The U.S. Has Fallen Behind in Numerical Weather Prediction: Part I

It's a national embarrassment.  It has resulted in large unnecessary costs for the U.S. economy and needless endangerment of our citizens.  And it shouldn't be occurring.

What am I talking about?   The third rate status of numerical weather prediction in the U.S.  It is a huge story, an important story, but one the media has not touched, probably from lack of familiarity with a highly technical subject.   And the truth has been buried or unavailable to those not intimately involved in the U.S. weather prediction enterprise. This is an issue I have mentioned briefly in previous blogs, and one many of you have asked to learn more about.  It's time to discuss it.

Weather forecasting today is dependent on numerical weather prediction, the numerical solution of the equations that describe the atmosphere.  The technology of weather prediction has improved dramatically during the past decades as faster computers, better models, and much more data (mainly satellites) have become available.

Supercomputers are used for numerical weather prediction

U.S. numerical weather prediction has fallen to third or fourth place worldwide, with the clear leader in global numerical weather prediction (NWP) being the European Center for Medium Range Weather Forecasting (ECMWF).  And we have also fallen behind in ensembles (using many models to give probabilistic prediction) and high-resolution operational forecasting.  We used to be the world leader decades ago in numerical weather prediction:  NWP began and was perfected here in the U.S.  Ironically, we have the largest weather research community in the world and the largest collection of universities doing cutting-edge NWP research (like the University of Washington!).   Something is very, very wrong and I will talk about some of the issues here.  And our nation needs to fix it.

But to understand the problem, you have to understand the competition and the players.  And let me apologize upfront for the acronyms.

In the U.S., numerical weather prediction mainly takes place at the National Weather Service's Environmental Modeling Center (EMC), a part of NCEP (National Centers for Environmental Prediction).   They run a global model (GFS) and regional models (e.g., NAM).

The Europeans banded together decades ago to form the European Center for Medium-Range Forecasting (ECMWF), which runs a very good global model.  Several European countries run regional models as well.

The United Kingdom Met Office (UKMET) runs an excellent global model and regional models.   So does the Canadian Meteorological Center (CMC).

There are other major global NWP centers such as the Japanese Meteorological Agency (JMA), the U.S. Navy (FNMOC), the Australian center, one in Beijing, among others.   All of these centers collect worldwide data and do global NWP. 

The problem is that both objective and subjective comparisons indicate that the U.S. global model is number 3 or number 4 in quality, resulting in our forecasts being noticeably inferior to the competition.  Let me show you a rather technical graph (produced by the NWS) that illustrates this.  This figure shows the quality of the 500hPa forecast (about halfway up in the troposphere--approximately 18,000 ft) for the day 5 forecast.  The top graph is a measure of forecast skill (closer to 1 is better) from 1996 to 2012 for several models (U.S.--black, GFS; ECMWF-red, Canadian:  CMC-blue, UKMET: green, Navy: FNG, orange).  The bottom graph shows the difference between the U.S. and other nation's model skill.

 You first notice that forecasts are all getting better. That's good.  But you will notice that the most skillful forecast (closest to one)  is clearly the red one...the European Center.  The second best is the UKMET office.  The U.S. (GFS model) is third...roughly tied with the Canadians.

 

  

Here is a global model comparison done by the Canadian Meteorological Center, for various global models from 2009-2012 for the 120 h forecast.  This is a plot of error  (RMSE, root mean square error) again for 500 hPa, and only for North America.  Guess who is best again (lowest error)?--the European Center (green circle).  UKMET is next best, and the U.S. (NCEP, blue triangle) is back in the pack.

Lets looks at short-term errors.  Here is a plot from a paper by Garrett Wedam, Lynn McMurdie and myself comparing various models at 24, 48, and 72 hr for sea level pressure along the West Coast. Bigger bar means more error.  Guess who has the lowest errors by far?  You guessed it, ECMWF.

 I could show you a hundred of these plots, but the answers are very consistent.  ECMWF is the worldwide gold standard in global prediction, with the British (UKMET) second.   We are third or fourth (with the Canadians).   One way to describe this, is that the ECWMF model is not only better at the short range, but has about one day of additional predictability:  their 8 day forecast is about as skillful as our 7 day forecast.   Another way to look at it is that with the current upward trend in skill they are 5-7 years ahead of the U.S. 

