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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Drak your really need to stop curiupting the young minds.......ROFLMAO
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Quoting TampaSpin:


OMG the thought.....LMAO


LOL
Member Since: October 15, 2008 Posts: 11 Comments: 2312
Quoting Drakoen:


I guess it would be interesting.... I don't think magniloquent has a very positive connotation lol.


grandiloquent, maybe... no that has a similar connotation... eloquent, but that's boring
Member Since: October 15, 2008 Posts: 11 Comments: 2312
Quoting TampaSpin:


OMG the thought.....LMAO


LOL!
Member Since: October 28, 2006 Posts: 57 Comments: 30620
Quoting Drakoen:


How would you know that?


OMG the thought.....LMAO
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Quoting Drakoen:


How would you know that?


Wait, what are you asking... I was just saying that the bottom of a bikini is a little thing, and I thought it was a thong, and drag does not appeal to me, and a guy wearing it is not good. Except for a good cause. But still... remember, I'm still young, I have no idea about a lot of things.
Member Since: October 15, 2008 Posts: 11 Comments: 2312
Quoting hurristat:
It was bad enough without a thong... bad images...


How would you know that?
Member Since: October 28, 2006 Posts: 57 Comments: 30620
Quoting hurristat:
I just thought it was interesting because they always say 1000 feet and wouldn't it be interesting if it actually cut off at exactly 1000 feet, so I could look out my window and see the snow turning to rain??

BTW, you seem very magniloquent today, Drak (in the good way, not the bad way). Effervescent and flamboyant?? only on this blog


I guess it would be interesting.... I don't think magniloquent has a very positive connotation lol.
Member Since: October 28, 2006 Posts: 57 Comments: 30620
Quoting CybrTeddy:


You know, I believe the Remains of Karen did that.
(Old joke from 2007 Hurricane season, will be used throughout all the next hurricane season)


Any storm that would make the rounds like that would have to be a female name storm!!! ROFLMAO
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Quoting Drakoen:


Not for you I hope...
It was bad enough without a thong... bad images...
Member Since: October 15, 2008 Posts: 11 Comments: 2312
Quoting Drakoen:


You're in the the transition zone ;P
I just thought it was interesting because they always say 1000 feet and wouldn't it be interesting if it actually cut off at exactly 1000 feet, so I could look out my window and see the snow turning to rain??

BTW, you seem very magniloquent today, Drak (in the good way, not the bad way). Effervescent and flamboyant?? only on this blog
Member Since: October 15, 2008 Posts: 11 Comments: 2312
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?


You know, I believe the Remains of Karen did that.
(Old joke from 2007 Hurricane season, will be used throughout all the next hurricane season)
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Just found something very interesting...LOOK at the MJO map.....Below.....look at the forecast temperature map, and then look at the precep. map.......looks like alot of moisture coming out of the South in the next 10 days.....looks like major ice or snow storm coming if this cold air stays in place.....


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Quoting hurristat:


It would be cool, and probably a Cat. 5 somewhere along the way. But think of having say, a Hurricane Barry, then Hurricane Barry, then Hurricane Barry, then Typhoon Barry, then Cyclone Barry, then maybe dying. That would be one heck of a deep system. Probably have to beat Tip by a mile.


I like how the Indian Ocean names their strong hurricanes lol. "Very severe cyclonic storm", "Super cyclonic Storm." Ours seems primitive.
Member Since: October 28, 2006 Posts: 57 Comments: 30620
anything for the cause....
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Quoting presslord:
done with the dress....but...

looking forward to bikini season....


Not for you I hope...
Member Since: October 28, 2006 Posts: 57 Comments: 30620
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?


It would be cool, and probably a Cat. 5 somewhere along the way. But think of having say, a Hurricane Barry, then Hurricane Barry, then Hurricane Barry, then Typhoon Barry, then Cyclone Barry, then maybe dying. That would be one heck of a deep system. Probably have to beat Tip by a mile.
Member Since: October 15, 2008 Posts: 11 Comments: 2312
done with the dress....but...

looking forward to bikini season....
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Quoting presslord:
atmo.....will do.....Tampa....no more dress...I swear...

drak....efervescent...like Alka Seltzer....


What's with the ellipsis? You sure you're done with that dress lol.
Member Since: October 28, 2006 Posts: 57 Comments: 30620
atmo.....will do.....Tampa....no more dress...I swear...

drak....efervescent...like Alka Seltzer....
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Quoting TampaSpin:


I hope its not because he's back to wearing a dress again............ROFLMAO


Yea. It's giving him some flamboyancy LOL
Member Since: October 28, 2006 Posts: 57 Comments: 30620
Hey, press.

I thought of ya around Halloween. My 4 year old was a pirate and I had him running around shouting Argggg! -and- Swab the decks ya scalawag or ye shall walk the plank to Davey Jones' locker!

Was fun.

BTW, let me know when/if you guys make another trip to SE TX. If you go though the southern stretches of LA, I could meeet up with y'all and spring for a meal.
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Quoting Drakoen:


You seem very effervescent today lol. I'm doing pretty good I guess...

You?


I hope its not because he's back to wearing a dress again............ROFLMAO
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Folks layoffs happening everywhere......It is just going to put the economy in a worse hole than its already in......just my opinion but, it appears its going to get alot worst before any improvemnet occurs!
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Quoting presslord:
Drak!!! My man!! How ah ya?


