By Meteorologist Tom Skilling
Never in 143 years of record-keeping has the Chicago area tallied 24 zero-degree or colder temperatures in a winter season by Feb. 11. Never—that is—until THIS season.
It’s Tuesday morning’s bone-chilling sub-zero official low at O’Hare which has established that dubious meteorological milestone.
The current winter season now ranks the 7th-coldest on the books since 1871. It’s jumped ahead of the 1993-94 and 1978-79 seasons in terms of 0-degree and lower temperatures.
Area enters an 11th consecutive day below freezing; 69% of Chicago’s winter days have produced “below normal” temps
The 0-degree tally isn’t the only metric underscoring the severity of the 2013-14 season.
Tuesday marks the 11th consecutive day the temperature, which first dipped below freezing at 9 pm, Jan. 30, has failed to reach or break above 32.
Winter 2013-14 now ranks among Chicago’s 5% coldest since 1871
Since Dec. 1, temps here have averaged 18.3-degrees— a reading cold enough to rank among the 5% coldest winter seasons over the term of the area’s 143-year official observational record. It’s the 7th coldest average temp on record for the the period and has fallen 7.9-degrees below the long-term average of 26.3-degrees dating back to 1871.
The beginnings of a changing pattern to tease area Thursday with its first 32 in 2 weeks; more significant warming—even the potential for a February thaw—ahead next week
Changes loom. They’ll be slower than many winter weary Chicagoans would like to see. But, the area may end up with a temperature approaching 32-degrees for the first time in nearly 2 weeks Thursday. That “warming” won’t last long. Moderately colder air is to sweep back into the area Friday into Saturday. But, warming is to resume again Sunday and continue into next week. If all proceeds then as current forecasts suggest, the Chicago area could find itself in the midst of something approaching a February thaw.
Just how much warming is to take place will be monitored carefully in the days ahead. The Lower 48’s extensive snow pack, a feature able to slow or limit warming in many situations, will play a crucial role in determining the extent of any temperature increase.
One thing seems certain. The shifting pattern will at least produce an interruption in the sub-zero chill of recent months.
Milder pattern likely transitional; warm Pacific Ocean waters may well reinstate colder, snowier regime in time
But the milder pattern we’re predicting may well be transitory. Pacific Ocean temperatures remain unseasonably warm—a key factor in the producing the cold, snowier than normal winter to which the Chicago area been subjected more than three months. It’s hard to see how the comparatively mild dome of air likely to develop over those warm waters won’t contribute to renewed northward buckling of North America’s jet stream into Alaska. It’s a trend the Weather Service’s long range climate model has picked up on and appears is the basis for its prediction of a return to colder than normal temps in March hand in hand with its forecast of elevated precipitation levels.