National Weather Service United States Department of Commerce

Fire Weather Concerns Continue in Southern California; Early Season Winter Storm To Impact East and Ohio/Mississippi Valleys

Elevated to critical fire weather threats persist for southern California through Thursday, before hopefully subsiding on Friday. A complex early winter storm is expected to produce heavy snow from the Mid MS Valley to western OH Valley and Interior Northeast, potentially significant icing in the south-central Appalachians and heavy rain from the Southeast to Mid-Atlantic coast the next few days. 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