Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 201 PM EDT Tue May 04 2021 Valid 00Z Wed May 05 2021 - 00Z Fri May 07 2021 ...Severe thunderstorm and flash flood threats will affect locations from the Lower Mississippi Valley to the Upper Ohio Valley and East Coast Tuesday night and early Wednesday... ...Cooler and quieter weather will translate eastward from the Mississippi River Valley to the Appalachians through Thursday, in the wake of a cold front... ...Dry and unseasonably warm temperatures continue in the West... Most of the active weather across the lower 48 will focus ahead of a cold front that extended from Lakes Erie and Ontario into the Lower Mississippi Valley as of Tuesday afternoon. Above average temperatures and ample moisture ahead of the cold front will support scattered to widespread thunderstorms from portions of the Ohio Valley to the Gulf Coast, some of which will be severe. The latest outlook from the Storm Prediction Center (SPC) supports the greatest threat for tornadoes, large hail and damaging straight-line winds from central Louisiana to portions of Mississippi, Alabama and Tennessee through Wednesday morning. Many of these same areas will also see scattered to numerous coverage of flash flooding from some of the more intense thunderstorms. The cold front will continue to move east through Wednesday, clearing the coast of New England late Wednesday evening, while stretching southwestward into the southeastern U.S. Thunderstorms ahead of the cold front will continue to pose a threat for severe weather for much of the East Coast on Wednesday, south of the Mason-Dixon line, but the threat will be reduced (Marginal Risk) in comparison to today's Enhanced Risk from SPC in place across the South. Cooler and drier weather will follow behind the cold front, from the Great Plains to the Mississippi River Valley for Wednesday, reaching the East Coast for Thursday. Across the western U.S., an upper level ridge will move eastward while strengthening over the next 36 to 60 hours. The result will be an expansion of above average temperatures on Wednesday from California and Nevada into Oregon and Washington. Temperatures will be roughly 10 to 20 degrees above average across the West Coast states into Nevada on Wednesday, with the anomalous warmth spreading eastward to the Continental Divide for Thursday. Chances for precipitation will also diminish during the day on Wednesday from the central Rockies to the northern High Plains. By Thursday morning, the coast of northern California into the Pacific Northwest will see a return of precipitation while also cooling down in the wake of a Pacific cold front. Otto Graphics available at www.wpc.ncep.noaa.gov/basicwx/basicwx_ndfd.php