National Weather Service United States Department of Commerce

Severe Thunderstorms Possible in Northern Plains; Critical Fire Weather in Central Plains

Strong to severe thunderstorms with large hail and damaging winds are possible in parts of the Dakotas and western Minnesota through tonight. Meanwhile, dry and very hot weather will result in critical fire weather conditions for parts of the central Plains. An area of low pressure in the western Gulf of Mexico may bring heavy rainfall to parts of coastal Texas by Thursday. Read More >

 

 

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The Clearing Index is an Air Quality/Smoke Dispersal Index used to regulate open burning and as input for other air quality decisions throughout Utah. The Clearing Index is defined as the Mixing Depth (depth of the mixed layer in 100s of feet above ground level) multiplied by the Transport Wind (average wind in the mixed layer in knots). Clearing Index values below 500 are considered poor ventilation and open burning is restricted under these conditions. Any Clearing Index values above 1000 are considered excellent ventilation and are referred to as 1000+. Data for the Clearing Index on these web pages are derived from several operational atmospheric computer models. The data will be reviewed and may be edited by NWS meteorologists before dissemination.
   
An example calculation of the Clearing Index:
Mixed Layer Depth = 10000 feet
Transport Wind = 8 knots
Clearing index = (10000/100 feet) X 8 knots = 800
   
Note: Clearing Index is 1000+ if measurable precipitation or cold front passage occurs.
   
Utah Smoke Management Program