More heavy rain is possible in the northeast later this week in places that just don’t need it; Vermont, which has been dealing with epic floods over the last 36-48 hours, could see more heavy rain and a renewed flood threat by Thursday. The National Weather Service’s Weather Prediction Center (WPC), in their latest Excessive Rainfall Outlook, says there’s an elevated risk of excessive rainfall once again over all of Vermont, western New Hampshire, eastern New York, northeastern Pennsylvania, and northern New Jersey Thursday into Friday.
According to the WPC, an expansive trough centered near the Hudson Bay will maintain generally lowered heights across the eastern continental United States as a broadly cyclonic flow envelops the region. Technically, within this cyclonic flow, multiple shortwaves will rotate west-southwest to east-northeast through the flow, leading to regions of enhanced mesoscale ascent through height falls and positive vorticity advection. In lay terms, these shortwaves will drive pockets of moisture and instability into the northeast, bringing areas of focused rainfall and thunderstorm development to the northeast.
“The environment from the Central Appalachians into the Northeast will be favorable for heavy rain regardless of the coverage and organization of thunderstorms,” the WPC warns. Precipitable Water values as high as 1.75″ will be advected northward; these thermodynamics will support rainfall rates of 1-1.5″/hour, while unidirectional flow parallel to the approaching boundary supports training of storms. This could result in rainfall of at least 1-3″ and perhaps more in a relatively short amount of time.
With exceptionally wet soils in place now, National Weather Service flash flood guidance suggests that additional rainfall of only a half inch to one inch per three hour period could create new flood problems.
Some epic rains have fallen over Vermont over the last 2 days. Unfortunately, some more rain could be headed to this region later this week. https://t.co/1cc6MNoPd1
— the Weatherboy (@theWeatherboy) July 12, 2023
Throughout towns in Vermont, canoes and kayaks have replaced cars on streets as flood waters persist from heavy rains on Tuesday. Up to 9″ of rain fell on parts of Vermont, creating widespread flooding conditions not seen since 2011’s Tropical Storm Irene.
In all, more than 4 million people were under or continue to be under flood warnings or watches across Vermont, New York, New Hampshire, Maine, and New Jersey this week. Swift-water rescue teams were activated in New York and Vermont to help with water rescues. While there have been no reports of deaths in Vermont, there is at least one confirmed flooding death in New York.