[ADEQ Forecasts] ADEQ Issues Air Pollution Health Watch for Thurs., July 10

[forecasts@lists.azdeq.gov]

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

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

Health message for Wednesday, July 9:  Active children and adults, and
people with respiratory disease, such as asthma, should limit prolonged
outdoor exertion.
 
Health message for Thursday, July 10:  Unusually Sensitive People should
consider limiting prolonged exertion outdoors.
 
Synopsis and Discussion
*A HIGH POLLUTION ADVISORY FOR OZONE REMAINS IN EFFECT FOR TODAY,
WEDNESDAY, JULY 9, AND
AN OZONE HEALTH WATCH HAS BEEN ISSUED FOR THURSDAY, JULY 10, 2008*
So far, July has not been a very good month for Ozone.  We have already
seen exceedances on 5 of the first 8 days this month.  Cave Creek,
Glendale Community College, North Phoenix, Phoenix Supersite, and West
Phoenix - all central and west Valley sites - exceeded the standard on
Tuesday.  This shows very clearly how the easterly flow that we are
seeing really has an affect on keeping locally-generated ozone from
escaping to the east.  Even more interesting is that Alamo Lake, a
strategically placed monitor located 100 miles northwest of Phoenix to
capture southern California ozone transport, saw elevated ozone
concentrations on Tuesday as well, likely from the Phoenix metro area
under that same easterly/southeasterly flow.  There were some
good-looking storms that skirted the mountains just east of the Valley
on Tuesday.  The outflow winds increased Particulate concentrations to
the mid "Moderate" range at Higley.  Otherwise, most other locations
were in or near the "Good" range.  Over the next several days, we will
see a significant increase in moisture from the southeast.  With
upper-level dynamics setting up, we should have a pretty good chance for
Valley thunderstorms late Thursday into early Friday.  Some of the
storms could produce heavy rainfall. This has the National Weather
Service discussing the possibility of issuing a Flash Flood Watch by
this time tomorrow if the confidence of the event remains high.  If such
an event does take place, there will be a considerable decrease the
amount of sunshine here in the Valley on Friday, thus limiting ozone
production.  Until then, however, we still have a high risk of exceeding
the health standard on Wednesday and Thursday.  Models are suggesting
that there may be slightly lower concentrations on Thursday than today,
possibly due to the anticipated clouds and thunderstorms pushing in by
early afternoon from the east.  Thus, we will go with an Ozone Health
Watch for Thursday on the heels of today's HPA.  Check back tomorrow for
the latest.  Have a good day!  -J.Paul

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