Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 429 AM EDT Thu Mar 30 2017 Valid 12Z Thu Mar 30 2017 - 12Z Sat Apr 01 2017 ...Severe thunderstorm potential today across much of the Ohio Valley and points southward to the Gulf Coast... ...Heavy snow likely for the Northern/Central Rockies, Great Basin and Wasatchs... ...Heavy rain possible for areas east of the Mississippi River... Widespread showers and thunderstorms are forecast for much of eastern half of the U.S. over the next couple of days as a robust low pressure system tracks eastward across the Midwest and through the Tennessee/Ohio valley today, reaching the Atlantic Coast by Friday evening. The Storm Prediction Center continues to identify conditions favorable for severe thunderstorm development across much of the Ohio Valley southward to the Gulf Coast today and tonight. The highest threat (Enhanced Risk) will extend from the southern half of Illinois and Indiana and Ohio, southward across the western Tennessee Valley and into Central Mississippi during this time. These outlined areas will be located nearest to the approaching cold front and will experience the best lift/instability. Additionally, some of these storms may produce heavy rainfall; which may increase the threat for flash flooding. Refer to SPC's Convective Outlooks and WPC's Excessive Rainfall Outlooks for specific details. This system is expected to reach the Appalachians/Mid-Atlantic region by Friday morning and will usher in showers and thunderstorms across this region beginning tonight. A mix of rain and snow may develop over parts of the Upper Great Lakes today and tonight, while a wintry mix of rain, snow, and ice is expected across the northeast starting tonight and continuing over the next couple of days. Winter Storm Watches and Winter Weather Advisories are currently in effect for portions of the Northeast as a result. Meanwhile, upper-level energy will continue to dig southward across the western U.S. today and tonight. At the surface, a series of low pressure system and frontal features will continue their track inland, reaching the western edge of the Central and Northern Rocky Mountains by this afternoon/evening. A stream of moist onshore flow will result in rain and higher elevation snow for the Pacific Northwest inland into the Central and Northern Rockies during this time, with snow expected to continue overnight. Snow, potentially heavy, will persist across the highest elevations of the Northern/Central Rockies and the northern portion of the Great Basin Friday night into Saturday. Winter Weather Advisories and Warnings are in effect for portions of the Bitterroots, and the Uinta and Wasatch Mountains. Flood Statements are also in effect for large portions of Idaho. The system is expected to split as it continues eastward from the Rockies during the day Friday, with one section moving into the north-central U.S., and another into the south-central U.S. The southern system will be the focus for more rain and thunderstorm development across the Southern Plains as we head through Saturday and into Sunday. Wix/Campbell Graphics available at www.wpc.ncep.noaa.gov/basicwx/basicwx_ndfd.php