cw3e-web - Center for Western Weather and Water Extremes

CW3E Welcomes Dr. Michael Warner

September 22, 2025

CW3E is excited to welcome Dr. Michael Warner as Watershed Sciences Integration Manager. Mike joins CW3E after eight years with the U.S. Army Corps of Engineers (USACE) Seattle District, where he served as a meteorologist with Water Management and technical lead for Forecast-Informed Reservoir Operations (FIRO) at Howard A. Hanson Dam. Most recently, he provided national leadership as a subject matter expert with USACE Headquarters’ Infrastructure and Installation Resilience Community of Practice, helping to shape climate adaptation and resilience policies across the nation.

Mike holds a Ph.D. in Atmospheric Sciences from the University of Washington, where his research examined West Coast atmospheric rivers and climate change. His background includes extreme precipitation analysis, seasonal hydrologic prediction, and climate-change-driven vulnerability assessments. He is passionate about bridging atmospheric science and water management by translating cutting-edge research into actionable strategies for reservoir operations, flood risk management, and water supply planning.

Mike looks forward to building on this foundation at CW3E by advancing FIRO nationwide, supporting AR Reconnaissance activities, and strengthening collaboration between scientists, water managers, and decision-makers to enhance community resilience. Mike welcomes opportunities to connect with colleagues and partners—please feel free to reach out to collaborate on advancing weather, water, and climate solutions.

CW3E Welcomes Dr. Shuang Yu

September 5, 2025

Dr. Shuang Yu joined CW3E in September 2025 as a Machine Learning Scientist. She earned her Ph.D. in Atmospheric Science from the Institute of Atmospheric Physics, Chinese Academy of Sciences. After completing her doctorate, she worked at IPSL/CNRS in France, focusing on wind energy projections and climate–renewable energy interactions. Most recently, she was a postdoctoral researcher at Lawrence Livermore National Laboratory, where she developed deep learning methods to improve climate model prediction and groundwater applications, leveraging advanced high-performance computing.

Her research lies at the intersection of atmospheric science and artificial intelligence. She has expertise in bias correction and downscaling of climate models, post-processing tools for weather forecasts, explainable AI, and uncertainty quantification. She also investigates climate extremes such as precipitation extremes, heatwaves, and wildfires, emphasizing their predictability, underlying mechanisms, and impacts on human and ecological systems. In addition, she applies AI techniques to integrated modeling of climate, groundwater, and energy systems, including wind energy forecasting and hydrology-driven water security prediction.

In her new role, Shuang will work with CW3E teams to advance AI-driven weather forecasting models and post-processing systems. Her efforts aim to enhance the accuracy and usability of forecasts for high-impact weather and climate events, supporting water and energy security across the western United States.

Congratulations to Dr. Cody Poulsen

September 4, 2025

Dr. Cody Poulsen at his successful hybrid defense with his advisor, CW3E Director Marty Ralph.

CW3E is proud to congratulate Dr. Cody Poulsen, who successfully defended his doctoral dissertation, “Precipitation Through Time: A Past and Present Analysis of Changes and Relationships in Western United States Seasonal Precipitation”, on July 23, 2025 at Scripps Institution of Oceanography.

As an undergraduate, Cody collaborated with CW3E post-doc Scott Sellars to adapt the Monterey Bay Aquarium Research Institute’s Video Annotation and Reference System (VARS) for meteorological applications. His senior thesis produced an atmospheric river (AR) metadata set for Water Years 2001 and 2011, identifying AR landfalls, and revealing striking contrasts in AR activity between December 2000 (no AR landfalls) and December 2010 (anomalously high AR activity). Cody’s research earned second place at the AEHS International Student Conference Competition, and at the ESYS Senior Symposium where he was awarded a San Diego Environmental Professionals Excellence Award.

For his Ph.D., under the guidance of Dr. Marty Ralph (chair) and committee members Drs. Christopher Charles, Michael Dettinger, Alexander Gershunov, Riuxue Jia, and David Stahle, Cody investigated hydroclimate variability in the western United States using both paleoclimate proxies and modern records. His dissertation provided new insights into the relationships between atmospheric rivers, orographic precipitation, and water availability across multiple timescales.

Beyond his research endeavors, Cody has also been a leader in CW3E’s community engagement efforts. He supported the 2021 CW3E Summer Intern Program, contributed to interactive booths at the 1st Annual Yampa Youth Water Festival, and participated in welcoming Webster Elementary students at the Scripps Pier to learn about atmospheric rivers and extreme weather, demonstrating his commitment to outreach and science education.

