Relocation and Modernization of Paradise Meadows Weather Station

Yosemite National Park » Relocation and Modernization of Paradise Meadows Weather Station » Document List

The California Department of Water Resources (DWR) installed thirteen remote snow sensors in Yosemite National Park, located at 6,000 - 10,000 feet in elevation, to provide hourly real time data. Beginning in 2016, these stations are being modernized and maintained collaboratively by DWR and Yosemite National Park personnel. These stations measure water content of the snow pack, snow depth, air temperature, relative humidity, solar radiation, soil moisture, and wind speed.

The weather station at Paradise Meadows (38.047°, -119.670°) was installed in 1980 and consists of a pole mounted with instrumentation and a snow pillow. In 2005, an enclosure box was installed on a tree adjacent to the pole just to the north which contains the data collection platform, battery supply, and transmitter. The current location of the pole/enclosure is 41 feet to the east of the snow pillow. This site is in designated Wilderness. The wilderness compliance for this project was included in the Programmatic Hydrometeorologic MRA which is complete.

This project will replace the pole with a ROHN tower which is climbable by technicians to perform routine maintained. The new ROHN tower will be installed directly adjacent to the snow pillow, thus co-locating the snow depth sensor and the pillow for accurate snow density calculations. All equipment at the site will be replaced and modernized with the current industry standard for weather and snow monitoring.

The Paradise Meadows station went offline in November of 2020, and park staff were unable to connect to the station and repair it due to how out of date it is. New sensors, as well as a new data collection platform and transmission platform will be upgraded and thus easier to work on. The new installation will have standardized equipment that is in line with DWR standards and compatible with 2021 software and technology. The current configuration of the site, with the snow depth sensor located in a different location from the pillow (on the pole), means that an accurate snowpack density cannot be calculated from the total water content measured by the snow pillow and the measured snow depth. The pole, and thus snow depth sensor is located in a tree well that melts out (zero snow) much earlier in the season than the snow pillow, resulting in mis-leading snow depths and inaccurate density calculations. Instrument maintenance on the pole also requires the use of a ladder, which must be transported via stock each time maintenance is required. The new tower and configuration will increase the visual impact of the site but will eliminate the need for pack stock to perform site maintenance. The new station will therefore be easily worked on by technicians due to the installation of the ROHN tower and modernization of equipment.

Project Actions:
1) Helicopter flight to deliver ROHN tower, cement for tower base, and new equipment to site.
2) Removal of old instruments from pole and enclosure, followed by removal of old pole and enclosure and associated structures.
3) Dig hole 3 feet in diameter by 3 feet deep at new tower location adjacent to the snow pillow.
4) Trench and remove wiring between the old enclosure location and the snow pillow and re-trench for connection to the new tower. It is anticipated that a trench approximately 50 feet long, 1ft wide, and 1ft deep would need to be dug to remove the old cables and wiring. A new trench approximately 10 feet long, 1ft wide, and 1ft deep would be dug to install the new connection. Both trenches would be backfilled after wiring is connected.
5) Install concrete base for the new ROHN tower and set the tower in the concrete. Mixing will occur in tarps.
6) Mount and install new instrumentation and enclosure on the new ROHN tower.
7) Connect all instrumentation and bring the station back online.