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Stormy Weather in the Northwest; Fire Weather Threat Redeveloping in Southern California this Weekend

An active fall storm pattern in the Pacific Northwest is bringing heavy rain and high elevation snow to the region which will persist through this weekend. Strong winds associated with this system will bring a renewed period of critical fire weather to southern California later this weekend into next week. Read More >

A storm system will clip the Yosemite National Park area tonight through Friday morning bringing a chance for rain and snow. Snow levels will begin above 9,500 feet tonight and rapidly drop to about 8,500 feet by early Friday morning. This will bring winter like conditions to hikers in the backcountry and may impact travel through Yosemite Park along Highway 120, Tioga Pass.


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Upper Air Observations

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California Wind Profiler Data Can be Found Here

Information About the Upper Air Program Can be Found Here

Why Do Forecasters Still Rely on Weather Balloons?

Twice every day, from nearly 100 locations in the United States, the National Weather Service launches weather balloons, carrying instrument packages called radiosondes. Radiosonde sensors measure upper-air conditions such as atmospheric pressure, temperature and humidity, wind speed and direction. The data is important for aviation safety, and meteorologists use radiosonde information to prepare weather forecasts. Details...