We celebrate Cody’s accomplishments and look forward to his continued contributions to advancing the understanding of western U.S. hydroclimate.

Dr. Cody Poulsen writing his name on the wall at Surfside, a Scripps tradition.

Poulsen, C., R. Clemesha, I. Howard, A. Gershunov, M.D. Dettinger, Z. Zhang, R. Luna-Niño, D.W. Stahle, F.M. Ralph, 2025: The 1991 California ‘Miracle March’: precipitation myth or miracle?. Environmental Research Communications, 7(5). https://doi.org/10.1088/2515-7620/add3cc

Kirby, M.E., J. Barbosa, J.A. Carlin, G.M. MacDonald, J. Leidelmeijer, N. Bonuso, J. Han, B. Nauman, J.A. Radick, A. Woodward, S. O’Barr, C. Poulsen, K. Nichols, and R. Ramezan, 2023: Holocene hydroclimatic variability recorded in sediments from Maddox Lake (northern California Coast Range). Quaternary Research, 115, 1–19. https://doi.org/10.1017/qua.2023.18

Howard, I., D.W. Stahle, M.C.A. Torbenson, D. Granato-Souza, and C. Poulsen, 2023: The flood risk and water supply implications of seasonal precipitation reconstructions in Northern California. San Francisco Estuary and Watershed Science, 21(1). https://doi.org/10.15447/sfews.2023v21iss1art2

Howard, I., D.W. Stahle, M.D. Dettinger, C. Poulsen, F.M. Ralph, M.C.A. Torbenson, and A. Gershunov, 2023: A 440-year reconstruction of heavy precipitation in California from blue oak tree rings. Journal of Hydrometeorology, 24(3). https://doi.org/10.1175/JHM-D-22-0062.1

Congratulations to Dr. Wen-Shu Lin

September 2, 2025

CW3E congratulates Dr. Wen-Shu Lin on the successful defense of her doctoral dissertation, “Characteristics and Subseasonal Predictability of Atmospheric Rivers Over Western North America,” on June 10, 2025. Wen-Shu joined CW3E as a graduate student in 2019 after completing her B.S. in Atmospheric Science at National Taiwan University.

Her research at CW3E, co-advised by Dr. Joel Norris and Dr. Marty Ralph, focused on climate variability, precipitation, and atmospheric dynamics, with particular emphasis on the variability of atmospheric rivers and regional climate on subseasonal timescale. Building on her undergraduate work investigating sea surface temperature and precipitation relationships under global warming, Wen-Shu’s research explores how climate variability shapes extreme weather events and water availability in the western United States.

After completing her PhD program, Wen-Shu will continue her research at CW3E as a postdoctoral scholar, beginning in October 2025. She will work with Dr. Zhenhai Zhang and other CW3E colleagues to investigate the interaction between shortwave troughs and atmospheric rivers, as well as their impacts on the forecasts of landfalling atmospheric rivers along the U.S. West Coast. We celebrate Wen-Shu’s accomplishments and look forward to her continued contributions to the atmospheric science community.

Lin, W.-S., J.R. Norris, M.J. DeFlorio, J.J. Rutz, J.M. Cordeira, and F.M. Ralph, 2025: Characteristics of precipitation patterns in moisture-dominated versus wind-dominated atmospheric rivers over western North America. Journal of Geophysical Research: Atmospheres, 130(9). https://doi.org/10.1029/2024JD041966

Lin, W.-S., J.R. Norris, M.J. DeFlorio, and F.M. Ralph, 2024: Local and object-based perspectives on atmospheric rivers making landfall on the western North American coastline. Journal of Hydrometeorology, 25(5). https://doi.org/10.1175/JHM-D-22-0155.1

CW3E Welcomes Jeff Zimmerman

August 5, 2025

Jeff Zimmerman joined CW3E in July 2025 as a Program Manager. Jeff will serve as a liaison to the NWS River Forecast Centers and Office of Water Prediction, working to leverage the NWS hydrologic forecast information to advance FIRO priorities. Jeff comes to CW3E after a 32 year career in the National Weather Service (NWS). A significant portion of this time was spent supporting the implementation and execution of the NWS Hydrologic Services Program. He served as a senior leader in a variety of positions across the NWS, and brings significant experience in areas such as strategic planning, budget planning and execution, project leadership, management and supervision, and mentorship.

