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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Quoting Beachfoxx:
LOL, ye of hardy stock! While me, complains of cold... while you temps must be at least 20° lower than mine!!! Geez... but I must add, that the GOM was absolutely gorgeous today. North wind had it lying flat, waters emerald and sand sugar white!


More like 10-15... anyway, I have snow so, yeah, beat that. LOL : )
Member Since: October 15, 2008 Posts: 11 Comments: 2312
226 - Beachfoxx - You really hurt my feelings, I am an Officer and a Gentleman, I would never tear the little legs off of a harmless arachnid. I would however whack em, smack em, stomp em, whomp em, smash em, slash em, flatten em, and otherwise ruin their whole day. LOL
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Member Since: Posts: Comments:
LOL, ye of hardy stock! While me, complains of cold... while you temps must be at least 20° lower than mine!!! Geez... but I must add, that the GOM was absolutely gorgeous today. North wind had it lying flat, waters emerald and sand sugar white!
Quoting hurristat:


No, you're fine... Anyway, if you want to know what my weather is, I live less than 10 minutes away from the Dr., so you can look at his weather to see mine. You don't need to apologize.
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Quoting Beachfoxx:
Poor Grandaddy Long Legs! LOL

Do you remember the restaurant June's Dunes??? I still crave one of those burgers on a Saturday!


If you're asking me, never heard of it. Only been to FL once.
Member Since: October 15, 2008 Posts: 11 Comments: 2312
Quoting RTLSNK:
212 - hurristat - No, does not make you old.
One of the interesting paradoxes of time and nature is that when most young people are your age they just can't wait to be older, and when you get older you wish you were younger. Relax and enjoy your age now, every year time will drag you into the future anyway!! LOL


I actually am weird that way. I'm fifteen and already have the second mindset. I don't know why, though. Every day I live, I'm a day closer to my death... that's a happy thought. On the happier side, the hurricane season now ends in 8 days.
Member Since: October 15, 2008 Posts: 11 Comments: 2312
Quoting Beachfoxx:
Hurristat,

Should I say "I am sorry"? LOL Interesting, you in Mich, and today I had a customer from Mich. here looking at condos! LOL

And I have another customer looking at Sterling Shores!

Bizarre!!!!


No, you're fine... Anyway, if you want to know what my weather is, I live less than 10 minutes away from the Dr., so you can look at his weather to see mine. You don't need to apologize.
Member Since: October 15, 2008 Posts: 11 Comments: 2312
212 - hurristat - No, does not make you old.
One of the interesting paradoxes of time and nature is that when most young people are your age they just can't wait to be older, and when you get older you wish you were younger. Relax and enjoy your age now, every year time will drag you into the future anyway!! LOL
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Poor Grandaddy Long Legs! LOL

Do you remember the restaurant June's Dunes??? I still crave one of those burgers on a Saturday!
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Quoting Beachfoxx:
RTL must have left the blog to go and torture the big spiders coming into his garage to seek warmth!

LOL

He likes to yak a couple of the legs off, and then watch them stumble to their death!

ROFLMAO

*****(RTK, Forgive me, I just could not resist)***


I accidentally stepped on a daddy long legs' leg once, and it popped off and continued to twitch for over 5 minutes. It was weird.
Member Since: October 15, 2008 Posts: 11 Comments: 2312
Member Since: Posts: Comments:
Hurristat,

Should I say "I am sorry"? LOL Interesting, you in Mich, and today I had a customer from Mich. here looking at condos! LOL

And I have another customer looking at Sterling Shores!

Bizarre!!!!
Member Since: Posts: Comments:
RTL must have left the blog to go and torture the big spiders coming into his garage to seek warmth!

LOL

He likes to yak a couple of the legs off, and then watch them stumble to their death!

ROFLMAO

*****(RTK, Forgive me, I just could not resist)***
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Quoting Beachfoxx:
Hurristat,

Where are you???? and where is your fam's condo? in Destin?


I'm in Michigan, if that clarifies anything. I live in a house anyway. I like having a yard, even though mowing 1/2 an acre is annoying.
Member Since: October 15, 2008 Posts: 11 Comments: 2312
Quoting Beachfoxx:
Tampa,

What building?


