The National Weather Service in State College has upgraded to a flash flood warning for parts of Lancaster County and other parts of central Pennsylvania.
The warning began at 3:18 p.m. today and goes until 6:15 p.m.
The weather service says radar has "indicated repeated development of thunderstorms producing persistent heavy rain across the warned area. Up to two inches of rain has already fallen. Flash flooding is expected to begin shortly."
Some locations that will experience flooding include: Elizabethtown, Denver, Mount Gretna Heights, Lawn, Kleinfeltersville, Reinholds, Schoeneck, Penryn, Mount Gretna and Three Mile Island.
A flash flood warning means that flooding is imminent or occurring, the weather service said. "If you are in the warned area move to higher ground immediately. Residents living along streams and creeks should take immediate precautions to protect life and property," the weather service said.
The county had earlier been under a flash flood watch.
"Heavy showers and thunderstorms will push through the region this afternoon and evening," the weather service said.
The possible torrential downpours pose the highest risk.
Thursday's high will be 85 with temps dipping down to 71 tonight.
There's an 80% chance of rain today, with scattered showers in the morning and possible thunderstorms to start this afternoon, mainly after 1 p.m.
Temps will continue to build this week, with highs staying in the upper-80s.
After today's storms, the county should see a string of sunny days.