Weather Alerts for California

Recent Locations: San Francisco, CA

1. Air Quality Alert for: Calabasas and Agoura Hills; Eastern San Fernando Valley; Eastern San Gabriel Mountains; Eastern Santa Monica Mountains Recreational Area; Interstate 5 Corridor; Los Angeles County Beaches; Los Angeles County Inland Coast including Downtown Los Angeles; Los Angeles County San Gabriel Valley; Santa Clarita Valley; Santa Susana Mountains; Western San Fernando Valley; Western San Gabriel Mountains and Highway 14 Corridor; Western Santa Monica Mountains Recreational Area

2. Air Quality Alert for: Calabasas and Agoura Hills; Eastern San Fernando Valley; Eastern San Gabriel Mountains; Interstate 5 Corridor; Los Angeles County Inland Coast including Downtown Los Angeles; Los Angeles County San Gabriel Valley; Santa Clarita Valley; Santa Susana Mountains; Western San Fernando Valley; Western San Gabriel Mountains and Highway 14 Corridor

3. Air Quality Alert for: San Bernardino and Riverside County Valleys-The Inland Empire; San Bernardino County Mountains; Riverside County Mountains; Santa Ana Mountains and Foothills; Coachella Valley; San Gorgonio Pass Near Banning; Orange County Inland

4. Extreme Heat Warning for: Coachella Valley; San Diego County Deserts; San Gorgonio Pass Near Banning

5. Extreme Heat Warning for: Joshua Tree NP West; Joshua Tree NP East; Imperial County Southwest; Salton Sea; Chuckwalla Mountains; Imperial County Southeast; Imperial County West; Imperial Valley; Chiriaco Summit; Palo Verde Valley; Chuckwalla Valley

6. Extreme Heat Watch for: Del Norte Interior; Northern Humboldt Interior; Southern Humboldt Interior

7. Extreme Heat Watch for: Western Siskiyou County; Central Siskiyou County; Eastern Curry County and Josephine County; Jackson County

8. Heat Advisory for: Northern Trinity; Southern Trinity; Northeastern Mendocino Interior; Northern Lake County; Southern Lake County

9. Heat Advisory for: Northwestern Mendocino Interior; Southeastern Mendocino Interior

10. Heat Advisory for: Riverside County Mountains; San Diego County Mountains

11. Heat Advisory for: San Bernardino and Riverside County Valleys-The Inland Empire

12. Heat Advisory for: San Diego County Inland Valleys

13. Heat Advisory for: Shasta Lake Area / Northern Shasta County; Burney Basin / Eastern Shasta County; Northern Sacramento Valley; Central Sacramento Valley; Mountains Southwestern Shasta County to Western Colusa County; Northeast Foothills/Sacramento Valley; Western Plumas County/Lassen Park

14. Wind Advisory for: Santa Barbara County Southwestern Coast; Santa Ynez Mountains Western Range

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Current U.S. National Radar--Current

The Current National Weather Radar is shown below with a UTC Time (subtract 5 hours from UTC to get Eastern Time).

National Weather Forecast--Current

The Current National Weather Forecast and National Weather Map are shown below.

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