Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 254 AM EST Tue Jan 23 2024 Valid 12Z Tue Jan 23 2024 - 12Z Thu Jan 25 2024 ...Heavy rainfall and concerns for flash flooding will exist through Thursday morning across the Lower Mississippi Valley... ...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 by the middle of the week for much of the eastern half of the country... Temperatures across a vast portion of the central and eastern U.S. will moderate as a series of storm systems from the Pacific Ocean cross the Southwest before ejecting east across the southern states. This pattern will be favorable for widespread area of unsettled weather for the Midwest, Ohio Valley, Great Lakes, Northeast, and large areas of the South through the middle of the week. Multiple waves of low pressure advancing along a slow-moving front across the Lower Mississippi Valley will encounter a resurgence of moisture and instability from the Gulf of Mexico which will aid in development of heavy showers and thunderstorms today through Thursday. Several inches is expected which will increase the threat for flooding across the South. The Weather Prediction Center has issued a Moderate Risk of excessive rainfall across portions of these areas, and locally significant flash flooding may be possible given the expectation of as much as 4 to 8 inches of rain going through Wednesday. The resurgence of warm air and moisture northward over the retreating cold air will foster areas of freezing rain today and into Wednesday across areas of the Midwest, Lower Great Lakes, and the Northeast. The cold air may still be deep enough to result in some accumulating snowfall as well, and especially for areas of Lower Michigan and southwest New York where a few inches of snow will be possible. For areas where freezing rain are expected, there may be as much as a tenth of an inch of ice accretion which will result in locally hazardous travel conditions. The Southwest will be cooler through midweek was the frontal systems pass through. The intrusion of Pacific air downstream across the central and eastern U.S., and southerly flow off the Gulf of Mexico, will result in considerably milder temperatures by midweek for the eastern half of the country. A few locations may have daily high temperatures as much as 20 degrees above seasonal average by Wednesday. Campbell/Orrison Graphics available at https://www.wpc.ncep.noaa.gov/basicwx/basicwx_ndfd.php