Significant storm next week will bring rain, strong winds

A powerful upper level trough is forecast to develop in the Eastern United States next week, within an amplified upper level height pattern. A strong disturbance is forecast to eject eastwards from the Western United States, and eventually amplify into the Southeast United States during this upcoming weekend. Thereafter, the disturbance will move up the East Coast while slowing down — and allowing a surface low pressure to amplify.

Forecast models have jumped around a bit with the positioning of this surface low pressure, but recently have come into better agreement on the track, taking the surface low inland over the Mid Atlantic states and then off the coast. A considerable amount of modified, warm air exists ahead of the storm system — so the threat with the system is not winter weather. Instead, an anomalously moist atmosphere and very strong jet dynamics are expected to create the potential for torrential rain and very strong winds near the coast.

The potential for heavy rain and wind begins with the anomalous moisture fetch which is forecast to move into the area from late Sunday into Monday. The GFS suggests precipitable water values (the amount of moisture available in the atmosphere) will be nearly 350% of normal for this time of year. Essentially — the amount of moisture content in the atmosphere will be extremely anomalous.

This is thanks to a strong low level jet — which is the movement of wind and moisture in the lower levels of the atmosphere. This low level jet strengthens on Monday as the storm system moves inland over the Mid Atlantic. Along with the advection of anomalous moisture, enhanced lift is expected to develop near this low level jet. This will create an environment very favorable for the development of heavy precipitation.

Forecast models suggest the development of this heavy precipitation underneath a negatively tilted upper level trough. This is important, as the atmospheric jet dynamics are enhanced as the upper level jet strengthens and the tilt of the upper and mid level system changes. With both of these things in mind, support for torrential rain exists throughout the area on Monday.

The juxtaposition of all of the above listed features in the atmosphere will also lead to the potential for strong wind gusts, particularly along the New Jersey and New York shoreline, on Monday. As the storm system strengthens to our southwest, the gradient between the low pressure system and a high pressure to our northeast will be enhanced. This will naturally enhance the potential for gusty winds.

But making matters more significant will be the development of the aforementioned low level jet. East/southeasterly winds are forecast to strengthen as the low level jet approaches, which will be particularly impactful for the mentioned coastlines. But even just inland, very strong winds are forecast to exist just above the surface. Heavy precipitation could mix these winds down towards the surface.

For instance, the GFS shows the presence of 61kt winds at 900mb. Any heavy precipitation or downward momentum could mix these winds towards the surface — and this will be especially true near the coast. Accordingly, the potential for wind gusts over 50 mph exists on Monday from the New Jersey and New York shoreline just inland, including New York City and Northeast New Jersey.

With all of this in mind, hazardous weather briefings are expected to be issued this afternoon. These will include overall hazard areas and details on the expected threats for impactful weather. In addition, zone forecasts will be updated this afternoon with separate zone information along the area coasts.

Stay tuned for further updates as the storm approaches, including the latest model information, forecast thoughts, and interactive details — including videos and more.