Sterling Shores...
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Hurristat no kidding I think your going to be a great weatherman one day. But I must say that coming from someone that hasnt got a hurricane prediction right this season. Keep on top of all your subjects, life is change. Case closed.
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Hurristat,

Where are you???? and where is your fam's condo? in Destin?
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Quoting Beachfoxx:
But will they all fit in a Bikini at one time???? LMAO


it would be a little lumpy, prob'ly
Member Since: October 15, 2008 Posts: 11 Comments: 2312
Quoting Beachfoxx:
Hurristat,

I swear, I would not complain... but for us, this is really cold, especially for this early in the winter season! Oh, I know, I can hear you say, "Wimp"! LOL and I say, "Yep, I am!" LOL


It's funny because I get hotter than you, and much colder than you, so when you guys get extremes its really funny LOL
Member Since: October 15, 2008 Posts: 11 Comments: 2312
Quoting Beachfoxx:
RTL....

This weather is too dang cold!! Bet the spiders are heading to your garage for warmth! Should be a good night for you to yank some legs off!

ROFLMAO......


LMAO
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But will they all fit in a Bikini at one time???? LMAO
Quoting hurristat:


What else rhymes: bess, caress, fess, confess, jest (kind of), mess, assess, and some more, they all fit. LOL
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Quoting Beachfoxx:
My apologies to all...

For I fear, it was I

that first said "Press in a Dress"...

My apologies, cause I now fear,

Our dear Press, will dress

in something much less!

BIKINI.....


What else rhymes: bess, caress, fess, confess, jest (kind of), mess, assess, and some more, they all fit. LOL
Member Since: October 15, 2008 Posts: 11 Comments: 2312
Tampa,

What building?
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RTL....

This weather is too dang cold!! Bet the spiders are heading to your garage for warmth! Should be a good night for you to yank some legs off!

ROFLMAO......
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Quoting gordydunnot:
My last statement was meant to stick with the weather.


ok, thank you
Member Since: October 15, 2008 Posts: 11 Comments: 2312
Family has a condo we own right on Destin Beach....:)
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Quoting RTLSNK:
197 - Beachfoxx - Hi Foxy, temp here in Macon is now 30*F and heading to 22!!!

198 - hurristat - you don't have to be sorry about being yourself, and as far as acting strangely and being random thats something the rest of us do all the time, LOL, just relax and go with the flow, hmmm, thats from the 60's, oh well, I am that old! hahaha


I know, I was just trying to dispel some rumours (spelled to make Cotillion happy)

I use that expression too... does that make me old, im 15, and Im also listening to 60s music right now...
Member Since: October 15, 2008 Posts: 11 Comments: 2312
Hurristat,

I swear, I would not complain... but for us, this is really cold, especially for this early in the winter season! Oh, I know, I can hear you say, "Wimp"! LOL and I say, "Yep, I am!" LOL
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My last statement was meant to stick with the weather.
Member Since: Posts: Comments:
My apologies to all...

For I fear, it was I

that first said "Press in a Dress"...

My apologies, cause I now fear,

Our dear Press, will dress

in something much less!

BIKINI.....
Member Since: Posts: Comments:
Quoting Beachfoxx:
OH and the temp.... its 33° and going down, down, down! Freeze warning!


Lows here in the mid to high teens. It's awesome. It's always fun to see Floridians complain about warm temperatures which they think are cold. It got down to the 40s in the summer where I live, and got up to 93 the next day. Gotta love Michigan.
Member Since: October 15, 2008 Posts: 11 Comments: 2312
Quoting Beachfoxx:
Tampa, weather like this makes me question Global Warming! LOL

This is FLORIDA..... and I am freezing body parts off!

LOL


Im not going to ask what body parts.......LMAO
Member Since: Posts: Comments:
Tampa, weather like this makes me question Global Warming! LOL

This is FLORIDA..... and I am freezing body parts off!

LOL
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197 - Beachfoxx - Hi Foxy, temp here in Macon is now 30*F and heading to 22!!!