Most forecasters understand the frequent superiority of the ECMWF model.  If you read the NWS forecast discussion, which is available online, you will frequently read how they often depend not on the U.S. model, but the ECMWF.  And during the January western WA snowstorm, it was the ECMWF model that first indicated the correct solution.  Recently, I talked to the CEO of a weather/climate related firm that was moving up to Seattle.  I asked them what model they were using:  the U.S. GFS?  He laughed, of course not...they were using the ECMWF.

A lot of U.S. firms are using the ECMWF and this is very costly, because the Europeans charge a lot to gain access to their gridded forecasts (hundreds of thousands of dollars per year).  Can you imagine how many millions of dollars are being spent by U.S. companies to secure ECMWF predictions?  But the cost of the inferior NWS forecasts are far greater than that, because many users cannot afford the ECMWF grids and the NWS uses their global predictions to drive the higher-resolution regional models--which are NOT duplicated by the Europeans.  All of U.S. NWP is dragged down by these second-rate forecasts and the costs for the nation has to be huge, since so much of our economy is weather sensitive.  Inferior NWP must be costing billions of dollars, perhaps many billions.

The question all of you must be wondering is why this bad situation exists.  How did the most technologically advanced country in the world, with the largest atmospheric sciences community, end up with third-rate global weather forecasts?   I believe I can tell you...in fact, I have been working on this issue for several decades (with little to show for it).  Some reasons:

1.   The U.S. has inadequate computer power available for numerical weather prediction.  The ECMWF is running models with substantially higher resolution than ours because they have more resources available for NWP.   This is simply ridiculous--the U.S. can afford the processors and disk space it would take.  We are talking about millions or tens of millions of dollars at most to have the hardware we need.   A part of the problem has been NWS procurement, that is not forward-leaning, using heavy metal IBM machines at very high costs.

2.  The U.S. has used inferior data assimilation.  A key aspect of NWP is to assimilate the observations to create a good description of the atmosphere.   The European Center, the UKMET Office, and the Canadians using 4DVAR, an advanced approach that requires lots of computer power.   We used an older, inferior approach (3DVAR).  The Europeans have been using 4DVAR for 20 years!   Right now, the U.S. is working on another advanced approach (ensemble-based data assimilation), but it is not operational yet.

3.  The NWS numerical weather prediction effort has been isolated and has not taken advantage of the research community.   NCEP's Environmental Modeling Center (EMC) is well known for its isolation and "not invented here" attitude.  While the European Center has lots of visitors and workshops, such things are a rarity at EMC.  Interactions with the university community have been limited and EMC has been reluctant to use the models and approaches developed by the U.S. research community.  (True story:  some of the advances in probabilistic weather prediction at the UW has been adopted by the Canadians, while the NWS had little interest).  The National Weather Service has invested very little in extramural research and when their budget is under pressure, university research is the first thing they reduce.  And the U.S. NWP center has been housed in a decaying building outside of D.C.,one  too small for their needs as well.  (Good news... a new building should be available soon).

4.  The NWS approach to weather related research has been ineffective and divided.  The governmnent weather research is NOT in the NWS, but rather in NOAA.  Thus, the head of the NWS and his leadership team do not have authority over folks doing research in support of his mission.  This has been an extraordinarily ineffective and wasteful system, with the NOAA research teams doing work that often has a marginal benefit for the NWS.

5.  Lack of leadership.   This is the key issue.  The folks in NCEP and NWS leadership have been willing to accept third-class status, providing lots of excuses, but not making the fundamental changes in organization and priority that could deal with the problem.

This note is getting long, so I will wait to talk about the other problems in the NWS weather modeling efforts, such as our very poor ensemble (probabilistic) prediction systems.  One could write a paper on this...and I may.

I should stress that I am not alone in saying these things.  A blue-ribbon panel did a review of NCEP in 2009 and came to similar conclusions (found here).  And these issues are frequently noted at conferences, workshops, and meetings.

Let me note that the above is about the modeling aspects of the NWS, NOT the many people in the local forecast offices.  This part of the NWS is first-rate.  They suffer from inferior U.S. guidance and fortunately have access to the ECMWF global forecasts.  And there are some very good people at NCEP that have lacked the resources required and suitable organization necessary to push forward effectively.

