Instant Summer, Just Add Heat and Ozone

Staff Writer, DB Holmes
Weather / Air Quality
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The heat gives us a break at the mid part of the week and then slowly builds back in as a cut off low spins away. For respiratory issues sufferers, the ozone has replaced dust and particulates in causing breathing difficulties. The ozone should return to a more normal range for this time of the year as clouds and cooler weather enter the picture this week.

May 19 Air Quality Forecast

Forecast Discussion: If the triple-digit heat came a little too early for you (104°F at Sky Harbor Friday and Saturday), take heart. Temperatures will "cool" to around 90°F by Wednesday as a trough of low pressure moves over Arizona. This trough will actually become cut off from the main flow, sitting over our area through next weekend as it eventually spins out and loses energy. This could eventually be good as far as wildfires go. Towards the end of the week, the low is expected to draw some moisture from the Gulf of Mexico into eastern Arizona. The mountains could see some showers next Saturday and Sunday. Regardless of the rain, the increased humidity should help reduce fire behavior. Ozone is the current topic of conversation. Yuma exceeded the 8-hour ozone health standard on Friday. Typically we'll see levels do the same in the Valley a day later. However, we were spared as the flow was more to the north-northeast rather than east-northeast. Unfortunately, Alamo Lake, Prescott, and Flagstaff all exceeded the standard on Saturday. Exceeding the ozone standard in those non-major-metropolitan areas is a classic case of ozone import from the west. Let's not forget that smoke from southern California may have played a role in enhancing the ozone development upstream. Looking forward, high clouds Sunday should keep ozone production down slightly. This may be just enough help to avoid exceeding the standard in Valley. Stronger winds develop Monday through Wednesday which should also help break up the invisible plume, decreasing the threat of elevated readings. Dust doesn't seem to be much of a concern for us this week, especially when moisture is drawn in later in the week.

Source: AIRNow, Weather Channel,

Ozone Concern and Triple Digit Heat for the Desert Valley

Staff Writer, DB Holmes

Weather / Air Quality
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Phoenix should have a quiet weather weekend as winds are subdued and temperatures remain hot. Ozone rose but now the westerly winds will pick up the smoke from the California wildfires. People with respiratory issues should take note.

Here is the rest of the forecast:

Forecast Discussion: Ozone levels soared into the upper Moderate range across the forecast area on Thursday, and that was without the help of southern California wildfire smoke. Now that the flow has switched out of the west, the likelihood of smoke-enhanced ozone affecting Arizona increases. In fact, locations north of the Valley (Prescott, Flagstaff) could see elevated concentrations the next several days. Locally, Valley concentrations will remain in the upper part of the Moderate range through Sunday. Winds will increase Sunday afternoon as another trough of low pressure approaches the region. This should break up the invisible daily plume of ozone, effectively lowering concentrations. PM10 levels should also remain in the Good range the next several days, increasing Sunday through early next week with stronger winds. Expect daytime temperatures to reach 102-104°F Friday through Sunday, decreasing Monday. Unfortunately, no rain is in the forecast for at least another 2 weeks.

Source: AIRNow 

Dusty, Unhealthy Air Quality from the Baja to Four Corners Region

Staff Writer, DB Holmes

Weather / Air Quality 
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A windy day across the state of Arizona. Dusty, unhealthy, and opaque air led to exceeding the air quality standards. This morning as dawn rose the air looked like fog. Upon smelling the air, one knew something was not right with the air.

Today's Unheathly Air

Forecast Discussion: Another dry cold front is currently marching through Arizona. Stronger winds along and ahead of the cold front have kicked up an impressive plume of dust, stretching from the northern Gulf of California to the Four-Corners region! The dust is being carried west to east with the western extent now entering Maricopa County. Overall, the dust plume now seems to be dissipating. Visibility has improved compared to early morning readings, but additional dust is still possible today under gusty winds this afternoon. The large amount of long-range dust transport overnight from the lower deserts of southeastern California and Arizona have pushed PM-10 readings into the Unhealthy category. Very high hourly average PM-10 concentrations this morning will likely result in exceedances of the federal standard at multiple monitors today. People should consider limiting outdoor physical activity due to unhealthy air quality. For tomorrow and Tuesday, breezy conditions persist, especially on Tuesday, but the direction turns more northeasterly allowing PM concentrations to fall into the upper Good to lower Moderate category. As the disturbance clears the area, ozone will drop with levels remaining near or slightly above Moderate thresholds. Clear skies and high temps in the mid 80s to lower 90s are expected.

Weather Conditions for this week:

More wind on Tuesday and a chance of sprinkles at the start of next week. A gradual increase in temperatures until triple digits dominate the long range forecast until September.

Source: AIRNow, Weather Channel