[ADEQ Forecasts] ADEQ Issues Air Pollution Health Watch for Thurs., Dec. 11

[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 Wednesday December 10: Unusually sensitive people
should consider reducing prolonged or heavy exertion.

Health message for Thursday December 11: Unusually sensitive people
should consider reducing prolonged or heavy exertion.
 
Synopsis and Discussion
A PM-2.5 HEALTH WATCH HAS BEEN ISSUED FOR THURSDAY DECEMBER 11
In the wake of Tuesday's surface cold frontal passage, stagnation of the
Valley air mass has begun in a big way.  The temperature at the 10K'
level overhead warmed an astounding 29 deg F during the past 24 hours;
another 18 deg F of warming is forecast to occur at the 5K' level by
Thursday morning.  Recent ACARS sounding data indicates that the mixing
depth has already lowered to near 4600' and is still dropping;
dispersion will ultimately be MARGINAL today.  Increasing high
cloudiness is advertised to occur by Thursday afternoon which will
inhibit atmospheric moisture even more. Fine particle (PM-2.5) levels
have increased significantly this morning; an hourly concentration
approached 40ug/m3 at one monitoring site at 8:00 a.m.  Under clear
skies and with a rather cold and dry air mass in place, a strong
surface-based inversion is likely to form by Thursday morning.  Since
increased fireplace use is also likely to occur, under these conditions
the added smoke emissions may bring fine particle concentrations toward
unhealthy levels. For these reasons a PM-2.5 Health Watch has been
issued for Thursday and may need to be extended for Friday.
Fortunately, a major weather pattern change toward windy and potentially
west conditions will begin over the weekend. -Reith  

**********************************************************************
NOTICE: This e-mail (and any attachments) may contain PRIVILEGED OR 
CONFIDENTIAL information and is intended only for the use of the specific 
individual(s) to whom it is addressed.  It may contain information that is 
privileged and confidential under state and federal law.  This information 
may be used or disclosed only in accordance with law, and you may be 
subject to penalties under law for improper use or further disclosure of the 
information in this e-mail and its attachments. If you have received this e-
mail in error, please immediately notify the person named above by reply e-
mail, and then delete the original e-mail.  Thank you.