Tropical Storm Joaquin to Track Near East Coast, Escalate Flood Threat

By Alex Sosnowski, AccuWeather.com Senior Meteorologist

September 29,2015; 10:09PM,EDT

 

 

Joaquin may converge with another slow-moving storm in the East to add to 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 flooding."

Joaquin Strenthening; May Threaten East Coast

Small stream and urban flooding are a given in this case. How significant river flooding becomes will depend on duration, intensity and location of the subsequent rounds of rain.
The nearly week-long pattern has the potential to put some neighborhoods of major cities under water and can flood some communities along streams.

Cumulative rainfall through Monday may reach one foot in some places.
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: 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.
During the first batch, the heaviest rain will fall from the central Appalachians through Tuesday night then New England and neighboring Canada on Wednesday.
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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, while 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 Raleigh, North Carolina, and 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 many of the major rivers may stay below flood stage through Friday.
Football fans heading to area high school and college football games may not only have to contend with pouring rain, but also muddy parking lots.
Joaquin's impact may come into play during the third round of rain, which will arrive during Monday and Tuesday. Joaquin is forecast to become a hurricane this week, prior to drifting along the Carolina coast.

There is the potential for another round of small stream flooding and perhaps flooding of unprotected areas along the major rivers. River flooding is often delayed and may not occur until after all of the rain has ended.
While the situation is not likely to become another Sandy, Irene or Isabelle, coastal flooding is a significant threat from the Carolinas to Maine, including in some of the inland bays and tidal rivers.
The period from Saturday into next Tuesday will bring onshore winds strong enough to cause 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.