[ADEQ Forecasts] ADEQ AIR QUALITY FORECAST FOR TUESDAY, FEBRUARY 03, 2009

[forecasts@lists.azdeq.gov]

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

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

Health message for Monday February 02: Unusually sensitive people should
consider reducing prolonged or heavy exertion. 

Health message for Tuesday February 03: Unusually sensitive people
should consider reducing prolonged or heavy exertion.  

Synopsis and Discussion
Local ACARS sounding data indicates that the best mixing depth over the
Valley today will be near 5200' and that dispersion will be in the FAIR
category.  A moderate (5-6 deg C) surface-based radiation inversion that
extends to near 1700'also managed to form overnight.  Higher a.m.
particle pollutant emissions associated with a return to weekday
activities have become temporarily trapped within this layer, resulting
in very high readings at some monitoring sites. Hourly coarse particle
(PM-10) concentrations at West Forty Third rose from 93.8ug/m3 at 6:00
a.m. to 154.6ug/m3 at 8:00 a.m.; at Durango PM-10 levels rose from
96.4ug/m3 at 6:00 a.m. to 162.9ug/m3 at 7:00 a.m. and to 323.6ug/m3 at
8:00 a.m.  The highest fine particle (PM-2.5) reading thus far has been
64.0ug/m3 at Durango at 8:00 a.m.  A strong ridge aloft will be near or
over the local forecast area thru Wednesday.  An increasingly stagnant
Valley air mass due to warming aloft (11 deg F at the 5K' level by
Tuesday afternoon) and mostly light winds will be offset to some degree
by vertical mixing from afternoon high temperatures near 80 deg F.  Even
though unhealthy PM-10 concentrations will not occur, levels are
expected to remain elevated over and adjacent to the Salt River channel.
On Thursday the approach of a vigorous but weakening upper level trough
and surface cold front will result in increasing winds by afternoon.
Even so, no blowing dust is expected at this time.  -Reith  

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