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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630
There are also them "what teach" and them "what do".
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636. IKE
TROPICAL WEATHER OUTLOOK
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
100 PM EST SUN NOV 23 2008

FOR THE NORTH ATLANTIC...CARIBBEAN SEA AND THE GULF OF MEXICO...

A TROUGH OF LOW PRESSURE IS PRODUCING A LARGE AREA OF SHOWERS AND
THUNDERSTORMS OVER THE SOUTHWESTERN CARIBBEAN SEA AND ADJACENT LAND
AREAS. DEVELOPMENT OF THIS SYSTEM...IF ANY...SHOULD BE SLOW TO
OCCUR DUE TO CLOSE PROXIMITY TO LAND. HOWEVER...HEAVY RAINFALL AND
LOCALIZED FLOODING IS POSSIBLE OVER PORTIONS OF PANAMA...COSTA
RICA...AND NICARAGUA DURING THE NEXT COUPLE OF DAYS.

ELSEWHERE...TROPICAL CYCLONE FORMATION IS NOT EXPECTED DURING THE
NEXT 48 HOURS.

$$

FORECASTER BROWN

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Quoting whatwhat1:
Another good link on Co2.


Link


Thanks, nice link.
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627
Dr Master's reflected your concerns to the letter in the above writings. Hard to predict short term meanders.
If you are indeed a farmer, then none of this is new to you.
LOL and good luck with your next crop...
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Another good link on Co2.


Link
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Excellent Post Dr. Masters.

Anyone who would like to discuss the upcoming storm affecting the Great Lakes please come to my Winter Weather Blog - Link
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Human induced global warming is nothing more than a money making scam.
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The site name leads to be biased, but the facts are true.

Link
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The problem with weather predicting is that it is so inaccurate because there are many causative and unpredictable factors. Last year this little town got snowbound for three days, no travel in or out. Then there was a snowstorm in May that endangered many new calves and colts. Yet this summer we only had one day of 100 deg temps, when normally we have at least two or three weeks of those. We also had seven inches of rain in a week during the last part of May, a total that has not been reached for 100 years. This caused the crops to grow hugely, yet also encouraged more wildlife weight and more grasshoppers. All of this while the NOAA predicted warmer temperatures in the first part of the year! One can almost trust the Farmer's Almanac, the locusts' singing, or the woolly bear caterpillars' forecasts more than the official reports!

What I want to know is, why are there so many official reports of 'droughts' when most of the folks in the 'afflicted' area - the ones who grow the food and raise the animals, and whose lives and livelihoods depend on the weather - are not seeing it?

These things make it hard for most people to trust the forecasters, because what they hear about global warming and trends are NOT what they see and actually experience. When there are too many anomalies, one cannot simply continue to dismiss them as mere anomalies but must recognize them as the norm, mustn't one?

All that said, thanks to the Wundergound's maps and charts, I was able to not only predict the so-called "freak" blizzard three weeks ago, while the weather stations and TV stations were saying it was not going to be that bad, but guesstimated to within a half-inch of how much snow actually stayed on the ground in our area. Power is still out in some areas after over 300 power poles were destroyed, but you won't see THAT on the Weather Channel... They can't pretend it didn't happen because it wasn't accurately predicted, though. Oh, wait; well, I guess they CAN, but that doesn't change the fact that it did...
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625. Skyepony (Mod)
Rob~ Here's the offical.

Member Since: August 10, 2005 Posts: 156 Comments: 36167
Hey TampaSpin thank you for all your updates this season!!!! MY girls love shrimp
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Quoting RobDaHood:
Anyone got a winter precip forcast for central florida? Our lake is down about 8 inches from full levels reached after Fay. Haven't had any rain to speak of in last couple months and fronts so far have been dry. Wonder if it will be as bone dry as last winter.

Yeah, rob
They are calling for another dry one at least south of Okee.
Water shortages last season were a challenge for completing the Central Broward Reg Park.
Fire Dept was worrying about water pressures all season should home fires spring up in one area.
I worry about my beloved Everglades.Fires are allways there, but the low water plays the devil with fish spawn.
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Quoting hurricane23:


Winter precip? Youre kidding right...

Dry season is in full force all across the florida peninsula.


