Winter forecast, part II: NOAA's predicts a warm winter for the Central U.S.

By: Dr. Jeff Masters , 2:51 PM GMT on November 21, 2008

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Let's follow up on yesterday's discussion about the long range forecast for the coming United States winter. Those of you outside the U.S. will probably be more interested in what the International Research Institute for Climate Prediction has to say for your country, and I encourage you to check out their excellent web site for their seasonal forecasts.

The official National Oceanic and Atmospheric Administration (NOAA) 90-day forecast for the upcoming winter, issued on November 20 by their Climate Prediction Center (CPC), calls for above average temperatures across the Central U.S. and Alaska. The remainder of the country has equal chances of above or below average temperatures. A dryer than average winter is expected over much of the Southern U.S., including the drought-stricken Southeast U.S.


Figure 1. Temperature forecast for the upcoming winter--December, January, and February 2009--made by NOAA's Climate Prediction Center. No areas of the country ar forecast to have an above-average chance of being colder than normal, but the Central U.S. has up to a 50% chance of having above-average temperatures.

How are the NOAA winter forecasts made?
NOAA uses several tools to make their forecasts. One key tool is their Climate Forecast System (CFS) model. This model includes a version of the GFS forecast model that we use for everyday weather and hurricane track forecasts. The CFS model also includes an ocean model that interacts with the atmospheric model. These models solve mathematical equations of fluid flow using a supercomputer for the entire globe, on a 100-km grid. NOAA also uses statistical models, which look at past winters and see how they depended on quantities such as sea surface temperature anomalies. Temperature trends are important, too--if it has been warmer than average the last ten years, it's a good idea to forecast a warmer than average winter.


Figure 2. Skill of the official 90-day forecasts issued 0.5 months in advance by NOAA's Climate Prediction Center. Note that the average skill over the past ten years is not very high (9 on a scale of 0 to 100), and has remained flat, indicating that our skill in making long-range forecasts has not improved.

How good are the NOAA winter forecasts?
NOAA rates its forecasts using the Heidke skill score, which is a measure of how well a forecast did relative to a randomly selected forecast. A score of 0 means that the forecast did no better than what would be expected by chance. A score of 100 depicts a "perfect" forecast, and a score of -50 depicts the "worst possible" forecast. For 90-day temperature forecasts issued 0.5 months in advance, NOAA has averaged a 9 out of 100 on the Heidke scale since 1995 (Figure 2). So, while there is some skill in forecasting what winter temperatures will be like, this skill is not much better than flipping a coin. Depressingly, Heidke skill scores for three-month precipitation forecasts are even worse, averaging just a one on a scale of 1 to 100 over the past 15 years.

Let's look at some examples. Last's year's winter temperature forecast issued in mid-November did poorly (Figure 3), failing to forecast that the U.S. would have equal areas with both above and below average temperatures. The 90-day forecast done in mid-November of 2005 for the winter of 2005-2006 was awesome, with a Heidke skill score of 45. However, the 90-day forecast done in mid-November of 2006 for the winter of 2006-2007 had virtually no skill, with a Heidke skill score of one.



Figure 3. Temperature forecast for Dec 2007-Feb 2008 issued by NOAA's Climate Prediction Center on November 15, 2007 (top). They predicted Equal Chances (EC) of either above or below-average temperatures for the Northwestern U.S. (white colored areas), and a 30-60% chance of above average temperatures over most of the remainder of the country. In reality, the U.S. experienced an average winter, with approximately equal areas of the country receiving above and below average temperatures (bottom). Image credit: National Climatic Data Center.

Why do seasonal forecasts do so poorly? Primarily, it's because the long-term weather patterns are chaotic and fundamentally unpredictable. To a lesser degree, we are limited by our imperfect physical understanding of what controls the climate, and our imperfect computer models we use to simulate the climate. As computer power continues to increase and our models include better representations of the weather and climate at finer grid sizes, I anticipate that seasonal forecasts will improve. However, given that long-range forecasts have not improved since 1995 despite a large increase in computer power, I doubt that this improvement will be more than 10-20% over the next thirty years.

