By Llarisa Abreu

PHILADELPHIA (CBS) – A Flood Watch has been issued for Montgomery, Philadelphia, Delaware and Chester Counties in Southeast Pennsylvania, all of South Jersey, and Delaware from 6 a.m. Thursday until midnight Friday. Overnight, a low-pressure system that interacted with Hurricane Zeta began to enter the region. It will draw moisture into the Delaware Valley starting early Thursday morning and will last through the first half of the day Friday.

We can expect a washout throughout Thursday with periods of heavy rain. Widespread rain amounts will be 1-3 inches but a few localized areas could be slightly higher.

While flash flooding is not a huge threat, flooding in low-lying and poor drainage areas is a problem we may have to deal with during the day on Thursday. The rain will likely come in three main waves: one Thursday morning, another (with Zeta’s remnants) Thursday evening, when the winds will be strongest, and yet another wave overnight into Friday morning.

Cold air will rush in behind the system, and it may come in quickly enough to change the rain to a brief period of wet snow or a wintry mix in the Poconos. Friday night, temperatures plummet to near freezing in the city, with upper 20’s possible in the colder suburbs. But a pattern shift will follow this system and we’ll finally see some sun emerge for the weekend. A cold but sunny Halloween will be followed by a slightly milder Sunday, but another front Sunday evening may bring some showers and will bring another shot of cold air for Monday.

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