Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 358 PM EDT Tue Jul 19 2016 Valid 00Z Wed Jul 20 2016 - 00Z Fri Jul 22 2016 ...Heavy rain possible over the Mississippi Valley and Great Lakes region... ...Showers and thunderstorms expected across the Mid-Atlantic/Southeastern U.S... ...Monsoonal moisture to bring convection across the Southwestern States... The upper level ridge sitting over the central United States will be a major factor in influencing weather patterns over much of the country for the next few days. A small upper level disturbance will continue sliding to the east around the upper level ridge. At the surface, a warm front stretched across the upper and mid-Mississippi Valley will lift north toward the Great Lakes tonight and into Wednesday morning. These factors--along with impressive amount of moisture feeding into the region and plenty of instability--will lift a complex of thunderstorms from the Mississippi Valley northeastward toward the Great Lakes tonight and into tomorrow morning. The cluster of storms will move eastward across the Lower Great Lakes and into the Ohio Valley by Thursday morning. Flash flooding will be a concern primarily for portions of the mid-Mississippi Valley, Ohio Valley, and Upper Great Lakes. Another round of showers and thunderstorms will move across the Upper Midwest/Great Lakes by Thursday evening as a surface low lifts north across the area. A boundary dipping south across the Mid-Atlantic and Southeastern states will fire off convection across these regions for the next few days. The boundary will approaches the Carolina coastline and slows down by this evening and will move off the coast by Thursday morning. During this time, the boundary will act as a focal point for convection--which will mostly be diurnally driven. The peak of the thunderstorm activity will occur during late afternoon/evening on both Tuesday and Wednesday afternoons. An abundance of moisture will be in place, and these thunderstorms could yield to heavy rainfall and possibly flash flooding. Once the front pushes off the coast by Thursday, some remnant convective activity could linger--but most of it will taper off throughout the day. As the upper level ridge continues to be centered across the central U.S., the flow around the ridge will drive monsoonal moisture northward across the Four Corners region. This will fire off showers and thunderstorms across the region--with a lot of influence from the topography. This will also be diurnally driven as the bulk of activity will occur during late afternoon and early evening hours. Expect this pattern to continue throughout the short term period. Elsewhere, typical summertime sea breeze thunderstorms will impact Florida and the Gulf Coast over the next few days. Heat from the upper level ridge will also continue through Thursday--with above average temperatures occurring across the Plains and the Mississippi Valley. Fanning Graphics available at www.wpc.ncep.noaa.gov/basicwx/basicwx_wbg.php