Seasonal forecast models vs. climate models
A common complaint one hears about global warming predictions made by climate models is, "How can we trust the predictions of these climate modes, when they so such a lousy job with seasonal forecasts?" It's a good question, and there is no doubt that seasonal forecasts have pretty marginal skill. However, there is a fundamental difference between making a seasonal forecast and making a 100-year climate forecast. A seasonal or a short-term weather forecast is what mathematicians call an "initial value" problem. One starts with a set of initial meteorological and oceanographic values that specify the initial state of the planet's weather, then solve the equations of fluid flow to arrive at the state of the atmosphere a few days, weeks, or months into the future. This forecast is highly sensitive to any imperfections one has in the initial conditions. Since there are large regions of the atmosphere and ocean we don't sample, it's guaranteed that the prediction will suffer significantly from imperfect initial conditions. Furthermore, the chaotic and turbulent nature of the atmosphere leads to many "bumps" in the weather pattern over time scales of days, weeks, and months. The nature of turbulence makes it impossible to accurately forecast these "bumps" that are superimposed on the mean state of the climate.

A 100-year climate forecast, on the other hand, is what mathematicians call a "boundary value" problem. Given an initial and final set of factors (called "forcings") that influence the climate, one runs a climate model 100 years into the future. The final state of the climate will depend on the strength of the forcings supplied. This type of model is not very sensitive to initial conditions, and is not trying to forecast the "bumps" of chaotic, turbulent atmospheric motion superimposed on the mean climate. Rather, one is trying to forecast the mean climate. As computer power increases and our physical understanding of how the climate works grows, these type of models will continue to significantly improve. While climate models do fail to properly simulate important aspects of our past climate, such as the Arctic warming of the 1930s, and the observed 0.1°C global temperature increase that occurs at the peak of the 11-year solar sunspot cycle, they have been very successful at simulating things like the global cooling triggered by the 1992 Mt. Pinatubo eruption, and the observed pattern of greatest global warming in the Arctic. I believe that climate models are already significantly more reliable than seasonal forecast models, and should continue to improve steadily in coming years.

Support the Portlight Christmas for Gulf Coast Kids Honor Walk
Saturday is the portlight.org Christmas for Gulf Coast Kids Honor Walk. This is a fundraiser to buy gifts for the kids along the Gulf Coast who might not have much in their stockings this year because of the ravages of Hurricane Ike. Our own StormJunkie will be walking up the Arthur Ravenel Jr. Bridge in Charleston, SC, and will be taking his webcam along. Tune in to the webcam site at 2:30 pm EST to follow the walk, and participate in a live chat. Sponsorships of any amount, small or large, are appreciated! The cam will go active about an hour before the walk. It should be a cold but beautiful day.

Jeff Masters

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Pot
Let me know if you see the cranes. Curious if they Island hop or head straight on down to S America.
Funny that they only pick up a few grasshoppers,june bugs and such on their spring return, when there are several ponds on the property. Mostly just resting and waiting on thermals to build, I reckon.
Rarely see one at a pond.
Member Since: September 11, 2008 Posts: 9 Comments: 10084
thanks for the link...nice.
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Rob. Our Pottery has shrunk from 18 workers to 1 right now. But the wife and I still do mosaics and some sculpture. She is the creative side of things. I run the kilns, blend the clays (locally dug), and when we were busy it was wild! I should have guessed to were into mud !
www.ajoupapottery.com
Member Since: October 24, 2005 Posts: 0 Comments: 24307
No prob, shep!

pottery, a pic of my girl on the blog today!
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Ditto rob
I could go on for hours relaying experiences with exotics. It was a wonderfull time in my life. Drove me deeper into my Darwinian roots comparing primate behavior to modern humans.
I was a blessed man.
Thanks for the welcome...
Member Since: September 11, 2008 Posts: 9 Comments: 10084
I'll look out for them Sheph. I do a bit of bird watching, and we are into Migratory season now.
Also, saw my first White tailed Page for the season today. Thats a day-flying moth, with metalic-green wings and long white tail. They come thru here in the thousands some years, from the south. You get to clean them out of the radiator grille on the car when they are plentyful.
Member Since: October 24, 2005 Posts: 0 Comments: 24307
129. theshepherd

Shep, enjoyed your comment on my blog tonight!

Welcome your stories anyday. You are a very interesting gentleman.
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Would love to see your pots. Had a ceramics art business until the 2004 hurricanes smashed my building. Love playing in the mud.
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Quoting Cotillion:


Tomorrow's windchill will make it feel about 15. Colder in rural areas. With blizzards overnight and on Sunday. What fun.