The last measureable precipitation at my house was on Oct. 25th(South Fort Myers).
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Actually no, I wasn't kidding. Florida does have a dry season, but last year we had an unusually long and VERY dry one. Just wondering out loud whether everyone's boats are going to be sitting on dry ground again, and whether I will have an extra 50 feet of beach that I don't normally have.
Member Since: September 2, 2008 Posts: 93 Comments: 30688
Nice convection in the SW caribbean this morning which has been pretty persistent the last couple of days BUT land interaction and a very hostile environment will keep this area at bay.
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Quoting RobDaHood:
Anyone got a winter precip forcast for central florida? Our lake is down about 8 inches from full levels reached after Fay. Haven't had any rain to speak of in last couple months and fronts so far have been dry. Wonder if it will be as bone dry as last winter.


Winter precip? Youre kidding right...

Dry season is in full force all across the florida peninsula.
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I don't think you'll see much of anything in the way of winter wx in FL, Rob.
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Anyone got a winter precip forcast for central florida? Our lake is down about 8 inches from full levels reached after Fay. Haven't had any rain to speak of in last couple months and fronts so far have been dry. Wonder if it will be as bone dry as last winter.
Member Since: September 2, 2008 Posts: 93 Comments: 30688
Out till later...
Member Since: August 23, 2008 Posts: 7 Comments: 5300
Long range forecasts remind me of Beavis and Butthead goes to the fortune teller. "whaddya want Mac?-er- I am Madame ROMA!"

"I see your are not the A students...nor the B students?...The C students??

NO I don't THINK so"

"Whoa BEAVIS-she's for REAL!"
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611. GBlet
Could we get a round of double expressos for the blog please? Wish I was getting snow for Thanksgiving. Looks like holiday storm will skirt us.
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610. GBlet
Thanks for info, I put the website out on our street sign this morning, so surely someone will take a chance and a look. Nothing like hustling liquor store customers, they are usually very generous!
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Quoting ILwatcher:
603. Hey, GB! We missed you on the bridge yesterday but you were there in spirit. SJ and press have said it will be another week or so before all of the pledges are turned in so there's no total yet. From what folks have said on SJ's blog it looks like it's been very successful from a number of perspectives.

Between the trip to Atlanta earlier this week and the walk with SJ yesterday the chat room has been buzzing with activity.

I can't wait for the next WU webcam adventure!


I claim credit! As it coincides with the only times I've been there... ;)
Member Since: August 23, 2008 Posts: 7 Comments: 5300
603. Hey, GB! We missed you on the bridge yesterday but you were there in spirit. SJ and press have said it will be another week or so before all of the pledges are turned in so there's no total yet. From what folks have said on SJ's blog it looks like it's been very successful from a number of perspectives.

Between the trip to Atlanta earlier this week and the walk with SJ yesterday the chat room has been buzzing with activity.

I can't wait for the next WU webcam adventure!
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602. Beachfoxx

You just need to come a little further south...68 right now and climbing...should see mid 70s winds about 13 from north, supposed to drop off too. However, when you're not freezing you butt off up there, your area is really nice. Everythings a compromise. Doesn't really seem fair that you go directly from Hurricane season to winter with no fall though.

Have a feeling that my buddies are all nursing hangovers this am...I came home when it got dark...they were supposed to be here by 10!
Member Since: September 2, 2008 Posts: 93 Comments: 30688
Some people walk through life in total oblivion!
Quoting GBlet:
I got stuck working, so I just hustled all of my customers. I was also very shocked by the number of people that seemed to have no idea that a hurricane had even hit. Are we really so caught up that we don't know what happens around us?
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605. GBlet
I got stuck working, so I just hustled all of my customers. I was also very shocked by the number of people that seemed to have no idea that a hurricane had even hit. Are we really so caught up that we don't know what happens around us?
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It went very well! Awesome!
Quoting GBlet:
Anybody have info on how Honor Walk went, I missed broadcast.
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603. GBlet
Anybody have info on how Honor Walk went, I missed broadcast.
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Vort,

Thats terrible.... They should be having warm weather now! Springlike temps!
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Good Morning All!
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Wow. Snow in Australia in the equivalent of May here! It's practically cyclone season on the other end of the continent!
Member Since: October 25, 2005 Posts: 19 Comments: 20742
Quoting RobDaHood:
594. TampaSpin

Thanks man!

I'm a rocker myself, but (don't tell my mates) cross over from time to time when no one's looking. (esp. Faith Hill)


Time to counter with some awesome 70s rock then...

Link

Member Since: August 23, 2008 Posts: 7 Comments: 5300
Quoting TampaSpin:
Got a 26Ft Triton now.......much better for the GOM.

Is that a shark u're pulling there, TS? Looks like a decent boat.

