Heavy rainfall possible in the East next week

A significant storm system is expected to evolve throughout a large majority of the United States over the next several days — with heavy rainfall impacts possible throughout the Eastern US by the middle part of next week. Much of this would come as good news to the drought-ridden areas of the Eastern US, but the uncertainties in regards to the storm systems exact evolution make forecasting the system extremely difficult. Intricate processes at work will determine exactly where and when the heavy rainfall occurs.

The storm system forms initially over the next 48 hours as a strong disturbance evolves into the Plains states. A strong low pressure system at the surface develops rapidly northward into the Dakotas. Precipitation will spread eastwards towards the Corn Belt by early Monday morning as a front boundary surges eastward. But this initial disturbance is not the only feature of interest. While significant aloft, a second disturbance will move through the Rocky Mountain range during the early part of the week, eventually interacting with the initial storm.

This will allow the front to surge eastward towards the Ohio and Mississippi River Valley, while interacting with more moisture. Enhanced lift for precipitation is also expected near the front as it surges eastward, — and not surprisingly, forecast models have begun to show fairly significant rainfall amounts across a large part of the Eastern United States. From a meteorological standpoint, this makes total sense.

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The devil is in the details, however, as it usually is. There are two separate disturbances being modeled to impact the Northeast US, and how they both evolve will have a huge impact on who sees what, and when. Models show an initial burst of heavy rainfall occurring on Tuesday morning and afternoon throughout the Northeast. This rainfall is associated with warm air advection — essentially a surge of warmer and more moist air throughout the atmosphere. The increased moisture and lift allows for an area of heavy rain to form right along a warm front.

This rain shifts northeastwards through New England. Meanwhile, a secondary disturbance near another front forms on Wednesday. Moisture surges along this front and is enhanced thanks to another strong area of lift in the atmosphere. But exactly where both of these features track will determine who sees the heavy rain. Accordingly, uncertainty is quite high in exact totals and timing for the event.

Nevertheless, the overall idea remains the same: Confidence is increasing that much of the Eastern US will see beneficial rains next week. Here in the Northeast and Mid Atlantic, the potential exists for very heavy rainfall if forecast model ensemble and operational guidance is correct in the handling of the aforementioned two key features. More details will emerge over the coming days!