Jeff spent 15 years in the NWS Western Region Headquarters in Salt Lake City. During his time in Salt Lake City, he gained an acute appreciation for the challenges related to water availability and water management across the western US. He served as the Chief of the Region’s Integrated Service Division, and was responsible for overseeing the implementation and execution of NWS meteorological and hydrologic services throughout the West. Jeff also served as the Deputy Regional Director for the Western Region. Towards the end of his career, Jeff returned to the Office of Water Prediction, where he led a team of professionals in the design, development and implementation of a set of quality assurance and evaluation activities to verify, validate and evaluate the performance of NWS hydrologic models and services, including the National Water Model, inundation flood mapping and probabilistic forecast services. He also served as the NWS liaison to all Forecast Informed Reservoir Operations (FIRO) activities, including interfacing with NWS River Forecast Centers, US Army Corps of Engineers, CW3E scientists and local water managers regarding NWS hydrologic forecast activities to support FIRO.

CW3E Welcomes Dr. Ben Moore

July 29, 2025

Dr. Ben Moore joined CW3E in July 2025 as a precipitation scientist and research data analyst. He holds a B.S. in Atmospheric and Oceanic Sciences from the University of Wisconsin–Madison (2008) and an M.S. (2010) and a Ph.D. (2017) from the University at Albany, State University of New York. Prior to joining CW3E, Ben worked as Research Meteorologist at the NOAA Physical Sciences Laboratory in Boulder, Colorado. His research in that position was focused on the predictability and governing dynamics of precipitation extremes and related weather systems. He worked on a diverse array of projects that included meteorological analysis of high-impact atmospheric river events, climatological analysis of western U.S. precipitation extremes, statistical evaluation and diagnosis of model precipitation forecasts, and investigation of the impacts of tropical errors on subseasonal prediction of precipitation extremes in California. In his research, Ben emphasizes application of a synoptic-dynamic meteorological perspective to identify processes driving extreme precipitation events and to diagnose errors in model forecasts.

In his new role, Ben will collaborate with the CW3E precipitation science, forecast verification, and modeling teams to conduct research aimed at advancing physical understanding and prediction capabilities for precipitation extremes and their impacts across the United States.

CW3E Publication Notice: An Overview of Drifting-Buoy Deployments in Atmospheric River Reconnaissance from 2019 to 2024

CW3E Publication Notice

An Overview of Drifting-Buoy Deployments in Atmospheric River Reconnaissance from 2019 to 2024

July 2, 2025

A new research article “An overview of drifting-buoy deployments in atmospheric river reconnaissance from 2019 to 2024” by international researchers David Lavers and Bruce Ingleby from the European Centre for Medium-Range Weather Forecasts (ECMWF), Luca Centurioni from the Lagrangian Drifter Laboratory at Scripps Institution of Oceanography, and Anna Wilson and F. Martin Ralph from CW3E, was published recently in the Quarterly Journal of the Royal Meteorological Society.

The Atmospheric River Reconnaissance (AR Recon) program was developed to increase the accuracy of Numerical Weather Prediction (NWP) forecasts of atmospheric structures, with a specific focus on landfalling atmospheric rivers (ARs) and their impacts. Accurate NWP forecasts rely on a network of atmospheric and oceanic data observations, including sea-level pressure, collected by drifting buoys outfitted with barometers.

During a meeting in 2018 at ECMWF, the importance of sea-level pressure observations gathered via buoys was discussed. The data gap in the North Pacific Ocean motivated a partnership between CW3E and the Lagrangian Drifter Laboratory (LDL) to increase the amount of barometer-outfitted buoys in the LDL’s Global Drifter Program (GDP) array, and deploy them to areas with sparse data coverage. This article (1) documents how this partnership has enabled an increase in barometric drifting buoys across the North Pacific Ocean and (2) assesses how the resulting data have impacted the ECMWF Integrated Forecasting System (IFS).

Currently, the GDP consists of approximately 1250 Lagrarian drifter buoys tracked on the sea surface by satellite. Through the AR Recon program, a subset of these buoys were upgraded with barometers to relay sea-surface temperature and sea-level pressure observations to shore, every hour, to be assimilated into NWP systems. Between 2019 and 2024, AR Recon deployed 309 specialized buoys using two platforms: U.S. Air Force C-130 aircraft from the 53rd Weather Reconnaissance Squadron and ships of opportunity (Table 1). Deployment sites were chosen strategically to fill observation gaps, especially in the North Pacific storm track region. Notably, during the 2024 AR Recon season, flights departed from Guam for the first time, allowing for a valuable increase of coverage over the western North Pacific. The study found that upgrading drifting buoys with barometers significantly enhanced surface pressure coverage over the North Pacific by expanding from just 106 reporting buoys in 2019, to 260 in 2024.

