Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 405 PM EDT Thu May 27 2021 Valid 00Z Fri May 28 2021 - 00Z Sun May 30 2021 ...A deep low pressure system will bring moderate to heavy showers and thunderstorms to much of the eastern and southern US before moving offshore Saturday evening... ...Enhanced risk of strong to severe thunderstorms and moderate risk of excessive rainfall over portions of the southern Plains and Middle Mississippi Valley through Friday morning... ...Cold spell in store for the Midwest, Ohio Valley and Northeast to start off Memorial Day weekend.. Showers and thunderstorms will continue throughout the southern Plains and Mississippi Valley overnight, spreading eastward as a low pressure system moves across the Midwest. Several of these thunderstorms are anticipated to become severe, bringing with them significant damaging winds, very large hail, and potentially a few tornadoes. At present, the Storm Prediction Center has issued an enhanced risk of severe weather for portions of northern Texas, Oklahoma, southwest Missouri, and northwest Arkansas. In addition to the severe weather threat, heavy downpours from multiple rounds of thunderstorms could result in flash flooding. The Weather Prediction Center has issued a moderate risk of excessive rainfall for portions of northeast Oklahoma, southwest Missouri, and northwest Arkansas through Friday morning. Pushed to the south and east by a descending area of Canadian high pressure, the system and its trailing cold front will reach the Gulf and East Coasts by Friday afternoon. Thunderstorms developing over the Mid-Atlantic and southwestern Plains could become severe, producing damaging winds a large hail. Meanwhile, moderate to heavy rain will is forecast to fall over southern New England on Saturday. The aforementioned Canadian high pressure system will also drive the southern transport of cold arctic air into the Midwest, Ohio Valley and Northeast early this weekend. On Friday and Saturday, daily highs across these regions will likely drop as much as 15 to 20 degrees below normal into the 50s and 60s. Over portions of the Upper Midwest and northern New England tonight's lows are forecast to drop to near or below freezing, promoting the issuance of Freeze Warnings and Watches and Frost Advisories for some areas through tomorrow morning. Elsewhere, a low pressure system moving through the Northwest is forecast to bring rain to the Pacific Northwest and Northern Rockies, some of which may transition into mixed precipitation or wet snow at higher elevations overnight and early Friday as temperatures drop behind a cold front. Friday night showers and thunderstorms are expected to develop across the north and central High Plains before moving east into the northern Plains and Upper Midwest on Saturday. Meanwhile, the formation of new low pressure center over southeast Colorado Saturday evening will bring widespread showers and thunderstorms to the central and southern Rockies and portions of the western Plains. Zavadoff Graphics available at www.wpc.ncep.noaa.gov/basicwx/basicwx_ndfd.php