Fasten those seat belts! The Stateline's in store for quite a meteorological roller coaster ride in the coming days, as wild swings in temperatures are all but certain.
The roller coaster's speeding rapidly downward Wednesday Evening, with some spots already reporting temperatures in the single digits. Before the sun rises Thursday Morning, Rockford's temperatures will be right around 0°, with most outlying locales, especially those to Rockford's west, falling a handful of degrees colder. And, though there's not quite as much wind with which to contend compared to Tuesday Night, there'll still be enough of a breeze to send wind chill values as low as -15°.
Despite Thursday being another day featuring wall-to-wall sunshine, we'll see no help in the temperature department. While one or two communities may briefly touch 20°, most spots will remain in the teens all day long.
There are two driving forces behind the unseasonable chill. First, the jet stream has buckled in such a way that it's unlocked a significant chunk of arctic air in Canada, and has sent that sprawling southward into the Central United States. At the surface, a sprawling, intense high pressure system continues to slide eastward, further reinforcing the cold air. So massive is this high pressure system that it's likely to bring atmospheric pressure readings here to within shouting distance of the all-time highest air pressure ever recorded! While a high this strong essentially squashes any potential of significant warming Thursday, it does guarantee the day will be cloud-free. Another silver lining; the high's close proximity to the Stateline insures that winds will be extremely light throughout the day.
The high slides off to the south and east gradually Thursday Night. As it does so, winds will gradually begin to shift to the south, and eventually the southwest. In doing so, our temperatures, which will still fall into the single digits during the evening hours, should level off and eventually begin to rise overnight. By daybreak Friday, temperatures may be back into the teens in a spot or two.
More pronounced warming commences during the daytime hours as the high pressure system continues to drift farther east, and our winds begin to strengthen out of the southwest. Those strengthening surface winds, working in tandem with another full complement of sunshine, will allow temperatures to reach well into the 30s, and even into the 40s across southern reached of the area Friday Afternoon. The jet stream will also be realigning during that time, allowing Pacific air to gush eastward. Such a development promises 40s here for both of our weekend days, with a run toward 50° not out of the question Sunday, should there be enough sunshine and if we're able to fully eliminate the remaining snow covering the Stateline. Stay tuned!