Tuesday, January 27, 2015

Forecast Lessons from the Northeast Snowstorm

The complaints swelled quickly this morning, both in the social media and the press:

National Weather Service forecasters had predicted two to three feet over New York City and adjacent suburbs for Tuesday and only about 8-10 inches showed up.

The city had been shut down overnight--travel banned on major roadways, mass transportation systems (e.g., subways) closed, schools and businesses closed--and all for a minor snow event!  A few samples from the press illustrates some of the commentary:

And then a National Weather Service forecaster even apologized for a  "blown forecast", something that doesn't happen very often.

Fortunately, NY Governor Cuomo had the right attitude!

And you had to expect that some global warming critic would use the forecast troublex to cast doubt on global warming predictions.

So what is the truth about this forecast event?   As I will describe below, although the forecast "bust" was not as bad as it might appear, it did reveal some significant weaknesses in how my profession makes and communicates forecasts, weaknesses that National Weather Service director Louis Uccellini says he recognizes and will attempt to fix.  

The general forecast situation was well understood and skillfully forecast starting on Saturday.   A low center (a midlatitude cyclone) would develop off the SE U.S. and then move northward up the East Coast--a storm commonly called a Nor'easter.  Here is a surface weather map at 4 AM PST this morning, when the storm was near its height.  In such a location, the storm can pull cold air off the continent while swirling in moisture from off the ocean.  The result is moderate to heavy snow to the west and north of the low center, as well as strong winds over the same areas.  Thirty years ago we could not forecast these storms with any skill. That has changed.

Although our models have been suggesting the development of a low center along the coast earlier in the week, it was not until Saturday that most of the models converged on essentially the same solution:  a low developing rapidly along the mid-Atlantic coast and developing into an intense low off of Cape Cod.  And that is what happened.

Virtually all of the models indicated that the precipitation (snow) would swing around the low, with a relatively sharp cut-off to the west of the cyclone center (see figure).

As the weekend progressed it was clear that although all the models had a similar idea, the position of the low center and associated precipitation varied.  The European Center (ECMWF) model, which did so well during for Superstorm Sandy and is on average the most skillful global model, was taking the low closer to the coast, pushing the heavy snowfall over the NY metropolitan area.  For much of the weekend, the National Weather Service's main high-resolution model, the NAM, did the same thing.   On the other hand, the National Weather Service recently upgraded global model, the GFS, was taking the center farther offshore, and predicted far less snow over NY City.   Here are the 30-h forecasts of the European Center and GFS models (solid lines are sea level pressure) valid 10 AM PST Tuesday...the difference in location is clear.

The Canadian and UKMET office models had solutions similar to the U.S. GFS.   

 NWS forecasters, mindful of the general superiority of the European Center model and comfortable with the workhorse NAM model, went with the European Center solution, which implied heavy snowfall over New York.  Their forecast on Monday afternoon was for 24-36 inches over New York city, eastern New Jersey, and into Long Island and Connecticut.  Not shown here are the heavy snows forecast for southeast New England.

The problem for the NWS was that they bet on the wrong horse and the low followed a track similar to that predicted by the GFS.  With the storm further offshore, the sharp gradient in snowfall moved eastward, resulted in NY City getting far less snow....roughly 10 inches in total.  

Here is the New York Times snow total map to see more details.  New York City got about 1/2 to 1/3 the predicted amount (although 10 inches is quite significant).  New Jersey got far less than predicted. But eastern Long Island and SE New England were right on target at 2-3 feet.

So there is no way one could call this forecast a major failure.  The NWS predicted a strong cyclone moving up the coast and they were right.  They predicted heavy snow over eastern Long Island and New England and were correct.  The snow forecast over New York was substantially overblown, but 9 inches is still a significant event.

But the forecast could have been much better and far more useful.  The forecasters failed to communicate the level of forecast uncertainty and did not change the forecast rapidly enough over New York when it was clear the storm was moving farther offshore.  And it reveals major deficiencies in how forecasts are made and communicate in the U.S.

