Forecaster: Coastal storm taking aim at the region won't be 'Karen' and won't be tropical

BETHLEHEM, Pa. — Combative computer models are starting to come more into agreement on a strong coastal storm expected in the region Sunday through Monday, forecasters say.

The storm is expected to have significant impact along the coast, with flooding possible in the coastal counties of New Jersey and Delaware, including Delaware Bay.

But as the system moves off the Carolina coast and begins to strengthen and lift northward, impacts farther inland — particularly in the Lehigh Valley — are not expected to be overly hazardous, Bobby Martrich of EPAWA Weather Consulting said.

Martrich lamented the numerous social media posts making the rounds Thursday, depicting the storm as a hurricane or a tropical storm.

“It is a classic nor’easter,” Martrich said in his latest video update. “There’s nothing tropical about this whatsoever.

“I keep seeing people saying it’s going to be a tropical storm named Karen. This is not tropical in any sense of the word.

“It is instead just a coastal low that will become a nor’easter. It’s called such because when it gets strong and it’s sitting [along the coast] you get a northeasterly fetch of wind involved with this."

Karen would've been the next named storm of the 2025 Atlantic Hurricane season. Friday morning, the National Hurricane Center said it was keeping an eye on subtropical storm Karen far from land, not the system expected this weekend.

Subtropical storms are hybrid systems that draw energy from both warm ocean waters and a horizontal contrast in atmospheric temperature.

Setup of storm 'very complex'

Martrich said that while the system coming this weekend likely will be quite strong — and could bring some light rain to the region as early as Saturday afternoon — the primary effects will be from coastal flooding, beach erosion, strong winds and heavy rain.

The heaviest rainfall and strongest winds were and are anticipated to be near the Atlantic coast, both Martrich and the National Weather Service are forecasting.

For the Lehigh Valley, the heaviest rainfall is still to be determined, but could potentially occur late Saturday night, through the overnight and Sunday, with rainfall continuing into and perhaps through the day Monday.

Overall, the weather service said a widespread 1 to 3 inches of rain is forecast across the entire region, with locally higher amounts possible near the coast.

“While that sounds like a lot, it is important to keep in mind that this will be falling over a 36- to 48-hour period," the latest forecast discussion said.

"It has been quite dry, as well. Given this, the thinking is that flooding due to heavy rain alone will be limited to poor drainage and urban areas.”

Unresolved differences

Both Martrich and the weather service say timing differences in some models have yet to resolve, and the setup of the storm is very complex.

“The only thing we’re doing is just looking at trends. This is where I have the pet peeve coming in here,” Martrich said.

“There’s a lot of Facebook pages mostly that are putting out maps and projections of rainfall. It’s way too early for that. If this was a winter storm, we wouldn't be putting a snow map out yet.

"We put something out in a responsible manner when we feel comfortable that this is what it's going to be.

"We're not going to wait until the last minute, but it's going to be the right information. It's not going to be something we're just guessing at, because that's all they're doing at this point."

Like Martrich, the weather service said the extent and severity of impacts in our area “will be directly related to the exact track and evolution” of the storm.

Residents are encouraged to monitor the latest briefing packages and forecast updates as things continue to evolve.