This problem at the National Weather Service is not a weather prediction problem alone, but an example of a deeper national malaise.  It is related to other U.S. issues, like our inferior K-12 education system.  Our nation, gaining world leadership in almost all areas, became smug, self-satisfied, and a bit lazy.   We lost the impetus to be the best.   We were satisfied to coast.    And this attitude must end...in weather prediction, education, and everything else... or we will see our nation sink into mediocrity.

The U.S. can reclaim leadership in weather prediction, but I am not hopeful that things will change quickly without pressure from outside of the NWS.  The various weather user communities and our congressional representatives must deliver a strong message to the NWS that enough is enough, that the time for accepting mediocrity is over.

Part II will discuss the problems with ensemble and high-resolution numerical weather prediction in the U.S.

The Revenge of La Nina

 Forecast Update and More on La Nina on KPLU at 9 AM Friday or online.

Last winter we were securely in La Nina conditions and the region experienced a miserable, cold, wet spring that lasted into mid summer.   Horror to all soccer and Little League parents.

This winter we have also been in a La Nina and since early February we have been colder and wetter than normal, with snowpack surging in our mountains.

Yes, it appears we are dealing with  the revenge of La Nina.

Beware the white side of the force

So how bad has it been?


 Here is the plot of temperatures at Sea Tac versus normal highs and lows for the past month.  Only four days have equaled or exceeded normal, while a large number of days have been below normal. 

Here is the departure of temperature from normal for the past 30 days:  the western U.S. has generally been colder than normal (dark green and blue), with western WA and Oregon, MUCH cooler than normal.  Maddeningly, nearly all of the nation east of the Rockies had been much WARMER than normal.

Precipitation has been greater than normal over the Cascades and western WA, resulting in a rapid build up of snowpack.  As you can see from the snow water equivalent on March 15th, much of our area is above normal.  But CA is still in a snow drought.

Between the 9th and 14th of March, Mt. Baker  added 59 inches of snow and now is virtually tied with last year's total on the same date (251 inches on the ground today, 252 inches a year ago).  Take a look at the snow water for the Seattle watershed (Cedar/Tolt)--way above last year and normal.  We are already well above the normal winter max snowpack at that site.

The fascinating thing about La Nina years is how often we have seen this late winter surge of snow, cold, and precipitation.   You never give up in February...March is often a big snow month.

So what is going to happen?   Are we going to have to endure a non-spring like last year?
There is some suggestion that our fate is different than last year...we will suffer...but the wet, chill will not last into summer.

First, the suffering.  The last extended runs of the best modeling system in the world (the European Center), indicates that upper troughing with cold, wet weather will last for at least the next ten days.   In fact, we will get quite cool this weekend, with a chance of lowland snow in the Puget Sound convergence zone on Saturday morning (but nothing heavy) and low snow levels (roughly 500 ft) ocer the weekend.  That means higher hills could see some flakes....but no real accumulations until you get to 1000 ft.   Continued snow in the mountains.

But something is changing:  La Nina is rapidly weakening.  As shown in the next picture, the cold anomalies in the central tropical Pacific are rapidly declining and some parts of the tropical eastern Pacific are now warmer than normal.   Predictive models suggest that La Nina will be over by the end of April.

As explained in previous blogs, La Nina often forces ridging in the eastern Pacific and troughing over the NW--producing the cold/wet pattern.   By early summer the La Nina forcing should be over.

The NWS runs a climate prediction system four times a day that predicts the weather out several months.    Here is what it is showing for temperature.  A bit colder than normal for early Spring, followed by near-normal temperatures for late spring into summer.  Maybe, just maybe, we will get out this infernal pattern.

I am buying my tomato seeds this week! 

Jabba the snowman is not happy.

Why is it so hard to forecast lowland snow?

Meteorologists can get windstorm forecasts right nearly all of the time.  We hit the record high temperatures in July 2009 nearly dead on.  We can give you a skillful forecast of a marine push in the summer.

But snow forecasts, although improving, are often in error.

Why?   Well, there are reasons....a lot of reasons.

