Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 400 PM EDT Mon Apr 17 2017 Valid 00Z Tue Apr 18 2017 - 00Z Thu Apr 20 2017 ...Periods of rain and high-elevation snow continue in the western U.S... ...Showers and thunderstorms expected from across the central Plains into the Great Lakes... ...Fine weather in the mid-Atlantic and Northeast will give way to showers and thunderstorms spreading in from the Southeast... The weather pattern will feature a mostly zonal flow with small disturbances moving across the country for the next couple of days. First of all the unsettled pattern continues to persist in the western U.S. as moisture from a couple of weakening Pacific cyclones moves across the region, with rain and high-elevation snow. The precipitation should last into Tuesday night before moving east into the northern Plains on Wednesday. This break in the precipitation appears short-lived as the next batch of precipitation is forecast to reach the West Coast during the day on Wednesday. The aforementioned moisture from the western U.S. will spread quickly into the northern Plains and the Great Lakes on Wednesday in advance of a developing low pressure system in the central Plains. Rain should become more widespread in the northern Plains Wednesday morning north of a stationary front. To the south of the front, a line of thunderstorms could form ahead of a dry line in the central Plains Wednesday afternoon as the low pressure center edges closer. Meanwhile, drier weather should return to New England down into the mid-Atlantic on Tuesday as a surface high pressure ridge builds in from southeastern Canada while showers and thunderstorms linger in the Southeast near a stationary front. The dry weather in the mid-Atlantic will be short-lived as lower-level moisture from the Atlantic will sneak in under easterly winds, resulting in low overcast with the possibility of light rain and drizzle later on Wednesday. Meanwhile, moisture from the Southeast will spread northward and merge with moisture arriving from the Great Lakes over the Ohio Valley and the Appalachians. By Wednesday evening, northern New England could see the arrival of some wintry precipitation. Kong Graphics available at www.wpc.ncep.noaa.gov/basicwx/basicwx_ndfd.php