Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 338 PM EST Mon Nov 09 2015 Valid 00Z Tue Nov 10 2015 - 00Z Thu Nov 12 2015 ...Heavy rain possible across portions of coastal North Carolina... ...Heavy snow possible across the higher elevations of the Intermountain West... ...Severe thunderstorms and flash flooding possible across portions of the central U.S. on Wednesday... A very active weather pattern will evolve across the contiguous U.S. over the next couple days, with a series of weather systems poised to impact nearly every region of the country. A developing low pressure system along the southeast U.S. coastline this afternoon will move northeastward along the coast -- moving into the Mid-Atlantic region on Tuesday. This system, along with an incoming upper-level disturbance crossing the Ohio valley, will bring widespread rain to much of the eastern U.S. tonight through Tuesday night. Instability will be confined to the warm sector of the system, from the coast of the Carolinas south to Florida -- and a few thunderstorms are possible in these areas. In addition, heavy rain will be possible through tonight across coastal portions of the Carolinas, where 1 to 2 inches of additional rain is forecast to fall. This heavy rain may lead to flooding in some areas. An amplifying upper-level trough and the associated surface frontal system are moving across the Intermountain West this afternoon. This system is bringing snow to much of the Intermountain West this afternoon, and this will continue into Tuesday for most areas. As the upper-level system crosses the Rockies, a new surface cyclone will take form in the central High Plains late Tuesday, prolonging the potential snowfall for Colorado. 5 to 10 inches of snow are possible for much of the Intermountain West, with the highest elevations of the Rockies forecast to receive in excess of 1 foot of snow. As the new surface low deepens over eastern Colorado/western Kansas Tuesday night, the system will wrap colder air into the north side of it. This will change rain to snow across the High Plains, with 2 to 5 inches of snow possible in northeastern Colorado, including the Denver area. The low pressure system will continue to deepen over the central plains on Wednesday as it begins to pull ample moisture northward from the Gulf of Mexico across the central U.S. With a surface temperature contrast of more than 30 degrees across the frontal boundary in the central U.S. on Wednesday, along with a very dynamic low pressure system, the stage will be set for an active day with the potential for severe thunderstorms and flash flooding. The Storm Prediction Center is forecasting a slight to enhanced risk of severe thunderstorms across much of the lower and middle Mississippi valley as well as portions of the lower Ohio valley on Wednesday. In addition, the warm front and surface low will serve to focus the potential for heavy rainfall, with flash flooding possible on Wednesday across portions of the Upper Midwest. Finally, another Pacific cold front will move into the northwestern U.S. early on Wednesday. This will spread another round of rain and mountain snows into the Northwest. Ryan Graphics available at www.wpc.ncep.noaa.gov/basicwx/basicwx_wbg.php