December is about to take a turn as colder air roars into central Indiana overnight. The mild spell of weather ends as a wind shifting cold front passes after 8 p.m.
It has been a mild open to the month, ranking among the warmest 33% on record. Four of the past five days have reached 50-degrees with an average temperature more than 2° per day above normal.
The jet stream is changing, allowing the colder air to surge south. For the first time in weeks, the polar branch of the jet stream will dive into the nation.
The blast of cold air will be jarring as the coldest air in over three weeks arrives early Tuesday morning. The northwest wind will be brisk, producing a wind-chill only in the low to middle teens! Area-wide temperatures Tuesday will not recover, lingering in the upper 20s by afternoon.