The National Weather Service Chicago predicted a cooler, wetter winter for Kane County in 2016-17, based in part on the La Nina effect, which favors drier, warmer winters in the southern United States and wetter, cooler conditions in the northern U.S.

But to prove the first rule of weather forecasting — that it’s quick-changing and unpredictable — what we’ve seen are record high temperatures, especially these past few days.

In fact, Wednesday’s (Feb. 22, 2017) forecast for Kane County, IL, calls for sunny skies and a high of 72 — temperatures more likely in May than February.

Since Saturday (Feb. 17, 2017), we’ve seen four days of record-high temperatures. You can see in the graph below that the Chicago highs were 67, 70, 69 and 70, topping the old record temps by anywhere from seven to four degrees.

The ‘Why’ Behind the Warmth

For the “why” behind the warmth, take a look at the info graphic at the top of this article, courtesy of the National Weather Service Chicago.

First, we’re in warm-weather “regime,” in which the weather pattern has been unusually warm for a long period of time. In our case this season, 90 percent of the days have been above average in warmth since, Jan. 14.

Second, we haven’t had a lot of snow. So there’s a little bit of a chicken-and-egg thing going on. No snow because it’s warm; warm because there’s no snow cover.

Third, that darned upper-level jet stream is keeping us balmy. Look at that map and see how sharply the jetstream angles north, then curves around the Great Lakes, acting like a very effective offensive line, blocking the northerly rush, providing a nice warm pocket for the quarterback — aka us.

Fourth, because of that jetstream arc, we’re getting a lot of warm from the southern plains states, which in turn have seen hundreds of record-high temperatures. The southwest winds Friday steered the mild temps our way.

SOURCE: NWS Chicago