Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 338 PM EDT Fri Jul 28 2017 Valid 00Z Sat Jul 29 2017 - 00Z Mon Jul 31 2017 ...Heavy rain for parts of the East Coast through Saturday, followed by cooler conditions over the weekend... ...Heavy rain and flash flooding possible for portions of the Southern/Central Rockies and adjacent High Plains... Much of the Mid-Atlantic region have had periods of heavy rain since this morning, which has already caused some instances of rapid runoff, rising creeks and ponding of water on major roadways. Additional rainfall is expected through at least Saturday morning, which will maintain an elevated risk for excessive rainfall and areal flooding from the central Appalachians to southern PA and NJ. This particular swath may see another 2 to 5 inches. In the wake of the storm, temperatures will likely be cooler than average for a few days. Monsoonal moisture streaming into the Desert Southwest, Four Corners and Central/Southern Rockies will keep scattered showers and thunderstorms possible through the weekend. As this moisture interacts with a weak frontal boundary over the western High Plains the likelihood of higher rainfall will increase across eastern Colorado and northern New Mexico. A few instances of flash flooding may be possible. Initial thunderstorm activity should congregate across the local mountain ranges before migrating toward the valley floors and the central High Plains. Campbell Graphics available at www.wpc.ncep.noaa.gov/basicwx/basicwx_ndfd.php