Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 355 PM EDT Sun Oct 22 2017 Valid 00Z Mon Oct 23 2017 - 00Z Wed Oct 25 2017 ...Widespread rain and thunderstorms for the eastern half of the nation through the start of the workweek... A cold front currently moving through the Upper Great Lakes to the Lower Mississippi Valley will continue to track eastward over the next couple of days. Plenty of moisture, a strong upper-level trough, and the front will help lead to widespread rain with some thunderstorms along and ahead of the front. Sunday night, thunderstorms containing heavy rainfall that could cause flash flooding are possible along the Central Gulf Coast and portions of the Southeast. On Monday, the front will linger through the Upper Great Lakes region but progress eastward through the Ohio Valley and Southeast. A slight risk of flash flooding is in effect for Monday and Monday night for parts of the Tennessee Valley and the Southern and Central Appalachians. By Tuesday, the front will push into the Mid-Atlantic, causing increasing rain and thunderstorm chances there and in the Northeast. Ahead of this front, the Mid-Atlantic and Northeast will have temperatures 10-15 degrees above average. Rainfall that could be heavy in some areas will linger in the Pacific Northwest on Sunday night as moist air from an atmospheric river continues to funnel into the area. The atmospheric river is expected to weaken and lift northward out of the area by Monday as an upper-level ridge builds in, so the Northwest is forecast to have quieter weather on Monday and Tuesday. A quickly moving low pressure system will make its way through the northern tier of the country over the next couple of days, before combining with the stronger frontal system moving through the East on Tuesday. The tail end of a cold front associated with this low pressure system will help cause lingering rain and snow showers for the Northern Rockies on Sunday night. The low is expected to produce rain showers for the Northern Plains to Upper Mississippi Valley on Sunday night and Monday. High wind is possible behind this system for the Northern High Plains. Very hot temperatures in the 90s and 100s for highs will combine with dry conditions and gusty winds to produce fire weather concerns for the central and southern portions of the California coast. The rest of the West will be warmer than average as well, with temperatures 10-15 degrees above average in most areas by Tuesday. Tate Graphics available at www.wpc.ncep.noaa.gov/basicwx/basicwx_ndfd.php