National Weather Service United States Department of Commerce

Heavy rain in the Central U.S.; Unseasonable Warmth in the East

Imelda remnants swept up with a cold front will produce heavy rain that could cause flash flooding from portions of the South Plains to the Great Lakes. Lorena remnants combined with a cold front will bring thunderstorms with heavy rain, and some severe storms with hail and damaging winds to Arizona Monday. Strong winds in northern California will bring increasing fire weather threats on Monday. 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