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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31F
67%
winds calm
wooly ears cold
Member Since: September 11, 2008 Posts: 9 Comments: 10077
I noticed that convection this morning also leftovers.
I went snooping around and came up with this from the Marine Discussion as an explanation for why the NHC isn't mentioning it in the TWO:


STRONG HIGH PRESSURE PASSING THROUGH THE
SOUTHEASTERN U.S. BEHIND THE SECOND FRONT WILL INDUCE A STRONG
PRESSURE GRADIENT IN THE CARIBBEAN...KEEPING WINDS GREATER THAN
20 KT ACROSS MUCH OF THE AREA THROUGH THE WEEKEND WITH SEAS IN
THE 8 TO 12 FT RANGE IN MOST OF THE WESTERN CARIBBEAN INTO
MONDAY.


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In every house I've ever been in w/cats and dogs -- no matter how large the dog -- it always seems the cats run the show.....

Anyway, I've got to fire up the stove, fed the young buck & get moving....I'll be back later this afternoon.... don't forget PORTLIGHT.ORG
Member Since: July 18, 2007 Posts: 30 Comments: 26536
Good morning!

Looking ahead towards Thanksgiving next week, it appears there is a possibility for a slight Severe Weather event in the southern plains/central/east Texas.
The Northeast could potentially experience a snow event as well...more information on that can be found in Sullivanweather's blog.



DAY 4-8 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0246 AM CST SAT NOV 22 2008

VALID 251200Z - 301200Z

...DISCUSSION...
CONVECTION IS EXPECTED TO BE MINIMAL TUE NOV 25TH AND WED NOV 26TH
AS MOSTLY STABLE CONDITIONS PREVAIL ACROSS THE CONUS IN THE WAKE OF
A DEEP LOW MOVING OUT OF NEW ENGLAND AND AN UPPER RIDGE COVERING
MUCH OF THE CONUS.

THEREAFTER...THE PAST SEVERAL ECMWF AND MREF RUNS HAVE BEEN IN VERY
GOOD AGREEMENT OF SHOWING A PROGRESSIVE SHORTWAVE TROUGH MOVING EWD
FROM THE SWRN STATES INTO THE SRN PLAINS NOV 27/28. THE 00Z MREF
CONTINUES THAT SAME TREND...WHILE THE 00Z ECMWF IS AN OUTLIER FROM
PREVIOUS ECMWF RUNS AND MREF. ALTHOUGH LATEST ECMWF SUGGESTS A LOWER
THREAT FOR SEVERE...MREF AND PREVIOUS RUNS SUGGEST A LOW THREAT FOR
SEVERE STORMS ACROSS TX DAY 6 AND/OR 7 AS GULF MOISTURE INCREASES
AHEAD OF APPROACHING SHORTWAVE TROUGH. HOWEVER... UNCERTAINTY
REGARDING THE LOCATION/SPEED OF UPPER TROUGH AND DEGREE OF
INSTABILITY PRECLUDE A SEVERE WEATHER AREA ATTM.


..IMY.. 11/22/2008


Photobucket

Photobucket


Member Since: Posts: Comments:
Good morning guys, hit a record this morning in Macon, Ga 21*F set in 1937.

Had a bad cat back in the 70's, outside female, very smart, 17 lbs, sort of adopted me, used to go across the street and jump small chain link fence into nasty German Shep's yard just to get him to chase her around the house and then head straight for the fence and jump over the fence onto small oak tree and watch the shep hit the fence going full speed. hahaha, saw her do it to him five or six times and he never caught on, he would hit the fence and bounce backwards a couple of feet!
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Good Morning -- just a few minutes b/4 we head out to thebarn for a polo game -- Went to Rob's blog first thing for a quick peek -- LOL -- where to start??? The Timber is amazing... and it looks like(from his paws) he's got more growing to do. And COTILLION - you and the cat!!! I could see the personality beaming from those eyes!

