.Severe Weather and Excessive Rainfall concerns for parts of the Central/Southern Plains and Mississippi Valley… …Critical Fire Weather potential over portions of the Southern High Plains today… …Cool and snowy in the Northwest; above average temperatures continue across much of the Central and Eastern U.S…. The month of May kicks off with severe weather and excessive rainfall threats over the Central U.S.. A developing low pressure system over the Central High Plains of Colorado will contribute to the initiation of scattered to isolated thunderstorms across the Great Plains today. The Storm Prediction Center issued an Enhanced Risk (level 3/5) of Severe Thunderstorms over parts of southwest Kansas into northwest Oklahoma this afternoon into the evening. A few tornadoes, very large hail and damaging winds are expected for the broader Central/Southern Plains region. The surface wave will lift into the Central Plains this evening and support enhanced rain rates over parts of northern Kansas, eastern Nebraska and western Iowa, where a Slight Risk (at least 15%) of Excessive Rainfall is in effect. Thunderstorms (some potentially severe) originating from a dryline in the Southern High Plains will grow as they propagate into a very moist environment in central and eastern Texas today. Given the saturated soils from recent heavy rainfall, a Moderate Risk (at least 40%) of Excessive Rainfall is in effect for portions of eastern Texas in between the Dallas and Houston metros this evening. Elsewhere, showers and thunderstorms should wrap up this afternoon across the Carolina/Southeast coast. Severe storms and excessive rainfall threats shift into the Mississippi Valley on Thursday as the low pressure system moves into the region. Scattered showers and thunderstorms will proliferate across the Central/Southern Plains and Mississippi Valley, where a Slight Risk of Excessive Rainfall is in effect. The MCS associated with tonight’s excessive rainfall threat will shift into the ArkLaTex region Thursday morning. An upper trough anchored over the Northwest will support below average temperatures across the region for the next few days. With cold air in place, an embedded shortwave impulse will contribute to high elevation snow across the Cascades and Northern Rockies. Between 6-12 inches of snow is forecast to accumulate with isolated higher amounts most likely over northwestern Montana by Friday morning. Temperatures will remain above average, for the most part, across the eastern half of the country through Friday before a cold front moderates things a bit heading into the weekend.