(1) You've got to get the amount of precipitation right--really right-- or you have a very bad snow forecast.  On most days, the forecasts hardly talk about the amount of precipitation, just the probability of precipitation.   Most people don't care whether .1 inch or .4 inch of precipitation falls...they would hardly notice it.  But a difference like that would be HUGE for a snow forecast.  Around here there is typically a 10 to 1 ratio of snow versus precipitation in the form of liquid water.  Thus, .1 inch of precipitation would be .1 inch of rain or, if cold enough, 1 inch of snow.  (Precipitation is always reported in terms of liquid water--so snow has to melted before measuring it).  So the difference between .1 and .4 inches of precipitation, which you would be oblivious to of if it were rain, would be the difference between 1 and 4 inches of snow.  That you would notice.

Getting the amount of precipitation exactly right is very hard, much harder than getting the probability of precipitation correct, thus making the snow forecast difficult.  I can tell you why in a future blog.

(2)  But it is worse than that.  The majority of time our temperatures are marginal for snow...we are right on the edge of rain or snow.  The reason...all the warm water (e.g., the Pacific and the Sound) close by.    On most days a few degree error would not even be noticed (like the difference between 58 and 61F), but that is a big error on marginal snow days.  It is very hard to reduce the error under a few degrees.

(3)  But it is even worse than that!   The temperature of the air is affected greatly by the evaporation and melting of precipitation.  And that is dependent on the intensity of precipitation and the relative humidity of the air below!   Remember:  virtually all of our precipitation starts as snow.  Usually it melts before it reaches the ground, but if the intensity is great enough, the evaporation and melting of the snow can cool the air below so that the freezing level (0C) and snow level (about 1000 ft below the freezing level where all the snow does melt) progressively head towards the surface.  So we need to get the intensity of precipitation right, the initial freezing level right, the relative humidity of the air below the precipitating clouds right....you get the message.  And this is hard.

(4)  And there is more.  To get the depth of the snow right, you also need to know the characteristics of the snow--is it dense or light?  That depends on crystal type and temperatures, which can cause the ratio to vary from 5 to 1 for wet snow to 20 to 1 for dry stuff.

(5)  There is another problem.  Snow is so infrequent and takes such unusual conditions to occur that meteorologists have less practice and experience that for more typical weather.  Why unusual?  Well, it is easy to be warm and wet around here (warm being in the 40s and 50s) for air coming off the Pacific,  pretty easy to be cold and dry (when we have high pressure over or to the east of us).   But it takes a lot of doing for us to be cold and wet.  The set up has to be just right.  Meteorologists are like anyone else:  you gain skill with practice.   Only old timers have lots of cases in their heads...and even that is not good enough since the modeling and observation systems have changed so much.

(6)  Still think it is easy to forecast snow?   Well, local meteorologists have more problems to deal with: a multitude of local effects.  The potential for snow is generally much less near local water bodies, particularly near sea level.  Chances increase greatly up on hills...even 200-300 ft can make a world of difference.   We have gaps that allow cold air to move through the mountains (like the Fraser River gap allowing cold air into NW Washington).  Convergence Zones (like the Puget Sound convergence zone) produce areas of enhanced precipitation and sometimes snow.   And their are dozens of local effects I haven't mentioned.

You get the picture.  Snow prediction is hard, real hard, particularly around here.   Forecasting winter snow back east,  say in  North Dakota, is a cake walk---you KNOW is will be cold enough.  Huge simplification.

So unless you are a Subaru advertising executive....have a little sympathy for the poor NW weathermen when a snow forecast goes wrong.  And keep in mind, a lot more technology is coming:  ensemble-based snow prediction, better use of the new dual-polarization radars, and more.  Meteorologists will make progress....and then we can attack even harder problems, freezing rain and shallow fog.

Major Storm Hits

This storm has so many interesting and intense features I just wanted to update everyone on the action.  Here is the latest infrared satellite photo--simply impressive.  You can see the swirling clouds around the low center, which is now crossing northern Vancouver Island...exactly what the models have been saying for a few days.  Cold unstable air is circling around from the west (the pattern of cloud and clear skies that has a mottled appearance). 