Still cold here in SRQ, hard to get moving w/out lots of coffee.. added cinnamin today, Some nice waves came in for Gomex surfers yesterday/Friday Afternoon -- missed them as we were working out the horses. The weather is just a bit too cold for these bones to be wet.
Member Since: July 18, 2007 Posts: 30 Comments: 26536
Gotta go do some things so I'll have most of the weekend to play. Best friend from childhood coming over for the weekend, I'll be checking in though, and try to post some more pet picks...including "the redhead's" black cat.

Hope everyone has a safe and good weekend!
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Quoting tkeith:
BTW I parked my big Poodle under Cotillions cat in your blog Rob, She got her tail whipped by the neighbors cat a few days ago...Cotillion, tell your cat to be nice...LOL


Haha. He's just grumpy. It's the big black one you'd be worried about. He's gone after seagulls and rottweilers before.. and won... He's a cutie though.
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274. Cotillion

Thanks, man. Always wondered what he looked like. Pretty little guy (the cat). And nothing wrong with you there either, you look happy.
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BTW I parked my big Poodle under Cotillions cat in your blog Rob, She got her tail whipped by the neighbors cat a few days ago...Cotillion, tell your cat to be nice...LOL
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Quoting tkeith:
I'm on my third cup Rob...first day below 40 here in New Orleans this season. Off to work, have a good day all.


Thanks for the pic of your dog, I love it!
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I'm on my third cup Rob...first day below 40 here in New Orleans this season. Off to work, have a good day all.
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271. Cotillion

Speaking of sharing links, thanks - hadn't seen the flash movies there. Need to poke a hole in my firewall or proxy to make them work, so I'll do that later or use other machine...this one is locked down pretty tight.
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Quoting RobDaHood:
Thanks,

Stay warm, man...I've got to go make some coffee. If you get bored pop over to my blog and check out the latest pic. Anyone is welcome to post a photo of their favorite animal companion, so your brainiac cat is welcome too...Promise the wolf won't bite.

back in a few.


I can't promise the cat won't though. ;)

Not the most flattering picture of myself, but it's the cat we're after! Posted it anyway.
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272. redavni

I've seen that before, but sure a lot of folks haven't so thanks for sharing. I know It took me a while to get my list together...now I need to spend the winter months sorting and organizing again.
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Hey all, I came across a great weather education site. I'm not sure if it's been posted here, but I thought I'd leave it here in case anyone else was interested. There is a ton of video presentations on every imaginable weather topic.

http://www.meted.ucar.edu
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The first movie here:

Link

Shows really well how this storm will develop.
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Thanks,

Stay warm, man...I've got to go make some coffee. If you get bored pop over to my blog and check out the latest pic. Anyone is welcome to post a photo of their favorite animal companion, so your brainiac cat is welcome too...Promise the wolf won't bite.

back in a few.
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Not quite Rob, though my county is bordering another (Yorkshire) which is under the snow warning. It's possible that as this system moves in, I may get snow tonight/Sunday morning.
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Cotillion =

Someone's going to get some snow after all...

Does that include you?
Sorry, can't remember exactly where you are

This is the station that most resembles my weather about 10 miles away, but my lows are usually 2-5 degrees higher.

Link

PS click graphic and it should take you to detail page on WU
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Seems a pretty nasty windstorm might occur in the Baltic States, Western Russia, Finland, Belarus. Expected to deepen over the next 24-48 hours from the mid 980s to what I can tell.. of about 956mb. Isobars are pretty tightly packed so storm conditions possible.

This one would be called by the Berlin University, 'Gabrijela.'
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Flash heavy snow warnings now in effect along the East Coast from Middlesbrough to Ipswich.

Someone's going to get some snow after all...
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Quoting RTLSNK:
Time for me check out too, goodnight all.


Me too.....goodnight All........
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i should probably go too. night everyone.
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Time for me check out too, goodnight all.
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Nite BeachFox
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That story would probably keep me up at night... wondering when the spiders were going to show up! LOL

*poof

I am really, really gone! Night!!!
Quoting hurristat:


You need to ask Pottery about his spider story. He lives in Trinidad, and it involves tarantulas. LOL
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Hurri & Stat! LMAO....

That's me! Both of them!

Send the straight jacket, it will make it easier on those who are "coming to take me away"! LOL

Night all.... stay warm!!!

