Just saw that. Here's the text from the NWS.
...FLOOD WATCH IN EFFECT FROM 2 PM EDT THIS AFTERNOON THROUGH THIS
EVENING...
* WHAT...Flash flooding caused by excessive rainfall is possible.
* WHERE...A portion of central Pennsylvania, including the following
counties, Adams, Cumberland, Dauphin, Franklin, Lancaster,
Lebanon, Schuylkill and York.
* WHEN...From 2 PM EDT this afternoon through this evening.
* IMPACTS...Excessive runoff may result in flooding of rivers,
creeks, streams, and other low-lying and flood-prone locations.
Flooding may occur in poor drainage and urban areas.
* ADDITIONAL DETAILS...
- Heavy showers and possible thunderstorms could train
northeast across the same locations leading to between 1 and
2 inches of rain in just 30 to 60 minutes. A few locations
could see rainfall totals in excess of 3 inches this
afternoon and evening.