Frigid Airmass to Bring Significantly Colder Temperatures; Heavy Lake-effect Snow; Fire Concerns Across the Central Gulf Coast

A frigid cold airmass will bring significantly colder weather across the eastern two thirds of the country early this week. Temperatures will tie or break many records across the Southeast through tonight. Moderate to heavy lake effect snow will continue downwind of the Great Lakes. Gusty winds and dry conditions will support an elevated fire weather threat across the Central Gulf Coast. Read More >

Definitions of a Fire Weather Watch and a Red Flag Warning

A Fire Weather Watch or Red Flag Warning is issued when the combination of dry fuels and weather conditions support extreme fire danger. These products are written for land and fire managers to highlight the increased fire danger.

Each NWS office creates local criteria for fire weather watches and red flag warnings. The criteria for northern Illinois and northwest Indiana include:

Sustained 20 foot winds of 20 mph or higher.
Afternoon relative humidity less than 25%.
10 hour fuel moisture at 8% or less for one day.

A Fire Weather Watch is issued up to 72 hours before the above conditions are expected to occur.

A Red Flag Warning is issued when the conditions above are expected to occur or are occurring within the next 24 hours.

Click to get to the NWS Chicago Fire Weather Page

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