Hermine Could Be a Northeast Headache Over Labor Day Weekend

Jon Erdman
Published: September 2,2016
Confidence is growing that Hermine's effects will be felt as far north as coastal New Jersey for the second half of the Labor Day weekend. Strong winds, coastal flooding, beach erosion, high surf, rip currents, heavy rain and flash flooding are all possible impacts.
(MORE: Hermine Forecast | Latest News | Interactive Hermine Tracker)
Although Hermine will likely be non-tropical by the time it nears the Northeast coast, it will still have significant impacts. Therefore, tropical storm watches have been issued from the Virginia Tidewater northward through the Maryland, Delaware and New Jersey coasts.

Watches and Warnings

National Weather Service (NWS) policy allows the National Hurricane Center (NHC) to issue advisories on and issue tropical storm watches and warnings for post-tropical cyclones, when the system continues to pose a significant threat to life and property.

What We Do Know

The tropical cyclone will be steered northeast around the west side of the Bermuda-Azores high-pressure system, and also be pulled somewhat by a southward dip in the jet stream, or trough, moving through the Great Lakes and Northeast.
But then something strange happens.
That Great Lakes/Northeast upper trough exits into the North Atlantic this weekend before fully grabbing hold of the tropical system and taking it along.

Potential Labor Day weekend atmospheric setup.

Upper-level high pressure building in behind it to the north of "Hermine" may trap the system for several days, encompassing much, if not all, of the Labor Day holiday weekend.

What We Don't Know

Unfortunately, there is still considerable uncertainty regarding where the system is when it gets trapped.
In general, there are three scenarios:

Offshore

• The system is pulled significantly far off the Northeast seaboard before getting trapped.
• Potential impacts of this scenario: Mainly only high surf, rip currents, possibly some coastal flooding/beach erosion.
• Chance of this scenario: Still possible, but chance is diminishing

Coastal Hugger

• The system either bends back toward the coast after being trapped by the upper ridge offshore or has a track much closer to the Northeast Seaboard.
• Potential impacts of this scenario: Strong winds (mainly near the coast), significant coastal flooding over multiple high tide cycles, beach erosion (possibly significant), high surf, rip currents, some heavy rain
• Chance of this scenario: Increasingly likely

Inland Track

• The system may track mainly inland, gradually slowing down.
• Potential impacts of this scenario: Heavy rain/flash flooding, strong winds (initially), high surf, some coastal flooding
• Chance of this scenario: Small chance

(MORE: Why Long-Range Model Forecasts in the Tropics Can't Often Be Trusted)
One other challenge worth mentioning is whether forecast models "start out on the wrong foot."
If the so-called model initialization - a first-guess analysis each model does of the current conditions - is off with the current position of Hermine, it's more likely to be wrong in the future. Initial errors become bigger errors with time.
Despite the ongoing drought in parts of the Northeast, heavy rain could eventually trigger flash flooding, particularly if the latter scenario plays out. Slow-moving former tropical cyclones have been prolific flash flood-producers in the past.
(MORE: 4 Tropical Storms that Overachieved)
And, even if the less likely (for now) offshore scenario came to pass, the dangers of rip currents and high surf could put a crimp into your beach plans.
(FORECAST: Ocean City, Maryland | Atlantic City, New Jersey | Nantucket Island)
Check back with us at weather.com for the latest on this potential Labor Day weekend storm.

MORE: Hermine Impacts (PHOTOS)