Tropical Storm Joaquin may converge with another slow-moving storm in the East to create a serious flooding situation into early next week.
According to AccuWeather Chief Meteorologist Elliot Abrams, "The dry spell and local drought conditions will be washed away by heavy rain and possible flooding."
The rainfall will occur in several stages through early next week. Each stage will bring the risk of flash and small stream flooding. Each subsequent stage will increase the coverage and severity of flooding, as well as the extent of travel delays and disruptions to outdoor activities.
JUMP TO: Tropical Storm Joaquin's Potential Impact on the East Coast
The first round of drenching rain, associated with a slow-moving storm, will sweep steadily northeastward through Wednesday. Much of this rain will be absorbed by the dry ground. However, too much rain will fall too fast for the ground to totally absorb in all areas.
This first batch of rain will deliver 1-3 inches is forecast with locally higher amounts.
The heaviest rain will fall from the central Appalachians through Tuesday night then New England and neighboring Canada on Wednesday.
According to AccuWeather Senior Meteorologist Brett Anderson, "From part of Maine to portions of New Brunswick, Nova Scotia and Prince Edward Island, up to 6 inches (150 mm) of rain will produce significant flooding and potential road closures from Wednesday afternoon and night."
A break in the rain is likely from late Wednesday through Thursday. Water levels on small streams will recede. Some of the major rivers will begin to rise a bit.
The second round of rain will begin right along the Atlantic coast and will spread slowly westward from Friday through Saturday.
This second batch is likely to cause significant urban flooding and major travel delays from Norfolk, Virginia, to New York City and Boston, as well as farther west to part of the Interstate 81 corridor.
Rain will collect on streets and highways, while low cloud ceilings and poor visibility will impact flights in and out of the major airports.
Where the soil became saturated with the first round, more rapid runoff and small stream flooding will occur. Noticeable rises are likely along the Delaware, Susquehanna, Connecticut and Potomac rivers. However, still water levels along much of these rivers may stay below flood stage.
Tropical Storm Joaquin's impact may come into play during the third round of rain, which will arrive during Monday and Tuesday. There is the potential for bring another round of small stream flooding and perhaps flooding of unprotected areas along the major rivers.
The period from Saturday into next Tuesday will bring onshore winds strong enough to cause minor coastal flooding, beach erosion and rough surf. How severe this becomes will depend on the whether a non-tropical storm acts alone or joins forces with Joaquin or its moisture.
AccuWeather will continue to provide updates on this potentially dangerous and damaging weather event in the mid-Atlantic and New England states, as well as neighboring Canada.