Arizona Air Quality Information

Easterly Monsoonal Winds Bring Smoke To Valley


Just in time for the first day of Monsoon 2021, a monsoon-like pattern will reside over the Southwest through the week. Specifically, this pattern involves a broad high-pressure circulation centered over the Four Corners region of the U.S. Now, instead of the normal westerly (from the west) wind flow over Arizona, winds over the state are out of the east.

It's this monsoonal wind shift that gives us some things to talk about:

First of all, for the past two days, these easterly winds have been pulling smoke from the Telegraph Fire, located just south of Globe, westward over the Phoenix Valley. As a result, afternoon skies over the Valley have appeared hazy or overcast. The overhead smoke has also given an orange hue to light that reaches the ground. The main difference today though, is that smoke is not getting as much lift as it did yesterday. As result, more smoke has been able to reach the ground or closer to it, causing a general haziness. As long as the wildfire remains active, the Valley could see more smoke on Wednesday, too.

View the smoke forecast for the Telegraph Fire here.

Secondly, the easterly winds could potentially result in locally higher ozone levels. On any given day, afternoon winds in the Phoenix Valley are usually out of the west, which causes ozone to move eastward throughout the day. But under easterly winds, ozone gets pushed back to the heart of the Valley. This effectively "traps" the ozone and enables it to accumulate more.

View the Phoenix Air Quality Forecast here.

Thirdly, the easterly winds will result in thunderstorms for areas in the high country north and east of the Phoenix Valley. However, since it's still pretty dry near the ground, these storms will mainly produce gusty winds. The gusty winds may even reach the northern or eastern portions of the Valley later in the afternoons/evenings, potentially resulting in brief blowing dust.