The Northeast braces for weather whiplash as shorts give way to parkas

(CNN)It has been a wild week of varying temperatures for parts of the eastern US, and it's about to get even more interesting.

Fresh off the heels of the season's coldest air last weekend and drastically warmer temperatures this week, the stage is set for a weather whiplash as shorts and T-shirts weather today will give way to parkas and scarves in a matter of hours.
A cold front sweeping through the eastern half of the country will usher in this much cooler air.
    Portions of the Midwest and Northeast will have experienced a 40-plus degrees temperature change from the start of the week compared to its end.

      Temperature roller coaster

        On Tuesday, St. Louis rose to a high of 73 degrees, nearly 20 degrees above its November average.
        But a glance westward reveals a potent frontal boundary draped across the heart of the nation. This system will be partly responsible for the seesaw of temperatures over the next few days and Thursday night, those highs in the 70s in St. Louis will be a distant memory as lows Friday morning dip into the upper 20s.
          In Chicago, the showers and gusty winds signaled the incoming front on Wednesday; still, highs managed to reach a balmy 62 degrees, well above the average of 48 degrees for this time of year.
          By Thursday, the seasonal switch flips as Chicagoans will need to bundle up in the afternoon with a temperature closer to 38 degrees and wind chills in the upper 20s.
          A similar scene will play out for millions across the Northeast between Thursday and Friday. On Thursday, it would make sense to reach for a pair of shorts and a T-shirt in New York City, Boston and Washington, DC. Highs will be near 70 degrees across all three cities, making it as much as 15 degrees above seasonal averages, but don't keep your parka too far away. As quickly as the warmth arrives, Friday ushers in the arrival of the cold front, allowing temperatures to nose-dive back to reality for millions. Friday's highs will struggle to reach 50 degrees for many in the Northeast, running 5-8 degrees below November averages.
          The passage of the front will also offer a brief shot of wintry weather on Thursday night into Friday morning, but it will be limited to favorable areas like the higher elevations of northern New England and northern Pennsylvania.

          A sign of things to come

          In the South last weekend, the coldest air of the season crept down to the Carolina coast, plummeting temperatures down into the low 30s. The rebound to warmth, however, was impressive regionwide. Cities like Atlanta, Charlotte, and Birmingham have since enjoyed some of their warmest weather since late October, with highs in the middle 70s.
          On Thursday, high temperatures will once again warm into the middle 70s, but a shot of reality arrives with the passage of the front during the overnight hours.
            Come Friday afternoon, temperatures will struggle to warm beyond the 50s across much of the South, and this may only be a sign of things to come as we head toward the busiest travel week of the year.
            Long-range forecast models continue to indicate a significant pattern change with the potential for multiple shots of arctic air on the horizon. Early forecasts show cities like Chicago could struggle to climb out of the 20s by Monday afternoon, while Atlanta may fail to reach 50 degrees by Tuesday afternoon; wintry weather may also accompany next week's storm in parts of the Midwest and Great Lakes region.