Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 400 PM EDT Tue Mar 30 2021 Valid 00Z Wed Mar 31 2021 - 00Z Fri Apr 02 2021 ...More heavy rain and scattered flash flooding possible for the lower Mississippi and Tennessee Valleys into tonight and Wednesday morning... ...Showers and thunderstorms moving through the East Coast on Wednesday will be followed rapidly falling temperatures on Thursday... ...Cold air funneling in behind a developing low pressure system will bring accumulating snowfall across Upstate New York while Santa Ana winds are expected to impact parts of California... The focus for much of the active weather during the next couple of days will be across the eastern U.S. as a low pressure wave is forecast to intensify rapidly along a strong cold front. This cold front is currently associated with a deep low pressure system moving across south-central Canada. Strong and gusty winds behind this system across the northern Plains will continue to diminish as the storm moves farther away into tonight. Temperatures 10 to 20 degrees below average will overspread much of the northern and central Rockies as well as the Plains on Wednesday but will make a sharp rebound to as high as the 70s on Thursday. Farther south, as the cold front pushes across the southern High Plains and the southern Rockies, gusty winds and low relative humidity could make conditions ideal for wildfires to spread uncontrollably. Meanwhile, a warm front lifting north out of the Gulf of Mexico today will usher in an abundance of moisture to the Lower Mississippi Valley, leading to an expansion of showers and thunderstorms as the aforementioned cold front approaches from the northwest. Heavy rain is forecast to spread across the Tennessee Valley by this evening and last into Wednesday morning. Total rainfall amounts of 1 to 3 inches could lead to flooding concerns from southern Arkansas to Middle Tennessee. Much of this region has experienced well above average rainfall over the last week. Any additional heavy rain will likely cause rivers to overflow their banks quickly. Low-lying areas prone to flooding are likely to see the most impacts. WPC has issued a Slight Risk of Excessive Rainfall that includes southern Arkansas, northern Mississippi, and west/central Tennessee. A few thunderstorms will also have the potential to produce damaging wind gusts and large hail. By Wednesday, showers and thunderstorms will slowly exit the Tennessee Valley and enter the Southeast and Mid-Atlantic. A few isolated instances of flash flooding will be possible from the southern Appalachians to the Mid-Atlantic. Severe weather will also be a concern for the Deep South on Wednesday, with a marginal chance up into the Mid-Atlantic. As the cold front reaches the Mid-Atlantic coast Wednesday evening, an area of low pressure is forecast to develop and strengthen as it swings northeast toward New England. This will help usher in much cooler temperatures behind the cold front, while also focusing moderate rain along the coast. Rain is likely to changeover to snow across interior portions of the Northeast and Lower Great Lakes as temperatures quickly drop to near and below freezing Wednesday night. A few inches of wet snow are expected by Thursday morning, mainly across western and northern New York State. Kong/Snell Graphics available at www.wpc.ncep.noaa.gov/basicwx/basicwx_ndfd.php