[ADEQ Forecasts] ADEQ Issues a Particulate Matter Health Watch (PM-10) and Ozone Health Watch for the Phoenix Metro Area for Friday, August 07, 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 Thursday, August 06: Unusually sensitive people
should consider reducing prolonged or heavy exertion outdoors.
 
Health message for Friday, August 07: Unusually sensitive people should
consider reducing prolonged or heavy exertion outdoors. 


Synopsis and Discussion

*PM-10 AND OZONE HEALTH WATCHES HAVE BOTH BEEN ISSUED FOR FRIDAY AUGUST
07*

An unusual but brief weather pattern change will occur over the state
the next few days.  The southern end of an anomalously deep and strong
(for August) upper level trough in the mid-latitude storm track will
pass overhead on Friday and Saturday.  Its impacts will include gusty
winds and cooler temperatures by Friday; winds at the 10K' level above
the Valley are forecast to be in the 30-35 mph range, and under sunny
skies with a forecast mixing depth near 12K', some of this momentum will
mix to the surface.  Recent thunderstorm outflow boundaries have
transported and/or produced locally dense blowing dust and high PM-10
levels with wind speeds less than this, so there are lots of fugitive
dust emissions possible under a longer wind event. No rainfall will
accompany the trough passage, so a PM-10 Health Watch has been issued.
In addition, several forecast models now show the wind direction
component at the 5K' level to be capable of transporting additional
ozone and its precursors from CA to AZ by Friday morning. Given the
timing, already elevated ozone levels, mostly sunny skies and afternoon
temperatures near 105 deg F, local ozone production may be enhanced
enough to result in near-to-unhealthy ozone concentrations by late in
the day.  Thus, an Ozone Health Watch has also been issued with the east
Valley at highest risk.

If you have any questions or comments regarding this forecast please
contact:

The Arizona Department of Environmental Quality
Office of Communications
1110 W Washington St, Phoenix, AZ 85007
(602) 771-2215
ms15@azdeq.gov


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