Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 347 PM EDT Sun Apr 18 2021 Valid 00Z Mon Apr 19 2021 - 00Z Wed Apr 21 2021 ...Snow to spread across Rockies, Plains and Middle Mississippi Valley over the next couple of days... ...Heavy showers and thunderstorms continue across northern/central Florida... A surge of cold air from Canada entered Montana early this morning. The cold surge will bring rapidly falling temperatures as well as a quick burst of snow down across portions of the northern Rockies to the High Plains tonight and into Monday, followed by the central Rockies and central High Plains by Monday evening. The highest snowfall amounts are forecast to occur along the Bighorn Mountains of north-central Wyoming, where over a foot of snow is possible. Other mountain peaks from northwest Montana to Wyoming, as well as the Black Hills of Wyoming and South Dakota, could see snowfall accumulations of over 6 inches. Winter Storm Warnings and Winter Weather Advisories have been issued. Light snow could extend as far east as the Middle Mississippi Valley and Midwest as a low pressure wave develops along the front and moves across the region. Meanwhile, active weather is expected to linger across northern to central Florida where a front will become nearly stationary. Occasional showers, heavy at times, together with embedded thunderstorms can be expected to continue through Tuesday. A few storms could turn severe. In addition, flash flooding will be a concern due to upwards of 5 inches of rain forecast to fall across northern/central Florida during the next few days. A Marginal Risk of Excessive Rainfall has been issued to highlight the potential hazard. Much of the lower 48 will experience below average temperatures over the next few days. The only exceptions will be found across southern Florida, New England, and along the West Coast where above normal temperatures remain locked in place. Avalanche Warnings are in effect for the Olympic mountains and Washington Cascades as a result of the heat and sunny conditions. A freeze watch is in effect for much of Kansas, Oklahoma as well as northwestern Arkansas due to the unusual cold surge forecast to arrive on Tuesday. Finally, residents in parts of the interior western U.S. as well as southern California should beware of an elevated risk of wildfire during the next couple of days. Red Flag Warnings were issued for parts of central/southern Utah into western Colorado. Kebede/Kong Graphics available at www.wpc.ncep.noaa.gov/basicwx/basicwx_ndfd.php