198 - hurristat - you don't have to be sorry about being yourself, and as far as acting strangely and being random thats something the rest of us do all the time, LOL, just relax and go with the flow, hmmm, thats from the 60's, oh well, I am that old! hahaha
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Quoting gordydunnot:
Young man my bad. I Know you like weather so I apologize. Just dont get old before your time.


No offense taken. You have the right to be suspicious, I wasn't mad, I was just making sure I didn't come off like that... I guess we must have a similar writing style. And a question... could you clarify your last statement, please?
Member Since: October 15, 2008 Posts: 11 Comments: 2312
Quoting Beachfoxx:
Tampa,

NW FL, on the Panhandle, Destin/Niceville area. Yep, windy day, made it feel much colder than the temp read! BRRRRRR I have put my flip flops in the closet until we have some wehater that is warmer!

Can I wish for Spring time to hurry up and arrive??????


Hell yes please......
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OH and the temp.... its 33° and going down, down, down! Freeze warning!
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Tampa,

NW FL, on the Panhandle, Destin/Niceville area. Yep, windy day, made it feel much colder than the temp read! BRRRRRR I have put my flip flops in the closet until we have some wehater that is warmer!

Can I wish for Spring time to hurry up and arrive??????
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Young man my bad. I Know you like weather so I apologize. Just dont get old before your time.
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Ha, ha, ha, now don't pick on my avatar.....Its Raymond the Tampa Bay Rays mascot......lol

Beachfoxx where you at in Florida.....its windy as hell here in Tampa tonite and 52deg.
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Quoting gordydunnot:
Hurristat is starting to sound like tropical amanda. And in closing I guess some of us are going to miss storm W, I wish him the best of luck. If not Storm please re far your convection and let everyone now you are ok.


Im sorry, Im just trying to be myself, but I completely forgot that acting strangely makes me sound like tropicalamanda. sorry, in the future, i'll be less random.
Member Since: October 15, 2008 Posts: 11 Comments: 2312
Popping in to say hi....
and I love "Archer Farm" water!

Well, I will love it until someone here decides to diagnose and tell me that the water is full of some wildly weird chemical compound, just discovered, that will kill you after consuming more than 100 bottles of Archer Farms water!

ROFLMAO

The weather here is cold. I think I need to consider moving south. More south! The the deepest, farthest point south! It is cold, windy and my bones are cold!

Yep, I admit, I am a wimp!
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Hurristat is starting to sound like tropical amanda. And in closing I guess some of us are going to miss storm W, I wish him the best of luck. If not Storm please re far your convection and let everyone now you are ok.
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Quoting hurristat:


(beats head against desk) I just realized your avatar was a walrus.


random...

(then again when I first saw his avatar I thought it was a bird wearing a coconut bra...)
Member Since: October 28, 2006 Posts: 57 Comments: 30486
Quoting TampaSpin:


Actually i did buy them at Target....i bought 3 different flavors.....wow are they good.


(beats head against desk) I just realized your avatar was a walrus.
Member Since: October 15, 2008 Posts: 11 Comments: 2312
Quoting hurristat:


Like Target brand??? no. that is the most random chip flavor I have heard of. Watch, the next flavor is going to be vegetarian sausages.


Actually i did buy them at Target....i bought 3 different flavors.....wow are they good.
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Quoting TampaSpin:
Has anyone every ate Archer Farms chips....they come in about 30 flavors..i swear the Cinnamon Sugar Tortilla chips i could eat the whole dam bag....dam they are addicting......lol


Like Target brand??? no. that is the most random chip flavor I have heard of. Watch, the next flavor is going to be vegetarian sausages.
Member Since: October 15, 2008 Posts: 11 Comments: 2312
Has anyone every ate Archer Farms chips....they come in about 30 flavors..i swear the Cinnamon Sugar Tortilla chips i could eat the whole dam bag....dam they are addicting......lol
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Quoting Drakoen:


...volatility.


weee, the letters are all tall and/or have dots.
Member Since: October 15, 2008 Posts: 11 Comments: 2312
Quoting TampaSpin:
Drak your really need to stop curiupting the young minds.......ROFLMAO


I think he got confused in his response lol. I sense some volatility.
Member Since: October 28, 2006 Posts: 57 Comments: 30486
Drak your really need to stop curiupting the young minds.......ROFLMAO
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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.

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