2006: warmest year on record in the U.S.

By: Dr. Jeff Masters , 9:18 PM GMT on January 09, 2007

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The United States recorded its warmest year ever in 2006, according to today's report issued by the National Climatic Data Center (NCDC). The 2006 annual average temperature was 55�F, 2.2�F (1.2�C) above the 20th Century mean and 0.07�F (0.04�C) warmer than the previous warmest year, 1998. The NCDC had estimated that 2006 would be the 3rd warmest year in U.S. history last month, but an unusually warm December pushed 2006 to the top. It was the warmest December on record in the Northeast U.S., and the 4th warmest December for the country as a whole. Only 1939, 1957, and 1933 had warmer Decembers. However, the statistics partially hide the extraordinary warmth that began on December 10 and continued until January 6, when New York City tied their all-time record January high temperature of 72�. During the month ending January 6, the Northeast was 14 �F above average, and the U.S. as a whole was 7� above average.



No cause for alarm?
"No cause for alarm. Enjoy it while you have it," said Mike Halpert, head of forecast operations at the National Oceanic & Atmospheric Administration's Climate Prediction Center, in a story run by CNN just before New York City's record warmth. The story continued, "The weather is prone to short-term fluctuations, and forecasters said the mild winter does not necessarily mean global warming is upon us. In fact, the Plains have been hit by back-to-back blizzards in the past two weeks." True, the weather across most of the U.S. has finally cooled off this week, and the rest of January should have near average temperatures. And I agree that one warm month of winter in one country in its warmest year in 112 years of record keeping is not evidence of global warming, particularly when there is a moderate El Nino episode going on. An El Nino can lead to significantly warmer winters in the U.S.--exceptional December warmth has also occurred in 1877, 1939, and 1957, all of which were moderate or strong El Nino years. I've plotted up a comparison of temperatures in December of 1957 vs 2006 (Figure 1), and one can see that the unusual warmth of December 2006 does have historical precedent. Taking a look at average U.S. December temperatures for all years in the historical record (Figure 2), we see that these temperatures do show quite a bit of noise, and there is no evidence of dramatic warming in the past 30 years.


Figure 1. Comparison of the departure of average temperature from normal for December 1957 (the the second warmest December on record in the U.S.) and December 2006. Image credit: NOAA.

Figure 2. Average December temperatures for the U.S. from 1895 to 2006. Image credit: National Climatic Data Center.

Rolling thirteens with the weather dice
Take a look at the trend December temperatures in Figure 2. It shows that the average temperature has warmed a little more than 1� F in the past century. It may not seem like much, but that is enough to significantly load the dice in favor of warmer winters. Six of the ten warmest U.S. winters on record have occurred in the past 15 years. Month long spells where winter is seemingly absent--as also occurred in January 2006, the warmest January in U.S. history--have become more common. Keep in mind that the weather of January of 2006--which blew away the previous record for warmest January by a huge margin (2� F)--occurred during a La Nina year, not an El Nino. What concerns me most is that the warming trend is not isolated to the U.S. The 1� F rise in temperatures the past century has occurred world-wide, thanks to global warming, and the temperature increase has been much higher in the Arctic--something the climate models have predicted would occur as a telltale sign of the human-caused addition of greenhouse gases to the atmosphere. In the past, an exceptionally warm winter month in the U.S., like December 1957 (Figure 3), was offset by much cooler weather elsewhere, such as we see in Alaska, Greenland, and northern Siberia. However, December 2006 had no such offsetting cool temperatures--it was more than 1� C above average over almost all the land areas of the Northern Hemisphere north of 40� north latitude (Figure 4). Colorado, whose three blizzards have been widely cited as evidence that winter has been severe elsewhere, still recorded temperatures about 1� C above normal in December 2006.


Figure 3. Global departure of temperature from average for December 1957, the second warmest December on record in the U.S. Note that the exceptionally warm temperatures over the U.S. are offset by much cooler weather elsewhere, such as in Alaska, Greenland, and northern Siberia.

