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

Share this Blog
3
+

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

Reader Comments

Comments will take a few seconds to appear.

Post Your Comments

Please sign in to post comments.

or Join

Not only will you be able to leave comments on this blog, but you'll also have the ability to upload and share your photos in our Wunder Photos section.

Display: 0, 50, 100, 200 Sort: Newest First - Order Posted

Viewing: 338 - 288

Page: 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 | 16 | 17 | 18 | 19Blog Index

Quoting TampaSpin:


We will agree to disagree......come back next Saturday and we will see who is correct...LOL



I can live with that.
Member Since: Posts: Comments:
Quoting TampaSpin:
Admin.....please Bann Stillwaiting for good...this is freaking crazy.


for your information,I've been on WU for 2 yrs and i've never been banned ,it all comes down to respect,I respect everyone until they disrespect me or anyone else,then the respect is gone,the amdins can tell the difference,there obviously a heck of alot smarter than you my friend...I'll tell you what you don't like my opinion so put me on ignore if you wish,otherwise just deal with others difference of opinion,as not all will share yours!!!!
Member Since: Posts: Comments:
Quoting 15hurricanes:
Northwest Florida- Tallahasee, Penscola

North Flordia- Jacksonville, St Augustine, Gainesville and Ocala

Central Florida- Tampa, Orlando, St Petersburg, Sarasota, Venice

South Florida- Naples, Marco Island, Miami, Ft Lauderdale, Key West!!!


Funny but, the media tends to include Tampa area by calling it SW Florida....never really figured it out.....i just follow along.
Member Since: Posts: Comments:
Quoting sullivanweather:
But a strong sub-tropical jet doesn't always translate into a storm moving up the coast.

The pattern next week into next weekend would steer any storm moving out of the Plains on a east-southeast course through the south, but in no way turning up the coast any further north than the Carolinas.


We will agree to disagree......come back next Saturday and we will see who is correct...LOL
Member Since: Posts: Comments:
But a strong sub-tropical jet doesn't always translate into a storm moving up the coast.

The pattern next week into next weekend would steer any storm moving out of the Plains on a east-southeast course through the south, but in no way turning up the coast any further north than the Carolinas.
Member Since: Posts: Comments:
Quoting sullivanweather:



You can't see the confluent flow over the Mid-Atlantic in that animation you posted?
Look at how the isobars converge over the Mid-Atlantic. No storm will be able to bust through that.


What i see is a very strong Subtropical Jet that gets even stronger allowing alot of moisture into the South and into the EAst Coast.
Member Since: Posts: Comments:
Admin.....please Bann Stillwaiting for good...this is freaking crazy.
Member Since: Posts: Comments:
Quoting TampaSpin:


I would have to somewhat disagree with you



You can't see the confluent flow over the Mid-Atlantic in that animation you posted?
Look at how the isobars converge over the Mid-Atlantic. No storm will be able to bust through that.
Member Since: Posts: Comments:
Look at this MJO forecast map at day 6-15....lots of moisture coming to the South...

Member Since: Posts: Comments:
Quoting 15hurricanes:
stillwaiting,

Sarasota is in the Central Florida!!

Not South!!
:(



ahhhh,i've lived here for 7 yrs,its considered South West Florida...you know not what you speak,but then again they say ignorance is bliss!!!!there are alot of your type on here, though I usually just don't pay attention to them....
Member Since: Posts: Comments:
Quoting all4hurricanes:

That thing's been there for several days If it persists the NHC will have to post something about it


I don't think it has any chance to develop....Shear is nearly 40-50kts in that area..
Member Since: Posts: Comments:
Quoting Orcasystems:


You can see the shear ripping the Northern part of it away.


That thing's been there for several days If it persists the NHC will have to post something about it
Member Since: March 29, 2008 Posts: 0 Comments: 2372
Quoting leftovers:
im a proud registered democrap. republican friends you had your chance. look what has happened. no wonder you lost.


Im so happy your proud.....you can now sit back and take the rest of the day off hopefully....lmao
Member Since: Posts: Comments:
Lefty, suggest you edit that. Just left the door wide open to be attacked... Lol.
Member Since: August 23, 2008 Posts: 7 Comments: 5300
Quoting sullivanweather:
Actually the large circulation for the Northeast US cut-off low will keep the system supressed to the south. IT won't be coming up the East Coast and the confluent flow over the Mid-Atlantic should weaken the system as it moves east.


