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Event Year: Date:

200MB.gif  200MB Chart valid from Aug 04/00Z thru Aug 06/06Z with Low pressure starting with variable winds in a monsoon condition followed by zonal (westerly) .
500MB Absolute Vorticity.gif  500MB Absolute Vorticity chart valid from Aug 04/00Z thru Aug 06/06Z low pressure starting with variable winds and small areas of absolute vorticity in a monsoon condition followed by zonal (westerly) winds.
500MB.gif  500MB chart valid from Aug 04/00Z thru Aug 06/06Z with high pressure in southern Nevada and a low pressure system in the Pacific Ocean off the California coast and light winds in a monsoon condition, followed by zonal (westerly) winds.
700MB Vertical Velocity.gif  700MB Vertical Velocity chart valid from Aug 04/00Z thru Aug 06/06Z also shows low pressure mostly damp conditions, and a diurnal cycle of daytime convective higher levels of vertical velocity. This pattern allows for local wind patterns to weakly transport wildfire smoke and recirculate local air in a mountain/valley airflow cycle.
850MB.gif  850MB chart valid from Aug 04/00Z thru Aug 06/06Z shows airflow conditions in a generally low pressure condition and a line of strong convergence, with some airflow from southern California. This pattern allows light wind speeds near the surface and increased ozone buildup combined with transport of wildfire smoke from California.
AIRNow AQI Peak O3.gif  AIRNow AQI Peak O3 valid from August 4th thru August 6th shows Moderate levels of Ozone in southern California turning to USG with a few periods of very unhealthy, The Las Vegas area shows mostly moderate levels with periods of USG in the afternoon of day of exceedance.
AIRNow AQI Peak PM.gif  AIRNow AQI Peak PM valid from AUgust 4th thru August 6th shows mostly moderate levels of Particulate Matter in central southern Californis and good conditions in the Vegas valley thru the period.
AIRNow AQI Peak.gif  AIRNow AQI Peak valid from August 4th thru August 6th shows Moderate levels of Ozone in southern California turning to USG with a few periods of very unhealthy, The Las Vegas area shows mostly moderate levels with periods of USG in the afternoon of day of exceedance.
AIRNow Hysplit.pdf  EPA AIRNow Hysplit product valid from August 4th thru August 6th shows airmass affecting the Las Vegas Valley had source region of Southern California at the high levels and our own local source recircullating.
Daily Weather Map 500MB.gif  Daily Weather Map 500MB valid from August 4th thru August 6th shows high pressure giving way to low pressure in the southwestern U.S.
DAQ Air Quality Forecast.pdf  DAQ Air Quality Forecast Valid for August 4th shows moderate levels expected on August 5th and for the remainder of the period. No forecast for August 5th, this was a weekend day.
DAQ Air Quality Index.jpg  DAQ Air Quality Index Valid for August 5th shows 2 sites that reached the Unhealty for Sensitive Group levels for Ozone: Joe Neal and Walter Johnson. Ten sites reached the Moderate level, while 3 sites stayed in the Good range.
DAQ Met Hourly Average.jpg  DAQ Met Hourly Average valid for August 5th showing low wind speeds and variable directions.
DAQ Ozone Animation.gif  DAQ Ozone animation valid from August 5th 17:00Z thru August 6th 06:00Z shows the Las Vegas region moving into the moderate levels during the day, into USG for a period in the afternoon of the 5th.
DAQ Pollutant Hourly Average.jpg  DAQ Pollutant Hourly Average valid for August 5th. One-hour average ozone concentrations were over 70 ppb at four sites in the valley.
DAQ RAOB.gif  August 5th animation of hourly upper-air temperature and humidity profiles as skew-T/log-P diagrams, and the associated winds aloft profiles showing speed and direction as "wind barbs". Diurnal cycle of temperature profile with light winds are shown.
National Weather Service Forecast Discussion.pdf  National Weather Service Forecast Discussion valid from August 4th thru August 6th shows the lingering low pressure disturbance and associated cloudiness giving way to drier air clearing the skies.
National Weather Service Observations.pdf  National Weather Service Observations valid from August 4th thru August 6th showing the valley-wide occurrences of light winds in a diurnal cycle of easterly winds in the morning sometimes turning to southerly or southwesterly in the evening. Early cloudiness associated with a monsoon circulation cleared midday, allowing for ozone levels to increase.
SFC.gif  This time sequence of surface pressure plots with reported regional weather conditions for August 4th thru August 6th shows the fair-weather pattern with weak pressure gradients and no significant other weather system features. This pattern allows for local ozone levels to increase.
Summary.pdf  The clearing skies allowed elevated ozone levels to occur in the Las Vegas valley. Two sites on the west and northwest sides of the valley exceeded the Standard. The AQI levels were 115 at the Joe Neal site and 101 at the Walter Johnson site.
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