Tampa.... that graphic is priceless! LOL

Quoting hurristat:


♪ They're coming to take me away, haha, they're coming to take me away, hehe...♪ LOL
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Sounds good to me. Night all!
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Quoting Beachfoxx:
G'night all....

I am going to crawl under layers and layers of blankets, calling it a night. Knowing tomorrow will be a warmer day!!!


night Beachfoxx
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Quoting Beachfoxx:
Nooooooooooo! I can smash the cockroaches with out screaming! The Spiders, well, I squeal, point, squeal again, and then run the opposite direction! LOL The are what I call a member of the creepy crawling family!!!!


You need to ask Pottery about his spider story. He lives in Trinidad, and it involves tarantulas. LOL
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G'night all....

I am going to crawl under layers and layers of blankets, calling it a night. Knowing tomorrow will be a warmer day!!!
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BeachFox this is for you........LOL

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Quoting Beachfoxx:
Looney is good! LOL Really good, that is until they put the straight jacket on you!

ROFLMCPO


♪ They're coming to take me away, haha, they're coming to take me away, hehe...♪ LOL
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Nooooooooooo! I can smash the cockroaches with out screaming! The Spiders, well, I squeal, point, squeal again, and then run the opposite direction! LOL The are what I call a member of the creepy crawling family!!!!
Quoting rainraingoaway:
Tell you what..I will sacrifice myself to take care of the spiders if someone will rid Texas of our Cockroaches!
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Quoting Beachfoxx:
Hurri... No promises there... But seriously, don't grow old before your time. Live your life to the fullest, make memories, laugh... alot! and enjoy the ride!


Yup, I edited my post to say something like that, but you already quoted it so it got lost. But yes Carpe Diem. And I have been trying. I'm going to an IB high school that is consistently ranked among the top 15 in the country by Newsweek, and was top in 2003. And I have all A's and one B. I'm trying to seize the day, by being proactive and challenging myself by going to this school. Hopefully, I can get into a good met school and become a met. My final goal is to be on the staff of the NHC or the TPC or something along those lines.

About Carpe Diem, I have a story about that. On the last day of 8th grade, we were watching Dead Poets Society, especially R. Williams' speech about carpe diem. Actually, then I was doing my hurricane maps, which are essentially me plotting all the storms of one year on one map and then putting it in a folder. So everything ties together.
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Tell you what..I will sacrifice myself to take care of the spiders if someone will rid Texas of our Cockroaches!
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Looney is good! LOL Really good, that is until they put the straight jacket on you!

ROFLMCPO
Quoting rainraingoaway:
Myself included!!
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236 - Tampa - I think you and Rob have both mentioned that method of insect control, you guys must live out in the country somewhere.LOL
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Myself included!!
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Rain,

Looney... we resemble that! LOL
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Quoting rainraingoaway:
Evening all. Wow. Things do get loony in here when the tropics are quiet.....which is a good thing.


Welcome to the Jungle... LOL!!
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Hurri... No promises there... But seriously, don't grow old before your time. Live your life to the fullest, make memories, laugh... alot! and enjoy the ride!
Quoting hurristat:


A better question to ask is: if we're on the same page now, will we be when the page turns?
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Evening all. Wow. Things do get loony in here when the tropics are quiet.....which is a good thing.
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240 - No - exactly my point!! haha
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Quoting Beachfoxx:
Wow! RTLSNK, you & I might be on the same page on this one....
Hurri, savor every day, seek every joy, experience every moment, breath in the wonders of nature and live each day like it might be your last.... Life can be short.
Carpe Diem!


A better question to ask is: if we're on the same page now, will we be when the page turns?
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ROFLMAO - RTL - ROFLMCPO
and Tampa that pic is perfect!
Quoting RTLSNK:
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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Quoting RTLSNK:
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


My question is, do they have a day once they're dead? LOL
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Wow! RTLSNK, you & I might be on the same page on this one....
Hurri, savor every day, seek every joy, experience every moment, breath in the wonders of nature and live each day like it might be your last.... Life can be short.
Carpe Diem!
Quoting hurristat:


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.
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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 : )
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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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