A Look Back
The first phase of the Hydrometeorology Testbed (HMT) was an outgrowth of NOAA's CALJET and
PACJET field projects from 1997–2003 on the West Coast of the U.S. While productive from a
research standpoint, the CALJET and PACJET experiences also suggested a need for a new model to
better engage operational communities in the research process, which led to workshops and
science meetings between the research and operational communities
(HMT Implementation Plan for Science & Service, 2009).
In the early 2000s enhanced observation sites known as atmospheric river observatories (AROs),
which include radar wind profilers, GPS water vapor sensors, standard surface meteorology
stations, and in some cases snow-level radars, were installed in the western U.S. by the
Physical Sciences Division (PSD) at the NOAA/Earth System Research Laboratory (ESRL). NOAA and
partners, such as the State of California and the U.S. Department of Energy, have provided
funding for additional observatories over the years, and there currently exists a
“picket fence” of AROs along the west coast
Map showing atmospheric river observatories along the US west coast.
Additional surface meteorological sites implemented by HMT supplement the ARO network and are maintained by PSD. A major goal of these observations,
and HMT in general, is to examine extreme precipitation and its hydrologic forcings to improve
The scientific results of field campaigns combined with long-term observations and researcher/
forecaster collaborations naturally led to the development of tools and products (such as the
Water Vapor Flux Tool or the
Atmospheric River Detection Tool)
to help forecasters predict heavy precipitation events. HMT R2O connections became more formal in August
2005 when a component of the HMT was established at the NOAA/NCEP Hydrometeorological Prediction Center
(HPC) (now known as the Weather Prediction Center (WPC)). For several years the HMT staff at WPC
have organized forecasting experiments where researchers can test their product or model in a
quasi-operational setting. These experiments include the Winter Weather Experiment and the Flash
Flood and Intense Rainfall experiment and focus on improving precipitation forecasts and
continue to be an important component of HMT.
In 2009 the first NOAA Testbed Workshop focused on best practices among emerging testbeds
associated with NOAA weather research and forecasting entities and partners
(Ralph et al. 2013). The HMT was represented at this workshop, as well as all subsequent
As researchers continued using HMT legacy instrumentation, for instance, during recent research
campaigns such as the Calwater2
and ENRR, and the WPC forecasting
experiments continued testing new models, products, and forecasting methods, the infrastructure
of HMT changed again in 2015 when U.S. Weather Research Program/Office of Weather and Air
Quality (USWRP/OWAQ) began competitively funding R2O projects for several NOAA testbeds,
including the HMT. A second phase of USWRP/OWAQ funding began in summer 2017.
Visit our projects page for past and present HMT-funded projects.
More details about the history of HMT can be found in the timeline below, which includes links to documents.