A storm will form near the East Coast this weekend. Here are the possible scenarios.
By this weekend, two significant storms will be swirling in the western Atlantic, with one that could hit the East Coast with heavy rain, strong winds, big waves and coastal flooding.
The impact of that coastal storm could begin this weekend and stretch from the Carolinas to the Mid-Atlantic and New England – exacerbated by higher tides from this week’s supermoon.
Winds from the coastal storm are expected to blow Tropical Storm Jerry – a separate storm that formed east of the Caribbean islands on Tuesday – away from the United States, but not before that storm passes near the northern Leeward Islands late Thursday into Friday where tropical storm watches are in place.
The coastal storm – which may meet subtropical criteria and earn the name Karen – may pose a significant risk to North Carolina’s Outer Banks, where several homes have recently succumbed to the ocean’s power.
But since the storm isn’t expected to form until later this week, there are still a few different scenarios that could play out before forecast details become clearer.
The coastal storm won’t start forming for several days.
A cold front, which brought a swath of rain to the Northeast and Mid-Atlantic early Wednesday, will meet warm, moist air over the Southeast. This clash of air masses creates baroclinicity – a variation of temperature across distance – which will help fuel the storm’s development.
This mix of tropical and nontropical characteristics means that the storm may be subtropical – a hybrid type of storm that could earn the name Karen.
Meanwhile, in the eastern Atlantic, Tropical Storm Jerry formed on Tuesday, the 10th named storm of the Atlantic season. Although Jerry was a disorganized mass of thunderstorms early Wednesday – due to inconsistent atmospheric winds near the storm and its high speed – the Hurricane Center expects the storm will intensify into a hurricane on Thursday as it approaches the northern Leeward Islands.
As of Wednesday morning, Jerry was about 890 miles east of the Leeward Islands and had winds of 50 mph, moving quickly westward at 23 mph.
Jerry could cause flash flooding, tropical-storm force winds and dangerous sea conditions for nearby islands from Thursday into Friday. As a result, tropical storm watches are in effect for the following islands:
-Antigua, Barbuda, and Anguilla
-St. Kitts, Nevis, and Montserrat
-St. Barthelemy and St. Martin
-Sint Maarten
-Saba and Sint Eustatius
-Guadeloupe and the adjacent islands
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Storm scenarios
The coastal system’s track and intensity will become clearer later this week, but there are a few main storm scenarios at this point. Here are the scenarios in order of likelihood:
Scenario 1
As of early Wednesday, the most likely scenario involves a storm that forms near the Carolinas and pushes northward into the Mid-Atlantic and Northeast, bringing the potential for widespread impacts this weekend into early next week.
Depending on how strong the storm becomes, this scenario could bring moderate to locally significant coastal impacts, such as damaging winds, big waves, beach erosion and heavy rain, to a swath of states from the Carolinas to New England.
The key to this scenario is a disturbance in the upper atmosphere above British Columbia, some 2,500 miles away from the East Coast. This disturbance will track across Canada in the days ahead. If it dips southward toward the Great Lakes, it could scoop the forming coastal storm northward, flinging its rain and wind into the Northeast.
Over the next day or two, more weather observations in the vicinity of the Canadian disturbance should lead to more confident forecasts of its future path -and the path of the coastal storm.
• Scenario 2
Another scenario involves a coastal storm that develops and becomes slow-moving near the Carolinas and/or Mid-Atlantic, bringing the potential for moderate to locally significant impacts that could linger in the same area for days.
This scenario could play out if the key upper-atmosphere disturbance remains farther north in Canada and fails to lift the coastal storm northward.
• Scenario 3
A third scenario is for a storm that spawns further offshore, sparing the coast of the worst impacts.
While this outcome looks least likely, it could unfold if the disturbance in Canada moves more quickly southward into the Eastern U.S., nudging the coastal storm to the east into the Atlantic.
Tropical Storm Jerry
Jerry will near the northern Leeward Islands late Thursday into Friday, where 2 to 4 inches of rain could cause flash flooding, especially in higher terrain.
The storm’s rate of strengthening from Wednesday into Thursday is critical to its own path and potential impacts. If Jerry strengthens faster, it will become a taller storm, affected by stronger winds aloft that will blow it to the north before reaching the islands. Think about a sailboat – if it hoists its sails, it’s going to catch the wind, which will determine where it goes. For now, Jerry remains relatively weak – which could allow it to remain farther south.
The most likely scenario is a track near or just north of the northern Leeward Islands – close enough for storm impacts there. While Jerry will probably track to the east of the Virgin Islands and Puerto Rico, residents there should closely monitor the forecast.
Residents of Bermuda should also keep an eye on Jerry, though the storm will most likely veer to the east of the island late in the weekend, sparing it from direct impacts.