I want your snow where do you live roughly
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Yo pot
Sand Hill Cranes are headed your way.
They never land here in the route south, but always get them in the back pasture(dove field) in the spring. Stand around mostly. Don't seem to eat much.
Member Since: September 11, 2008 Posts: 9 Comments: 10084
Rob. All is well.
Planning to leave here early in the am to set up a sale of our Pots, then to Monos Island off the northwest of the island, for 2 days of bliss.
Hope the wahoo comply with the messages I have been beaming their way.....
Member Since: October 24, 2005 Posts: 0 Comments: 24307
Last year stank for snow we got only one school day off and only 12 hours of possible sledding conditions most of it at night this year I am hoping mother nature will compensate
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Hey there Pottery,

Been watching your weather today. Hopefully things are drying out a little. Hows every Lil thing?
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Evening all.
Showers here today, with sunshine in between. Very nice weather.
Looking at the big picture, it seems like we will get some rain tonight, and after that, nothing on the horizon.
Looking dry in the Atl right now.
Member Since: October 24, 2005 Posts: 0 Comments: 24307
Quoting Drakoen:


Dave Schwartz was a weirdo anyways. Sorry to hear about the rest. A lot of people getting laid off because of the economy.


""
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Quoting Cotillion:
#120,

Crazy. One of us had thought vibes that went Trans-atlantically... Lol

I know lol. I'm sure it has happened, one way or another. Maybe the storm "transfered energy" to another storm. I know West Pac typhoons can hit Alaska as a extratropic storm or the Pac NW.
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#120,

Crazy. One of us had thought vibes that went Trans-atlantically... Lol
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Quoting Drakoen:
There is a interesting system spinning in the extreme southwestern Caribbean with a 1009mb along a diffused stationary front. No mention of it by the NHC.


NHC is in thanksgiving mode.
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Quoting Cotillion:
While extremely unlikely, just had a thought:

Is it possible for a storm to leave Africa, form, go right across the Atlantic, across the Pacific, through the Indian Ocean and back to Africa?

That is so strange, I just "asked The Experts" on the Weather Channel by email that question.
Hi, I am Joey from Kingston NY. I've always wondered, when Hurricanes or Nor'easter s leave the North Atlantic Ocean after hitting the U.S.A. and Europe, can you actually follow these storms around the world on satellite and follow theme back to Alaska or the Pacific Northwest? Example, the Superstorm of '93, did the storm travel across the world after leaving North America?

Thank-you and loyal Weather Channel watcher since 1985
Joey.
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While extremely unlikely, just had a thought:

Is it possible for a storm to leave Africa, form, go right across the Atlantic, across the Pacific, through the Indian Ocean and back to Africa?
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Quoting Drakoen:
There is a interesting system spinning in the extreme southwestern Caribbean with a 1009mb along a diffused stationary front. No mention of it by the NHC.


I've seen it there for weeks. Dissipating and reforming, stationary.
Member Since: July 8, 2005 Posts: 259 Comments: 24018
*20 are economists

The head of the IPCC is an economist...

Those economist sure seem to get themselves involed in a lot of stuff...
Member Since: March 8, 2007 Posts: 273 Comments: 12612
Quoting Seastep:
Oh, and below is an interesting one that has not been answered to date that I am aware of. Please, if anyone has information to the contrary, do not hesitate to post. I'll read it. I listen to both sides and then make an intelligent decision. I think it's obvious the way I am leaning at the moment, but I don't believe we know enough yet. Read, read, read. JMO.

In particular, would love for this to be answered from the linked:

"If you believe there is evidence of the CO2 driver theory in the available data please present a graph of it."

Link

And here's the graph using same MSU sat data from the letter:



Again, open, but would really like an answer to this one in particular.

They make a compelling presentation that sounds good on paper. I would, however,like to have read a response from Switzerland on the claims. That would only be fair.
Also read the links to "peer review" evaluations on climate models. Noticed they were from 2006.
As Dr Masters pointed out, the computers are getting better and input of new data is carefully evaluated as even a small error can bring the house down.
To be sure, critical debate and highly felt opnions will certainly encourage a more deligent search for the perfection of systems.
I do however, wonder how much credence can be given to 1880 data placed on the same graph with complex 2008 data. It's almost apples to oranges. But , I guess they only have what they have.
Member Since: September 11, 2008 Posts: 9 Comments: 10084
108 pat
thanx....oh goody, are we back in the blues again tonight?
By the way, has your son found Keb Mo yet?
Member Since: September 11, 2008 Posts: 9 Comments: 10084


Fats Domino - I'm Walkin

Support the portlight Honor Walk ..Link

Dont be left behind tomorrow.


