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Persistent wet weather to extend flooding risk in Northeast as rainfall records rack up

By Alex Sosnowski • Aug 15, 2018 at 10:18 AM

Persistent rainfall and flooding are likely in parts of the northeastern United States that have already received record-shattering rainfall this summer.

"The weather pattern this summer is one of the most dramatic outbreaks of rain ever to hit Pennsylvania and other states in the region in a non-tropical storm setting," according to AccuWeather Chief Meteorologist Elliot Abrams.

The recent deluge has been on par with the type of rainfall that can be unleashed by a tropical storm or hurricane.

For example, at Wilkes-Barre/Scranton International Airport, Pennsylvania, 4.34 inches of rain fell on Aug. 13, which shattered the old record for the date set in 1955. The location received more rain in one day than what typically falls for the entire month of August.

More downpours Thursday-Sunday

Some locations have already recorded their wettest summer on record, such as State College, Pennsylvania.

Williamsport, Pennsylvania, is likely to have two back-to-back months of record rainfall. Following the wettest July on record, the wettest August on record is on the doorstep.

The tropical downpours have been triggered by frequent storms as well as tropical moisture funneling into the area from the Gulf of Mexico and the Atlantic Ocean, according to AccuWeather Hurricane Expert Dan Kottlowski.

A persistent area of high pressure off the Atlantic coast is helping to direct the fire hose of moisture.

The 1955 rainfall was directly related to Hurricane Connie. That tropical system tracked northwestward across Pennsylvania and was later followed by Hurricane Diane and catastrophic flooding in the Delaware Valley later in August.

Some locations have already recorded their wettest summer on record, such as State College, Pennsylvania.

Williamsport, Pennsylvania, is likely to have two back-to-back months of record rainfall. Following the wettest July on record, the wettest August on record is on the doorstep.

The tropical downpours have been triggered by frequent storms as well as tropical moisture funneling into the area from the Gulf of Mexico and the Atlantic Ocean, according to AccuWeather Hurricane Expert Dan Kottlowski.

A persistent area of high pressure off the Atlantic coast is helping to direct the fire hose of moisture.

What lies ahead for the Northeast?

Following another day of flash flooding and record-breaking rainfall on Tuesday, a break in the weather pattern is in store for much of the mid-Atlantic states on Wednesday.

Storm total rainfall for the event that began this past weekend and should conclude Wednesday will average 4-8 inches with an AccuWeather Local StormMax of 12 inches.

Temperatures are forecast to surge to steamy levels as sunshine returns at midweek.

On Thursday, the lull in shower and thunderstorm activity will continue in the mid-Atlantic and spread to New England. However, even with the lull, spotty pop-up downpours are still expected.

Late this week and into this weekend, another storm will push in from the Midwest.

Showers and thunderstorms, some with enough rain to renew or bring flash flooding to areas that have escaped thus far, will spread slowly eastward spanning later Thursday to Sunday.

Locations that stand the best chance of at least one downpour each day include the central Appalachians, the mid-Atlantic and southern New England.

The heaviest total rainfall may fall across northern New York state and New England this time. However, portions of the Atlantic seaboard could still be hit hard.

"A great amount of moisture will be available in the atmosphere on Friday along the Interstate-95 corridor," according to AccuWeather Senior Meteorologist Bernie Rayno.

Another lull in the pattern is likely early next week.

However, yet another storm is forecast to push eastward during the middle part of next week.

There is the potential for next week's storm to stall and create another flash flood concern.

On the other hand, if this storm manages to move swiftly through, it may be a "one and done" scenario as far as a shower or thunderstorm is concerned.

AccuWeather meteorologists are concerned the slow-moving storm scenario may win out as that scenario has occurred multiple times this summer.

Flood risk may continue beyond the summer

Even though a lower-than-average count of hurricanes and tropical storms is foreseen, due to a developing El Niño, there is still the risk of a tropical system with direct impact in the eastern United States this autumn.

Well into the autumn, river, small stream, lake and reservoir levels are likely to remain above average in a large part of the Eastern states, with the possible exception of parts of New England and northeastern New York state.

Local, state and federal officials should remain vigilant well beyond the short-term issues.

Given the saturated state of the ground, declining evaporation rates and no sign of prolonged dry weather, any tropical system that comes calling could lead to a regional flooding disaster.

Likewise with the saturated ground, any gusty thunderstorm, let alone a tropical storm, can topple scores of trees and lead to regional power outages.

EDITOR’S NOTE: Alex Sosnowski is a AccuWeather senior meteorologist.

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