[ADEQ Forecasts] ADEQ Daily Air Quality Forecast for Fri., Nov. 30

[forecasts@lists.azdeq.gov]

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

Health message for Thursday, Nov 29: Unusually sensitive people should
consider reducing prolonged or heavy exertion.

Health message for Friday, Nov 30: No health impacts are expected.

Synopsis and Discussion
Today should be the last high particle-pollutant day to contend with for
a while. The air mass over the valley remains quite stagnant this
morning and per local ACARS sounding data the mixing depth started out
at a paltry 1900' with POOR to MARGINAL dispersion. Some peak hourly
PM-10 concentrations include 308.3ug/m3 at the Durango site at 7:00 a.m.
and 283.2ug/m2 at South Phoenix at 8:00 a.m.  Thankfully, a major
weather pattern change is underway that now appears destined to deliver
a significant rainfall event to the Valley on Friday and Saturday.
Considerable and deep sub-tropical moisture exists off the Baja coast
thanks to a persistent low-latitude circulation that has been also been
responsible for transporting lots of mid and high clouds over the local
forecast area since Monday.  The catalyst for the incipient heavy
rainfall will be the approach of a major short wave trough in the
mid-latitude storm track - currently taking shape off the Pacific
NW/British Columbia coasts.  The two features will merge to the west of
Arizona by Friday afternoon and move east over the state.  Valley
rainfall totals of up to an inch are predicted and if realized, would go
a long way toward contributing to better air quality over the metro area
for many days to come. -Reith