Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 300 PM EST Thu Feb 07 2019 Valid 00Z Fri Feb 08 2019 - 00Z Sun Feb 10 2019 ...Heavy snows should come to an end late tonight across the Upper Great Lakes, with heavy rainfall possible in the Ohio and Tennessee Valleys... ...Big temperature swings expected as the arctic front sweeps eastward Thursday from the Southern Plains into the Mid to Lower Mississippi Valley and Ohio Valley and across the Eastern Seaboard on Friday... ...Accumulating snowfall possible across much of the Western U.S. with significant accumulations possible near Seattle... A deepening area of low pressure currently located in the Upper Great Lakes region, will continue moving northeastward into eastern Canada by early Friday. Expect heavy snowfall to continue to the north and west of the low tonight, with blizzard conditions possible as gusty winds accompany this system. South of here, a strong cold front will push through the Ohio Valley this evening, with heavy rainfall and thunderstorms possible along and ahead of the boundary. Flash flooding and isolated severe thunderstorms remain a threat into this evening. Warm air surging northward ahead of the cold front will continue to support well above normal temperatures across much of the Eastern Seaboard tonight, but expect temperatures to drop quickly back to near normal values during the day on Friday following the passage of the cold front. Strong surface high pressure dropping into the Central U.S. behind the Eastern U.S. system will allow for a much below normal airmass to filter into the Plains region and eastward towards the Midwest and Ohio Valley. The coldest spot is expected to be across the Northern Plains where high temperatures are forecast to stay below zero into this weekend. Across the Midwest, and as far south as Texas, temperatures could be as much as 10 to 20+ degrees below normal Friday and into Saturday. The Western U.S. should stay active through much of the short range period as a series of upper level systems affects the region. Snow levels will be falling as a strong mid-upper level low strengthens and drops into the Pacific Northwest by this weekend. While the heaviest snow accumulations will be in the higher terrain of the Cascades and into the Sierra Nevada, accumulating snowfall is also possible at the lower elevations too, including Seattle and Portland. Winter storm warnings are in effect for the greater Seattle region for 6+ inches of snow in some locations. Santorelli Graphics available at www.wpc.ncep.noaa.gov/basicwx/basicwx_ndfd.php