Atmospheric River Reconnaissance: A Research And Operations Partnership

Atmospheric rivers (ARs), narrow corridors of intense water vapor transport, provide essential precipitation. On the west coast of the U.S., the absence of ARs causes drought, and ARs are associated with almost all flood hazards. In recent years, a Research and Operations Partnership (RAOP) called Forecast Informed Reservoir Operations (FIRO) has been developed that is focused on water supply resilience and flood hazard mitigation and is conducting several viability assessments at key watersheds in the western U.S. with significant precipitation inputs from ARs. FIRO requires improved AR forecasts to maximize success. With this and other motivations, Atmospheric River Reconnaissance (AR Recon) was developed as an interagency, international RAOP that collects unique observations in the northeast Pacific to improve AR landfall forecasts and associated precipitation forecasts during the cool season (November – March). Motivated by early demonstrations of value, AR Recon observations are now officially called for in the U.S. National Winter Season Operations Plan, with leadership at the Center for Western Weather and Water Extremes (CW3E) in close partnership with NOAA National Centers for Environmental Prediction (NCEP), US Air Force Weather Reconnaissance Squadron, NOAA/Aircraft Operations Center and key collaborations with ECMWF, NRL, NCAR and others. The foundational observations within AR Recon are dropsondes, which provide atmospheric vertical profiles of temperature, moisture, winds, and pressure at targeted locations over the northeast Pacific, but AR Recon includes many other data streams via robust partnerships. Partners include the Scripps Lagrangian Drifter Laboratory-based NOAA funded Global Drifter Program, prototype data streams for airborne radio occultation based at Scripps, and targeted radiosonde releases by CW3E. CW3E partners closely with NCEP Environmental Modeling Center to carry out near real-time data denial experiments to examine the data impact on the Global Forecast System. Data denial efforts are also conducted in partnership with other global operational modeling centers in the off-season. This presentation will cover the accomplishments of the AR Recon RAOP with a focus on results from data impact studies, program evolution, and future plans to continue to advance national weather services in partnership with NOAA and other agencies.