Complex setup, powerful coastal storm to graze area

An anomalous and powerful coastal storm is likely to graze the area late this weekend and early next week, with a tremendous breadth of precipitation as the center of low pressure passes hundreds of miles to our east in the Atlantic Ocean. Forecast models have come into better agreement on the evolution of  a large and intense mid and upper level system, with an impressively strong trough moving from the Southeast States to a position southeast of New England by Monday.

NAM model depicting a powerful mid level trough off the East Coast on Monday.

A strong mid level trough with impressive shortwave energy will approach the Southeast Coast on Sunday, with a surface low forming off the coast of Georgia and South Carolina. As the mid and upper level low cuts off from the jet stream, this surface low will rapidly deepen and move up parallel to the East Coast – while remaining a few hundred miles offshore. Bands of heavy precipitation from this storm will rotate northwestward, from the Western Atlantic Ocean, precariously close to our area, specifically Long Island.

Models are teetering on the edge of significantly impacting our area with this storm. Some higher resolution models track the center of low pressure farther west, bringing bands of moderate to heavy precipitation as far west as New York City. Other global models, such as the GFS and Euro, keep the storm farther east, with bands of precipitation associated with the storm remaining generally offshore.

Adding complexity to the setup is an impressive upper level jet streak structure, which could support northwest advection of precipitation. This will allow for bands of precipitation to expand very far northwest from the surface low pressure, and adds intrigue to the setup and potential for a westward shift as the storm draws closer.

NAM model showing an impressive jet streak in the upper levels of the atmosphere that may support precipitation moving farther west toward our region Monday.

At this time, very good agreement amongst global models and ensembles increases confidence that our area will avoid significant impacts from the storm. But higher resolution models depicting some banding making it as far west as Long Island suggests that we maintain a low confidence forecast moving forward, with room for error. Jet streak structures like the ones depicted have often led to precipitation moving farther northwest than forecast.

In terms of sensible weather, it appears likely that some bands of precipitation will approach our area on Monday. Periods of steady snow are possible on Monday across Long Island, specifically the east end. Farther west over New Jersey, it doesn’t appear likely that the storm will have any impacts on the region at this time.

Monitoring trends and mesoscale analysis as the storm evolves will be critical over the next 24 hours or so. Even a slight westward shift could result in tremendous forecast impacts for our area. Stay tuned for updates and additional details (including things like snowfall totals) as this powerful storm evolves.