NOAA Researchers Ready for Wet, Windy Pacific Coast Storm
ESRL Polarimetric X-Band Radar located at Blue Canyon, CA. (Larger image)
The snow level product allows forecasters to see if the forecasted snow level (based on numerical models) is too high or too low. Notice that the blizzard warning indicates that snow levels in the Sierra will be 5000 to 6000 ft through the night of Jan. 3 before lowering. The Chico wind profiler is already showing snow levels below 4500 ft. (Larger image)
The upslope water vapor flux product allows forecasters to see how strong the forcing is (winds and water vapor) for increasing the coastal mountain rainfall. The strong water vapor flux within this storm has already produced nearly 3" of rain at Cazadero (coastal mountains north of San Francisco). (Larger image)
“Batten down the hatches!” The Sacramento Bee newspaper recommended on Jan. 3, 2008 that residents of Northern California prepare for a potent weekend storm coming in overnight and expected to pound the coast and inland locations with wind and rain, and high snowfall expected in the high Sierra.
Researchers with NOAA’s Earth System Research Laboratory and National Severe Storm Laboratory are already ready for the storm – they’re set to brave extreme conditions to study what they are calling a “once-in-a-decade storm” in California that may last four days.
As a part of NOAA’s Hydrometeorological Testbed (HMT) project, this crew of researchers, working in concert with NOAA’s National Weather Service forecasters, have set up an array of instruments on the ground to study these storms that have raged in from the Pacific Ocean over the past 10 years.
The NOAA Hydrometeorological Testbed is a national strategy that works regionally to enhance weather forecasts and accelerate weather research into operations. HMT combines state-of-the-art observing systems and numerical modeling to develop tools for forecasters who make decisions about watches and warnings for high-precipitation events, like the one beginning Jan. 3 that is expected to last four days. Such events can cause flooding, bollix up transportation of all types and cause landslides and other threats to people and property.
The City of Sacramento sits at the confluence of the Sacramento and American Rivers and represents a flood risk that is comparable to New Orleans and Hurricane Katrina; lessons learned in the HMT in this region can be applied elsewhere, and particularly to the entire West Coast.
Last month, researchers began preparing for this winter’s storms, adding precipitation and soil moisture measurement sites at high elevation in the Sierra Nevada east of Sacramento. These monitoring stations will provide more comprehensive coverage of the American River Basin over previous monitoring seasons.
Among the many instruments, including everything from simple river gauges to complex radars and computer-intensive modeling capability, is the HYDRO-X radar, located high in the Sierra at Blue Canyon. At that location, researchers expect to record some rain but primarily will face five feet of new snow, or more, on top of the three feet of snow already on the ground from previous storms, and winds in excess of 60 knots whipping up blizzard conditions.
This year, Blue Canyon is the focus of ESRL research aimed at improving NOAA's radar-derived quantitative precipitation estimation (QPE) capabilities using high-resolution, gap-filling radars. Blue Canyon is centered amongst dense network of precipitation gages and other instrumentation that can be used to evaluate and verify the radar QPE over the North Fork of the American River.
A new site for the scanning, polarimetric, Doppler radar at one site will provide enhanced quantitative precipitation estimates (QPE) covering the entire basin of the North Fork of the American River for the first time. State-of-the-art forecasting techniques, new tools to distribute information to the operational offices, and efforts to synthesize and integrate information (such as QPE), complete these efforts.
The HMT provides a laboratory – an exciting, even scary, wet and windy laboratory this weekend – for NWS hydrologists and meteorologists to work closely with researchers from NOAA’s Office of Oceanic and Atmospheric Research to develop and evaluate new methods of monitoring and predicting extreme precipitation.
See the Urgent Winter Weather Message issued by the Sacramento National Weather Service Forecast Office.
January 3, 2008