Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 407 AM EDT Sat Apr 05 2025 Valid 12Z Sat Apr 05 2025 - 12Z Mon Apr 07 2025 ...Life-threatening, catastrophic, and potentially historic flash flood event continues from the Lower Ohio Valley and Mid-South to the ArkLaTex through Saturday... ...Severe weather risks continue for parts of the Ohio, Tennessee, and Lower Mississippi Valleys Saturday and portions of the southern Appalachians and Southeast Sunday... ...Moderate to locally heavy snow showers expected for the Southern Rockies and Southern High Plains Saturday... ...Highly amplified flow pattern brings large temperature swings across the U.S. the next several days... Several waves of low pressure acting on a nearly stationary frontal boundary will continue to be the focus for life-threatening flash flooding from the Lower Ohio Valley to the Mid-South to the ArkLaTex through Saturday. Deep moisture pooling along the front combined with impressive dynamics will set the stage for persistent rounds of intense thunderstorms capable of producing torrential downpours throughout the region. This will especially be the case for the Ozarks and Mid-South, where the best moisture, instability, and forcing overlap. Storm initiation and movement roughly parallel to the boundary will continue to lead to repeated rounds of heavy rainfall over the same hard-hit areas, leading to significant to extreme, potentially historic, rainfall totals over increasingly saturated soils. A High Risk (at least 70%) of Excessive Rainfall remains in effect through Saturday, highlighting an increasingly dangerous and life-threatening situation. Outside of the High Risk, Moderate and Slight Risks also continue to be in place over broader areas of the Ohio Valley into the south-central U.S. where scattered to numerous instances of flash flooding can be expected. As has been said repeatedly for the last several days, this has the makings of a catastrophic, potentially historic heavy rainfall and flash flood event, with some locations potentially seeing rainfall amounts as high as 10-20" when all is said and done. The repeating rounds of heavy rainfall will also likely cause many rivers to exceed their banks, with the potential for catastrophic major flooding across the Ozarks, portions of the Lower/Middle Mississippi Valleys, and the Lower Ohio Valley. Unfortunately, the risk of major river flooding will likely continue into early next week, long after the last drop of rain has fallen. The stalled frontal boundary finally begins to move late Saturday into Sunday, taking the axis of heaviest rainfall along with it. With the front on the move, the focus for heavy rainfall shifts eastward into parts of the Southeast on Sunday. While the increasingly progressive nature of the front should help to reduce the flooding threat overall (especially compared to the last few days), substantial moisture along the front will still support downpour producing thunderstorms that are capable of flash flooding. As a result, a Slight Risk (at least 15%) remains in place. The threat of excessive rainfall wanes considerably by Monday, with only a Marginal Risk (at least 5%) in effect along the Southeast U.S. coastline. Severe weather continues to be a concern this weekend with additional risks forecast from the ArkLaTex to the Ohio Valley on Saturday and across the southern Appalachians and Southeast on Sunday. Given plentiful moisture, instability, forcing, and wind shear, the parameters are in place for another day of damaging wind gusts, large hail, and several tornadoes across the region. As a result, the Storm Prediction Center maintains an Enhanced Risk (level 3/5) from eastern Texas to western Tennessee. A broader Slight Risk is in place from Texas through the Lower Ohio Valley. On Sunday, the severe weather threat shifts eastward into parts of the southern Appalachians and Southeast. The Storm Prediction Center continues to highlight a Slight Risk (level 2/5) for the potential for severe thunderstorms capable of producing damaging winds and possibly a few tornadoes. An upper-level low spinning over top a chilly post-frontal air mass within upslope flow across the Southern Rockies and Southern High Plains will support moderate to locally heavy snow showers Saturday into early Sunday. Snowfall accumulations will mostly favor the higher mountain ranges across eastern New Mexico, though modest accumulations upwards of 3 to 6 inches are possible across the Texas Panhandle as well. The upper low ejects eastward on Sunday, allowing for some wet snow to fall across parts of Oklahoma, Kansas, and Missouri. Some light, minor accumulations on colder, elevated surfaces are possible. The highly amplified flow pattern across the United States will lead to large temperature swings over the next few days. Outside of the Northeast and northern Mid-Atlantic, temperatures across much of the Eastern U.S. will climb well above seasonal norms on Saturday. Meanwhile farther west, much colder than average temperatures will reside from the Upper Midwest to the Intermountain West and Southern Rockies. After several chillier than normal days, the West Coast will gradually begin to warm back above normal. Then Sunday into Monday, the chilly air mass over the Central and South Central U.S. spreads eastward, bringing an end to the above normal warmth across much of the East. Out West, the warming trend continues as warm anomalies continue to expand eastward into Intermountain West. Cooler than normal temperatures will remain in place across the Central U.S., with another cold front bringing a reinforcing shot of colder air into the northern Plains and Upper Midwest on Monday. Miller Graphics available at https://www.wpc.ncep.noaa.gov/basicwx/basicwx_ndfd.php