Forecast Details for Mercer Island, WA

Recent Locations: Mercer Island, WA

Overnight: A 40 percent chance of rain before 4am. Mostly cloudy, with a low around 42. East wind around 7 mph.

Thursday: Rain likely, mainly before 5pm. Mostly cloudy, with a high near 50. East northeast wind around 5 mph becoming south southwest in the afternoon. Chance of precipitation is 70%. New precipitation amounts of less than a tenth of an inch possible.

Thursday Night: Rain, mainly after midnight. Low around 44. East wind 6 to 9 mph becoming north northeast after midnight. Winds could gust as high as 23 mph. Chance of precipitation is 80%. New precipitation amounts between a tenth and quarter of an inch possible.

Friday: Rain. High near 55. East wind around 18 mph becoming south in the afternoon. Winds could gust as high as 29 mph. Chance of precipitation is 100%. New precipitation amounts between a tenth and quarter of an inch possible.

Friday Night: Rain likely, mainly after 4am. Mostly cloudy, with a low around 43. South wind 14 to 18 mph, with gusts as high as 29 mph. Chance of precipitation is 70%. New precipitation amounts of less than a tenth of an inch possible.

Saturday: Rain. High near 50. Chance of precipitation is 80%. New precipitation amounts between a tenth and quarter of an inch possible.

Saturday Night: Rain. Low around 42. Chance of precipitation is 80%.

Sunday: Rain likely. Mostly cloudy, with a high near 49.

Sunday Night: Rain likely, mainly before 10pm. Mostly cloudy, with a low around 40.

Monday: A chance of rain. Partly sunny, with a high near 49.

Monday Night: A chance of rain. Mostly cloudy, with a low around 38.

Tuesday: A chance of rain. Partly sunny, with a high near 48.

Tuesday Night: A chance of rain. Mostly cloudy, with a low around 37.

Wednesday: A chance of rain. Partly sunny, with a high near 46.

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Current U.S. National Radar--Current

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National Weather Forecast--Current

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National Weather Forecast for Tomorrow

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North America Water Vapor (Moisture)

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Weather Topic: What are Shelf Clouds?

Home - Education - Cloud Types - Shelf Clouds

Shelf Clouds Next Topic: Sleet

A shelf cloud is similar to a wall cloud, but forms at the front of a storm cloud, instead of at the rear, where wall clouds form.

A shelf cloud is caused by a series of events set into motion by the advancing storm; first, cool air settles along the ground where precipitation has just fallen. As the cool air is brought in, the warmer air is displaced, and rises above it, because it is less dense. When the warmer air reaches the bottom of the storm cloud, it begins to cool again, and the resulting condensation is a visible shelf cloud.

Next Topic: Sleet

Weather Topic: What is Snow?

Home - Education - Precipitation - Snow

Snow Next Topic: Stratocumulus Clouds

Snow is precipitation taking the form of ice crystals. Each ice crystal, or snowflake, has unique characteristics, but all of them grow in a hexagonal structure. Snowfall can last for sustained periods of time and result in significant buildup of snow on the ground.

On the earth's surface, snow starts out light and powdery, but as it begins to melt it tends to become more granular, producing small bits of ice which have the consistency of sand. After several cycles of melting and freezing, snow can become very dense and ice-like, commonly known as snow pack.

Next Topic: Stratocumulus Clouds