Thomas Creek Estates Weather Stations

The Thomas Creek Estates (TCE), and Thomas Creek Estates 26 (TCE26) weather stations are located in the western side of the Thomas Creek Estates suburb in Reno, Nevada. This website is intended to document and measure the local microclimate differences between the weather station and the rest of the southwest Reno suburbs and the Reno-Sparks urban area. It also serves as a neighborhood weather resource.

These weather station sites lie on an easterly facing pediment slope at the base of the Sierra Nevada mountains. In addition to the strong radiative cooling of the sites on clear nights, cold air currents flow out of the mountains down from the Whites Creek and Thomas Creek canyons to the west and across the weather station sites resulting in a significantly cooler night time microclimate than areas not on the Mt. Rose alluvial fan. If the cold air currents are too fast (~3 to +5 mph), turbulent mixing with the overlying warmer air occurs and the cooling ceases until the winds diminish.

The Digitar Weather Master, Model-ALT-6, which was gable mounted, proved that roof mounts for weather stations are not ideal locations for anemometer mounts. Winds perpendicular to the roof peak are typically increased by 15 to 20% due to the compression and acceleration of the air as it is forced up and over the top by the roof damming effect. During major wind storms, wind readings from 70 to 75 mph (sometimes even exceeding 80) would be common, but with the current mounts, winds have not exceeded 65 mph over the last ten years. Thus the gable or roof top wind measurements may be accurate for the shingle-ripping speeds observed above the roof, but they are not reflective of the unimpeded wind speeds crossing open fetch. So the all-in-one type weather stations can not correctly measure both wind speeds or rainfall amounts at the same time because of how/where the stations must be mounted.

The Thomas Creek Estates weather station is a 24-hour, fan-aspirated (24hr FARS), Davis Vantage Pro 2 wireless station mounted two meters (6') above native vegetation (sagebrush, bitterbrush, ephedra, native grasses), rocks, and soil at an elevation of 4984'. The anemometer is mounted 3.66 meters (12') above the ground level for evapotranspiration (ET) calculation purposes. A Davis 7720 Rain Collector Heater has been added to the ISS to melt snowfalls and freezing rain. Note: This is one of the few heated rain gauges in the Truckee Meadows other than the NWS gauge at the airport.

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It has been shown time and time again that an unheated Davis VP2 is far superior to the all-in-one type weather stations for measuring the water amounts collected during snow fall events. The snowfall catch volume on the VP2 is larger than the all-in-ones because its cone top diameter is eight inches versus the four inches of the all-in-ones. Plus its depth to the funnel hole at the bottom of the cone is at least twice that of the all-in-ones. Also the plastic bodies of all of the all-in-ones are white which retards melting of snow catch while the black cone of the VP2 warms with solar radiation and frequently melts the snow as it falls or soon after its cessation. Frankly the water measurements of snow falls measured by all-in-ones will be much less than the actual amounts; therefore, because most of the annual water received in the TCE area is as a result of snow falls, any annual water measurements posted by an all-in-one (and this includes Davis Vantage Vues) are too low. Note that the snowfall water amount catches of the TCE station were compared to that of a four-inch diameter, Stratus RG202 rain gauge and in general, the TCE weather station amounts exceeded those of the Stratus. This is believed to be due to the larger diameter top of the Davis cone that presents a larger surface collection area that is able to catch flakes that have been partially lofted upwards by the turbulence of the wind against the sides of the collection device during blowing snow events and is less likely for wet snow to clump at the top and clog the tube. There are some heavy, wet snowfalls that exceed the heater's melting rate (0.25 in of water/hr or roughly 2.5 in of snow/hr). So for the 10th anniversary replacement of the TCE ISS, the original conical rain cone was retained instead of the new aerodynamic rain cone. A ten-inch chicken wire cage was added above the cone to increase the snow catch during certain heavy, wet snowfall events (this is described below).

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Davis has recognised the wind turbulence problem above the cone reducing the rainfall catch of light rain drops in heavy winds. They have redesigned their rainfall cones to have an aerodynamic "wasp waist" shape instead of the sloping walls of the older models. Frankly I do not feel that the turbulence reduction above the cone by this aerodynamic improvement is enough to catch all wind-driven snow flakes and the addition of wire cages above the cones improves the snowfall catch.

The calibration of the Thomas Creek Estates station has been verified by comparison with a NIST-traceable, factory calibrated, Nielsen-Kellerman Kestrel 3500 pocket weather meter for temperatute and humidity.

The Thomas Creek Estates 26 weather station is a non-aspirated, wireless weather station assembled from the following Davis components: a 6332 anemometer transmitter, a 6410 anemometer, a 6830 temperature/humidity sensor, a rain gauge, and a 6450 solar sensor mounted on a telescoping flagpole. The anemometer and temperature-humidity sensor are mounted eight meters (26') above the native ground surface. The unheated rain gauge is two meters (6') above the ground. Unheated rain gauges can significantly underreport the snow water contents if the snowfalls fill the volume of the catch cone and then stack above the rim of the gauge. At this point, additional snow begins to slough off the sides of the snow stack resulting in a less than true accumulation. To mitigate this sloughing on the TCE26 rain gauge, chicken wire has been wrapped around the cone for about four inches inches above the rim. This prevents snow stack sloughing for this additional cage height and effectively deepens the catch volume of the cone. This cage along with the upwind brush that is nearly the height of the rain gauge also mitigates the wind turbulence above the cone during windy snow fall events. Often times the water catch of the TCE26 station exceeded that of the heated TCE station by 5-35% for certain heavy, wet snowstorms. When compared to the measured snow depths and estimates of the water content of the snow, the TCE26 station water measurements with its "extender" wire cage seems more accurate in these instances than the TCE station with its heated rain gauge. The location of the solar sensor on the original TCE station prevented a cage from being used on it, but the 10th anniversary TCE ISS has a relocated solar sensor allowing the addition of a wire cage. Note: The TCE rain gauge without the cage always matched the TCE26 rain gauge during blowing and calm rains indicating that an extender cage does not interfere with or affect rainfall collection.

