Forecast Details for Portland, OR

Recent Locations: Lubbock, TX Santa Clarita, CA Portland, OR

Tonight: Mostly clear, with a low around 39. East wind around 5 mph becoming calm in the evening.

Friday: Sunny, with a high near 59. Light south wind.

Friday Night: Partly cloudy, with a low around 43. Calm wind.

Saturday: Rain, mainly after 4pm. High near 56. Calm wind becoming south around 6 mph in the morning. Chance of precipitation is 80%. New precipitation amounts between a tenth and quarter of an inch possible.

Saturday Night: Rain. Low around 49. South wind around 5 mph. Chance of precipitation is 80%. New precipitation amounts between a quarter and half of an inch possible.

Sunday: Rain. High near 53. Chance of precipitation is 90%.

Sunday Night: Rain, mainly before 10pm. Low around 42. Chance of precipitation is 80%.

Monday: Rain likely, mainly after 10am. Mostly cloudy, with a high near 52.

Monday Night: A chance of rain. Mostly cloudy, with a low around 40.

Tuesday: A chance of rain, mainly before 4pm. Mostly cloudy, with a high near 50.

Tuesday Night: A slight chance of rain. Mostly cloudy, with a low around 36.

Wednesday: A slight chance of rain. Partly sunny, with a high near 52.

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

Thursday: A chance of rain. Mostly cloudy, with a high near 51.

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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

Tomorrow National Weather Forecast and Tomorrow National Weather Map are show below.

North America Water Vapor (Moisture)

This map shows recent moisture content over North America. Bright and colored areas show high moisture (ie, clouds); brown indicates very little moisture present; black indicates no moisture.

Weather Topic: What is Condensation?

Home - Education - Precipitation - Condensation

Next Topic: Contrails

Condensation is the process which creates clouds, and therefore it is a crucial process in the water cycle. Condensation is the change of matter from a state of gas into a state of liquid, and it happens because water molecules release heat into the atmosphere and become organized into a more closely packed structure, what we might see as water droplets.

Water is always present in the air around us as a vapor, but it's too small for us to see. When water undergoes the process of condensation it becomes organized into visible water droplets. You've probably seen condensation happen before on the surface of a cold drink!

Next Topic: Contrails

Weather Topic: What are Cumulonimbus Clouds?

Home - Education - Cloud Types - Cumulonimbus Clouds

Cumulonimbus Clouds Next Topic: Cumulus Clouds

The final form taken by a growing cumulus cloud is the cumulonimbus cloud, which is very tall and dense. The tower of a cumulonimbus cloud can soar 23 km into the atmosphere, although most commonly they stop growing at an altitude of 6 km.

Even small cumulonimbus clouds appear very large in comparison to other cloud types. They can signal the approach of stormy weather, such as thunderstorms or blizzards.

Next Topic: Cumulus Clouds