Fact: today is January 10th. I know that because I checked the calendar this morning. ;-) Plus, I’ve been counting down the days to my birthday, which is tomorrow, the 11th. I just seemed like I was just celebrating my birthday. My, how the time flies! Ok, I digress…
January 10th: you know as well as I do it doesn’t feel like January outside! Today, we will
break shatter our standing high temperature record of 45 established in 1980. With highs in the upper 40s and lows in the 20s, one could arguably claim it’s late March. It’s absolutely unbelieveable! In all my memory, I can’t remember a time when daytime highs were constantly in the 30s and 40s in early January. In addition, I can’t remember a time when the first day of winter came and went, and we haven’t had a whole lot of snow to show for it. Can you?
I don’t want to bore you with statistics, because we science people are good at that. But just roll with me for a second. Let’s consider December 2011 alone. Last month, the overall, average temperature (mean) was 32.6 degrees, more than five degrees above the normal. Think about that for a moment, and also note the mean temperature was above freezing! It’s certainly not our warmest December on record; that happened in 1931. But quite impressive! So far, January’s mean temperature is 25.7 degrees, more than 10 degrees above normal.
Many are asking: why in the world is it so warm outside? Well, the “world” has a lot to with it. I’m not talking about climate change, a topic I do want to discuss in the future, but from an unbiased point of view. In short, I’m talking about the position of the polar jetstream, combined with other weather events.
Take a look at Figure 1. In general, the jetstream is a current of fast moving air in the higher levels of the atmosphere. There are two jetstreams in each hemisphere, the polar and subtropical. The polar jet is the strongest because is supported by the large temperature difference between the poles and mid-latitudes. Meanwhile, the subtropical jet’s main driving force is Earth’s rotation. My point: the jetstreams, especially the polar jet, separate colder air from warmer air. As you see in Figure 1, the polar jet is positioned north of Wisconsin, meaning mild temperatures for us!
There’s a lot of discussion as to why the polar jet is north of us. The most agreed upon theory is the Madden/Julian Oscillation. (MJO) I know, big phrase, and it’s even bigger problem to describe given its complexity. The bottomline is the MJO is a pressure disturbance in the tropics that can modify the track of the jetstreams. In our case, the disturbance, now located in the Pacific, is causing the polar jet to track north of the Midwest.
Looking ahead, with an incoming cold front Wednesday morning, temperatures will dive below the seasonal average. Thursday and Friday, we’ll be lucky to make it into the upper teens, 30 degrees colder compared to today and Monday. But this cold snap is just a short-term deal. For one, there’s no snow on the ground, so our temperature can rise quickly with the sun’s help. Secondly, the Climate Prediction Center (CPC) suggests temperatures will remain at or just above average through the rest of the winter season – back to the whole MJO thing. The center does suggest near or above average precipitation though. That’s good, in my opinion. Since December 1, we’ve received less than a foot of snow, less than a decent winter storm. Unbelievable…
Stay tuned for more from Beyond the Forecast…
This post was written by Nick Grunseth on January 10, 2012