In the 70s my dad used to run a pair of Evinrudes. I don't know if they were as fuel efficient, but they ran pretty darn well. He doesn't do much boating now, but he swore by outboards. . . .
Member Since: October 25, 2005 Posts: 19 Comments: 20742
594. TampaSpin

Thanks man!

I'm a rocker myself, but (don't tell my mates) cross over from time to time when no one's looking. (esp. Faith Hill)
Member Since: September 2, 2008 Posts: 93 Comments: 30688
Morning all.

It's about 75 degrees here now, and isn't forecast to get much warmer. This is a bit cooler than average for us, more like mid-December weather. There's a crisp little breeze blowing from time to time to make u feel REALLY cold. . . . lol. However, the sun is shining most of the time, so it should be a good day.

The snow videos were cool, Ips. I also want to point out the size of the CARS in those pics . . . lol

Later! (Gone to get coffee and warm coconut bread . . .)
Member Since: October 25, 2005 Posts: 19 Comments: 20742
Young child feared drowned, as storms wreak havoc



FOUR-YEAR OLD CHILD swimming in a Central Queensland water hole was swept away yesterday when a flooded dam ruptured, spilling 6000 megalitres of water.

The dam burst following a weekend of unseasonal weather that battered eastern Australia. Snow fell, gales lashed the coast, knocking down trees and power lines, and crops were extensively damaged in a bout of unseasonal weather that brought an icy chill to eastern Australia.

Orange was expected to be declared a natural disaster zone after snowfalls obliterated millions of dollars' worth of hail netting and uprooted orchards, while roads between Bathurst and Oberon were closed as 10 centimetres of snow fell around the Blue Mountains.

Rockhampton police said rescuers and a helicopter were searching for a girl, aged three or four, who was washed away when an inflatable rubber bladder on the Bedford Weir, near Blackwater, burst.

"Apparently there is a swimming hole below the weir wall for the public, which is quite popular on a hot day," said Sergeant Noel Melrose.

No other information about the missing child has been released at this stage.

A spokesman for the NSW Bureau of Meteorology said the chilly spell was caused by cold air, originating from Antarctica, moving up the NSW coast. A severe weather warning was issued for the NSW coast south from Wooli, near Grafton, to Gabo Island, with winds of 65 kmh, and gusts of up to 90 kmh predicted last night.

More than 1000 homes across the Illawarra and Blue Mountains were left without power on Saturday as gale-force winds uprooted trees and sent branches crashing into electricity lines.

In Sydney the temperature hovered about 15 degrees for most of the day - compared with the monthly average of 20 - the result of an intense low-pressure system.

Gale-force winds were most severe in the western suburbs, where the State Emergency Service responded to 380 calls for help.

Tim Hall, a fruit farmer near Orange, said his property had more than $300,000 in damage caused by more than 10 centimetres of snow and strong winds that flattened dozens of fruit trees. He said he had never seen anything like it, and neither had his neighbours.

Officers from the Department of Primary Industries will view the damage during the week to assess if affected property owners will be eligible for natural disaster assistance.

For all you Fathers with girls......incredible song......

Member Since: September 2, 2007 Posts: 177 Comments: 20430
So regarding the stories on predictions:

Well, if NOAA and the Wolly Bears are about even on the predictions, I think the Wolly Bears are at least more entertaining. The racing is especially appealing to me...

My local concern is that we have had a huge production of mast--almost dangerous to go walking for rolling about on acorns. This is great for the bears and the dear (and the coyotes and the raccoons and the squirrels, etc). Some say this is a prediction of a harsh winter, others are saying it's a result of the drought. Any research on the correlation of mast production and weather patterns?

I know we're colder than normal now, and that has usually meant we warm up in December. Chaos rules, and all we can hope for is rain around here.
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Ya right on that one Tampa.

Every child should have the opportunities our's have.

Have a good Day. Im out to move some furniture with some folks.
Have to get cranking.

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Good morning!
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I dont go near that Lake till March Now,..as in it fishing.


Brrrrrrrr...
N Winds can ruin ya,...
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Quoting Patrap:
Then you'll have to cruise thru here in the Spring..
We can do it right..

Daugther is a High School Senior ..she can dig in with the Best too.


My friend your doing thing the right way...be proud of what you have accomplished with your kids....I know i am....my girls can tell there father anything....and i love it...
Member Since: September 2, 2007 Posts: 177 Comments: 20430
Time for me to hit the shower, get dressed, and go play...Hope you all have a great Sunday!

Back later
Member Since: September 2, 2008 Posts: 93 Comments: 30688

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About

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