Code Orange bad air day in Delaware (July 12, 2014)

The air quality forecast has worsened.  Officially:  Code Orange on Saturday, Code Yellow through Monday.

In my view Code Orange for ozone plus Code Yellow for particles = Code Red (unhealthy for everybody).

Fortunately, the temperature/humidity/pollen forecasts are not too bad.  But this air quality can still make you sick, especially, if you are young, old, or addicted to breathing.  Take it easy.

Some background info and commentary.

Official forecast below:

From: Penn State Air Quality Forecast Office <>

State of Delaware Air Quality Forecast for:

Saturday, July 12, 2014


Fine Particles (PM2.5): CODE YELLOW (MODERATE)



Saturday will be an Air Quality Action Day for ozone for Delaware.  Surface stagnation overnight and through the morning will allow pollutants to accumulate, similar to conditions on Friday.  Mostly sunny skies, light winds, and recirculating flow aloft will promote rapid ozone formation in the afternoon, with daily concentrations reaching the Code Orange range, primarily in northern Delaware.  Particles will also respond to the light winds by rising into the low Moderate range.

A warm front will lift over the region from the south on Sunday, resulting in warm and humid conditions.  Warm air arriving aloft will limit vertical mixing, which will help to keep particles in the Moderate range.  Increasing clouds in the afternoon and sustained southerly surface winds, along with the chance for scattered showers, will limit ozone to the Good/Moderate threshold.  Monday will be hot and humid, with widespread afternoon clouds and precipitation as a cold front slowly approaches from the west.  Ozone will be in the upper Good range, while particle will linger in the Moderate range in the humid air mass.


Penn State Air Quality Forecast Office (PSAQFO)
The Pennsylvania State University
Department of Meteorology

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