The top of the TCE26 cage also has bent up wire spikes to deter birds from landing on it. If a period of hard freezes and cloudy skies follows a snowfall and prevents solar melting, sublimation can reduce the true amount of snow water melt and thus the TCE26 can under report the true amount of snow melt. Click the TCE26 photo for construction details of this non-standard Davis weather station.

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The calibration of the Thomas Creek Estates 26 station has been verified by a week-long comparison to the nearby TCE station while the TCE26 temperature/humidity station was mounted at the same height. The temperatures and humidities were identical for the two stations during this test period. Note that both of the 10th anniversary rebuilt weather stations have Sensiron SHT31 temp/hum sensors which has improved the accuracy and sensitivity of both temperature and humidity measurements.

Both of the Thomas Creek Estates weather station sites are rated as Class 3 (CRN3, error >=1 C, no artificial heat sources or reflective surfaces within 10 meters and ground covered by native vegetation) station sites according to the Siting Classification for Surface Observing Stations on Land. The quality rating of these station sites exceeds that of 48% of all USHCN weather stations in the U.S. Less that 11% of the surface area within 30 m surrounding the sites is artificial reflective surface. By definition, if less than 10% of the surrounding surface is reflective, then the site is rated as Class 2. The Thomas Creek Estates sites could more accurately be rated as better than Class 3 which would exceed 80% of all USHCN weather stations.

The air around the TCE station heats and cools faster than other surrounding stations due to the thermal radiation effects of the surrounding native brush. The 24hr FARS then shortens the response time to those air temperature changes. The temperatures reported by this station would be those felt at head height on a non-windy day if you walked in a shrubby or brushy area on your property. Whereas the temperatures reported by TCE26 are cooler during the day and warmer at night as long as the winds are calm.

Both of the stations have an open fetch in the prevailing wind and storm directions (southerly through westerly) in excess of 400 feet from the stations. The roof peaks of houses WSW and SW are about 450 feet from the TCE station and range from 20 to 30 higher than the anemometer. Wind and gust speeds for the Thomas Creek Estates station have been crosscorrelated with data from the nearby Wolf Run weather station and Galena weather stations during major storms. In addition, wind and gust speeds for the station were compared to the Kestrel 3500 wind meter readings collected at six feet beside the station. From the wind speed differences versus the height differences, the surface roughness length of the fetch in the prevailing wind direction during storms is estimated at between 0.10 to 0.20 m, see Roughness and Wind Shear. The wind shear fractions are listed below for various surface roughnesses. These calculations are believed to be accurate during relatively laminar wind flow. The table below shows that the wind speeds measured by TCE26 at 8m are within 94 to 97% of those of an anemometer mounted at 10m (33') in the same location.

Wind Shear and Roughness

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Supplementing the data from the weather stations is a 6345 Leaf and Soil Moisture/Temperature Station. This station is equipped with two soil temprature sensors buried four and eight inches deep in the soil below the station. These sensors are reported as Soil Temp 1 and 2 respectively on the daily summary page. The station also has a leaf wetness sensor that reports the wetness of surfaces on the daily summary page as Leaf Wetness 1 in a range of 0 to 15. There is a temperature probe installed behind the leaf wetness sensor at 0.8m above the soil surface to measure the temperature of the Leaf Wetness sensor's surface and is reported as Leaf Temp 1 on the daily summary page. Arctic Silver heatsink paste was applied to this temperature sensor to enable accurate transfer of temperatures from the leaf sensor. This probe is not solar shielded so during the day the temperatures will reflect some degree of solar heating of the leaf sensor even though this sensor faces north. At night when the dewpoint equals this leaf surface temperature, dew or frost condensation will form on vegetation and outdoor metal surfaces and there can be fog in the air. Note that the Soil Temp 1 and Leaf Temp 2 on the daily summary page are simply bugs in the Davis Weatherlink.com reporting. The details of the leaf and soil station installation are shown in the photo below.

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The wireless data from the weather stations are received and converted to TCP/IP traffic by Davis WeatherlinkIP(WLIP)-equiped, Envoys. Their data are fed to dual, linked Sheevaplug Meteohubs on a local switch to minimize network cross traffic. These Meteohubs generate the weather graph uploads, other web site features, and update the WeatherUnderground and WeatherforYou sites. An NSLU2 Meteohub is used for experimental weather prediction and web site development purposes.

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The Mt. Rose Live camera image is from a StarDot Netcam XL camera uploading every three minutes during daylight hours. This camera updates to both this website and WeatherUnderground.

The historical temperature records for the Thomas Creek Estates station prior to August, 2008 were compiled from those measured at the one-mile distant, Wolf Run weather station database and corrected for the site and sensor elevation differences by the average adiabatic lapse rate. There is also an annual precipitation relationship to elevation. The precipitation records for the Wolf Run station after 2008 were compared to the TCE records for an additional precipitation correction factor prior to August, 2008. See also Correction to the Wolf Run water measurement for the Dec, 2004 monster snow storm.