Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 426 PM EDT Sun Mar 26 2017 Valid 00Z Mon Mar 27 2017 - 00Z Wed Mar 29 2017 ...There is a moderate risk of severe thunderstorms over portions of the Southern Plains... ...Rain/freezing rain possible over parts of the Northeast... ...Heavy rain and snow across the Northwest U.S. through Monday... A complex system will impact much of the Central/Lower plains and eastern U.S. over the next couple of days. Two main low pressure systems will be in play: the first will move across the Upper Great Lakes tonight and into Southeast Canada Monday as it continues to weaken, and the second will continue to strengthen as it moves across the Southern Plains tonight, and into the Mid/Lower Mississippi Valley Monday. This second system will eventually traverse the Ohio Valley Monday night, before reaching the Atlantic Coast by Tuesday. A series of frontal boundaries will connect these two systems, and will be the epicenter for precipitation and convective activity. In the northeast U.S., precipitation will be in the cold sector of the northern most low pressure system, falling as a freezing rain over the next couple of days. Freezing Rain Advisories and Winter Weather Advisories are in effect from far eastern New York upwards through Maine. Widespread rain, heavy at times, and scattered thunderstorms will occur from the Mid Atlantic to the Upper Great Lakes tonight into Monday on the warm side of the low pressure system, especially along the frontal boundary regions. This will eventually dissipate throughout the day Monday as the system continues to weaken and move northeast. For the strengthening Southern Plains system, showers and thunderstorms are also expected generally just ahead of the associated cold front. Given the strong nature of this system, and the strong pull of warm and unstable air flowing in off the Gulf of Mexico, this will combine with ample lift along the frontal boundary and low pressure system, creating the ingredients necessary to produce strong to severe convection. The Storm Prediction Center has outlined a portion of south central Oklahoma and a small portion of northeast Texas as being in an enhanced risk for severe weather this evening and overnight, with an enhanced and slight risk expanding farther to encompass much of Oklahoma, portions of Northeast Texas, and far eastern Oklahoma. High winds, large hail, and tornadoes are all possible hazards as storms develop. Please refer to the Storm Prediction Center's web page for more information: www.cps.ncep.noaa.gov. The area of concern will shift eastward by Monday, with much of the western Ohio and Tennessee Valleys being outlined in a slight risk for severe weather during this time. Over the West Coast, a low pressure system and occluded surface cold front will move onshore this evening, continuing to move eastward to the Rockies by Monday evening. The system will produce rain and higher elevation snow over parts of the Pacific Northwest/Northern California this evening and overnight, spreading inland and affecting parts of the Great Basin on Monday, then reaching the Central Rockies/Southwest by Monday evening. Onshore flow will keep precipitation in place across much of the Pacific Northwest over the next couple of days. Winter Weather Advisories are in effect for the highest elevations of the Cascades and the northern half of the Sierra Nevadas where some locations could see in excess of 10 inches of total snowfall. The area of low pressure will eventually sink southeast into the Central and Southern Plains Tuesday into Wednesday, once again tapping into warm and unstable air flowing inland from the Gulf of Mexico. This combination may result in another round of showers and thunderstorms, some of which could be strong to severe Tuesday and heading into mid-week. Wix Graphics available at www.wpc.ncep.noaa.gov/basicwx/basicwx_ndfd.php