[ADEQ Forecasts] ADEQ AIR QUALITY FORECAST FOR THURSDAY, JANUARY 29, 2009

[forecasts@lists.azdeq.gov]

For more information, please visit our Web page:
http://www.azdeq.gov/ensemble.pdf

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

Health message for Wednesday January 28: No health impacts are expected.


Health message for Thursday January 29: Unusually Sensitive People
should consider limiting prolonged exertion outdoors. 

Synopsis and Discussion
   As mentioned in yesterday's forecast, the Valley Brown Cloud did in
fact make a return Wednesday morning under a stronger inversion.  In
addition to that, mixing heights will be lower, around 5,000 feet the
next couple of days.  These inversions aren't expected to break, so
particle pollution accumulation within this lower layer will be much
greater than in previous days.  One positive thing to note will be
increased surface winds on Thursday.  With high pressure over Utah and
low pressure over northern Mexico, the gradient between the two will
increase.  This means that the wind flow will be from north and
northeast towards the south and southwest on Thursday.  Speeds will be
greatest along canyons, washes and rivers, especially the Colorado River
region.  So, despite the lower mixing heights and stronger inversion on
Thursday, there will be better dispersion due to increased surface
winds.  Thus, air quality will not deteriorate much further on Thursday.
   Conditions improve Friday through the weekend with lighter winds and
afternoon desert temperatures reaching the low to mid 70s.  Low
"Moderate" range fine particulate levels (PM-2.5) are possible Thursday
through Sunday.  We'll continue to assess everything, so check back
tomorrow for more.  Until then, have a good day!  -J.Paul

**********************************************************************
NOTICE: This e-mail (and any attachments) may contain PRIVILEGED OR 
CONFIDENTIAL information and is intended only for the use of the specific 
individual(s) to whom it is addressed.  It may contain information that is 
privileged and confidential under state and federal law.  This information 
may be used or disclosed only in accordance with law, and you may be 
subject to penalties under law for improper use or further disclosure of the 
information in this e-mail and its attachments. If you have received this e-
mail in error, please immediately notify the person named above by reply e-
mail, and then delete the original e-mail.  Thank you.