Seven days after the remnants of Hurricane Ida brought devastating flooding and tornadoes to the Mid-Atlantic and Northeast, a cold front sweeping through the region could trigger another round of hazardous weather.
On Tuesday, the same cold front headed into the Northeast was responsible for more than 200 reports of severe weather in the Great Lakes region. Southern and central Wisconsin were battered by large hail, with multiple reports of stones ranging from the size of golf balls to softballs. Near Appleton, a 4.5-inch hailstone was observed. It was the biggest hail report in the state in 14 years and tied for the second-largest on record.
Severe storm threat
On Wednesday, the National Weather Service placed the region from Northern Virginia to southern Vermont in a Level 2 out of 5 risk zone for severe storms.
“Scattered damaging thunderstorm wind gusts and a few tornadoes are expected across portions of the Mid-Atlantic region and Northeast,” it wrote Wednesday afternoon.
Surrounding the Level 2 risk zone, the Weather Service has outlined a Level 1 risk for severe storms from northern South Carolina to the New Hampshire-Maine border. Overall, about 75 million people in the Mid-Atlantic and Northeast have an elevated risk of severe storms as the cold front passes.
The zone most susceptible to tornadoes may focus from northeastern Maryland to southeastern New York state, generally west of New York City. Some isolated instances of large hail could also occur in this area.
While a few short-lived tornadoes are possible, a repeat of Ida is not anticipated. During that storm, 14 twisters touched down from Virginia to Massachusetts, including several significant tornadoes rated EF2 or higher on the 0-to-5 scale for intensity.
Around Washington, some strong to severe storms are possible between about 5 and 10 p.m. Wednesday, possibly extending into the overnight hours, but the more intense activity may focus to the north and northeast.
Flooding threat
Some of Wednesday’s storm could unleash very heavy downpours, increasing the risk of flooding, particularly from eastern Pennsylvania into parts of southern New England. These are some of the same areas that Ida deluged with three to nine inches of rain.
“Given the saturated soils from Ida, locations in eastern PA, northern NJ, southern NY, western MA/CT, and southern VT are most susceptible to flash flooding,” the Weather Service tweeted.
The Weather Service has issued flash flood watches from southeastern Pennsylvania to the Lower Hudson Valley, including New York City’s western suburbs, where one to two inches of rain could fall in a short period.
These amounts are a far cry from those Ida produced but could still cause problems, as some areas have seen as much as 600 percent of their normal rainfall in recent weeks.
“It will not take much rainfall to cause flash flooding of urban, flood prone, and other low-lying areas,” the Weather Service in Mount Holly, N.J., wrote.
The cold front coming through is relatively fast-moving compared with Ida and will not have access to nearly the amount of tropical moisture that fueled Ida.
The National Weather Service Middle Atlantic River Forecast Center’s daily briefing indicated that it does not expect enough rain to fall over a large enough area to cause significant river flooding from this event.
During Ida, seven rivers in the Northeast recorded all-time peak floods, according to Dartmouth College researcher Evan Dethier.
By Thursday morning, the chance of rain will diminish from Washington to New York as the front pushes toward the Atlantic coast. Dry weather is then predicted between Friday and early next week.
