National Weather Service United States Department of Commerce

Fire Weather Conditions in the Northwest U.S.; Heavy Rain in the West and South-central U.S.

Extreme heat is waning over the Pacific Northwest. Dry, gusty winds, and isolated dry thunderstorms will bring critical fire weather to the Pacific Northwest and Intermountain West. Heavy rain and thunderstorms continue across portions of the Great Basin, Rockies, and central/southern Plains into the Ozarks. An atmospheric river will bring heavy rain and strong winds to southwest Alaska. Read More >

Dispersion Index Table

DISPERSION INDEX TABLE

 
Dispersion Index Interpretation
>100 Very Good (but may indirectly indicate hazardous conditions.)
60-100 Good (typical burning values)
41-60 Fair to Good (climatological afternoon values for most inland forests.)
21-40 Fair (stagnation if accompanied by persistent low wind speeds.)
13-20 Poor to Fair (stagnation, if persistent; better than average for nighttime.)
7-12 Poor (stagnant, but near average at nighttime.)
1-6 Very Poor (climatological nighttime value for most locations.)