...Shower and thunderstorm activity across the Southeast is expected to spread northward into the Mid-Atlantic states...
Rainfall totals will continue to add up across the Southeast and Carolinas this weekend where a frontal boundary will remain stretched through the region. In general the widespread shower and thunderstorm activity should be on the decline as the boundary gradually weakens over the next few days...but a deep slug of moisture streaming northward out of the Gulf of Mexico should allow for some organzied areas of moderate to heavy rains to develop over the Florida Panhandle and westward across the Central Gulf Coast.
Also...a surface low along the lingering frontal boundary is expected to slightly intensify while it tracks up the Eastern Seaboard on Sunday ...bringing the chance for showers and thunderstorms northward into
the Mid-Atlantic states. The low should stay far enough away from the
coast to keep the heaviest precipitation just offshore. However... upslope flow against the Central Appalachians could lead to some higher totals farther inland.
Weather should stay relatively quiet across the rest of the Nation.
A weak frontal boundary sagging through the northern tier will trigger some convection as it crosses the Northern Plains and Upper Midwest Sunday into Monday...but thunderstorm activity will be isolated and rainfall totals should stay on the lighter side.
Out west...monsoonal moisture combined with afternoon heating will lead some scattered showers and thunderstorms across the central Great Basin...Southwest...and Central/Southern Rockies.
Farther north...a Pacific cold front moving inland over British Columbia
could bring some light showers into the extreme northwestern U.S..