PM Update: Torrential rain tonight and Monday throughout New England

Happy Sunday! We hope you have all been able to enjoy a lovely weekend — which, weather wise, turned out to be reasonably pleasant. This will change later this evening, and is already in the process of doing so throughout much of the Mid Atlantic. A warm front currently situated over the Northern Mid Atlantic states has served as the focal point for the development of thunderstorms this afternoon, but these are quickly merging into a larger-scale threat of heavy rain.

Heavy rain will continue to shift northward this evening as the warm front begins to respond to a developing impressive synoptic-scale storm evolution. A large and impressive shortwave disturbance is forecast to move northward from the Mid Atlantic into the Northeast, aiding in the development of widespread lift for heavy precipitation. This will allow a threat of heavy rain to spread northward from the Mid Atlantic into PA, NJ, and NY later tonight.

The mentioned shortwave is quite strong and will also promote the development of an impressive surface low pressure, which is likely to develop across Eastern PA and parts of NJ tonight. Heavy rain is likely for a few hours into the early morning of Monday, falling torrentially at times as very impressive moisture coincides with impressive lift across the mentioned areas. Localized flooding is likely to occur during this time frame and may create issues during the morning commute.

During the mid morning hours, the heaviest rain is likely to shift into New England, with lighter rain and eventually drying working into NJ, PA and the NYC regions. Across New England, the situation will become exacerbated by the development of impressive mid and upper level atmospheric features. Closing mid level low pressure areas will promote impressive lift to the north of the low pressure, and very heavy rain is likely across parts of Eastern NY and New England.

This will continue for quite some time, moving gradually northeastward towards the New England coast as the day goes on. Additional rain is likely to develop across much of PA and NJ during the afternoon hours as showers and thunderstorms are expected to redevelop near a cold frontal boundary. Some of these may be strong and pose a threat for lightning and strong wind gusts as the afternoon and evening go on. The low pressure will gradually shift away from the Northeast states Monday afternoon and evening.

The main concern through Monday morning is the potential for flash flooding, as highlighted by the National Weather Service where Flash Flood Watches have been posted. Remember never to drive into flood waters, no matter how shallow or deep they may appear to your eye. If you live in a typically flood-prone zone, make sure to have a plan in place should waters rapidly rise. Stay tuned for updates throughout the evening on the Dashboard.