Let me explain my logic.

National Weather Service (NWS) forecasters have the benefit of many weather prediction models, and in this case there was significance between them regarding the low position as it passed northward east of Long Island.

The European Center (ECMWF) model and the NWS NAM model had a more westward track and lots of snow over New York City.  

In contrast, the NWS GFS model, recently upgraded as new computer resources became available to the NWS, had a more eastward track and far less snow.  It is well known that the GFS is generally far more skillful than the NAM; in fact, many of us in the field believe the NAM should be retired.

The UKMET office model, number two in the world (after ECMWF), was like the GFS.
So was the Canadian global model.

So there was considerable differences among the major models, which suggested a lot of uncertainty over the exact location of the low center and the western edge of the heavy snow.

NWS forecasters also have large ensemble forecast systems, in which many different U.S. models are run with different starting points and model physics (e.g., how convection and clouds work).   These ensemble systems were  also indicating SUBSTANTIAL uncertainty in the snow forecasts over New York.  Let me show you.

Here are the snow total forecasts over New York from the NWS SREF (Short-Range Ensemble System) using forecasts starting at 09 GMT on January 26 (1 AM PST Monday).  These plots show the cumulative snow total predictions.  There is a HUGE spread in the forecasts. Some are as high as 35-40 inches while others are around 5 inches.  The National Weather Service at that time was going for 24-36 inches over NY, which is only achieved by a minority of the forecasts (perhaps 30% of them).

To put it another way, if these forecasts were equally probable (and they probably aren't), there was roughly a 70% chance that the official forecasts were too high.  Instead of predicting 2-3 feet, consider if that forecasters had said there was a 30% chance of more than 2 feet, a 35% chance of 1-2 feet, and a 35% chance of less than a foot.   No one would be writing critical headlines if they had done so and decision makers would have gotten far better information. And the fact that forecasters used terms such as "historic storm" was guaranteed to push the media into a feeding frenzy.

There is something else.  By late Monday, it was clear that the European Center and NAM forecasts were going wrong, and other U.S. modeling systems, like the newly operational High Resolution Rapid Refresh System (HRRR) indicated that NY would not get the big snow dump.  

Want to see it? Here is the HRRR 15 total snow accumulation over the Northeast ending 4 AM Tuesday.  Just a wonderful short-term forecast that verified well.   Such predictions were consistent in time and with virtually all modeling system initialized during Monday evening...the heavy snow predictions should have been dropped sooner.

So what needs to be done now to ensure this failure mode does not happen again?

First, the U.S. needs to enhance its ensemble forecast systems, the systems that facilitate the creation of probabilistic predictions.  If you have say 100 equally likely forecasts, and half go for 2 feet of snow, then the probability of 2 feet of snow might be 50% (this is simplistic, but you get the idea).  The National Weather Service have sponsored a number of studies by the National Academy of Sciences, studies that have strongly advised that the NWS enhance its ensemble systems and move vigorously to probabilistic predictions..   Unfortunately, the NWS has not followed this advise, with a poorly supported  "high-resolution" Short-Range Ensemble System (SREF) with a coarse resolution of 16-km. The U.S. needs a large convection-resolving (2-3 km grid spacing) ensemble, with sophisticated statistical post-processing to give reliable probabilities for snow and other important quantities.

Second, the NWS has to move to a much more probabilistic form of forecasting preparation and dissemination, one in which forecast uncertainties are made clear to users.  The computer workstations used by NWS forecasters and NWS websites are not designed to facilitate probabilistic prediction.  This needs to change.

Superstorm Sandy led to a widespread understanding that NOAA had let its computer resources decline to third tier status, and thus the problem was addressed.

Perhaps, the January 27, 2015 snowstorm issues over New York will lead toa  realization that forecast uncertainties need to be communicated to the public and that the NWS has to dedicate sufficient resources to make this happen.

