For the period from April, 2000 to September, 2008, the nearby (one-mile distant) Wolf Run weather station temperature data was recording temperature data. In order to splice this temperature record to that of the TCE station, adjustments for the two stations' differences had to be made. The Wolf Run station is 114 feet lower in elevation (note that its published location is in error, is mistakenly located approximately 1.5 miles WNW of its actual location, and has been listed in error for its existance) than the TCE station and it is situated next to the mowed and watered grass of the Wolf Run golf greens as opposed to the native brush vegetation, dirt, and rocks surrounding the TCE station. The Wolf Run station's temperatures were recorded at 10-minute intervals versus the 5-minute intervals of the TCE station. The TCE station has a solar-powered FARS with a battery for night time power which permits a rapid response to temperature changes and makes an integrated mean temperature calculation more accurate. It is unknown if the Wolf Run station has a FARS. Pictures taken from a distance do not show any solar panels that would power one. If the mean temperatures were calculated by averaging the high and the low mean temperatures, then a FARS wouldn't be needed.
To complete the Wolf Run temperature series for the first three months of 2000, the average temperatures for those months for the years of 2001 through 2008 were used. To fill in the monthly temperatures for July and August of 2005 when the station was apparently non-operational, the monthly averages for the three years before and the three years after were used. To fill in the monthly temperatures for December, 2015 and January, 2016 when the station was apparently once again non-operational, the monthly averages for the three years before and the two or one year after were used. The Wolf Run station over its lifespan has had 98.1% uptime. This compares to 99.9% uptime for the TCE station. The Wolf Run station is operated by the Desert Research Institute, an educational-funded agency versus the privately operated TCE station.
The monthly mean temperatures of any weather station can be calculated in two different ways: the simple average of the monthly maximum and minimum means or by the Davis integration method which records the temperature for each archive interval (every five minutes for the TCE station) and then averages all those intervals over the period of a month. If the simple average method is used the difference between the average of the monthly maximum and minimum means and the monthly mean should be zero. This difference was computed for the Wolf Run station for the period from 2000 to 2017 and it was only 0.08 °F proving conclusively that Wolf Run uses the simple average method to arrive at the monthly mean temperature. It is unclear what method the Wolf Run station uses to arrive at those monthly maximum and minimum means.
The simple average method has been used to calculate mean temperatures for the weather records for years because it only requires that the maximum and minimum temperatures be recorded on a non-automated station; however, it also assumes that the temperatures increase and decrease linearly throughout the day to the maximum and minimum which is simply not true. The temperature rise and fall more nearly approximates a sinusoidal curve if the sky is clear and an irregular sinusoidal curve on cloudy days. The integration method more accurately captures the temperature change throughout the day.
The yearly average means for the Wolf Run and TCE station were compared for the years 2009 to 2014 (after 2013 the temperatures spiked up due to the El Niņo and after 2014 this spike seems to have skewed the temperature difference between the stations). The averaged difference between the two stations is 0.40 °F with the Wolf Run being hotter. To adjust the Wolf Run temperatures to those of the TCE station before 2009, 0.40 °F has been subtracted from all monthly mean temperatures. Note that the U.S. Standard Atmosphere lapse rate for the stations' elevation difference of 114 feet would be 0.41 °F.
A similar comparison was conducted for the annual mean maximum, the annual mean minimum, the mean monthly highest, and the mean monthly lowest temperatures between the two stations. The respective adjustments to the Wolf Run temperatures to correct them to the TCE temperatures are +1.08, -1.08, +1.08, and -1.08 °F. The tall native brush vegetation adjacent to the TCE station and its 24-hour FARS are probably the reasons for the more extreme temperature ranges relative to the Wolf Run station. During the day, the solar heating of the brush surfaces warms the adjacent air and during the night, outgoing thermal radiation from the brush surfaces, chills the adjacent air. Specifications for weather station siting state that they are to e located over mowed grass; however, mowed grass in our desert climate would be unnatural conditions and would require frequent watering which would be even more unnatural conditions. So the Wolf Run station has correct siting condions that are absolutely unnatural for the high desert.
The adjusted Wolf Run temperatures have been combined with the TCE temperatures. The monthly means, weighted by number of days per month, were averaged to give the annual means. Then step plots of the annual mean, the annual mean maximum, and the annual mean minimum temperatures for this century for the Thomas Creek Estates area were plotted. These plots are shown below along with linear curve fits of the annual means. The curve fits only used the years from 2001 to 2013 because 25% of the temperature data for 2000 had to be estimated and the El Niņo spiked temperatures anomalously after 2013.
The temperature trends for the maximums were very slightly increasing and for the means and minimums were slightly decreasing until 2014. After 2013, all temperatures spiked up from the previous trends. These temperature increases undoubtedly have been related to the exceptionally strong (the strongest ever recorded in the 67 years of records) El Niņo that began in mid-2014 and completed in mid-2016. Note that since the 2014 temperature spike, the means have been trending down. The overall net effect of the temperature trends over the 13 years before the El Niņo spike is seen in the linear fits of the means. The maximums have been very slightly declining, but the mean and the minimums have been moderately declining. The annual mean had a linear fit trend with a moderate decline this century at a rate of -0.90 °F per decade before the spike. Since 2014, the spike has cooled enough to make the last 18 years into essentially a no temperature change trend.
As of mid-2016, the Pacific Ocean has entered into a La Niņa. This should cool the temperatures of the Thomas Creek Estates even more IF these La Niņa conditions persist and strengthen. This cooling could revert back to the cooling trends shown prior to 2014 in all the means.
In the above graph, the deviations from the respective linear fit lines are plotted for the mean maximun, mean, and mean minimum temperatures. It seems that when the mean maximum deviation is significantly below the mean minimum deviation (red line below blue line), the mean deviation for the subsequent year is below that of the antecedent year. So because this condition was observed for 2017, then this rule would forecast a cooler mean temperature for 2018. If the annual mean temperature for 2018 is only 50.4 °F as tabulated in the ANNUAL CLIMATOLOGICAL SUMMARY for the entire year, the deviation of the mean temperature from the annual mean linear fit trend will equal zero.
The average annual and water year precipitation amounts from 2000 to 2012 for the Thomas Creek Estates are 9.64 and 9.17 inches respectively. The precipitation amounts after 2012 were not used to compute the averages. The period from 2013 to 2014 was considered a drought by the various water authorities servicing the TCE water system - Washoe County and TUMWA. The 2017 wet year was probably a 155-year event (the last similar deluge occurred during the 1861-1862 winter) that will not repeat in a lifetime and would skew the averages.
In the above plot of the annual precipitation, the white band represents precipitation amounts that are within +/- 15% of average. The surplus (blue) or deficit (red) color gradients become solid colors at +/- 50% of average. The blue dotted line is the average annual precipitation.
In the above plot of the water year precipitation, the white band represents precipitation amounts that are within +/- 15% of average. The surplus (blue) or deficit (red) color gradients become solid colors at +/- 50% of average. The blue dotted line is the average water year precipitation.
Prediction for 2018: Thanks to the unusually wet March, if the remaining months of 2018 have only average precipitation, then the annual precipitation for 2018 will be above average and in the light blue zone.