Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 340 AM EDT Sat Apr 21 2018 Valid 12Z Sat Apr 21 2018 - 12Z Mon Apr 23 2018 ...Heavy rain possible over parts of the Southeast, Tennessee Valley, Lower Mississippi Valley, and Southern Plains... ...Heavy snow possible over parts of the Northern Rockies... ...Temperatures will be 10 to 20 degrees below average over parts of the Central/Southern Plains... A storm over the Southern High Plains will move eastward to parts of the Lower Mississippi/Tennessee Valleys by Sunday evening. The system will produce snow over parts of the Central Rockies that will end by Saturday evening. In addition, showers and thunderstorms will develop over parts of the Southern Plains that will move eastward into the Lower Mississippi Valley and the Central Gulf Coast by Sunday morning. By Sunday evening, the showers and thunderstorms will move into parts of the Southeast/Eastern Gulf Coast. Rain will also develop over parts of the Central Rockies and Central/Southern Plains that will move into parts of the Middle Mississippi and Tennessee Valleys by Sunday morning. The rain will also move into parts of the Ohio Valley and the Southeast by Sunday evening. Furthermore, southeasterly flow off the Atlantic will aid in producing showers and thunderstorms over Florida through Sunday evening into Monday. Meanwhile, a front over parts of the Pacific Northwest/Northern Intermountain Region will move eastward to the Northern Plains into the Northern Rockies by Sunday evening. The system will produce rain and higher elevation snow over parts of the Pacific Northwest into parts of the Northern Intermountain Region that will taper off by Saturday evening. Upper-level energy over the Eastern Pacific will move onshore over the Pacific Northwest on Sunday morning continuing to the Northern Intermountain Region by Sunday evening. The energy will aid in producing scattered rain over parts of the Northern Intermountain Region on Sunday evening. Ziegenfelder Graphics available at www.wpc.ncep.noaa.gov/basicwx/basicwx_ndfd.php