Weather

Precipitation report
Snowpack & streamflow update
Weather stations & data/reports
Weather maps

NCWCD Weather Station Network

NCWCD staff strive to maintain accurate and current reports. However, all data are subject to revision due to potential equipment and sensor error or malfunction. The user assumes all liability for use of any data and reports, and agrees to hold the District harmless.

The NCWCD weather station network has 23 automated sites and provides daily reference evapotranspiration (ET) for crops and turf. The ET data are used to conserve water used for irrigation. While individual parameters used to calculate ET are available, the primary public service of the weather station network is irrigation management. Thus, not all weather stations have snowfall measurement devices. The urban locations are turf field sites where installation of a weighing bucket for solid precipitation is not practical. There are 13 rural sites that have weighing buckets.

Weighing bucket

High winds significantly reduce the accuracy of a weighing bucket particularly for snowfall. The wind deflects the snow from falling in the catch, which can cause snowfall readings to be 50 to 80 percent less than the actual amount.

Units: the weighing bucket measures water content in inches rather than the physical depth of the snow.

Weighing bucket snow under catch example
Precipitation gauge information

Tipping bucket

The tipping bucket measures rain. It does not measure snow accurately because the snow falls into the collector funnel where it may be blown away before it melts and is measured. If a snowfall reading does occur, it generally will happen after the storm has passed and the snow has melted inside the collector funnel.

Tipping bucket accuracy: 1.0 percent up to 2 inches/hour (50 mm/hour)

Limitations: tipping buckets are prone to clogging as debris and dust collect in the funnel hole, preventing rain from passing through freely.

Relative humidity

Accuracy at 20º C
+/- 2 percent RH (0 to 90 percent RH)
+/- 3 percent RH (0 to 100 percent RH)

Air temperature

Anemometer

Wind speed range: 0-224 mph (mechanical breakdown may occur at 120 mph)
Wind speed accuracy: +/- 0.6 mph or 1 percent of reading
Wind direction: Azimuth 360º mechanical, 355º electrical (5º open)
Wind direction accuracy: +/- 3º

Solar radiation

Sensitivity: Typically 90 µA per 1000 W m-2
Linearity: Maximum deviation of 1 percent up to 3000 W m-2.
Stability: < ± 2 percent change over a one year period.
Response Time: 10 µs.
Temperature Dependence: 0.15 percent per °C maximum.
Cosine Correction: Cosine corrected up to 80° angle of incidence.
Azimuth: < ± 1 percent error over 360° at 45° elevation.

Data corrections

While servicing the station or during a power outage, data is unavoidably lost. While some weather station networks leave these voids to user interpretation, the NCWCD uses appropriate data correction methods to fill in missing data, especially during brief outages. This is important for modeling and year-to-date totals.