[ADEQ Forecasts] ADEQ AIR QUALITY FORECAST FOR THURSDAY, JANUARY 15, 2009

[forecasts@lists.azdeq.gov]

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

For transportation alternatives:
http://www.valleymetro.org

Health message for Wednesday, January 14: Unusually Sensitive People should consider limiting prolonged exertion outdoors.

Health message for Thursday, January 15: Unusually Sensitive People should consider limiting prolonged exertion outdoors.
	
Synopsis and Discussion
   Another strong inversion (about 10-14 degrees F) has settled over the Valley Wednesday morning.  Based on a forecast high of about 74°F, it may not break until around 2pm Wednesday afternoon.  The best mixing will take place from 2-5pm with maximum mixing heights near 3800 feet.  This means that the distinct line drawn by the inversion layer will be visible much of the day before improving by the afternoon.  The weather pattern will not change much the next several days with high pressure over the Pacific coast region staying put.  Thus, we can enjoy afternoon desert temperatures in the mid 70s through the weekend under mostly sunny skies and relatively light winds.  
   Mentioned in yesterdays discussion was the chance for possible Valley rain this time next week.  Models have been inconsistent on this scenario, but the latest run has put the driving mechanism behind the potential rain, a digging trough of low pressure, back in the forecast.  The timing and location of the trough as it nears the region remain in question.  It appears that it may not happen until the week of the 26th.  That's still too far out to make any definite calls at this time.  So as always, we'll keep watching to see if anything comes of it.
   Air Quality-wise, particulate concentrations remain nearly unchanged with both PM-2.5 and PM-10 levels in the lower "Moderate" category.  Slight increases in both are expected the next several days with little mixing available to clear it out.  Check back tomorrow for the latest.  Until then, have a good day!      -J.Paul  

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