City Creek Nature Notes – Salt Lake City

March 2, 2017

March 1st

Filed under: Weather — canopus56 @ 6:07 pm

Visualizing the Drought

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Monthly Snowfall at Salt Lake International Airport: 1953-2012, 7 Month Moving Average. Source: Weather Warehouse (2017) (data).

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Pacific Quasi-Decadal Oscillation. Source: ENSO Blog Team, NOAA, and National Climate Data Center (2014).

4:00 p.m. Winter continues to hold against pre-spring for another day, and even though the temperatures are low, it is clear all day.

Using snowfall data for the Salt Lake Airport from 1953-2012, I am able to visualize Utah’s current drought that affects the canyon and its wildlife. Smoothing the monthly snowfall data and plotting in 3D shows how the overall volume of annual snowfall grows through 1977. This is also a period in which the Pacific Quasi-Decadal Oscillation (PQDO) (Feb. 7th) was in its cool, or drought phase. This was also a period of declining Great Salt Lake levels. From 1977 to 1997, the PQDO was in a warm, or increasing precipitation phase, except for chaotic dips around 1989 and 1996. Those PQDO dips correspond to extreme snowfall events. This was a period of rising Great Salt Lake levels. After 1997, the PQDO was in an extended cool-drought phase, and this corresponds to an extended period of lower volume annual snowfall at the airport. This was a period of falling Great Salt Lake levels. Notably, annual snowfall during the PQDO cool-drought phase from 1997 to the present appears much lower than the prior PQDO cool-drought phase prior to 1977, i.e. – a severe drought. Whether this is the year that the PQDO switches back to the warm-wet phase and ends the drought in the canyon remains to be seen.

Recent research implicates the PQDO in the debate over climate change. In 2014, climate scientists Steinman at the University of Minnesota and Mann and Miller at Pennsylvania State University used sophisticated statistical analyis of the PQDO and its sister oscillation, the Altantic Muti-Decadal Oscillation (AMO), to provide an explanation of why global temperature rise in last few years has been less than predicted (Steinman et al). The AMO has a longer 50 to 70 year cycle; the PDO has about a 12 year cycle. The researchers concluded that since 2000, the AMO has been in a flat-positive “warm” cycle, but this is offest by the extended PQDO “cool phase”. Their combined effect has suppressed temperatures and produced a “false pause” in the signal of climate change. Steinman and colleagues suggest that when both cycles oscillate simultaneously to their warm phases, the cycles will no longer mask climate change and temperatures will rise quickly. But their reasoning is based on a highly statistical analysis derived from computer models and an unstated level of uncertainty.

In Thoreau’s “Journal” on March 1st, 1854, he records as the first day of spring. Thoreau comments that chickadees are the most numerous bird. He also sees two hawks, an owl, a bluejay, sparrows, pigeons, a snow bunting, and a downy woodpecker. On March 1st, 1855, he hears chickadees and crows.

On March 1st, 1902, the local weather bureau reported that February was one of the warmest and least precipitation Februarys on record (Salt Lake Tribune).


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