Sunday, January 25, 2015

Record Warmth and River Fog

Update:  at 2 AM Monday it was 60F at Paradise Ranger Station on Mount Rainier.  This is at 5500 ft!   And this morning there is one of the most intense low-level inversions I have ever seen.  Here is the plot from the Seattle vertical sounder.  10-12C (almost 20F) difference in the lowest few hundred meters.  Amazing.

For warm weather lovers, today did not disappoint.  As shown in a plot of today's high temperatures, many stations in western Washington climbed in the mid-60s, with a number of stations on the western slopes of the Cascades reaching 70F and more.

In Oregon, several locations in the foothills of the Cascades and coastal mountain got into the upper 70s and 80s.  Cool foggy air was trapped at the lowest elevations of the Willamette Valley, as illustrated by satellite image at 1 PM below.  Temperatures stayed in the upper 40s in that fog.

Seattle's high of 63F was the second warmest January day in the entire record.  Some of the warmest temperatures were in the mountains and upper slopes. Why?

The reason is clear if we look at a vertical sounding at Salem, Oregon at 4 PM today (red lines in temperature, blue dashed line is dew point).  The vertical axis is pressure (700 is roughly 10,000 ft, 850 is about 5000 ft).  There was a shallow layer of cool, moist air topped by a very strong inversion,with temperature increasing with height.  That is why the warmest locations were found at elevations of a few thousand feet.

Today I was biking along the Cedar River Trail with some friends and I saw something interesting:  river fog.   Fog that was hanging at low levels right about the river.  Here are some pics:

Why such fog?   We had warm, relatively moist air and quite cold water in the river (being fed by lots of snow melt!).  This warm, moist air was cooled by the cold river water to its dew point...producing fog.

Tomorrow may be even warmer in some places.

In contrast, far colder than normal temperatures are in place over the East Coast, where parts of the Northeast are expecting an historic snowstorm.

Saturday, January 24, 2015

Summer in January

Summer air is above us right now.  I am not kidding.    And the temperatures at the surface we woke up to this morning (mid-50s over Puget Sound country) were indistinguishable from our normal summer lows (lower to 50s F).

And it is going to get warmer tomorrow.

Let me illustrate the profound nature of the warmth we are facing.  A lower atmosphereic level meteorologists often look at is at a pressure of  850 hPa (located about 5000 ft above the surface).

This morning (at 4 AM) the temperature at this level measured by a radiosonde (weather balloon and sensor) on the Washington Coast (Quillayute) was 7.5C with a freezing level of roughly (10,000 ft).   See sounding below for the details (red is temperature, blue dashed is dew point).

A warm front has moved through this morning and even warmer air is coming in--here is the forecast from the UW WRF model at 850 hPa for 1 AM Monday morning.  Shading and the blue lines are temperature.

14 C air over Seattle!.  For those of you who are not meteorologists, this is crazy warm.  Let me prove it.

The NOAA storm prediction center has a wonderful site that provides the climatology of the upper air data around the U.S.   Let's take a look at the climatology of 850 hPa temperatures at Quillayute (UIL) on the Washington Coast throughout the year.  The black line indicates the average temperatures for the day (dark black is a smoothed version).  The red line shows the extreme warmest temperature on each day.  The green line is the temperature forecast for Monday AM.

Pretty amazing.  The temperatures on Sunday and Monday will probably exceed the all time records for the date.    They are WAY WARMER than the average temperatures for July and August, our warmest months.  So the air above us tomorrow will be warmer than typical summer temperatures.

The only thing holding us back from having temperatures in the 80s is that the sun is way weaker this time of the year and the cooling effects of clouds.

Today there is considerable cloudiness, but there will be only some high clouds tomorrow and few clouds on Monday.  Here is the cloud forecast for Monday..sunny,with summer air above us!

