Northeast braces for significant flash flood threat Tuesday into Wednesday

New York City at the center of Northeast flash flood threat

The Northeast is at risk of significant flash flooding Tuesday from an unusually strong, slow-moving storm that could drop more than a month’s worth of rain in places. Lead Meteorologist Brandon Miller breaks down the forecast.

3:31 • Source: CNN

New York City at the center of Northeast flash flood threat

3:31

• Overview: A slow-moving coastal storm is set to unleash multiple rounds of heavy rain across the Northeast from Tuesday into Wednesday, raising the risk of significant flash flooding. Widespread rainfall totals of 3 to 5 inches are forecast, with locally higher amounts possible.

First responders are already reporting flash flooding near Bradford, Pennsylvania, according to the National Weather Service, with urban areas, streets and underpasses at particular risk.

• Timing: Storms were already underway Tuesday morning from upstate New York to West Virginia, but the most concerning flood threat in the Northeast will likely ramp up in the afternoon and continue overnight into Wednesday morning as the system crawls northeast.

• Forecast confidence:

We are confident there will be flash flooding somewhere in the Northeast, but pinpointing exactly which towns or cities will experience the most significant impacts is less certain.

Despite all of our forecast models and other modern forecasting tools, it’s still hard to know exactly where bands of rain will set up over the two days. Urban, low-lying and poor drainage areas will be most prone to flooding. Some roads are likely to flood and creeks and streams could also overflow their banks.

A Level 3 of 4 flood risk is in place Tuesday into early Wednesday from Philadelphia into New Jersey, the New York City metro area, upstate New York and western Connecticut. A Level 2 of 4 flood risk extends from Baltimore and Delaware into upstate New York and southwestern New England.

The greatest concern for flooding is just west and north of New York City, where widespread rainfall totals of 3 to 5 inches are forecast, with locally higher amounts greater than 7 inches possible.

The focus of the flood threat is expected to shift north Wednesday as a strengthening coastal storm pulls a deep plume of Atlantic moisture into the region. A Level 2 of 4 risk of flooding rain covers a large portion of New England, including Boston and Portland, Maine. An additional 1 to 3 inches of rain could fall across the region through Wednesday night.

The flood threat will be most concerning in areas that are soaked on both days.