A big dip in the jet stream will bring mid-winter temperatures and an end to the growing season in the Rock Hill area this weekend, forecasters say.
Below-freezing temperatures are expected early Sunday, with another surge of even colder air predicted to arrive by the middle of next week.
Preceding each of the cold blasts will be a rain-producing system, expected to bring more than an inch of precipitation to the Rock Hill area, according to forecasters.
It was only a month ago that temperatures were climbing into the 80s and the humidity was still at summertime levels, but all that is gone.
In its place is a winter-like pattern, caused by a large buckling of the jet stream over the eastern half of the country.
A low-pressure system, responsible for Friday’s rain across the region, is expected to push eastward, allowing cold high pressure to settle in from Canada. High temperatures are only expected to reach the low 50s Saturday, which is mid-January levels.
That will be followed by the coldest night so far this season, forecasters say.
Originally, computer guidance indicated overnight lows would be near freezing, but the National Weather Service’s Jake Wimberley says it now appears temperatures will be even colder.
“A freeze is looking increasingly likely for most of our zones, where the growing season is still considered active,” Wimberley said.
That means readings in the upper 20s are likely Sunday morning, with afternoon highs barely reaching 50.
On the heels of that cold air will be a storm system, expected to develop late this weekend in the Gulf of Mexico and move northward Monday and Tuesday.
The system will spread rain into the Rock Hill area by midday Monday, lasting about 24 hours.
Rainfall from that system could total between 1 and 2 inches, according to computer guidance.
Once the storm system moves up the coast, another surge of cold air will follow.
High temperatures Wednesday and Thursday are not expected to climb out of the 40s, despite sunny skies, forecasters say.
The longer-range computer guidance indicates a trend toward milder weather arriving sometime during Thanksgiving week.
Steve Lyttle on Twitter: @slyttle