NOAA Hydrometeorological Testbed (HMT) 2005 Campaign

Link to fullsize image of SSM/I satellite composite image of integrated water vapor
SSM/I satellite integrated water vapor composite showing an atmospheric river impacting the California coast.
Link to fullsize image of HMT 2005 deployment.
HMT 2005 deployment.


  • NOAA Environmental Technology Laboratory
  • NOAA Aeronomy Laboratory
  • NOAA Forecast Systems Laboratory
  • NOAA National Severe Storms Laboratory
  • NOAA National Centers for Environmental Prediction
  • NOAA National Weather Service-Western Region
  • NOAA California/Nevada River Forecast Center
  • NOAA Office of Hydrologic Development
  • U.S. Geological Survey
  • University of Washington
  • Scripps Institute


A demonstration project focused on improving quantitative precipitation estimation (QPE) and quantitative precipitation forecasting (QPF) in mountain areas to improve hydrologic forecasts and warnings. This project uses the Hydrometeorological Testbed (HMT) approach which has been proposed to address the nation's regions that are most vulnerable to fresh-water flooding.

The HMT will accelerate critical research and development and its transition to operations. It has been adopted in NOAA's and OAR's Strategic Plans and recommended by the Hydrology Team of the Science and Technology Infusion Plan (STIP) and the U.S. Weather Research Program (USWRP). The HMT will improve use of existing NOAA observational, modeling, and human infrastructure, identify critical gaps in NOAA's current observing and modeling capabilities, and recommend how to fill those gaps based on proof-of-concept results.

HMT-2005 Field Operations

As in winters dating back to the 1997/98 El Niño, ETL's Regional Weather and Climate Applications Division will operate a network of 915-MHz wind profiling radars along the Pacific coast from northern Oregon (as part of NOAA's Coastal Storms Initiative) to southern California, as well as others in California's central valley and Sierra Nevada foothills. From early December 2004 through March 2005, ETL will continue to conduct focused observations in the flood-prone Russian River region north of San Francisco and will begin a modest effort in the American River Basin (ARB) in the Sierra Nevada southwest of Lake Tahoe. The ARB will be the focus of future HMT efforts in California (see map).

During HMT-2005, a variety of precipitation measurement devices will be tested and evaluated at Blue Canyon, which is at an elevation (1610 m) that receives a mix of predominantly snow and some rain during the course of a winter season. These benchmark evaluations will be used to determine which types of gauges will work best in future HMT studies focused on the ARB.

One of the scientific foci related to the HMT-2005 field operations is to begin studying the impacts of atmospheric rivers as they traverse the coastal mountains of California and extend eastward toward the Sierra Nevada. Atmospheric rivers are narrow channels of moisture emanating from the subtropical moisture reservoir. On average, these features account for more than 90% of the global poleward transport of water vapor, and they are responsible for producing heavy precipitation that often results in flooding when and where they impact the U.S. West Coast. An array of four global positioning system (GPS) integrated water vapor sensors deployed along two east-west baselines stretching from the California coast to the Sierra Nevada will augment the existing network of GPS water vapor sensors already in place in California and will help document the inland protrusion of atmospheric rivers.

One of these GPS sites will be at the U.S. Forest Service Station at Lee Vining, on the east side of the Sierra. This meteorological monitoring site is part of a new collaborative effort between the Scripps Institute, the U.S. Geological Survey, and NOAA. Another aspect of this collaboration during HMT-2005 is water isotope measurements collected in precipitation at ETL's long-term coastal mountain monitoring site near Cazadero, California. Through analysis of the isotopic properties of precipitated water, a better understanding of precipitation development processes can be obtained.

HMT-2005 Goals

  • Demonstrate the concept of a regional Hydrometeorological Testbed as a conduit to infuse new science and technology into operations.
  • Continue to develop a climatology of orographic precipitation along the coastal mountains of California north of San Francisco to examine linkages between climate and weather.
  • Study the microphysical features and orographic precipitation mechanisms in storm clouds over the coastal mountains and Sierra foothills.
  • Continue testing experimental polarimetric radar estimations of rainfall rate and classification of hydrometeor types using HMT-2004 datasets.
  • Conduct water isotope measurements to learn more about precipitation development processes.
  • Test and evaluate different precipitation measurement devices for use in future HMT efforts that will deal with mixed precipitation.
  • Begin to establish field sites in and around the American River Basin for future HMT studies.

HMT-2005 Observing Sites

Instrument(s) or measurement(s)


Period of Operation
915-MHz integrated boundary-layer observing system (wind profiler, radio acoustic sounding system, 10-m meteorological tower)
Astoria, OR* ongoing
Bodega Bay, CA 12/04-3/05
Chico, CA# ongoing
Chowchilla, CA# ongoing
Grass Valley, CA 12/04-3/05
Lost Hills, CA# ongoing
Point Piedras Blancas, CA 12/04-3/05
2875-MHz vertically-pointing cloud/precipitation radar
Cazadero, CA12/04-3/05
Grass Valley, CA 12/04-3/05
Precipitation accumulation, temperature, relative humidity, soil moisture, soil temperature
Blue Canyon, CA+12/04-3/05
Healdsburg, CAongoing
Rio Nido, CAongoing
10-m meterological tower
Blue Canyon, CA12/04-3/05
Cazadero, CA12/04-3/05
Lee Vining, CA**ongoing
GPS integrated water vapor receiver
Bodega Bay, CA 12/04-3/05
Grass Valley, CA 12/04-3/05
Lee Vining, CA1/05-ongoing
Point Piedras Blancas, CA 12/04-3/05
Raindrop disdrometer Cazadero, CA 12/04-3/05
Water isotope measurements Cazadero, CA** 1/05-3/05
*Deployment is part of NOAA's Coastal Storms Initiative (CSI)
#California central valley profilers are funded by the Central California Ozone Study
+Special precipitation accumulation sensors at Blue Canyon consist of a heated tipping bucket rain gauge, a hot plate gauge, and a snow-depth sensor.
**In collaboration with the US Geological Survey and Scripps Institute