[ADEQ Forecasts] ADEQ AIR QUALITY FORECAST FOR SATURDAY, APRIL 4, 2009

[forecasts@lists.azdeq.gov]

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

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

Health message for Friday, April 3, 2009: Active children and adults,
and people with respiratory disease, such as asthma, should limit
prolonged exertion outdoors.
 
Health message for Saturday, April 4, 2009: Unusually Sensitive People
should consider limiting prolonged or heavy exertion outdoors.
 
Synopsis and Discussion
*A PM-10 HIGH POLLUTION ADVISORY REMAINS IN EFFECT FOR FRIDAY, APRIL 3,
2009*
   Another very strong wind event will send dust in to the air once
again Friday afternoon.  You may be looking out the window to wonder
where it is right now, but it is coming!  Flagstaff currently (at 10am)
has sustained winds above 30 mph with winds gusts exceeding 40 mph.
Winslow has already had gusts exceed 60 mph!  The pressure gradients
will continue to tighten across the deserts the next several hours, and
we will begin to see sustained winds out of the west around 25-35 mph by
about 2 pm this afternoon.  Visibility could drop to less than a mile in
some desert spots at times, especially along the Interstate 10 between
Los Angeles and Phoenix, I-10 between Phoenix and Tucson, as well as
Interstate 8 between Yuma and Casa Grande.  With the wide-spread blowing
dust on Friday, PM-10 concentrations here in the Phoenix forecast area
are expected to exceed the 24-hr standard as winds will not drop off
until Saturday morning.  Thus, there is a PM-10 High Pollution Advisory
in effect through midnight Friday.  People with respiratory issues may
want to make plans to stay indoors this afternoon and evening.     
   The trough will push east by Saturday afternoon, but afternoon
temperatures will remain in the mid 70s.  Dust may linger through
Saturday afternoon, but enough will drop out of the atmosphere that the
24-hr concentration will be below the health standard on Saturday
further improvement is expected on Sunday with afternoon desert
temperatures reaching the low to mid 80s under mostly sunny skies and
relatively light winds.  
   The other side of the double-edged sword will be the Ozone
concentrations.  Troughs similar to this one tend to import Ozone and
precursors from southern California and western Arizona.  Combined with
locally generated ozone, concentrations could reach the mid "Moderate"
range on Friday and Saturday, dropping off a bit on Sunday.  There's a
lot going on this weekend weather and air quality-wise, so check back on
Sunday for the latest.  Until then, have a great weekend!  -J.Paul

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