It appears that last night's runs underpredicted the strength of the system a bit...the pressure at Solander Island, on the northern Vancouver Island coast dropped to 962 hPa.  This is a very intense low for our neck of the woods.  The more intense storms on record only get down to the low 950s.

And the wave heights did not disappoint.  Some of the buoys have shown significant wave heights of over 30 ft!  Here are a few examples at buoy 41 off the WA coast and buoy 50 off the Oregon coast:

As I noted in previous blogs, the NWS Wavewatch III model indicated the potential for a big wave event...it was correct.

By the way, if you ever want to check out coastal conditions a really great site is SurfWA.

And the Langley Hill radar on the WA coast provided its value again, indicating the approach of the front from offshore.  Look at radar image from around 6 AM this morning...the front is seen offshore...the line of convection that has a series of intense elements (cores) and weaker areas (gaps).  Classic ocean frontal signature.   And by tracking it we knew exactly when this key feature was going to make landfall hours ahead (more on this in a future blog).

 And winds?  On the coast, winds of up to 50-70 mph were commonplace, such as the 60 kts at buoy 41 off the central WA coast:

More impressively, we are experiencing one of the strongest wind events of the past few years over NW Washington and SE Vancouver Island.  Winds at Trial Island, just off of Victoria have gusted to at least 60 knots (69 mph).  Buoy 88, over the eastern side of the Strait to 50 kts (see below)

Winds are fairly strong (30-40 mph) over Puget Sound, but weaker over land.   Here are the 7 AM winds from the Kingston Ferry...winds (sustained) to 36 knots. Note how much weaker the winds are closer to the shore where they are coming off of land.  Water is aerodynamically fairly smooth and allow strong acceleration.

Anyway, an impressive storm and well predicted.   It is perhaps ironic that we have gotten so good at predicting major Pacific storms coming off the ocean, yet have so much trouble in getting minor snow events correct.  Twenty years ago we were unable to forecast major cyclones coming off the ocean...we not only can do that now, but have great skill in determining the resulting  local wind patterns.  Two decades have changed everything.  Don't forget that when you listen to a weatherman jokes or view a Subaru commercial ("you don't need a weatherman if you have a Subaru").

Storm Update

Its showtime.   The coastal storm is now rapidly intensifying offshore and winds are increasingly over the coast and over NW Washington.  The latest runs indicate a similar path as previous model forecasts, with the low crossing the northern portion of Vancouver Island.  But the storm is now forecast to be weaker by about 10 hPa (the low is now predicted to be in the low 970s as it makes landfall, instead of the low 960s).   Still a serious storm, but a significant notch lower in intensity.

Here is the latest infrared satellite image. You can see the developing storm with a cloud free notch on its western side...the low center is near the apex of that notch.

We also have water vapor imagery (I rarely have shown this on the blog).  At this wavelength we are seeing atmospheric water vapor, with the dark areas indicating dry conditions in the upper troposphere.  Such darkening is a good indicator of rapidly developing systems.

 Along the coast pressure is falling and winds are rising to 40 kts and more.  To illustrate here are the pressure and wind observations at buoy 46041 off the central Washington coast.

Here is the forecast sea level pressure chart for 4 AM this morning. 975 hPa low moving northward off our coast and intense coastal pressure gradients.

We still expert big winds over northwest Washington, particularly the western side towards San Juan Island and Victoria.  Here is the sustained wind forecast for 8 AM tomorrow (Monday) morning.  The dark blue are winds of 45 kts and there are even red (50 kts).  Strong, but lesser winds, over Puget Sound.  These are very intense conditions for the inland waterways.  Gusts will be higher.

The coast will get hit hard around 3 hrs earlier.   Here are the sustained winds at 5 AM--very strong winds along the coast (50kt sustained and higher).

The NWS Wavewatch 3 model is still predicting waves of 8-9 meters (roughly 25 ft)...see chart below for 8 AM Monday.

With low pressure (which results in higher water level) and high tides at 4-4:30 AM, water levels will be quite high during the morning.  If you are going storm watching on the coast, keep safe--some coastal areas will be inundated and logs can be thrown around by the turbulent waters.

And did I mention the moderate to heavy rain over the lowlands and heavy snow in the mountains (over a yard of the white stuff in the Olympics for example).