Dozens of cities in eastern, southern US set new rainfall records in 2018

Rainfall records were shattered across the eastern and southern United States during 2018, but what led to such a persistently wet year?

The rainy weather on New Year’s Eve across the Ohio Valley and mid-Atlantic was somewhat of a fitting end to what was the wettest year on record in many locations.

Dozens of cities from the lower Mississippi Valley to the southern Atlantic Seaboard, mid-Atlantic and Ohio Valley received 125-180 percent of their normal yearly rainfall in 2018.

For example, Washington, D.C., received 66.28 inches of rain last year, when 39.74 inches typically falls in the city in one year.

To put this type of rainfall in context, the average yearly rainfall in the more tropical climate of Mobile, Alabama, is 66.15 inches.

In addition to Washington, D.C., Baltimore; State College, Lancaster and Pittsburgh, Pennsylvania; Wheeling and Charleston, West Virginia; Jackson and Lexington, Kentucky; Lynchburg, Virginia; and Asheville, Raleigh and Wilmington, North Carolina; are among the other cities where 2018 became the wettest year on record.

It took until the last day of 2018 for Pittsburgh to join in on the record-setting rainfall.

The 0.75 of an inch of rain that fell on New Year’s Eve pushed the city’s yearly total to 57.83 inches, surpassing the previous record of 57.41 inches which was set in 2004.

In Atlanta, 2018 set its mark as the second wettest year on record, falling just shy of the 71.45 inches of rain that fell in 1948.

Jackson, Mississippi, and Little Rock, Arkansas, recorded their second and fourth wettest years on record, respectively.

The excessive rainfall has left rivers throughout the South and mid-Atlantic running abnormally high for this time of year.

As the deluge persisted farther east, it was a different story on the West Coast, where drought and wildfires were rampant.

The Camp Fire in Northern California became the deadliest and most destructive fire in the state’s history in November.

So what was the cause of the unusually wet and record-setting year in the South and East?

It was a combination of factors, according to AccuWeather Meteorologist Kyle Elliott.

“An abnormally strong Bermuda high pressure system prevented cold fronts from diving southward out of Canada and into the eastern United States as is typically the case every couple of weeks from July through September,” Elliott said.

Strong high pressure systems like the one that was in place act like a roadblock in the atmosphere.

“As a result, storm systems basically came to a standstill for days on end in the eastern half of the nation,” Elliott said.

This led to a firehose of tropical moisture being directed into the Ohio Valley and mid-Atlantic for much of the summer and early fall months.

“In addition, three tropical systems (Florence, Gordon and Michael) impacted a large portion of the East,” Elliott said.

“Gordon and Florence slowed down significantly once they made landfall, which allowed these systems to dump extreme amounts of rain over several days,” Elliott added.

Nearly one quarter of Wilmington’s 102.40-inch total rainfall for 2018 fell in four days during Florence.

The city also set a new mark for the most rain in one year during the hurricane, breaking the previous record of 83.65 inches set in 1877.

Major flood risk to remain a concern

"Because of the saturated state of the ground in so many areas of the South and Northeast, there is the risk of a rare widespread flood situation this winter," AccuWeather Senior Meteorologist Alex Sosnowski said.

"One massive, slow-moving rainstorm could bring a river flooding disaster as the ground cannot absorb much moisture at this point," Sosnowski said.

While streams are running high and some of the large rivers are near or above flood stage, there has been enough separation between storms to keep most rivers from reaching major flood stage.

"While we don't foresee such a storm over the next couple of weeks in these areas, low evaporation rates during the winter may tend to keep the major flood risk on the back burner for many weeks and perhaps something that has to be dealt with in the spring," Sosnowski said.

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