[ADEQ Forecasts] ADEQ Issues Air Pollution Health Watch for Tues., Dec. 4

[forecasts@lists.azdeq.gov]

Health message for Monday, Dec 03: No health impacts are expected.

Health message for Tuesday, Dec 04: Unusually sensitive people should
consider reducing prolonged or heavy exertion.

Synopsis and Discussion
A PM-2.5 HEALTH WATCH HAS BEEN ISSUED FOR TUESDAY DECEMBER 04
A very warm ridge aloft building over the state has contributed to rapid
stagnation of the air mass over the Valley.  During the 24 hour period
ending at 5:00 a.m. this morning the temperature at the overhead 5K'
level rose 18 deg F and nearly 13 deg F at the 10K' level.  By Tuesday
afternoon the temperatures at these levels are forecast to rise by
another 14 and 9 deg F, respectively, while the surface temperature
increases by only 4 deg F.  Data from the latest ACARS soundings reveals
that the 7 deg C surface-based radiation that formed overnight extends
to nearly 2100' and that the best mixing depth has lowered to below
2800'; dispersion is MARGINAL.  Monitoring data indicates that the
rather dense Valley Brown Cloud currently over much of the Valley
consists primarily of fine particles (PM-2.5), the production of which
has been augmented by above average relative humidity values and
apparent fireplace usage.  Thru 9:00 a.m. the 10-hour average PM-2.5
levels at both the West Phoenix and Durango sites were near 30ug/m3 and
a peak hourly concentration of 63.1ug/m3 occurred at Durango at 7:00
a.m.; a secondary spike will typically occur during the evening hours.
Due to these elevated levels and ongoing stagnant air mass
characteristics, a PM-2.5 Health Watch has been issued for Tuesday as a
precaution for those with heart or lung disease.  -Reith

For more information, please visit our Web page:
http://www.azdeq.gov/environ/air/ozone/ensemble.pdf

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