Let's look at the WRF temperature forecasts for Sunday afternoon at 2 PM.  Temperatures well into the 60s over western Washington and around 70F over the western slopes of the Cascades.  The only issue with this forecast is that there will be a low-level inversion between cooler air at the surface and warmer air aloft.  That will keep some low clouds in on Sunday morning, something the model tends to mix out too quickly.  But where the clouds burn off it will get warm quickly.

And warm or warmer on Monday.  A weak front comes through on Tuesday and then the ridge builds again for warm and dry conditions.  The latest NOAA extended (6-10 day) temperature forecast (below)  indicates much warmer than normal temps on the West Coast and cooler than normal over the eastern U.S.

The extraordinary warm temperatures and persistent high pressure has led to very  low snowpacks in some locations, particularly the Olympics.  Here is the last cam shot of the Hurricane Ridge parking lot and surroundings today.   Hard to believe for late January...MOST OF THE GROUND IS BARE!

Is this warmth associated with human-caused global warming?  The answer in a future blog.

 And enjoy summer in January.

Thursday, January 22, 2015

Sea Fog and Lowered "King Tides"

Local weather enthusiast and the maestro of Skunk Bay Weather Greg Johnson sent me some impressive imagery and video of sea fog off of Point No Point on the Kitsap Peninsula around 8 AM yesterday (January 21st).  Click on the image or link to view it.

Why such a nice display of this shallow fog?

We start with relatively warm water......here is the sea surface temperature at the Orca buoy at Hansville, only a few miles away from the Point No Point lighthouse (I got this on the wonderful Nanoos website provided by the University of Washington).  The water was around 49F.

It turns out, that the air temperatures were relatively cold that morning,dropping into the mid 30s, as shown by the observations at Greg's Johnson's Skunk Bay Weather Site, which is quite close to Point No Point:

Same story at Port Townsend

So relatively cold air was passing over water, water about 12-15F warmer.  Moisture from the warm water was able to saturate the cold air (cold air can "hold" less water vapor than warm air) producing the shallow fog.   This kind of fog is also called "steam fog".

 The other big water story are the "King Tides" that will be occurring the next few days. Here is a plot of the predicted and observed tides.  They will be particularly high Friday and Saturday.  

But here is an interesting observation--the observed tides (red) are less than predicted (blue).  Why?

The reason is that atmospheric pressure is running higher than normal and high pressure pushes the water down, reducing the water level.  So perhaps we should call them "Queen Tides" this year.  A fascinating aspect of King Tide periods is that they give you a feeling what the typical tides will be in roughly 150 years from now due to global warming---if we let it happen

Tuesday, January 20, 2015

What Should Governor Inslee Do About Climate Change?

The press is full of coverage of Governor Inslee's proposed climate plan, revealing vast differences in the viewpoints of Democrats and Republicans, particularly about the controversial cap and trade program.
In this blog I will suggest an alternative plan, that might be acceptable to both sides of the aisle.  Maybe.

Our governor really cares about climate change....and he should.   Mankind is emitting huge amounts of carbon dioxide into the atmosphere and there surely will be serious climate impacts later in this century.   A few years ago as a Congressman, Jay Inslee visited the UW and several of us briefed him about some of the latest research findings.   I was impressed with his interest and passion in the subject...not your average politician.  How many politicians have written books on the climate issue, like Inslee's Apollo's Fire?  You got to respect his willingness to get in front of a major societal issue.

Washington Governor Jay Inslee

Recently, Governor Inslee announced a climate action strategy, centered around a one-billion dollar cap and trade plan.   And he has made several executive decisions to support clean energy.

But I am worried about whether his approach will be effective.   Recent changes in the makeup of the Washington State legislature have reduced the chances that any cap and trade plan will be enacted--and the success of cap and trade in other venues has not been impressive.

So if I was Governor, what would be MY program?

Here is my plan:

I.   Secure a better understanding of how our climate has changed during the past century and how it will change during the next 100 years.

 If our state is going to deal with climate change, we must understand what has happened and what will happen.  You can't make robust policies without solid information, right?   As a weather/climate scientist let me assure you there are major weaknesses in our knowledge on both counts--but with some effort we can fix the deficiencies.

