An unusually strong dip in the jet stream for early July will bring much cooler temperatures to the Rock Hill area and the rest of the Carolinas for the weekend.
Then the heat will return.
National Weather Service forecasters say temperatures won’t climb above the low and mid 80s Saturday and Sunday, and some much-needed rain also is predicted.
The dip in the jet stream will allow a cold front to move into the region Friday. Scott Krentz, of the National Weather Service office in Greer, says the front’s arrival will be preceded by what he calls “a busy convective day” across the region. Convection is the process by which clouds build into showers and thunderstorms, and Krentz says much of the area could see that activity Friday afternoon and evening.
The rain would be welcome.
More than 3.3 inches of precipitation was reported in June at the Rock Hill airport, which is just a bit below average. But about 40 percent of that fell in the first few days of the month. A heat wave and low rainfall over the past three weeks has left area lawns and gardens thirsty.
Highs are expected to reach the low 90s Thursday and Friday.
The cold front is expected to move slowly southward Saturday, and its plodding pace will allow showers to remain in the forecast much of the day. High pressure over New England will send a northeast breeze into the Rock Hill area, and temperatures are only expected to reach the lower 80s.
That will be a big turnaround from recent conditions. Temperatures have hit or exceeded 90 six straight days (through July 4) in Rock Hill and have reached that mark 18 of the past 21 days.
Sunday is expected to be a very nice day, with sunshine, low humidity, and a high around 85 degrees. After another nice day Monday, with low humidity and a high of 88, the heat is forecast to return Tuesday.
Krentz says high pressure is expected to build early next week over the Ohio Valley. He said that will send temperatures back into the low and mid 90s, but humidity levels will remain low.
“It will make for hot but not too uncomfortable conditions for July,” Krentz says.
Steve Lyttle on Twitter: @slyttle