AUSTIN (KXAN) — A new study published in Proceedings of the National Academy of Sciences found that western wildfires can increase instances of severe, hazardous weather in the central United States.

Wildfires have increased in recent decades, happening more frequently and burning more land area. The study found that heat and atmospheric particles (smoke) created by large wildfires in the western U.S. lead to heavier rainfall rates and larger hail in states that are downwind. As wildfires are expected to become more severe in a warmer climate, the influence of wildfires on severe weather may become increasingly important.

The Colorado State University study created a model to examine wildfires, mainly in California and Oregon, and how they affect weather downstream, mainly in Colorado and Wyoming.

The authors found that active wildfires increase incidences of heavy rainfall rates downwind by 38% and significant severe hail events of egg-size hail or larger by 34%. This is due to the fact that western wildfires enhance surface high pressure and westerly/southwesterly winds, producing enhanced moisture and atmospheric particle transport to the central U.S. This also increases wind shear in central U.S. thunderstorms and the amount of “spin” in the storms.

Schematic depiction of wildfire effects on severe convective storms in the CUS.
Schematic depiction of wildfire effects on severe convective storms in the central U.S.

Since prevailing atmospheric winds do not typically carry smoke from western wildfires directly into Texas, the effects of wildfire smoke on Texas’ severe weather were not examined in this study.