[ADEQ Forecasts] ADEQ Issues Same-Day High Pollution Advisory for Today, Fri., May 1

[forecasts@lists.azdeq.gov]

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

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

Health message for Friday, May 1: Unusually sensitive people should
consider reducing prolonged or heavy outdoor exertion outdoors.

Health message for Saturday, May 2: Unusually sensitive people should
consider reducing prolonged or heavy outdoor exertion outdoors.  

Synopsis and Discussion
*THE OZONE HEALTH WATCH FOR FRIDAY, MAY 1, 2009 
HAS BEEN ELEVATED TO A SAME-DAY HIGH POLLUTION ADVISORY*
   Thursday saw the first two ozone exceedances of the season here in
the Phoenix forecast area.  Tonto National Monument climbed to 81 parts
per billion (or 114 AQI) while Apache Junction checked in at 76 ppb (or
101 AQI). Two others (Fountain Hills and Queen Valley) nearly exceeded
that standard.  The latest readings show levels on average around 2-6
ppb above where they were 24 hours ago.  For this reason, we are
elevating the Ozone Health Watch currently in place to an Ozone High
Pollution Advisory.  Active children and adults, as well as people with
chronic respiratory issues should take it easy Friday afternoon and
evening.  Other people looking to exercise outdoors, such as joggers and
cyclists, may want to think about alternate plans as well.  Once the sun
goes down, ozone begins to break down, reaching the lowest levels
somewhere around 3-4 am.  
   We have another weather disturbance moving in from the west.  This
system is likely responsible for importing additional ozone and
precursor into the forecast area.  Imported ozone/precursors combined
with locally generated ozone have led to this current ozone situation.
Mid and high level clouds moving into the region ahead of this system
make it appear worse than it actually is, but remember, ozone is a
colorless, odorless gas.  The clouds just indicate a bit of upper-level
moisture, not increased pollution.
   Winds are expected to increase Saturday as the associated front
pushes through the region.  It's possible to see sustained winds around
20-25 mph with occasional stronger gusts.  These winds should push this
ozone plume east along with the accumulating precursors.  Thus, Saturday
and Sunday should be much lower than the past 24 to 48 hours.  Due to
increased winds and potential blowing dust on Saturday, particulates are
expected climb into the mid "Moderate".  All pollutants should fall back
into the "Good" category on Saturday with the exception of few ozone
sites which may be "Moderate".  Check back on Sunday for the latest
weather and associated air quality.  Until then, have a great weekend!
-J.Paul

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