Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 259 AM EST Mon Mar 06 2017 Valid 12Z Mon Mar 06 2017 - 12Z Wed Mar 08 2017 ...Heavy snow will continue today across portions of the Pacific Northwest, California, and the Intermountain West... ...Widespread showers and thunderstorms possible for much of the eastern U.S. over the next couple of days... Continued onshore flow across the Pacific Northwest will promote more snow showers today well into the Intermountain West. These will slowly taper off throughout the day and overnight. Winter Storm Warnings and Winter Weather Advisories remain in effect for portions of the northwest U.S. through today for continued snow concerns. Meanwhile, a low pressure system continues to gain considerable strength as it moves into the Northern Plains this morning. This low will shift northeast into the Upper Mississippi Valley this evening, and then South Central Canada overnight. An extensive cold front associated with this low will push eastward across much of the central U.S. throughout the day, then across the Mississippi Valley and Southern Plains tonight. It will then continue eastward, reaching the Atlantic Seaboard by Wednesday morning. Strong return flow along the back side of a departing high is allowing a warm moist air to flow northward from the Gulf of Mexico through the Mississippi Valley Region. This is sparking scattered showers and thunderstorms across much of the southeast U.S. As the cold front approaches today, this warm, moist, and unstable flow will be further enhanced, causing more widespread shower and thunderstorms for much of the Mississippi River Valley this evening, then pushing eastward ahead of the cold front overnight and into Tuesday. Much of the northern plains can expect precipitation in the form of a wintry mix of rain, snow, and sleet, transitioning to all snow today. Winter Weather Advisories are in effect for portions of the Northern Plains. Wix Graphics available at www.wpc.ncep.noaa.gov/basicwx/basicwx_ndfd.php