Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 251 AM EST Sun Nov 27 2016 Valid 12Z Sun Nov 27 2016 - 12Z Tue Nov 29 2016 ...Heavy rain possible over parts of the Lower/Middle Mississippi Valley and parts of the Tennessee Valley... ...Heavy snow possible over the Cascades and Sierras... ...Snow possible over the Rockies into Great Basin and Mogollon Rim... ...Temperatures will be 15 to 20 degrees above average over the Northern/Central Plains and Upper Mississippi Valley... A progressive system will track through the western states, cross the Rockies and traverse through the central U.S. over the next few days. Another system will follow suit from the Pacific Northwest and will plunge through the central/southern Rockies into the southern Plains by midweek - which will reinforce the cooler airmass and precipitation. Much of the West will have mountain snow and valley rain during this time. Gulf moisture streaming northward into the Plains will feed into the approaching system. Strong to severe thunderstorms, along with heavy rainfall, will be possible on Monday for the central Gulf coast and Middle/Lower Mississippi valley. The threat for flash flooding will be elevated across this region. Please refer to SPC for additional information on the threat for severe thunderstorms. Showers and thunderstorms will develop ahead of the front over the central and southern Plains on this afternoon into evening before spreading eastward into parts of the Mississippi Valley and Upper Great Lakes/Western Ohio Valley by Monday. Snow will develop on the northwest side of the precipitation shield late tonight into Monday over parts of the Northern/Central Plains. For the East, snow and rain over parts of the Great Lakes into the Northeast will end by this afternoon and over the Northeast tonight as low pressure off the New England Coast continues to move further away. Easterly flow off the Atlantic will aid in producing showers and thunderstorms over southeastern Florida through Monday. Campbell Graphics available at www.wpc.ncep.noaa.gov/basicwx/basicwx_ndfd.php