Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 359 PM EDT Tue Sep 25 2018 Valid 00Z Wed Sep 26 2018 - 00Z Fri Sep 28 2018 ...Widespread rain and thunderstorms are forecast in the eastern third of the U.S., ahead of a strong cold front... An upper-level trough centered over the central U.S. will make its way slowly eastward over the next couple of days. As it does so, it will push a strong cold front currently located in the Upper Midwest through the Middle Mississippi Valley and into the Southern Plains south and eastward. Moisture will stream ahead of the front, leading to widespread rain and thunderstorms from the Southern Rockies to the Northeast U.S. Some areas could see flash flooding and severe weather from these storms. More specifically, there is a Slight Risk of excessive rainfall/flash flooding through Tuesday night for parts of the Tennessee and Ohio Valleys, as well as for portions of the Northeast. Wednesday and Wednesday night's highest threat for flash flooding will be in the Tennessee Valley and Southern Appalachians. Slight Risks of severe weather cover parts of the Upper Midwest, Upper Great Lakes, and Ohio Valley regions through Tuesday night. The risk shifts east with the front on Wednesday, with a Slight Risk of severe weather in place in the Mid-Atlantic region and Northeast. Temperature-wise, the cold front will separate cooler than average temperatures north and west of the front from warmer than average temperatures to the south and east. As mentioned, ahead of the front, warm and moist air will stream into the Southeast, Ohio Valley, and Eastern Seaboard. Many record warm minimum temperatures could be set on Wednesday morning. High temperatures along the Eastern Seaboard will be around 10 degrees above normal on Wednesday before the front passes. Behind the front, high temperatures will be widespread in the 60s to lower 70s. Temperatures in the Southern High Plains may not get higher than the 50s on Wednesday, however, which is 20 to 30 degrees below normal! The western U.S. will be warmer than average, under the influence of an upper-level ridge. High temperatures of 10 to 15 degrees above normal will be widespread there. Warm temperatures plus low humidity will lead to elevated fire danger in northern California in particular. Another frontal system is forecast to drop southeastward into the north central U.S. on Wednesday and Thursday. This will help cause rain showers in the Northern Plains and into the Upper Midwest. Snow showers are expected to mix in on Thursday in the Northern High Plains behind the cold front. That second shot of cool air will lead to high temperatures in the 40s and 50s there on Thursday. Tate Graphics available at www.wpc.ncep.noaa.gov/basicwx/basicwx_ndfd.php