Weather Alerts for California

22. Flood Watch for: Lassen-Eastern Plumas-Eastern Sierra Counties; Greater Lake Tahoe Area; Mono; Mineral and Southern Lyon Counties; Greater Lake Tahoe Area; Greater Reno-Carson City-Minden Area

23. Flood Watch for: Yosemite NP outside of the valley; Yosemite Valley; San Joaquin River Canyon; Upper San Joaquin River; Kaiser to Rodgers Ridge; Kings Canyon NP; Grant Grove Area; Sequoia NP; South End of the Upper Sierra

24. Red Flag Warning for: Trinity

25. Red Flag Warning for: Western Klamath National Forest; Central Siskiyou County Including Shasta Valley; Shasta-Trinity National Forest in Siskiyou County; Siskiyou County from the Cascade Mountains East and South to Mt Shasta; Modoc County Except for the Surprise Valley; Umpqua National Forest; Western Rogue Basin including the Illinois Valley; Siskiyou Mountains; Eastern Rogue Valley; Southern Oregon Cascades; Klamath Basin and the Fremont-Winema National Forest; South Central Oregon Desert including the BLM Land in Eastern Lake and Western Harney Counties

26. Red Flag Warning for: Western Klamath National Forest; Central Siskiyou County Including Shasta Valley; Shasta-Trinity National Forest in Siskiyou County; Siskiyou County from the Cascade Mountains East and South to Mt Shasta; Modoc County Except for the Surprise Valley; Umpqua National Forest; Western Rogue Basin including the Illinois Valley; Siskiyou Mountains; Eastern Rogue Valley; Southern Oregon Cascades; Klamath Basin and the Fremont-Winema National Forest; South Central Oregon Desert including the BLM Land in Eastern Lake and Western Harney Counties

27. Special Weather Statement for: Northern Trinity

28. Special Weather Statement for: San Bernardino and Riverside County Valleys-The Inland Empire

29. Special Weather Statement for: Southern Trinity

30. Special Weather Statement for: Tehachapi

31. Special Weather Statement for: Western Plumas County/Lassen Park; West Slope Northern Sierra Nevada

32. Special Weather Statement for: Western Siskiyou County

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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 Precipitation?

Home - Education - Precipitation - Precipitation

Next Topic: Rain

Precipitation can refer to many different forms of water that may fall from clouds. Precipitation occurs after a cloud has become saturated to the point where its water particles are more dense than the air below the cloud.

In most cases, precipitation will reach the ground, but it is not uncommon for precipitation to evaporate before it reaches the earth's surface. When precipitation evaporates before it contacts the ground it is called Virga. Graupel, hail, sleet, rain, drizzle, and snow are forms of precipitation, but fog and mist are not considered precipitation because the water vapor which constitutes them isn't dense enough to fall to the ground.

Next Topic: Rain

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