Figure 4. Global departure of temperature from average for December 2006. Note that the almost the entire globe north of 40� north latitude was more than 1� C above average, with large areas more than 6� C (11� F) above average.

All this unusual heat in the northern high latitudes is going to significantly slow down the formation of ice over the Arctic Ocean this winter. Furthermore, the lack of the usual snows across the Arctic may allow the snowpack to melt much earlier than normal in spring, resulting in more record warmth in the Arctic this summer. Arctic sea ice coverage, already down 20% in the past 20 years, is likely to continue to shrink in 2007. As sea ice melts in response to rising temperatures, it creates a positive feedback loop: melting ice means more of the dark ocean is exposed, allowing it to absorb more of the sun's energy, further increasing air temperatures, ocean temperatures, and ice melt. The observed changes in the ice cover (Figure 5) indicate that this feedback is now starting to take hold, and the weather dice will continue to get more loaded towards rolling higher numbers in 2007. I do think we're due for a cold winter next year--part of the warmth of the past two winters is probably due to the normal random fluctuations in the weather, and Nature has been rolling twelves more often than snake eyes of late. However, we're not going to see snake eyes too much more. December's weather in the Northeast U.S. may have been a case of the weather dice coming up thirteen--weather not seen on the planet since before the Ice Age began, 118,000 years ago. The weather dice will start rolling an increasing number of thirteens in coming years, and an ice-free Arctic Ocean in summertime by 2040 is a very real possibility, as indicated by computer modelling studies published in the Journal of Geophysical Research last month. This possibility is cause for alarm, and I, for one, had a lot of trouble enjoying the phenomenally warm weather of the past month here in Michigan.


Figure 5. Percent change in coverage of Arctic sea ice in Decembers from 1979-2006, compared to the 1979-2000 average. The Polar Ice Cap has shrunk by about 15% in December, and 20% in summer, over the past 20 years. Image credit: National Snow and Ice Data Center.

Check out the realclimate.org post on this winter's anomalous warmth.

I'll be back Thursday afternoon or Friday with a look at the status of El Nino. Will it still be around during hurricane season?

Jeff Masters

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298. weatherboykris
4:41 PM GMT on January 10, 2007
Seasons like that happen
Member Since: December 9, 2006 Posts: 125 Comments: 11346
297. weatherboykris
4:40 PM GMT on January 10, 2007
what about the '33 hurricane season?We missed a few storms that year.We probably had something like 24-25
Member Since: December 9, 2006 Posts: 125 Comments: 11346
294. weatherboykris
4:38 PM GMT on January 10, 2007
but hurricane activity,is not increasing beyond normal deviations
Member Since: December 9, 2006 Posts: 125 Comments: 11346
293. weatherboykris
4:37 PM GMT on January 10, 2007
yes
Member Since: December 9, 2006 Posts: 125 Comments: 11346
292. Thunderstorm2
4:37 PM GMT on January 10, 2007
Oh! He is way beyond that Nowadays!
so he was a hurricane expert
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291. weatherboykris
4:37 PM GMT on January 10, 2007
I've noticed that STL.look at the maps I posted above.
Member Since: December 9, 2006 Posts: 125 Comments: 11346
288. weatherboykris
4:35 PM GMT on January 10, 2007
I've got to go.Be back later.
Member Since: December 9, 2006 Posts: 125 Comments: 11346
286. weatherboykris
4:33 PM GMT on January 10, 2007
I see it very well our human impact on global warming is changing hurricanes for the worse.
I wasn't talking about global warming's effects on hurricanes.Global warming's effects on hurricanes has not been proven,and I'm skeptical.
Member Since: December 9, 2006 Posts: 125 Comments: 11346
285. Thunderstorm2
4:31 PM GMT on January 10, 2007
Yeah but no one is listning to the warning about the effects of Global Warming so we really need a project of some sort.
and yes it is cold in orlando.

