In the Northeast, the risk of sudden and severe flooding is increasing as persistent rain and occasional thunderstorms are being fueled by a persistent Omega blocking pattern across the United States.

An “Omega block” is named after the Greek letter Ω and disrupts the usual zonal flow of weather systems.

The FOX Forecast Center said the blocking pattern has caused a so-called cutoff low-pressure system to stall over the Tennessee and Ohio valleys. This system is feeding moisture off the Atlantic Ocean, funneling precipitation into the region.

“A cutoff low means that it’s cut off from the main flow, meaning that there’s nothing around to steer it, meaning that it doesn’t move very fast at all,” FOX Weather Meteorologist Ari Sarsalari said. “So, this thing is going to linger around the East Coast for a couple of days.”

The FOX Forecast Center said that, depending on the position of the frontal boundary, the easterly winds at the surface may enhance the precipitation in some higher-terrain areas, especially across portions of western Connecticut.

Rain totals could approach 3-5 inches if the front struggles to move.

However, the FOX Forecast Center said there remains some uncertainty regarding the timing and location of the heavier rain bands as they reorganize and shift over the next few days.

The rain bands are expected to be narrow with occasionally heavy rain and a chance of some thunderstorms.

It won’t rain all the time in most places. However, several rounds of rain with embedded downpours can be expected.

Flash flooding is possible, but forecasters said significant flooding appears unlikely due to the scattered nature of the storms.

The threat zone includes the New York City and Poughkeepsie areas in New York, as well as Hartford, Waterbury, New Haven, New London, Bridgeport and Stamford in Connecticut.

Omega blocking pattern fuels flood threat this week

A rather unusual weather pattern for early May is setting up across the U.S., one that meteorologists warn will lead to a stagnant pattern with prolonged periods of warmth in some areas and steady rain in others.

This so-called Omega block will cause two distinct regions of precipitation to dominate the workweek: one stretching from the southern Plains to the Gulf Coast and another affecting the Northeast.

“Plenty of moisture will be underneath those lows,” FOX Weather Meteorologist Jane Minar said. “It’s a slow-moving pattern that will kind of keep us locked in place with rain.”