You seem very effervescent today lol. I'm doing pretty good I guess...

You?
Member Since: October 28, 2006 Posts: 57 Comments: 30620
Good evening everyone..........
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Drak!!! My man!! How ah ya?
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Not sure if it is right, but Slidell's airport NWS office reporting 28F, at 9pm CDT, but the forecast low is for 30F.

Weird, though, the wunderground page says the report is 32F, the NWS page is the one claiming 28F. I think I believe it as some of the personal weather stations around here in western St Tammany and away from Lake P are showing similar temps.

If our dewpoint is in the teens and stays that way, we could be a bit colder tonight than the upper 20s forecasted. Some of the PWS say dewpoint is upper 20s, some as low as 10.

If anything, as someone mentioned here earlier, urban influences on a weather observation almost always are with a positive bias (warmer).

Aside: the comment about temp obs next to a runway or whatever are referring to real observation stations being used in real peer-reviewed research and show a real warming trend over the last few decades. Too bad these obs are used to validate real models and are ultimately going to be used to make real decisions.
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Quoting hurristat:


I have a question. My house is somewhere between 995-1005 feet. Actually I think its at exactly 1000 feet. Does that mean it snows on top of my house and rains on the ground??? (LOL)


You're in the the transition zone ;P
Member Since: October 28, 2006 Posts: 57 Comments: 30620
Quoting sullivanweather:
There were 5 of those storms on yesterday's GFS run...

This biggest concern for me with the upcoming storm for Monday-Wednesday will be initial boundary layer temps as the precip moves on Monday afternoon/evening. Right now it looks like anyone under 1,000' is likely to remain rain until the strong dynamics pull through.


I have a question. My house is somewhere between 995-1005 feet. Actually I think its at exactly 1000 feet. Does that mean it snows on top of my house and rains on the ground??? (LOL)
Member Since: October 15, 2008 Posts: 11 Comments: 2312
I think something might be forming in the Indian ocean but otherwise nothing
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evening everyone have to read thru all the posts
Member Since: October 15, 2008 Posts: 11 Comments: 2312
Quoting Drakoen:
lol #124 exactly my point.

Dennis Smith got the boot too....he has been there , wow I think since the 80's.
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lol #124 exactly my point.
Member Since: October 28, 2006 Posts: 57 Comments: 30620
Florida Teen Live-Streams His Suicide Online
Abraham Biggs, 19, Was Egged On by Fellow Bloggers, Cops Say
By EMILY FRIEDMAN
Nov. 21, 2008 A Florida teenager who used a webcam to live-stream his suicide Wednesday was reportedly encouraged by other people on the Web site, authorities told ABCNews.com.

Authorities say approximately 1,300 people watch as the boy takes his life. "People were egging him on and saying things like 'go ahead and do it...'"
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area of interest
est pos
79.9w/12.7n
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I probably should be going now...weekend and all. Have enjoyed the conversation and hope you all have a really great weekend. Will be keeping an eye out for sandhill cranes and for pottery's weather. And pottery, hope your sales are terriffic. Goodnight!
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Well, early start for me too.
I'm out till Sunday night.
Have fun, all.
Member Since: October 24, 2005 Posts: 0 Comments: 24685
Rob, heheheh.
Member Since: October 24, 2005 Posts: 0 Comments: 24685
A zillion Snow Geese and others took off in the same moment, and flew over our heads 20 ft. above.

I hope that while you were gawking, that you had the sense to keep you mouth closed - LOL
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Hi there Sugar. Thanks for the compliment. We used to ship. All over the place. Now we dont have the capacity really. The home sales keep us busy enough. Sorry.
Member Since: October 24, 2005 Posts: 0 Comments: 24685
Nite sugar, have fun and bring us back some pics!
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Sheph. Not sure if I have ever seen a Sand Crane here. Will need to check my books. Where do they start the migration from ?
Most incredible bird experience for me, was at Bosque del Apache. Early morning, Feb 2004. A zillion Snow Geese and others took off in the same moment, and flew over our heads 20 ft. above. Amazing noise ! Left my wife and my sister in tears........
Member Since: October 24, 2005 Posts: 0 Comments: 24685
Darn, I gotta run. Our flight leaves at the crack of dawn, and I still have to motivate 2 teens to pack.....see ya'll in a week!
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Thanks sugar.
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Pottery, she says thank you and hello!
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138. theshepherd

Don't know where you are, but they come here (highlands county FL) by the thousands some years. Often see them in the calladium fields. Will drive out there tomorrow and see if they are around. Have seen a few here at the lake, but probably just the year-rounders.
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Just in for a quickie...LOL! Rob, your lady is lovely; the dog is, too! Pottery your lady's mosaics are incredible. I have a degree in Fine Arts, and I can appreciate her talent and craftsmanship.Do you ship??
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Rob. Pretty lady. Take care of her. Tell her I said "Hello"
Member Since: October 24, 2005 Posts: 0 Comments: 24685
Rob, an image of my house, 160 yrs old, wooden construction, if you click on "visit us".
Member Since: October 24, 2005 Posts: 0 Comments: 24685
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: 10139

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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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