Phoenix Forecast

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Air Quality Hourly Forecast | Phoenix

Click on each day to view forecast.

Monday Forecast:

Alert: Ozone High Pollution Advisory in effect for Monday

Ozone

119 AQI
Max 8-hr Avg: 76 ppb

PM10

51 AQI
24-hr Avg: 55 µg/m3

PM2.5

33 AQI
24-hr Avg: 8.0 µg/m3

Tuesday Forecast:

Alert: Ozone High Pollution Advisory in effect for Tuesday

Ozone

115 AQI
Max 8-hr Avg: 75 ppb

PM10

52 AQI
24-hr Avg: 58 µg/m3

PM2.5

33 AQI
24-hr Avg: 7.9 µg/m3

Wednesday Forecast:

Alert: Ozone Health Watch possible on Wednesday

Ozone

93 AQI
Max 8-hr Avg: 68 ppb

PM10

49 AQI
24-hr Avg: 53 µg/m3

PM2.5

32 AQI
24-hr Avg: 7.6 µg/m3

Thursday Forecast:


Ozone

84 AQI
Max 8-hr Avg: 65 ppb

PM10

48 AQI
24-hr Avg: 52 µg/m3

PM2.5

28 AQI
24-hr Avg: 6.7 µg/m3

Friday Forecast:


Ozone

80 AQI
Max 8-hr Avg: 64 ppb

PM10

48 AQI
24-hr Avg: 52 µg/m3

PM2.5

28 AQI
24-hr Avg: 6.7 µg/m3

Air Quality By Pollutant:

Pollutant
Monday
6/24/2019
Tuesday
6/25/2019
Wednesday
6/26/2019
Thursday
6/27/2019
Friday
6/28/2019
O3
119
115
93
84
80
PM10
51
52
49
48
48
PM2.5
33
33
32
28
28
Pollutant
MON
TUE
WED
THU
FRI
O3
119
115
93
84
80
PM10
51
52
49
48
48
PM2.5
33
33
32
28
28
O3 = Ozone, PM10 = Particles ≤ 10 microns, PM2.5 = Particles ≤ 2.5 microns

Forecast Discussion:

Big air quality story in the short-term is ozone. An Ozone High Pollution Advisory is in effect for today. A combination of the weather pattern and other local factors (i.e., the large Woodbury Fire burning in close proximity to Phoenix) are ideal for new ozone formation at the surface and accumulation of aged ozone aloft in the metropolitan area.

This morning, evidence of ozone accumulation aloft is apparent. The high elevation Humboldt Mountain monitor is registering hourly ozone readings between 64 and 68 parts per billion (ppb) since midnight. That is about 15 ppb higher than typical this time of year at that site. The outside influence on our local ozone is likely the nearby wildfire.

The Woodbury Fire is now 112,000 acres in size, with growth over 16,000 acres logged on Sunday alone. Substantial smoke output is being captured by satellite imagery. Occasionally, smoke can be seen drifting over the Phoenix area. It is important to note that 24-hour PM2.5 readings in Phoenix have been in the Good AQI range. This indicates that smoke is staying mainly above ground-level. This is great news for air quality considerations at the surface in terms of fine particulates that are an indicator of smoke impacts.

However, wildfire smoke plumes are complex and have been linked in research studies to enhance ozone nearby and downwind of wildfires as the plume may contain ozone pollutant precursors. Any aged wildfire influenced ozone trapped in above ground inversions (similar to what is likely happening at Humboldt Mountain based on weather balloon data) will tend to fumigate toward the surface with daytime vertical mixing. With that additional ozone contribution expected to add to the typical new ozone formation the city experiences daily, we are at risk for exceeding the federal ozone standard today.

Prevailing winds in the coming days will dictate smoke plume movement and pollutant dispersion in general. The stagnant ridge pattern in place today transitions towards low pressure troughing by Wednesday. That is when the wildfire plume of the Woodbury Fire (and any wildfire influenced ozone aloft) gets steered more prevalently to the northeast away from the metropolitan. Clearing winds associated with a trough pattern lingers for the rest of the week. Until winds get established midweek, widespread higher peak ozone readings are forecasted for the city. The Ozone High Pollution Advisory is extended for Tuesday, June 25, 2019.

Unfortunately, the Tonto National Monument monitor is positioned in closer proximity and downwind of the wildfire in the Superstition Wilderness. Continued ozone and smoke impact potential is greater at that location, despite better dispersion later in the week. For now, forecasted 8-hour maximum ozone AQIs are below the exceedance threshold of 71 ppb.

Stay tuned for air quality forecast updates this week!


- J. Malloy
ADEQ Meteorologist


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