Two New Snow-level Radars Installed in Northern California
As part of the HMT-Legacy Project with the California Department
of Water Resources, HMT engineering staff from NOAA's Earth System Research Laboratory installed
two new award-winning, snow-level radars in northern California in November/December 2011. The first radar site is located near the Orville Dam below Lake Oroville, one of the largest
reservoirs in California. The second is in the Lower Klamath River Basin
in the town of Happy Camp. Siting a snow-level radar in this basin was the
brainchild of Rob Hartman, Hydrologist-in-Charge at the California/Nevada
River Forecast Center (CNRFC). "The CNRFC models and
forecasts several tributaries of the Lower Klamath River as well as the
mainstem at three locations in California. Historically, these basins have
been very sensitive to errors in our estimation of rain-snow elevation
based on lapsed surface observations of air temperature," said Hartman.
"Seemingly small errors in rain-snow elevation estimation (< 500 ft) can result in very
different hydrologic model response. Having a continuous observation of
rain-snow elevation really helps CNRFC hydrologists diagnose model
performance and ultimately provide better forecasts into the future."
The two new snow-level radar sites represent the fifth and sixth
deployments of a ten-station network that will be completed over the next
year and a half. The map shows the locations of the six radars that have
been installed to date. An additional radar is slated for Kernville, near
Lake Isabella, at the southern tip of the Sierra Nevada. The snow-level
observations are available to end users and the general public in near real
time via a Google map display
and through a clickable data inventory table.
An example of the snow-level product from the Happy Camp snow-level radar
is shown.
Currently, a snow-level is derived only when a radar brightband is detected
during precipitation. Hourly averaged freezing levels (a similar variable
used in weather and hydrologic forecasting) are then transmitted to NWS
Region Headquarters in the data format used by the CNRFC. Soon, this
product will include model analysis of the freezing level in addition to
the observationally-based values in order to provide a continuous stream of
freezing levels for use in hydrometeorological analysis and forecast tools.
"The snow-level product developed by HMT has changed the way we do
business with respect to the snow level," said Art Henkel, the Development and Operations Hydrologist at
CNFRC.