[ADEQ Forecasts] ADEQ Daily Air Quality Forecast For May 16-17, 2008

[forecasts@lists.azdeq.gov]

For more information, please visit our Web page:

http://www.azdeq.gov/ensemble.pdf


Health message for Friday, May 16:  Unusually sensitive people should consider reducing prolonged or heavy exertion outdoors. 
 
Health message for Saturday, May 17:  Unusually sensitive people should consider reducing prolonged or heavy exertion outdoors. 
 
Synopsis and Discussion

*An Ozone Health Watch remains in effect for Friday, May 16, 2008*

Winds remain light out of the east Friday morning, but what a mixed bag of weather we saw here in the Valley on Thursday, huh?  It started with partly cloudy skies and ramping ozone levels, but by 3:30 pm, clouds thickened, virga moistened the atmosphere enough, and in many locations, in south Phoenix, there was rain!  That's right, actual drops of rain!  It was very Monsoon-like.  Sky Harbor officially received a TRACE, which is less than 0.01 inches, but enough to be measured.  Thus, the streak of 80 consecutive days without measurable rain here in Phoenix has been broken.  Needless to say, the rain and cold, dry outflow wind from the storms shut down ozone formation and actually helped to break it up.  Therefore there were only three local monitors that reached the "Moderate" range despite being on track for a possible exceedance had the storms not materialized.  That's a good thing!  There were also some periodic spikes in dust due to the brief gusty winds, but Particulates only climbed to the low part of the "Moderate" range for the 24-hr average.  High pressure will take charge this weekend, and if you're thinking of heading out of town to beat the heat, this weekend would be as good as any.  Afternoon desert temperatures are expected to reach 108°F on Monday and Tuesday of next week.  That's 13 degrees above normal for this time of year, so it will cool down by the end of the week.  Ozone could rebound into the mid "Moderate" range by Sunday but particulates should remain in the "Good" range as the mixing heights will drastically increase under this ridge of high pressure, allowing any suspended particles to mix out.  Check back Sunday for more on this heat and what it means for air quality next week.  Have a great weekend!  -J.Paul
 

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