57 F / 14 C
Clear
Humidity: 45%
Dew Point: 36 F / 2 C
Wind: 8 mph / 13 km/h / 3.6 m/s from the North
Wind Gust: 17 mph / 28 km/h / 7.7 m/s
Pressure: 30.40 in / 1029 hPa
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283. weatherboykris
4:30 PM GMT on January 10, 2007
I think there is a Global Warming project, but if there isn't then we will have to get one
Even if there is a global warming project, it is one to try to decrease human impacts on the environment,not increase them.Cold in orlando,Thunder2?
Member Since: December 9, 2006 Posts: 125 Comments: 11346
282. Thunderstorm2
4:28 PM GMT on January 10, 2007
What about the global warming project? Are we passing that one?
I think there is a Global Warming project, but if there isn't then we will have to get one
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281. weatherboykris
4:29 PM GMT on January 10, 2007
Is he a modern day hurricane expert?
Member Since: December 9, 2006 Posts: 125 Comments: 11346
280. weatherboykris
4:28 PM GMT on January 10, 2007
That's stupid.It makes no sense.Are you telling me a faster moving storm will weaken more over cold water than a slow moving storm.Who's Hugh Willoughby anyway?
Member Since: December 9, 2006 Posts: 125 Comments: 11346
278. weatherboykris
4:27 PM GMT on January 10, 2007
Hey thunder
Member Since: December 9, 2006 Posts: 125 Comments: 11346
277. weatherboykris
4:27 PM GMT on January 10, 2007
I asked Dr. Masters what he though of the upcoming hurricane season.He replied:

It looks like El Nino will be gone by then, so expect an active hurricane season.

Jeff
Member Since: December 9, 2006 Posts: 125 Comments: 11346
276. Thunderstorm2
4:25 PM GMT on January 10, 2007
Good Morning everyone
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275. weatherboykris
4:26 PM GMT on January 10, 2007
We are affecting it for the worse,not the better!Why can't you see that we don't know enough about hurricanes effects on the environment to mess with them?!
Member Since: December 9, 2006 Posts: 125 Comments: 11346
273. weatherboykris
4:21 PM GMT on January 10, 2007
And besides Cyclonebuster, you're idea ignores the fact that for fast moving storms or storms that are already very strong,it just wouldn't have much effect.
Member Since: December 9, 2006 Posts: 125 Comments: 11346
272. weatherboykris
4:20 PM GMT on January 10, 2007
What about the global warming project? Are we passing that one?
What global warming project?
Member Since: December 9, 2006 Posts: 125 Comments: 11346
269. weatherboykris
4:18 PM GMT on January 10, 2007
They tried and they failed.They accepted that it was impossible and/or impractical and let it go.
Member Since: December 9, 2006 Posts: 125 Comments: 11346
268. weatherboykris
4:16 PM GMT on January 10, 2007
They are two peas in a pod both intertwined and related!

No,they really aren't.Weather is tlaking about storm systems, forecsting and forecast models.Weather modification is talking about something that many people have tried and failed.Two words :Project Stormfury
Member Since: December 9, 2006 Posts: 125 Comments: 11346
267. weatherboykris
4:14 PM GMT on January 10, 2007
You've had bad experiences with hurricanes haven't you,cyclonebuster.You're out for revenge.
Member Since: December 9, 2006 Posts: 125 Comments: 11346
264. weatherboykris
4:05 PM GMT on January 10, 2007
If we build another row at the Cape then the another 400 miles is spared up the coast and in eight days the whole East coast is spared
1. You'd need 8 days of lead time to protect the East Coast?
2.I thought there would be no pumps.If there's no pumps and the tunnels depend on natural processes,then won't SSTs always be cool?
3.Can't we just talk about weather,not modifications of the weather?
Member Since: December 9, 2006 Posts: 125 Comments: 11346
263. ricderr
3:57 PM GMT on January 10, 2007
Simple right???

