Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 507 PM EDT Fri Jul 26 2013 Valid 00Z Sat Jul 27 2013 - 00Z Mon Jul 29 2013 ...Showers and thunderstorms will continue to shift away from the Northeast through Saturday... ...Showers and thunderstorms will effect much of the eastern half of the country... ...Convection will continue in the Desert Southwest... The low associated with the strong cold front that has pushed off the East Coast will continue to lift north of Maine causing the showers and thunderstorms to begin tapering off. Most of the heavier precipitation will leave Maine by Saturday morning although some scattered showers may linger. The quality air mass which has brought cooler temperatures and lower dew points through the Middle Atlantic and Northeast will come to an end by the weekend as another system makes its way to these regions. A frontal boundary draped over the Mississippi Valley and southern Plains will continue to move toward the Middle Atlantic and Northeast through the short term period. However, prior to its East Coast arrival, showers and thunderstorms will affect the Plains and Southeast through Saturday and into Sunday morning. The surface low associated with this frontal boundary is currently making its way east-northeast into the Great Lakes. Showers and thunderstorms will concentrate along and ahead of the surface low. Some of this activity could be severe in addition to producing heavy downpours. The heavier precipitation will lift to the north, along with the surface low, which will leave scattered thunderstorms in the Lower Great Lakes and Ohio Valley by Saturday morning. To the south, flash flooding will be a concern as a disturbance treks across the Southeast. This disturbance coupled with a surface low as a focus and an abundant amount of Gulf moisture will reinforce heavy rainfall especially in the lower Mississippi Valley. By Saturday, this focus of heavy rainfall will shift into the Southeast. The precipitation will finally arrive into the Middle Atlantic and portions of the Northeast by Saturday evening and will continue through the rest of the weekend. The Desert Southwest will continue to have scattered convection across its region throughout the short term period. Monsoonal moisture and daytime heating will trigger these thunderstorms. The Pacific Northwest will have a cold front moving inland by Saturday and will continue to move into the Northern Plains by Monday; however, most of the precipitation will be in Canada. Fanning Graphics available at www.wpc.ncep.noaa.gov/basicwx/basicwx_wbg.php