Low pressure will spread a widespread area of soaking rain across the Ohio Valley and mid-Atlantic through Saturday, then move off the East Coast by Mother’s Day and create high surf, rip currents and coastal flooding along the Eastern Seaboard into next week.
This storm system will first trigger a threat of severe thunderstorms in parts of the Southeast before becoming an East Coast soaker into the start of the weekend.
Periods of rain and a few thunderstorms drenched the Ohio Valley and mid-Atlantic on Friday. The soaking rain will linger in the mid-Atlantic states for much of Saturday.
The heaviest rainfall along the Interstate 95 corridor from New York City to Philadelphia, Baltimore and Washington is expected to fall Friday night and Saturday morning.
Most areas will dry out overnight Saturday as the low-pressure system slides offshore, yielding a dry Mother’s Day for much of the eastern U.S. However, stubborn clouds and light showers could linger along portions of the immediate coast from southern New England to the Outer Banks of North Carolina.
An inch or two of rain is expected across much of the Ohio Valley and mid-Atlantic, though it will be spread out over many hours, which will limit the flooding risk in these regions. Locally higher amounts over 2 inches are possible in some areas.
The greatest risk of localized flash flooding will be in southern Ohio, western and central Pennsylvania and West Virginia, where the soils are most saturated. These areas have picked up as much as 200 percent of their average rainfall over the past 30 days.
The National Weather Service has issued Flood Watches from parts of Ohio and eastern Kentucky into West Virginia, western and central Pennsylvania, Maryland and northern Virginia.
In addition, temperatures will be cooler than average due to the persistent clouds and showers. Gusty winds will make it feel like it’s only in the 30s and 40s from Boston to Philadelphia through Sunday.
High surf, rip current, coastal flood threats
The low-pressure system will be situated off the coast of North Carolina by Mother’s Day, and it won’t move much through the middle of next week.
That’s because the jet stream will be parked well to the north, so there won’t be any disturbances in the atmosphere to nudge this system away from the East Coast.
A high-pressure system will also be located over Maine and Canada’s Quebec province. The clockwise winds around this high will combine with the counterclockwise winds around the low-pressure system near the Eastern Seaboard, generating persistent northeasterly onshore winds.
This will be an exceptionally long-duration event, with coastal areas getting pounded by 40- to 50-mph wind gusts almost nonstop from Saturday through Wednesday.
Minor to moderate coastal flooding will become a concern at times of high tide beginning Sunday morning from the Jersey Shore to North Carolina as these strong northeasterly winds blow the water toward the coastline. Large, persistent waves will also cause severe beach erosion.
Showers from the low-pressure system might occasionally move onshore between southern New England and Florida through the middle of next week, but they should not result in a complete washout at the beaches on any particular day. Later in the week, the low might backtrack toward the southeastern U.S. and increase the chance of rain along portions of the Southeast coast.
Because of the threat of rip currents, you’re advised to use caution if you have beach plans on Mother’s Day or any day next week. According to the National Weather Service, an average of 60 people are killed by rip currents each year in the U.S. So far this year, rip currents have already been blamed for 14 deaths.
Many beaches use color-coded flags to warn visitors of the day’s rip current risk.
If you see a green flag, strong rip currents are not expected that day, so you should be able to swim safely. However, beware of the yellow and red flags. A yellow flag means there is a moderate risk of strong rip currents, while a red flag indicates a high risk. Take extreme caution when entering the water if a yellow or red flag is posted on the beach.
You can find NOAA’s official rip current forecasts at this link.
Subtropical development not ruled out
It’s not out of the question that this low-pressure system meandering off the East Coast could briefly become a subtropical depression or subtropical storm next week. A storm designated as subtropical means it has characteristics of both a tropical and a non-tropical cyclone (a low-pressure system that you would typically find over land in the U.S.).
The National Hurricane Center issues routine advisories for subtropical depressions and subtropical storms, just as it does for tropical depressions, tropical storms and hurricanes.
The odds of this happening are low, but in the outside chance it develops into a subtropical storm with winds of at least 40 mph, it would earn the name “Alex,” the first on the naming list for the 2022 Atlantic hurricane season.
Although hurricane season doesn’t officially begin until June 1, the past seven seasons have all spawned at least one named storm before that date.
Regardless of what this system is called (or not called), the impacts along the East Coast will be the same as we outlined above.