An increasing frequency of downpours, on top of already locally heavy June rainfall will raise the threat of flooding in part of the eastern third of the nation into the first week of July.
Initially, downpours will tend to be isolated and flooding will limited to urban, poor drainage areas and right along small streams.
However, as the pattern continues to evolve and a swath of tropical downpours stalls in the region, flooding problems can become more widespread and much more serious.
Some communities in the Midwest got a taste of what such a weather pattern can deliver Tuesday night into early Wednesday.
The system from the Midwest will stall in the East and change its orientation from west to east to more southwest to northeast.
Runoff from additional rounds of heavy of rain, on a daily basis in some cases, could push rivers to very high levels and flooding in the days ahead.
A stream of moisture from the Gulf of Mexico, Caribbean and the Atlantic will converge and may be compressed into bands of intense rainfall or a firehose effect. Downpours can repeat for hours and shift back and forth over states and counties therein from Florida to Georgia, the Carolinas, the Virginias, Delmarva, Pennsylvania, New York, New Jersey and New England.
In the pattern, some days areas right along the coast will be hit and other days locations near I-95 or the Piedmont or Appalachians can be targeted by torrential rainfall.
When the Appalachians are being hit, the sun could be out along the coast and also the other way around.
A Bermuda high over the Atlantic and a building zone of high pressure in the West will create the swath of potentially flooding rainfall over the eastern third of the nation.