National Weather Service United States Department of Commerce

Excessive Heat in Southern California; Tropical Storm Ian Expected to Rapidly Intensify

Excessive heat is possible through Wednesday over southern California. Strong thunderstorms may pose some risk for severe weather across parts of the upper Ohio Valley into the northern Mid Atlantic coast. Tropical Storm Ian is forecast to approach the Florida peninsula at major hurricane strength by midweek, and poses a risk of dangerous storm surge, hurricane-force winds, and heavy rainfall. Read More >

 

 

Mouse over the images below to see better detail, or click for full scale view

 
 
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