Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 247 AM EST Wed Jan 24 2024 Valid 12Z Wed Jan 24 2024 - 12Z Fri Jan 26 2024 ...Heavy rainfall and concerns for flash flooding for portions of the Lower Mississippi Valley, Tennessee Valley and Gulf states through Friday morning... ...A swath of freezing rain and some accumulating snowfall will impact portions of the Midwest, Lower Great Lakes, and the Northeast... ...Much milder air with temperatures surging well above normal can be expected through the middle of the week for much of the eastern half of the country... Repeated rounds of convection is expected across the south-central U.S. as a low pressure system tracks east through the Lower Mississippi Valley through the end of the week. Deep moisture transporting northward from the Gulf of Mexico along with upper level support for continued lift and instability will be conducive for moderate to heavy downpours from the Southern Plains, Gulf states, Mississippi/Tennessee Valleys and the Southeast. The eastward progression of this frontal boundary will be slow so the threat for excessive rainfall and associated flooding will remain elevated. A Moderate Risk of excessive rainfall is in effect for areas including eastern Texas, Louisiana and southern Mississippi through Thursday morning. The swath of precipitation will shift eastward with the potential for training within a rich moisture environment. A Slight Risk for excessive rainfall is in effect for portions of the Gulf states and the Southeast Thursday and Friday. Elsewhere, a deep low pressure system will spread Pacific moisture across much of the Northwest leading to coastal rainfall and mountain snow for much of the Pacific Northwest and northern California. To the north of this system warm air advection into the Midwest and Great Lakes will promote freezing rain and snow showers for those areas today before spreading into the Northeast on this afternoon/evening with light accumulations expected. The aforementioned warm air advection caused by the emerging storm system in the Gulf Coast/Southeast and the deepening upper low over the Southwest powering it will promote a significant warming trend across the Midwest and East Coast through the end of the work week. There will be a lot of snow melt across the Midwest, Mid-Atlantic and Northeast this week with highs well into the 40s and 50s and lows 40-50 degrees above average in many places. These anomalous low temperatures will likely break many records, particularly east of the Mississippi Wednesday and Thursday night. Campbell Graphics available at https://www.wpc.ncep.noaa.gov/basicwx/basicwx_ndfd.php