Season	2019	2020	2021	2022	2023	2024
	32[0]	64[16]	30[10]	50[10]	56[10]	86[20]

Table 1. (from Lavers et al. (2025)). The number of buoys released in each Atmospheric River Reconnaissance season. DWSB buoy numbers are included in the total and referenced separately in brackets.

To assess the value of buoy observations in the ECMWF IFS system, this study uses Forecast Sensitivity to Observation Impact (FSOI), which estimates how individual observations affect 24-hour forecast error. FSOI and observation-minus-background (O−B) values were analyzed for buoys in the North Pacific and North Atlantic from 2019 to 2024.

Figure 1. (Fig. 6 from Lavers et al. (2025)): (a) Scatterplots of the average forecast sensitivity observation impact (FSOI) against the standard deviation of the observation-minus-background (O − B) departures at each buoy in the North Pacific and North Atlantic and from Atmospheric River Reconnaissance (AR Recon) calculated over 1 January to 31 March 2024. The number of drifting buoys and the Spearman rank correlations between the average FSOI and the standard deviation of the O − B departures are given in the legend; the North Pacific number includes AR Recon buoys. (b) The Gaussian-estimated density function of the average FSOI for drifting buoys in the North Pacific and North Atlantic and from AR Recon; the average values are given in the legend. (c) The Gaussian-estimated density function of the standard deviation of the O − B departures for drifting buoys in the North Pacific and North Atlantic and from AR Recon; the average values are given in the legend.

Analyses using FSOI found that, on average, the sea-level pressure observations from drifting buoys reduced 24-hour forecast errors, highlighting the value of a more complete buoy network for NWP overall (Fig. 1). The additional observations help to anchor the model, providing a more accurate picture of upstream sea-level pressure patterns and associated atmospheric river events.

This study reinforces past research demonstrating the positive impact of AR Recon drifting buoy observations on forecast skill (Reynolds et al. 2023) and the positive impact of buoys with sea-level pressure observations more generally (Horányi et al. 2017; Centurioni et al. 2017a; Ingleby and Isakson 2018, among others). The results in this study clearly demonstrate the value of sustained and expanded monitoring in data-sparse but meteorologically important regions. These findings underscore the importance of continued investment in targeted observation strategies to reduce forecast uncertainty, especially for atmospheric river events that drive high-impact weather along the North American West Coast. In particular, this study provides a strong case to begin targeting rapidly developing systems and ARs with buoys, particularly systems that are forecast to be extreme.

Centurioni, L., Horányi, A., Cardinali, C., Charpentier, E., & Lumpkin, R. (2017). A Global Ocean Observing System for Measuring Sea Level Atmospheric Pressure: Effects and Impacts on Numerical Weather Prediction. Bulletin of the American Meteorological Society, 98(2). https://doi.org/10.1175/BAMS-D-15-00080.1

Ingleby, B., & Isaksen, L. (2018). Drifting buoy pressures: Impact on NWP. Atmospheric Science Letters, 19(6), e822. https://doi.org/10.1002/asl.822

Horányi, A., Cardinali, C., & Centurioni, L. (2017). The global numerical weather prediction impact of mean-sea-level pressure observations from drifting buoys. Quarterly Journal of the Royal Meteorological Society, 143(703). https://doi.org/10.1002/qj.2981

Lavers, D.A., Centurioni, L., Wilson, A.M., Ingleby, B. & Ralph, F.M. (2025). An overview of drifting-buoy deployments in atmospheric river reconnaissance from 2019 to 2024. Quarterly Journal of the Royal Meteorological Society, e5049. https://doi.org/10.1002/qj.5049

Reynolds, C.A., Stone, R.E., Doyle, J.D., Baker, N.L., Wilson, A.M., Ralph, F.M., Lavers, D.A., Subramanian, A.C., & Centurioni, L. (2023). Impacts of Northeastern Pacific Buoy Surface Pressure Observations. Monthly Weather Review, 151(1). https://doi.org/10.1175/MWR-D-22-0124.1

CW3E Welcomes Kyla Van Maanen

June 13, 2025

Kyla Van Maanen joined CW3E in June 2025 as a Research Project Coordinator. In her new role she will support teams across the Center by coordinating meetings, planning events, and managing timelines. Kyla holds B.A. degrees in Environmental Studies and Studio Art from Pitzer College, and an M.S. in Marine Biology from Northeastern University. Her Master’s thesis work assessed how UNFCCC-funded adaptation projects in developing countries have contributed to coastal resilience to climate change.

