What Hast the Thunderstorms Brought?

The last few days have brought regular afternoon and evening thunderstorms to the Salt Lake Valley.  It's worth taking a closer look at the drivers for the storms and who has gotten the rain.  

On average, the 500-mb heights in August are characterized by  a ridge that is centered roughly over west Texas and a trough over or just to the west of the Pacific coast.  This pattern yields mean easterly flow at 500-mb over central Mexico which turns clockwise (cyclonically in meteorology speak) near Baja California before moving into Utah.  

Source: climatereanalyzer.org

The pattern above is characteristic of the so-called North American Monsoon.  This monsoonal pattern has been amplified the past several days.  As an example, below are the 500-mb height anomalies (departures from average) for today.  Positive height anomalies over the western US and Mexico are strongest over west Texas and the Mexican border area to the west, right where the 500-mb ridge is on average.  In contrast, negative height anomalies are strongest just off the Pacific Coast.  

Source: climatereanalyzer.org

Thus, the current pattern is one in which the primary monsoon circulation features, the ridge over west Texas and the trough off the Pacific coast, are stronger than average.  

This pattern has brought us enough monsoon moisture and perhaps some large-scale lift from the Pacific trough to allow surface heating to generate scattered to widespread thunderstorms each afternoon and evening.  These storms have generally moved from southwest to northeast across northern Utah.  This can be seen in the radar-estimated precipitation for the past 24-hours, which covers last nights storms.  Precipitation was heaviest in a band oriented roughly from southwest to northeast near the southern shore of the Great Salt Lake and into the Bountiful area Mountains.  A second band of heavier precipitation extends over what I'll jokingly call the "Herriman rain forest" in the southwest Salt Lake Valley.   

https://mrms.nssl.noaa.gov/qvs/product_viewer/

If we look over a 3-day (72-hour) period, we see that everyone in the valley has seen some rain, but the big winner is the southern Oquirrhs and the Herriman rain forest, with one area near Herriman seeing over 1.25".  

https://mrms.nssl.noaa.gov/qvs/product_viewer/

There's a lot of variability in the valley.  One can find some areas around Cottonwood Heights that may have seen < 0.2", while other areas in the central and western valley are over 0.5".  The maximum near Herriman is over 1.5", but if you move a bit to the east toward I-15 there is a band with < 0.5".  Then there's another streak of heavier precipitation over Draper.  

This is the nature of these hit-and-miss thunderstorms.  I wish we had got a bit more at my place, but am glad we got something.