National Weather Service United States Department of Commerce

Severe Thunderstorms in Portions of the Mississippi Valley and Great Lakes

A few severe thunderstorms with large hail, are expected across parts of the middle and upper Mississippi River Valley tonight through early morning. Snow and a wintry mix overnight in the Upper Midwest into the Great Lakes can cause hazardous travel conditions. Fire weather concerns continue for a large portion of the central and southern High Plains and Four Corners region this evening. Read More >

Smoke dispersal is categorized by using the Ventilation Rate. Ventilation Rate forecasts for a specific point can be found using the Fire Weather Dashboard. Click a spot on the map and scroll down to find daily and hourly Ventilation Rate values for the next few days.

 

Fire Weather Dashboard

 

The link above is configured to display smoke dispersal categories as shown here:

 

  Smoke Dispersal Vent. Rate, knot-feet (x1000)
     Excellent             150 or greater
     Very Good 100 to 149.99
     Good 60 to 99.99
     Fair 40 to 59.99
     Poor less than 40

 

Ventilation Rate = Transport Wind (kts) Mixing Height (ft)