Weather Alerts for California

21. 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

22. 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

23. Red Flag Warning for: Trinity

24. 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

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. Special Weather Statement for: Joshua Tree NP East

27. Special Weather Statement for: Northern Trinity

28. Special Weather Statement for: Northern Trinity; Southern Trinity

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

30. Special Weather Statement for: Shasta Lake Area / Northern Shasta 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 are Contrails?

Home - Education - Cloud Types - Contrails

Next Topic: Cumulonimbus Clouds

A contrail is an artificial cloud, created by the passing of an aircraft.

Contrails form because water vapor in the exhaust of aircraft engines is suspended in the air under certain temperatures and humidity conditions. These contrails are called exhaust contrails.

Another type of contrail can form due to a temporary reduction in air pressure moving over the plane's surface, causing condensation. These are called aerodynamic contrails.

When you can see your breath on a cold day, it is also because of condensation. The reason contrails last longer than the condensation from your breath is because the water in contrails freezes into ice particles.

Next Topic: Cumulonimbus Clouds

Weather Topic: What are Cumulus Clouds?

Home - Education - Cloud Types - Cumulus Clouds

Next Topic: Drizzle

Cumulus clouds are fluffy and textured with rounded tops, and may have flat bottoms. The border of a cumulus cloud is clearly defined, and can have the appearance of cotton or cauliflower.

Cumulus clouds form at low altitudes (rarely above 2 km) but can grow very tall, becoming cumulus congestus and possibly the even taller cumulonimbus clouds. When cumulus clouds become taller, they have a greater chance of producing precipitation.

Next Topic: Drizzle