Rockin' robins... and tornadoes too

Robins hopping around after any winter, let alone this one, are quite a sight. It's typically heralded as a major sign of spring. However, it turns out that some robins actually spend the winter in the Midwest. So why do we rarely see them during those cold months? It turns out they spend a lot more time in flocks and not out alone during the winter, so they're not nearly as spread out. The Great American Bird Count also found what appears to be a pretty strong relationship between the probability of seeing a robin and the depth of snow on the ground. The chance of seeing robins drops sharply when you get an inch or two of snow on the ground. It looks like the robins will have plenty of reason to venture out next week as we get rid of much of our remaining snow.

Blogger Carrie posed a couple questions the other day:

• Question #1: I heard somewhere (and I thought it was here) that this upcoming season's temperatures are supposed to be below average but that we are supposed to have a more active severe weather season. Just curious how that works. I thought the temperatures would need to be higher for severe weather to be more active?

Indeed, it was here. Adam wrote about it on the blog on February 21. In general, La Nina leads to cooler average temperatures, which does seem counterintuitive. My understanding of how that works is that we're dealing with a three-month average temperature, so the temperatures over that time period can offset each other. Remember that this past winter was only a half-degree below normal, despite having some very cold spells. Likewise, the spring may have some exceptionally warm days. The big thing to keep in mind is that we're dealing with fairly long-term averages and predictions based on past trends. They don't translate down to individual days very well at all.

• Question #2: On the same note, because the severe weather season is supposed to be more active, to me that means more chances of Tornadoes, (which I am very fearful of), are there any areas in Illinois that would be more susceptible to Tornadoes than others or are all areas pretty much at the same risk?

I had to go look this up because I didn't have any idea. The probability of tornadoes, as you might guess, shifts northward as the spring and early summer wear on. The National Severe Storms Laboratory has a nifty animation that shows the chance of a tornado hitting within 25 miles of any point on the map on the time shown (based on 20 years of data). The day is on the bottom of the image (80MMDD - 800520 would be May 20).
Far left is the probability of a tornado for around May 20; near left is for around June 17. In the middle of May, nearly all of Illinois has about a one-half percent chance of a tornado occurring nearby. In the middle of June, northern Illinois has a slightly higher chance than southern Illinois; the chance is 0.75%-1% here. So, to the short answer is that in May, there's basically an equal risk; in June, there's a slightly higher risk in northern Illinois than southern Illinois. Again, these are long-term probabilities that help us see when our "prime" tornado season is.

Here's an image that shows the number of tornadoes per 1000 square miles. Northern Illinois and southern Wisconsin have slightly more tornadoes based on this analysis method than most of the rest of the state.

The big thing to remember is this: tornadoes can happen any time of year (as we learned in January) and what happens in one year can be quite different from the next. The best thing you can do is to be prepared and remember that the 13News Weather Team here to help keep everyone safe during severe weather.