National Weather Service United States Department of Commerce

Atmospheric River Bringing Heavy Rain to Southern California and Heavy Snow to the Sierra Nevadas

A strong atmospheric river will continue heavy rain over southern California through Friday. The heaviest rainfall is ongoing today in the Los Angeles Basin. Flash and urban flooding is possible. A prolonged heavy snowfall has begun over the Sierra Nevada Mountains and will continue through Friday. Travel will become increasingly difficult over the passes due to snow and strong winds. 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)