Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 319 AM EDT Sun Oct 22 2017 Valid 12Z Sun Oct 22 2017 - 12Z Tue Oct 24 2017 ...Large storm system to affect the eastern half of the nation... Heavy rain and high elevation snow will be the main weather story across the Pacific Northwest and northern Rockies through Sunday morning as a strong low pressure system tracks eastward across the region. This atmospheric river will likely result in several inches of rainfall across parts of western Oregon and Washington, with some locations getting in excess of five inches as a storm total before the event is over by Sunday night. Conditions will improve markedly by Monday and Tuesday as a strong upper level ridge builds in, displacing the active storm track well into Canada. The cold front currently tracking across the Mississippi River valley and Texas will continue tracking eastward. Although the worst of the severe weather threat has ended, some strong to severe storms will still be possible across parts of the Deep South on Sunday. With a wave of low pressure developing along this front over the lower Mississippi River valley, moisture inflow from the Gulf of Mexico will be enhanced and this could lead to areas of heavy rainfall from Mississippi to the southern Appalachians. Elsewhere across the continental U.S., expect mild to warm weather to continue across the east with widespread 70s for highs through Monday before cooler conditions arrive by the middle of the week. Fire weather concerns will continue across parts of California over the next few days with very dry conditions and gusty winds expected. A big heat wave is also in the forecast for southern California, with widespread 90s and 100s expected through Tuesday. D. Hamrick Graphics available at www.wpc.ncep.noaa.gov/basicwx/basicwx_ndfd.php