There has been quite a ramp up in pollution over the Salt Lake Valley over the past three days. Trend charts for the DAQ observing site at Hawthorne Elementary on 700 East show we reached well into the unhealthy for sensitive groups category yesterday, with a PM2.5 peak of 48.7 ug/m3 at noon (maroon line).
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| Source: UDAQ |
Even the 24-h average moved into unhealthy category last night and reached at 38.8 ug/m3 at 6 am this morning.
I generally anticipate that it will take 3.5 days for the 24-h average to get to the unhealthy for sensitive groups category, but in this event we did it in about 2. Good work Utah!
This morning's sounding from the Salt Lake City airport shows that a strong inversion remains in place with temperatures increasing from -6.1C/21˚F at the surface to 4.8C/41˚F at 801 mb/6500 ft.
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| Source: SPC |
The sounding from yesterday afternoon showed that the mixed layer over the valley only reached 850 mb/5270 ft, so basically all the pollutants are trapped within about 1000 feet of the valley floor.
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| Source: SPC |
A weak trough is moving through tonight that will cool temperatures some at mountaintop levels, but probably not enough to crack the inversion. Real relief probably won't come until Sunday when a stronger system moves through.
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