After soaring into the lower 50s Saturday afternoon, the temperature pendulum swings in a much colder direction next week.
A strong southwest wind pushed temperatures up 15° to nearly 20° above normal. A wind shift associated with a cold front arrives after midnight, and will deliver the first installment of colder air for Sunday.
The air mass will be colder, but hardly considered “bitter” or “arctic”. Nonetheless, temperatures Sunday afternoon in the mid/upper 20s will be a good 20° to 25° colder than Saturday afternoon.
The true Arctic front doesn’t dive south of central Indiana until predawn Monday morning. This will unleash some of the coldest air we’ve endured in a few years. Though we did have a single digit low back in early January (with a 5″ snow pack), this will be a several day cold snap.
Temps Monday morning will range from near 10° above in Lafayette to mid-teens elsewhere. A steady diet of northwest wind keeps temps from budging much Monday. In fact, numbers should go single digit shortly after sunset Monday and pave for bitter cold start Tuesday morning.
Tuesday lows will be in the 0 to 3° above range, with a stinging wind chill of -10° to 15°! Wednesday and Thursday mornings likely will feature single digits lows as well.
Obviously bitter cold is a huge headline of the forecast. But we’re also circling Thursday/Friday for importance too. Long-range models suggest a mid-latitude system will bring a threat of accumulating snow and/or wintry mix. Based on the latest ensemble (takes average of all output of a model to eliminate extremes) output of the GFS (American), European and Canadian models (image below) I’m opting for more of a snow solution for central Indiana. The white line (540 line of 1000-500mb thickness) is a rough gauge of the rain/snow line. Keep in mind this is only one tool in forecasting precip type, and very subject to change. So stay tuned for updates down the road.