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Re: 87

Read that, presslord (and kudos for your recent work, btw).
But still no list of names other than Schwartz and Smith.
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There is a interesting system spinning in the extreme southwestern Caribbean with a 1009mb along a diffused stationary front. No mention of it by the NHC.
Member Since: October 28, 2006 Posts: 57 Comments: 30490
There seems to be a system in the SW Caribbean under 20 kt of wind shear and a weak anticyclone. As for us in S. Ontario, the snow has picked up at my location, and we could get about half an inch of snow by the time it stops tonight. The extended GFS model from here shows a potential Hudson's Bay low pattern over Southern Ontario starting December (actually, the 18Z model now shows less of that pattern). We could get about four inches of snow Monday and Tuesday. Looking at that model, combining 12Z and the beginning of 18Z models, it looks like we could get about a total of a foot of snow by December 6. That's nothing compared to parts of SW Ontario, some areas are getting a metre (three and a half feet) of snow!
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Member Since: September 10, 2007 Posts: 0 Comments: 11151
yes it will be NE.

repeat after me

let it snow
let it snow
let it snow
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Were heading into a blocking pattern,it's going to be interesting where the end of the week storm goes
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Yes Cot.

Tues/wed then Sat/Sun if the models pan out for me =)
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Looking at the latest GFS run...

Snow on.. Sunday morning, Tuesday morning and Thursday evening for me.

Envious, Bone?
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hoping the storms that the models are predicting actually occur. Would be nice to have some snow to go along with this frigid weather.
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Quoting all4hurricanes:

same here but it just dropped below also the wind chill here makes it feel like 9

I don't know how this could end up being a mild winter they predicted a cold one last year right and they were right for everywhere but here I'm hoping our weather will defy predictions this year too I WANT SNOW



Tomorrow's windchill will make it feel about 15. Colder in rural areas. With blizzards overnight and on Sunday. What fun.
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Quoting Cotillion:
Temperature dropping like a bomb.

Was about 10C for most of today...

Now just a shade above freezing. Going to be so cold tomorrow.

same here but it just dropped below also the wind chill here makes it feel like 9

I don't know how this could end up being a mild winter they predicted a cold one last year right and they were right for everywhere but here I'm hoping our weather will defy predictions this year too I WANT SNOW

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Temperature dropping like a bomb.

Was about 10C for most of today...

Now just a shade above freezing. Going to be so cold tomorrow.
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Seastep so according to the link and chart provided recent warmings are attributed to urban heat islands, solar radiation, and other environmental factors such as ocean currents and land use and not corrolated to CO2 emissions by an extremly large margin.

Again thanks for the sourced information.
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sulli thanks for the explination. So basically once the system arrives start as a rain ocast, rain/snow mix interior (below 1000) snow higher elevations throughout. Then as the atmo cools due to evaporation the interior should see all snow.

Also have you an opinion on the weekend storm? So far I have only noticed the GFS being persitant with it. Probably same scenario then as tuesdays? Rain/snow w/ changeover od does it sit far enough to the 40/70 to keep everyone in frozen precip?

Thanks sulli. I seem to grasp the concepts but miss the details on occasion.
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No problem Bone.
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Quoting presslord:
Weather Channel lays off staff
By KRISTI E. SWARTZ

The Atlanta Journal-Constitution

Wednesday, November 19, 2008

The Weather Channel, which NBC Universal bought in September, has laid off some of its staff. It is unclear how many people were cut or whether they are receiving a severance package.

NBC Universal and Weather Channel officials would not comment beyond a statement.

“The economic realities of recent months have created challenges for everyone in our business. In addition, when NBC Universal purchased the Weather Channel earlier this year, we expected that there would be cost synergies as part of company reorganization. While it is always difficult to lose valued employees, we are doing our best to minimize the impact, and remain committed to providing the highest quality content that our viewers have come to expect from the Weather Channel.”







"I tell ya Folks,..we've not seen a Economic Storm Like this in quite awhile..,

..Back to you in the Studio"..




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as you stated I love reading the papers and other info especially sourced materials and papers.

Knowledge is power
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Quoting Drakoen:


Dave Schwartz was a weirdo anyways. Sorry to hear about the rest. A lot of people getting laid off because of the economy.


who were the others?
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Seastep thanks for the link!
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Oh, and below is an interesting one that has not been answered to date that I am aware of. Please, if anyone has information to the contrary, do not hesitate to post. I'll read it. I listen to both sides and then make an intelligent decision. I think it's obvious the way I am leaning at the moment, but I don't believe we know enough yet. Read, read, read. JMO.

In particular, would love for this to be answered from the linked:

"If you believe there is evidence of the CO2 driver theory in the available data please present a graph of it."

Link

And here's the graph using same MSU sat data from the letter:



Again, open, but would really like an answer to this one in particular.
Member Since: Posts: Comments:

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Jeff co-founded the Weather Underground in 1995 while working on his Ph.D. He flew with the NOAA Hurricane Hunters from 1986-1990.