I would have to somewhat disagree with you.

Member Since: Posts: Comments:
Actually the large circulation for the Northeast US cut-off low will keep the system supressed to the south. IT won't be coming up the East Coast and the confluent flow over the Mid-Atlantic should weaken the system as it moves east.
Member Since: Posts: Comments:
Morning everybody. We're having GREAT weather here, that is, cool, breezy, but also sunny, so don't be surprised if I'm not in the blog much today, even though it is Saturday LOL.

Back later!

Edit: This is a Nassau, Bahamas, update for those that don't know my location . . .
Member Since: October 25, 2005 Posts: 19 Comments: 22101
Quoting Orcasystems:


Don't feel bad.. he wrote that, and I was looking for the Hockey post.


ROFLMAO....that was great......
Member Since: Posts: Comments:
Quoting Orcasystems:


Don't feel bad.. he wrote that, and I was looking for the Hockey post.


Lol! Well, England's football team always suffers from a lack of decent left wingers... probably why I can't spot them anymore. ;)
Member Since: August 23, 2008 Posts: 7 Comments: 5300
Complete Blog Refresh
Mirror Site (New Format)
Member Since: Posts: Comments:
This is the Tuesday forecast map....look at the plum of moisture coming into the West coast.....wait tell it gets to the Midwest and hits that cold air as the low taps into the GOM. Big winter storm coming over Thanksgiving weekend to the MidWest, South, and EAST coast.

Member Since: Posts: Comments:
Quoting Cotillion:


Where? I don't see any.


Don't feel bad.. he wrote that, and I was looking for the Hockey post.
Member Since: Posts: Comments:
uh oh....time to get "attacked" by the cool people again....I come in peace!!!!...RELAX and have a drink TS,its the weekend!!!!
Member Since: Posts: Comments:
Actually I'm a registered independent...

I don't beileve in political parties because I like to be able to think for myself.

Do the research, learn the facts. You'll see that liberal, conservative, green or working families party the decision to move to renewable energy will benefit us all.
Member Since: Posts: Comments:
Quoting TampaSpin:
Looks like the left wingers are up and at it again.....wow......unreal.


Where? I don't see any.
Member Since: August 23, 2008 Posts: 7 Comments: 5300
Looks like the left wingers are up and at it again.....wow......unreal.
Member Since: Posts: Comments:
Quoting RobDaHood:
Tampa,

Wierd how they alway say "cooler inland" but we have been consistently warmer all week

Link

Station about 10 miles from my house, we're a little warmer on the lake.


anywhere around water is warmer.......for instances...at Lake Okachob.......it can be as much as 10deg warmer around the lake.....and 5-7 miles away be 10deg colder.....been there and seen that before.....the temp of the water keeps the air warmer..
Member Since: Posts: Comments:
Quoting stormlvr:
Considering the massive costs and long term life style changes associated with the "global warming" theory, I believe we should demand near perfection from the climate change forecasts and the associated modeling. A good start would be verification of all forecasts since the late 80's and public debate with a growing number of skeptics.


That comment just makes me want to cry. It shouldn't need to be spelled out.

Global warming has little to do with lifestyle changes. GW is like 7th on the list of why we need renewable energy. Why we need to recycle. Why we shouldn't use 3 mile to the galleon super-SUVs.

Lowering pollution extensively, making sure we don't run out of energy - the lifeblood of everything these days -, not draining the planet we live on of everything without putting something back...

...comes under that wonderful banner entitled "Common Sense."

Member Since: August 23, 2008 Posts: 7 Comments: 5300
Tampa,

Wierd how they alway say "cooler inland" but we have been consistently warmer all week

Link

Station about 10 miles from my house, we're a little warmer on the lake.
Member Since: September 2, 2008 Posts: 96 Comments: 31980
Good Evening, went body-boarding at the beach the other day, nice waves. not too cold, Dr.Masters enjoy your weekend should be a good one today with Michigan and Ohio State.
Member Since: Posts: Comments:
what a morning here in SWFL,Just perfect...about 55 degrees w/ a nice breeze and not a cloud in the sky!!!!!
Surfmom:GOM just about flat NO ACTION!!!,might check out some fishing though....
Anyone see that hilarious "Palin pardons turkey" clip from msnsbc........funniest thing i've seen since they lost the election..lol
Member Since: Posts: Comments:
Quoting stormlvr:
Considering the massive costs and long term life style changes associated with the "global warming" theory, I believe we should demand near perfection from the climate change forecasts and the associated modeling. A good start would be verification of all forecasts since the late 80's and public debate with a growing number of skeptics.



