.  Big relief for California.

What about temperatures? Both fall and winter are predicted to be warmer than normal by 1-2C.  Substantially less warm than last winter over us. That  will reduce our snowpack.

So temperatures and precipitation are running near normal now and I expect the same will be true for precipitation overall until the first of the year.  There will be rain and storms and we will have an opportunity to fill our reservoirs.   After the new year it will be warmer and drier than normal, but not as warm as last year.  So there should be a far healthier snowpack on April 1, but less than normal.

Armed with this knowledge, the folks than manage our reservoirs should store as much water as possible as early as possible.  We tend not to have major floods in strong El Nino years, so they can fill the reservoirs higher than normal with less fear of dangerous overtopping.

The drought is not going to get worse and we should be in a much better place next spring than this year.  And California will get substantial relief.

I really worry that some of the media and in political circles are going too far in painting an end of the world picture for next year.   Crying wolf undercuts credibility.