Step 1: Strengthen the Office of the Washington State Climatologist (OWSC).

 OWSC has the responsibility to collect climate data for the State and to make it available to WA citizens and decision makers.  To provide a clear picture of previous changes in our state's climate.  This office is woefully underfunded (with a budget about 60K).   There is so much that they could and SHOULD be doing, but there is no funding.  The Governor and Legislature need to fix this.  Soon.

Step 2:  Begin an active program of regional climate simulation to get a far better understanding of the future regional implications of climate change.

To deal with Northwest climate change, it is essential to have reliable guidance on what will happen during the next century.   The guidance used today can be dramatically improved.  Global climate models do not produce consistent results about the regional implications of increasing greenhouse gases, and most of these models are far too coarse to consider the critically important terrain of the region.  To plan for the future, our state needs much better information, and there is a way to get it:  high-resolution regional climate models.    Secure a large number of global climate models and strain out the models that fail to get the current climate right.   Then run a  high resolution regional climate model for each global simulation to get the local implications (see sample below), and apply sophisticated statistical post-processing to provide calibrated regional climate predictions.

A regional climate prediction effort should be established immediately, with support from the State and others.  In  fact, a group of us have developed a plan to do so, found here.  Hopefully, we will be able to find some support for the effort.  The technology to secure far better future climate information is available and Governor Inslee should make regional climate prediction a top priority.   This could be highly bipartisan and would supply regional planners with the information they need for resilience and adaptation planning.

II.  Make our region more resilient to current conditions and future climate change.   

Step 3: Begin adaptation planning and infrastructure improvements.

Too many environmental activists look at adaptation as a dirty word, as if getting ready for future changes will lessen enthusiasm for mitigation (reducing emission of greenhouse gases).   But the truth is that our society is not sufficient resilient to the CURRENT climate  (e.g., the Oso landslide) and climate change will bring new stressors.   Substantial global warming is going to happen--we are simply not doing enough to stop it.  Therefore, the State and our Governor needs to make resilience and adaptation a priority--one that will pay great dividends no matter what happens.   What could be part of the Governor's resilience plan?

a.    Complete a lidar survey of the state to find all historical landslide locations.  Heavy precipitation is clearly going to increase under global warming and thus flooding and landslides will too.  Using the best advice of geomorphologists, our State must establish restrictions on new construction in vulnerable areas and begin the process of moving people from dangerous locations.

b.  Evaluate whether new reservoir capacity is needed in eastern Washington. Even today, there are years in which water for agriculture/fish is a problem;  what about 30-100 years from now?   There is already some discussion of expanding current reservoirs and/or adding new facilities.  A detailed examination of this issue, informed by the regional climate simulations noted above, is needed.    Beyond adaptation, should reservoir capacity be increased to allow a massive enhancement in eastern Washington agriculture to make up for the agricultural loses in increasingly drought-stricken California?  Folks need to eat.  Perhaps a huge opportunity for WA State agriculture.

c.  Considering the potential for increased river flooding, we must evaluate current development near rivers and begin the process of moving people away from vulnerable areas.  This may involve a buy-out program of some homes and businesses.  It also may include improved dikes and water works.

d.  Evaluate ways to lessen the impacts of sea level rise along the coast and near inland waterways.

In short, the State must begin a comprehensive evaluation of the threats to life and property accompanying global warming and then come up with and fund an explicit action plan to make the State less vulnerable for both current and future climate variations.  (see carbon tax below)

Everything mentioned above is relatively uncontroversial.   Now lets consider other parts of my climate plan.

III.  Deal with the regional transportation grid lock.

Few things waste more energy and provides more of an economic drain on the Puget Sound region, the economic engine of the State, then the worsening traffic crisis.   It is not only bad, but has gotten much worse in the last few years.  Unfortunately, regional political leadership has been extraordinarily ineffective in solving this crisis and the Governor needs to push the legislature and localities to get serious about transportation.    Consider just a few examples of local failures:

1.   As traffic has increased, King County Metro CUT bus service, with long wait and inadequate service on important commuter routes.

