* WHAT...Flash flooding caused by excessive rainfall is possible. * WHERE...A portion of central Pennsylvania, including the following areas, Adams, Bedford, Blair, Cambria, Clearfield, Columbia, Cumberland, Dauphin, Elk, Franklin, Fulton, Huntingdon, Juniata, Lancaster, Lebanon, Mifflin, Montour, Northern Centre, Northumberland, Perry, Schuylkill, Snyder, Somerset, Southern Centre, Southern Clinton, Southern Lycoming, Sullivan, Union and York. * WHEN...Through late tonight. * IMPACTS...Excessive runoff may result in flooding of rivers, creeks, streams, and other low-lying and flood-prone locations. Creeks and streams may rise out of their banks. Flooding may occur in poor drainage and urban areas. * ADDITIONAL DETAILS... - Scattered slow moving thunderstorms and locally heavy downpours will develop this afternoon and linger into this evening. Rainfall amounts could approach 2 to 3 inches in localized areas where slow moving storms persist the longest. - http://www.weather.gov/safety/flood