Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 231 AM EST Tue Mar 08 2016 Valid 12Z Tue Mar 08 2016 - 12Z Thu Mar 10 2016 ...Severe thunderstorms and flash flooding possible for portions of the southern plains and lower/middle Mississippi valley... ...Rain and mountain snow expected for northern California and the Pacific Northwest... ...Well above average temperatures expected from the Midwest to the Northeast... A large and anomalous upper-level low is digging into northern Mexico this morning, and will slowly move southeastward through the next couple days. At the surface, a low pressure system associated with the upper-low will move into western Texas by late this afternoon. A warm, moist, and unstable air mass across the southern plains and Mississippi valley ahead of this system will result in the development of widespread showers and thunderstorms today from the southern plains to the Great Lakes. Some thunderstorms may become severe across portions of the southern plains, where the Storm Prediction Center is forecasting a slight to enhanced risk of severe thunderstorms. Additionally, flash flooding is possible across portions of the southern plains and lower Mississippi valley. On Wednesday and Thursday, the axis of shower and thunderstorm activity will shift slightly eastward each day, with many of the same areas receiving widespread showers and thunderstorms. Excessive rainfall amounts of 5 to 10 inches, with locally higher amounts, are forecast across portions of the western Gulf Coast, southern plains, and lower Mississippi valley through Thursday morning, with additional rainfall possible during the day on Thursday. The potential for multiple days of heavy rainfall across the southern plains and lower Mississippi valley will result in an increasing threat of flooding and flash flooding through mid-week. A cold front will spread rain and mountain snow into the Pacific Northwest and northern California today. This system will weaken tonight into early Wednesday morning as it moves inland, bringing scattered areas of rain and snow to the Intermountain region. During the day on Wednesday, a stronger Pacific low pressure system will approach the northwestern U.S., once again spreading rain and mountain snow into the region. This round of precipitation will continue into Thursday. High pressure at the mid and upper-levels of the atmosphere will promote well above average temperatures through the next couple days from the Midwest to the Northeast. Afternoon high temperatures today are forecast to be 15 to 30 degrees above average across the Midwest and portions of the Mid-Atlantic. The warm temperatures will expand into the New England on Wednesday. Ryan Graphics available at www.wpc.ncep.noaa.gov/basicwx/basicwx_wbg.php