How Debby could impact NJ this week: 3 scenarios (2024)

UPDATE: Debby was upgraded to a hurricane Sunday night with maximum sustained wind speed of 70 kt with gusts to 85 kt. The National Hurricane Center expects the storm to make landfall in the Big Bend region of Florida on Monday morning.

By now, you may have heard that the Atlantic basin's fourth named tropical storm of the 2024 season has formed. And Tropical Storm Debby has been soaking the west coast of Florida this weekend.

As of 5 p.m. Sunday, the storm was centered a mere miles 100 west of St. Petersburg, Florida, packing maximum sustained winds up to 65 mph. (FYI, 75 mph would be a category one hurricane.)

The forecast for the next 72 hours (3 days) is pretty firm at this point. Debby is now expected to strengthen into a marginal hurricane before making landfall along Florida's Big Bend on Monday morning. It will then drive through inland Florida, Georgia, and South Carolina, producing a wide swath of 12 to 20 inches of rainfall.

That's a lot of water.

What happens after that? Big question mark. Model guidance continues to show a few different possible storm tracks. Obviously, the inevitable trajectory, speed, and strength of the storm will have a big effect on what weather and surf impacts New Jersey will feel from Debby.

I see three different possible scenarios playing out. Let's talk about the basics of each, including potential impacts and the probabilities (in my professional opinion).

Scenario #1: The Escape Route (10% chance)

After Debby exits into the Atlantic Ocean around the SC-GA border, it would just keep going out to sea.

In this solution, New Jersey could experience a brief period of breezy showers on the outer edge of the storm. And surf would be rough for a few days late week. But all storm impacts would be minor here.

Note that I consider this the least likely of the three scenarios here, by far. I might be tempted to lean more toward this solution if Debby becomes stronger than expected and its momentum forces a more easterly (out to sea) storm track.

Scenario #2: The Tropical Moisture Train (65% chance)

Due to a general lack of steering currents in the atmosphere right now, Debby may slow down and come to a halt around Wednesday. It may even make a "U-turn" and retrograde back to the west, over the inland Carolinas. Possibly staying there for several days.

As you might imagine, a stagnant tropical storm situation like this could create catastrophic levels of heavy rain and flooding across the southeastern United States.

Note that I consider this the most likely scenario of the three at this point.

For New Jersey, Debby's tropical moisture would get caught up in a pair of impending storm systems. One Tuesday into Wednesday. One Friday into Saturday. Both would then feature "enhanced" rainfall — heavier rain than would have otherwise played out without a deep pool of tropical moisture just to our south. Up to 6 inches of total rainfall would be possible from these two storm systems, significantly raising the risk of flash flooding and river flooding.

The threat for damaging winds and severe weather would be minimal. As would coastal impacts, although the Atlantic Ocean might get churned up as Debby's circulation finally departs sometime next week, raising concerns for rip currents and beach erosion.

Scenario #3: The Coast Hugger / Direct Hit (25% chance)

What if Debby does not stall? What if the storm just skirts right up the U.S. East Coast? It would end up just off the Jersey Shore around Friday-Saturday.

There is a worst-case scenario worth mentioning, and here it is. While it is absolutely not the most likely scenario at this time, the impacts in New Jersey would be pretty nasty.

Heavy rain would again take center stage, with widespread 4 to 8 inches of rain statewide. Again, lots of flooding issues.

Plus, we would have to add wind impacts, especially along the coast. I estimate 50+ mph winds for several hours. That could spark damage, power outages, etc.

And the wind would drive storm surge, an influx of ocean water, toward the coast. That would raise pretty serious coastal flooding issues too. (The magnitude of which would depend heavily on the storm track.)

Again, guidance is leaning away from this solution. But it is worth keeping in the back of our minds for now, as we continue to track the storm.

Bottom Line

Honestly? My gut is telling me the outcome will be a combination of Scenario #2 and Scenario #3 from above. The storm stalls over the Carolinas, then skirts generally along the coast (as a weak tropical storm) as it ejects out to sea.

The bottom line is this: New Jersey will feel some impacts from Debby in the next week. Tropically-enhanced rainfall, at the very least. The sticky wicket of this active forecast is threefold:
1.) When would those severe impacts develop, and how long would they last?
2.) How loudly will we have to ring flooding alarm bells?
3.) Whether other impacts (wind, surge, severe weather) are on the table too.

You know, New Jersey really could use a good drenching to quench any concerns about drought heading into the fall harvest season. (As of this writing, about 14% of the state is classified as being in "Moderate Drought".)

But flooding and wind, we could do without. Even a washed-out summer beach weekend would be a potential travesty.

Hopefully this article serves as an early heads-up to the potential for active, hazardous weather later this week. My intention is not to hype the forecast or frighten anyone, but rather to stay ahead of the storm with rational, down-to-earth information.

My number one rule in forecasting tropical storms: Never underestimate the rainfall potential of deep tropical moisture. (See: Ida, Irene, and Floyd.)

We will continue to monitor the forecast closely in the coming days, and you should too. Expect updates on-air throughout Monday. My next comprehensive weather blog entry will be posted late Monday or early Tuesday.

Dan Zarrow is Chief Meteorologist for Townsquare Media New Jersey. Follow him on Facebook for the latest forecast and realtime weather updates.