First Alert Weather Blog: Periods of Rain Stretch Across Several Days | NBC 10 Philadelphia

First Alert Weather Blog: Periods of Rain Stretch Across Several Days

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    NEWSLETTERS

    If you're heading outside on Saturday, you won't need your heavy coat. Warm temperatures will hit our region on Saturday, but will they stick around for Sunday? NBC10 meteorologist Krystal Klei has the details.

    (Published Saturday, March 25, 2017)

    Pennsylvania, Delaware and New Jersey fall under a rainy period over the next several days. This period isn’t a constant, widespread rain. Instead, it’s a spottier on-again, off-again forecast that will last through Tuesday.

    Warm Saturday

    A large storm system has been driving across the country, and is forcing warm air our direction ahead of the cold front that crosses through the Midwest Saturday morning. With a southwest flow, temperatures began mild Saturday and will continue warmer than average into the afternoon. Temperatures are forecast to hit the low 70 over portions of Philadelphia and areas south, such as South Jersey and Delaware.

    Through the afternoon, a surface cold front will slip to the south and a few disturbances in the atmosphere will ripple across our region. This will allow for continued periods of light and spotty rain into the evening. As the front passes overnight (called a backdoor front when it passes from the north/northeast), a brief period of more widespread light rain is possible. Overall, Saturday will still be a great day to get outdoors.

    Cooler, Damp Sunday

    Temperatures will fall Saturday night as the frontal passage allows winds to shift from a southwest flow, to a more easterly push. When winds come from the east, they pick up the cool air characteristics off the ocean water. The winds will also strengthen, bringing breezy gusts up to around 25 mph to the region. The cold front passage also allows colder air to spill into the area from the north. This will result in very little warming through the entire day. From low to mid 40s in the morning to only upper 40s for many in the afternoon Sunday.

    Light spotty showers pass Sunday morning, especially north. Along the Poconos, some brief freezing rain may occur. The rest of the day will be damp and mostly cloudy, with continued showers developing late day into the night as the storm system that was to the west begins to near the Delaware Valley. Take a look at the picture below for Sunday evening. The storm center is still to the northwest, but the area of rain is beginning to move in (green).

    Photo credit: Krystal Klei

    Best Days for Rain

    The best day for rain comes Monday, as the system actually passes across the region. The best chance of rain will be north and west of Philadelphia, but most areas should see at least some scattered showers. The rain will be steadiest in the morning, and scattered through the later day and night.

    At the same time, yet another rainy system moves in from the west. You can see the center near Missouri and Illinois:

    Photo credit: Krystal Klei

    Like Monday, Tuesday will see periods of more widespread rain. Again, the showers will be scattered and light to start in the morning. Through the early afternoon the area of rain may expand across the area, and linger into the early evening. This will mostly be light showers, as the green on the map below is light in color without pockets of yellow or orange (heavier activity indicator). 

    Photo credit: Krystal Klei

    By Wednesday morning, the moisture should move out and we’ll see several days of dry and sunnier conditions. Temperatures remain Spring-like, hovering around the 50s and 60s during the work week. Another wet period is possible by the weekend, more on that in the days to come!