That sort of makes no sense.

First of all, regardless of whether or not 'global warming theory' is correct we still need to move away from fossil fuels because they're unsustainable. Waiting for a 'perfect climate model' to begin the process of doing anything is pure silliness. Developing such a model may take decades and if the worst of the worst of climate model predictions are to come to pass from continued GHG emissions it'll be far too late to begin to do anything about it. Some say it's already too late so why continue to put off advancing technology?

If you think the current financial crisis is bad just wait until fossil fuel demand far outstrips supply and there's no infrastructure in place to be able to take the next step towards renewables such as solar, wind, tidal, geothermal, hydroelectric, etc...

It'll be hard to plant fields if there's no fuel to put into diesel farm equipment so there goes the food supply. Fuel will become so expensive that only the rich will be able to afford it (imagine fuel costing double or triple mortgages/rent payments per month).

Right now, with the economy tanking because of the extremely high fuel prices over the last 4-5 years, is a perfect time to put the necessary infrastructure in place to avoid these types of situations in the future AND to possibly advert a looming crisis of rapily rising temperatures and the consequences that go along with thatm, such as rising sea-levels (the big one) or month long heat waves during the summer that'll chase people indoors during the hottest times of the day (sort of what happens in Mexico; if you've ever been there you'd know what I'm talking about).

Forecasts made in the 80's are close enough to reality to see that climate scientists are on the right track, even though they may not be directly in the middle of the road (more off to the shoulder) but at least the field of climate science is heading in the right direction.
Member Since: Posts: Comments:
Quoting TampaSpin:
43deg with a 9mph wind.....shesh......


Victoria BC

Fog - 44F


* Wind: W 6m/h
* Sunrise: 7:33
* Sunset: 16:26

* Relative Humidity: 81%
* Pressure: 1,018.00 mb
* Visibility: 0.0 miles
* Ceiling: ft

Outlook for the Day, Sunny with a High of 48
Member Since: Posts: Comments:
43deg with a 9mph wind.....shesh......
Member Since: Posts: Comments:
Morning everyone.........BURRRRRR dam !!!
Member Since: Posts: Comments:
robdahood, like your dogs/ wives bit. lol
Member Since: Posts: Comments:
Guys, my contest is going on at my blog, since there's only one person I extended the end date to December 31st.
Member Since: Posts: Comments:
COLD here too this morning...supposed to crew on in a sailboat regatta this afternoon and trying to think of a valid excuse not to go! Going to FREEZE out there. Ugh. Hope no one goes in the drink!

Have a great day!
Member Since: Posts: Comments:
Complete Blog Refresh
Mirror Site
Member Since: Posts: Comments:
Quoting redavni:
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


Thank you, I added the link to the Blog.
Member Since: Posts: Comments:
Considering the massive costs and long term life style changes associated with the "global warming" theory, I believe we should demand near perfection from the climate change forecasts and the associated modeling. A good start would be verification of all forecasts since the late 80's and public debate with a growing number of skeptics.
Member Since: Posts: Comments:
Quoting hurricanemaniac123:
I noticed that flare up in the sw caribbean too.

There's some high shear around it, 20-40 knots, but it barely has any right now.

It might become a tropical depression, it depends on where it will go and how much shear is there.


You can see the shear ripping the Northern part of it away.

Member Since: Posts: Comments:
Until StormJunkie gets his live feed up this afternoon, you can take a look at the Arthur Ravenel Jr. Bridge where he's doing his walk:

SC DOT Traffic Cams
Member Since: Posts: Comments:
Morning weather in Wilmington
26F
Wind calm
good vis and clear sky
Forecast high 46 F
Member Since: Posts: Comments:
I noticed that flare up in the sw caribbean too.

There's some high shear around it, 20-40 knots, but it barely has any right now.

It might become a tropical depression, it depends on where it will go and how much shear is there.
Member Since: Posts: Comments:
31F
67%
winds calm
wooly ears cold
Member Since: September 11, 2008 Posts: 9 Comments: 10084

Viewing: 338 - 288

Page: 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 | 16 | 17 | 18 | 19Blog Index

Top of Page

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.

Local Weather

Partly Cloudy
74 °F
Partly Cloudy