Forecast Details for Grantham, PA

Recent Locations: Grantham, PA  
Current Alerts for Grantham, PA: Flash Flood Watch
Overnight: Showers and possibly a thunderstorm before 5am, then a chance of showers and thunderstorms after 5am. Some of the storms could produce heavy rain. Low around 67. Calm wind. Chance of precipitation is 90%. New rainfall amounts of less than a tenth of an inch, except higher amounts possible in thunderstorms.
Tuesday: Showers and thunderstorms likely, mainly before 2pm, then showers likely and possibly a thunderstorm after 5pm. Cloudy, with a high near 77. Calm wind becoming west around 5 mph in the afternoon. Chance of precipitation is 70%. New rainfall amounts between a tenth and quarter of an inch, except higher amounts possible in thunderstorms.
Tuesday Night: Showers likely and possibly a thunderstorm before 8pm, then a chance of showers and thunderstorms between 8pm and 2am, then a chance of showers after 2am. Cloudy, with a low around 64. Calm wind. Chance of precipitation is 60%. New rainfall amounts between a tenth and quarter of an inch, except higher amounts possible in thunderstorms.
Wednesday: A chance of showers, then showers likely and possibly a thunderstorm after 2pm. Cloudy, with a high near 80. Calm wind. Chance of precipitation is 70%. New rainfall amounts between a tenth and quarter of an inch, except higher amounts possible in thunderstorms.
Wednesday Night: Showers likely and possibly a thunderstorm before 8pm, then a chance of showers and thunderstorms between 8pm and 2am, then a chance of showers after 2am. Mostly cloudy, with a low around 67. Calm wind. Chance of precipitation is 60%. New rainfall amounts between a tenth and quarter of an inch, except higher amounts possible in thunderstorms.
Thursday: A chance of showers, then showers and thunderstorms after 8am. High near 81. Chance of precipitation is 80%. New rainfall amounts between a tenth and quarter of an inch, except higher amounts possible in thunderstorms.
Thursday Night: Showers and thunderstorms before 8pm, then showers likely and possibly a thunderstorm between 8pm and 2am, then a chance of showers after 2am. Low around 65. Chance of precipitation is 80%.
Friday: A chance of showers before 8am. Partly sunny, with a high near 78. Chance of precipitation is 30%.
Friday Night: Partly cloudy, with a low around 58.
Saturday: Mostly sunny, with a high near 80.
Saturday Night: A chance of showers. Mostly cloudy, with a low around 60. Chance of precipitation is 30%.
Sunday: A chance of showers. Partly sunny, with a high near 81. Chance of precipitation is 40%.
Sunday Night: A chance of showers. Mostly cloudy, with a low around 64. Chance of precipitation is 40%.
Monday: A chance of showers. Partly sunny, with a high near 84. Chance of precipitation is 50%.

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Weather Topic: What are Mammatus Clouds?

Home - Education - Cloud Types - Mammatus Clouds

mammatus clouds Next Topic: Shelf Clouds

A mammatus cloud is a cloud with a unique feature which resembles a web of pouches hanging along the base of the cloud.

In the United States, mammatus clouds tend to form in the warmer months, commonly in the Midwest and eastern regions.

While they usually form at the bottom of a cumulonimbis cloud, they can also form under altostratus, altocumulus, stratocumulus, and cirrus clouds. Mammatus clouds warn that severe weather is close.

Next Topic: Shelf Clouds

Weather Topic: What are Wall Clouds?

Home - Education - Cloud Types - Wall Clouds

wall clouds Next Topic: Condensation

A wall cloud forms underneath the base of a cumulonimbus cloud, and can be a hotbed for deadly tornadoes.

Wall clouds are formed by air flowing into the cumulonimbus clouds, which can result in the wall cloud descending from the base of the cumulonimbus cloud, or rising fractus clouds which join to the base of the storm cloud as the wall cloud takes shape.

Wall clouds can be very large, and in the Northern Hemisphere they generally form at the southern edge of cumulonimbus clouds.

Next Topic: Condensation