I'm surprised Andy hasn't posted this yet: NOAA has just written up the January weather summary and apart from the northeast and Australia, January was surprisingly... normal. Surprising, because this is apparently the first January since 1982 where the northern hemisphere land surface temperatures were at or slightly below normal (that's right, land in the northern hemisphere has apparently had 25 straight years of above average temps). More dramatic is the change from last year- GISS shows the largest drop in global January temperatures from one year to the next in their record keeping history, and the change in land surface temperatures in the northern hemisphere was over 4 degrees F. That's huge!
Paired with that, polar ice is roaring back due to a sustained cold spell in the arctic. Not only is the ice field back to near-normal in terms of size, scientists say that it in many places it is 10-20 cm thicker than at this time last year. They think that that might help reduce or even reverse slightly the summer retraction in ice that's been going on.
On the snow front, we had the most snow coverage in the northern hemisphere in a long time, the sixth most since records started to be kept in 1973 (36 years of data). The change from last year to this year is almost unprecedented: only the increase in snow coverage in January from the winter of 1981 to the winter of 1982 was more extensive. The cold and snow has been especially intense in Asia, as is witnessed by recent events in China.
In the southern hemisphere, the Antarctic recorded its greatest mid-summer sea ice extent ever. Australia was extremely warm, however, with a record setting heatwave in many places.
What does all this mean? Not much in the long run. Monthly trends tend to persist into the following month, but break down pretty quickly after that. Spring could come right on time (it did back in 1982). The big question is what's going to happen this summer. If you look at the northern hemisphere snow records (
available here) it's July and August that have seen the greatest decrease in snow cover since 1973. That's consistent with the loss of sea ice. Interestingly enough, if you run a linear regression you see that snow cover from October to December has been increasing slightly, and there has been very little change in September. It appears that the increased melt in the spring is being seasonally offset by increased snowcover in the autumn. That said, seasonal snow doesn't replace permanent snow, just like seasonal ice doesn't replace permanent ice. Until August snow coverage starts exceeeding 1 million square miles again (about 2.7 million square kilometers), snowy January's won't mean that much.
I know it's been warm out east, but here in Kansas it has been consistently cold- we've hardly had a warm spell since late November. However, the records show that Kansas just had an average January. I think that goes to show how much I've gotten used to milder winters.