OK...let's just say.....tunnels would work...now..we take the cold water from up north....and bring it south....the water up north..is replaced...(water seeks it's own level)by warmer water from the south..further eroding the polar ice cap...killing the fisheries of the north....which in turns..kills all the fisheries of the ocean...making it a polluted foul mess..and thus destroying earth and life as we know it....may i be the first to thank you from saving us from a hurrican cb
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260. AkTennisPlayer
6:51 AM AKST on January 10, 2007
Here in Homer, Alaska (aka The Banana Belt), we have been hit with the meanest winter in a long time. Extremely cold temperatures, lots of fluffy snow that is not melting at all, etc. Unlike interior Alaska, we have a maritime climate that usually protects us from the sort of cold seen in the interior regions. I'm not sure about the statistics but the -15 degree F temperature of yesterday morning is very rare indeed.
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259. weatherboykris
3:47 PM GMT on January 10, 2007
Things in So Cal could get very interesing

From what Ive heard, weather in south CA rarely gets very interesting.
Member Since: December 9, 2006 Posts: 125 Comments: 11346
258. lightning10
3:37 PM GMT on January 10, 2007
Things in So Cal could get very interesing if this does happen.

The 06z run of the WRF has an interesting new Twist. Unlike the
GFS...which shows the upper low beginning to turn southeastward Friday night...
pulling into Nevada and northwestern Arizona by Sat morning...the WRF continues to
show the system digging additionally Friday night...thanks to a very
potent vorticity wrapping around its western side. As a result...it pulls the
trough axis over sba County Friday night...placing l.A. County into a
more favorable location on the eastern side of a sharpening trough. It
also generates quite a bit more precipitation over l.A. County than either
the GFS or its previous runs. While this could be overdone...it
certainly warrants the addition of probability of precipitation to l.A. And vtu counties for
Friday night. In addition...since it is slower pulling the system through
the area...it is also somewhat less cold than the GFS for Thursday
night/Fri...but every bit as cold for Friday night/Sat morning. This
will have to be watched very carefully...because the farther west track
of the upper low would yield more precipitation over the forecast area...
particularly l.A. County...with a greater potential for significant
snowfall...even at elevations that do not normally experience snow.
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257. weatherboykris
2:55 PM GMT on January 10, 2007
Cooler than normal temps over Africa could lead to less dust.
Member Since: December 9, 2006 Posts: 125 Comments: 11346
256. weatherboykris
2:54 PM GMT on January 10, 2007
Near average shear:

Member Since: December 9, 2006 Posts: 125 Comments: 11346
255. weatherboykris
2:52 PM GMT on January 10, 2007
The CPC is calling for a more active than normal ITCZ between Africa and the Antilles by H-season

Member Since: December 9, 2006 Posts: 125 Comments: 11346
254. weatherboykris
2:49 PM GMT on January 10, 2007
I just looked at the 00 and 06z GFS models, and wow is winter going to make a comeback the next two weeks!
Member Since: December 9, 2006 Posts: 125 Comments: 11346
253. weatherboykris
2:45 PM GMT on January 10, 2007
h23,see my blog if you haven't already
Member Since: December 9, 2006 Posts: 125 Comments: 11346
252. drivecde
2:16 PM GMT on January 10, 2007
maybe we can send CB to the moon!I don't need anymore talk on Global Warming!
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251. hurricane23
8:47 AM EST on January 10, 2007
Its going to be interesting for sure to see how everything plays out during the next few months with a fading El Nino and warm SST'S across the atlantic basin we could be in for quite an active season.

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250. pottery
9:26 AM AST on January 10, 2007
Some more NEWS. Go to bbc.news.co.uk and scroll down to " business "
All is not well at all at all...........
Member Since: October 24, 2005 Posts: 0 Comments: 24388
249. pottery
9:14 AM AST on January 10, 2007
Drilling in the Alaskan Arctic to go ahead ????This is not good news. I also heard a news broadcast today that says that colonisation of the moon is up and running, and that this will "create great opportunities and beneifits for Industry...." This is the motivation ???????????
Member Since: October 24, 2005 Posts: 0 Comments: 24388

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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.