Improving Atmospheric River Forecasting

A program aimed at improving understanding and forecasting of atmospheric rivers is expanding across the U.S., giving NC State undergraduate and graduate students an opportunity to participate. The program, Coordinated University Soundings Program for Atmospheric River Reconnaissance (CUSP-ARR), led by the Center for Western Weather and Water Extremes (CW3E) at Scripps Institution of Oceanography, enlists 16 universities in the U.S. and Canada in an effort to collect data that can be used to study atmospheric rivers and other high-impact weather events.

The main function of CUSP-ARR is to launch weather balloons equipped with high-tech sensors called radiosondes in coordination with AR Recon missions. The balloons will provide broad-coverage observations during atmospheric rivers and other major precipitation events. This year, CUSP-ARR will provide land-based data that complements airborne campaigns over the Pacific,
Gulf and Atlantic Ocean basins.

CUSP-ARR is unique in that it is entirely powered by teams of faculty, staff, and students in university meteorology and atmospheric science programs. Students help lead launch
planning, weather balloon deployment, and tracking of radiosonde output through the upper atmosphere. Data collection runs through the end of February.

The Abstract sat down with Allison Michaelis, assistant professor in the Department of Marine, Earth and Atmospheric Sciences, to talk about what atmospheric rivers are and how NC State students and faculty are helping to improve their forecast.

The Abstract (TA): What are atmospheric rivers and why do we care about them?

Michaelis: Atmospheric rivers (ARs) are long, narrow corridors of enhanced moisture transport, often leading to rain and snow upon landfall. While ARs can bring vital precipitation to certain regions (e.g., California), they can also be associated with hazardous extreme precipitation. For example, ARs are responsible for almost half of California’s annual precipitation but are responsible for the majority of the state’s heavy precipitation events.

TA: Will collecting data on ARs help us predict rain/flood events more accurately? Do we have examples of extreme weather in N.C. caused by, or due to, ARs?

Michaelis: Yes – we are doing this work on atmospheric rivers to help improve forecasts of extreme rainfall and flood events. The primary AR Recon field campaign is focused on forecast improvement for the U.S. West Coast, particularly California. The purpose of CUSP-ARR is to then increase the number of observations downstream of landfalling atmospheric rivers to sample a variety of weather conditions to further improve forecasts over the continental U.S.

We can get atmospheric river conditions in N.C. but I don’t recall any specific extreme events. The term “atmospheric river” is relatively new in the literature (it was coined in the early 1990s) and even newer in the media. To this point, our atmospheric river work at CW3E has primarily focused on U.S. West Coast impacts but is starting to expand into examining other regions.

TA: What is the goal of this data collection?

Michaelis: This year, as AR Recon evolves into a globally coordinated effort known as the Global Atmospheric River and Reconnaissance Program (GARRP), CUSP-ARR plays an important role by providing land-based data that complements airborne campaigns over the Pacific, Gulf, and Atlantic Ocean basins. Through this unique partnership between research institutions, government agencies and universities, the program is creating a scalable model for distributed observation networks that can fill key gaps in the global observing system.

TA: How is NC State involved in this project?

Michaelis: Our involvement is to sample a variety of weather conditions associated with environments before and after an atmospheric river makes landfall along the U.S. West Coast. We’re doing this by launching radiosondes for data collection from Jordan Hall on campus. These observations can help us better understand the impact of ARs on the East Coast, though the East Coast isn’t necessarily our specific focus for this project.

Radiosonde launch equipment for CUSP-ARR partners is funded by the U.S. Army Corps of Engineers Forecast Informed Reservoir Operations award.

This post was originally published in NC State News.