2.  Rail service north and south (Sounder trains) is not only infrequent but is often stopped, for days and weeks, by mudslides on the tracks south of Everett.  Here we have a nation that could put a man on the moon, but we can't seem to stabilize a few miles of slopes above the tracks.  Sad.

3.  The city of Seattle has let crucial bicycle routes deteriorate (e.g., the Burke Gilman trail) and has failed to establish a safe north-south route into the city.  Instead they are putting millions in a bicycle rental system (Pronto) that is barely used and has painted bicycle symbols on streets (sharrows).

4.  A wonderful north-south rail corridor on the east side (where 405 traffic is at a standstill all the time) is GIVEN UP for a recreational trail.  Imagine if fast commuter rail went in instead. How in the world did this happen.

5.  Seattle light rail south of Seattle does not have its own right of way and is amazingly slow as it gets stuck in lights or gets into accidents with motor vehicles.

I could list a dozen more examples, but the message is clear:  local politicians have been missing in action in dealing with regional gridlock.  The governor needs to deal with this.  Some ideas to start:

More buses and frequent service especially for important commuter runs.
Repair and extend bike trails
End the slide mess and add more Sounder trains.
Use Uber/Lyft/taxis for less traveled bus routes to reduce use of expensive large buses.
Expand light rail around Seattle, particularly by adding a line down I5 to the airport.
Add rail service to Stevens Pass skiing.

IV.  Do what it takes to stop the coal trains, and particularly the proposed Cherry Point and Longview terminals.

Several groups have proposed the shipment of vast quantities of coal through new local ports.  Such huge coal shipments, burned in eastern Asia, would be major contributors to global warming.  They are also environmental and financial disasters for our region, tying up local traffic, which undermines local economic activity and produces polluting (and fuel consuming) tie ups.  And on top of it, the air pollution from Asia wafts back to us across the Pacific.   How many ways can you say disaster?  The Governor, local governments, and WA citizens need to use all the tools at their disposal to stop the building of huge coal shipment terminals.  The impacts of exporting coal using these trains is so large, that everything else we do to reduce our carbon footprint is in the noise level in comparison.  Put in the coal terminals and export ten of millions of tons of coal to China, and forget about your electric or hybrid car...it would be meaningless in comparison.

Oil train volume needs to be reduced as well, perhaps just enough to supply oil to our local refineries, removing the need for ships bringing oil into the Strait..  Even better, oil pipelines should be used instead of rail cars.

V.  Drop the Cap and Trade approach and move to a carbon tax

Cap and Trade, with a declining limit placed on carbon emissions and groups having to purchase emission rights, has proven to be a failure for reducing CO2 emissions, pretty much everywhere it has been tried.  The most spectacular failure has been in Europe (see NY Times article here).  Most environmental economists I have talked to believe a carbon tax (where a tax is placed on fuels) is much more straightforward and effective.  And a carbon tax has worked effectively in our northern neighbor, British Columbia.   Increasing the price of carbon is important now since the plummeting decrease in oil and gas prices is undermining the transition to fuel-efficient cars and renewable energy.  And with oil/gas prices declining quickly, most people would hardly notice a carbon tax.  The carbon tax would be high enough to help decrease demand for carbon fuels, but not high enough to hurt the economy.  British Columbia has shown this is possible.

The proceeds from a carbon tax could be used in a two ways.  One, would make it revenue neutral by allowing some other taxes (like the regressive sales) tax to be reduced.   Or some of the money could be used to improve the state's transportation system or deal with adaptation needs, something that would benefit to consumers and businesses alike.

Anyway, the above would be some of my policies as Governor and since it is doubtful I will ever fill that role, perhaps Governor Inslee might consider a few.