Professionally, Kyla has worked in art, environmental science, and at the intersection of the two. She spent her early career working in the Los Angeles art world as a collections manager, archivist, and executive assistant before pursuing graduate studies in marine science. After her degree she stayed at Northeastern to manage international research partnerships at the Global Resilience Institute. She then worked as a senior project manager on an NSF-funded ocean data governance research, and later developed collaborative and educational events for environmental grantmakers at the Biodiversity Funders Group. Most recently, Kyla directed international public art programs for the nonprofit PangeaSeed, facilitating collaborations between artists and scientists to create accessible visual art that translates conservation imperatives to increase ocean literacy.

Outside of the (home) office, Kyla loves spending time outdoors exploring the pockets of nature that persist in and around LA. She’s currently completing the UC California Naturalist certification to learn more about environmental interpretation, science communication, and identification of native flora and fauna. She also practices 35 mm film photography, enjoys trail riding in the foothills, and never misses a chance to dive in the kelp forests around the Channel Islands.

Kyla is excited to join CW3E’s collaborative and mission-driven team, and looks forward to contributing her skills in interdisciplinary project management, creative communication, and cross-sector partnership building to support impactful, applied climate and water research.

CW3E Welcomes Kristiana Chan

May 19, 2025

Kristiana (Kris-shana or Krissy) joined CW3E in April 2025 as a FIRO Research Project Coordinator, specializing in engagement, scheduling and meeting coordination for the Center’s FIRO Steering Committees. She holds a B.S. in Biology from the University at Albany, SUNY and an M.A.S. in Climate Science and Policy from Scripps Institution of Oceanography. Her capstone project focused on integrating Indigenous stewardship and Traditional Ecological Knowledge into California’s state policy toward wildfire mitigation.

Professionally, she mentored students and coordinated the summer program for her graduate program’s incoming class. Following this role she worked as a Policy Advisor for Councilmember Joe LaCava, District 1 of the City of San Diego. Here she worked on air quality initiatives, Tribal collaboration and farm animal rights. Notably, in collaboration with City Department Heads, she designed the Free4ME Implementation Plan that was adopted by City Council in 2023 to provide free menstrual products at city facilities. She also collaborated with UCSD’s Dr. James Nieh, on the successful decree of the City of San Diego as a Bee City, thereby committing the city to pollinator protections and reduced pesticide usage at City Parks. From this role, she moved into the private sector as an Environmental Justice and Engagement Specialist, consulting for CityWorks People + Places. Here she led several projects as a consultant with the City and County of San Diego, as well as other jurisdictional partners to ensure community members were well informed and collaborated with for new and upcoming projects. In this role, she used her training in equity and lived experience to advocate for improved community engagement with particular focus on historically marginalized communities.

Krissy is thrilled to join the CW3E team and looks forward to working with this highly collaborative, adaptive and growing team, bringing with her skills in relationship and team building, project management and community building.

In her free time, she can be found climbing, surfing, practicing yoga, reading, writing or partaking in light homesteading activities.

CW3E Welcomes Sawyer Smith

March 4, 2025

Sawyer Smith joined CW3E in February 2025 as a numerical weather prediction scientist and research data analyst on the CW3E modeling team. He holds a B.S. in Meteorology from Metropolitan State University of Denver (MSU Denver) and received an M.S. in Atmospheric Science from North Carolina State University in December 2024.

During undergrad, Sawyer took advantage of the wealth of opportunities for atmospheric scientists along the Front Range of Colorado, where he served as an Upper Air Observer for the National Weather Service in Boulder, CO and a Winter Weather Aviation Student Assistant at the National Center for Atmospheric Research.

His thesis work, which was funded by CW3E, focused on the sensitivity of orographic precipitation forecasts to the choice of microphysics parameterization along the Sierra Nevada using the West-WRF model. Ironically, cloud microphysics was neither his favorite nor his strongest subject in undergrad—in fact, it was the only meteorology class he did not ace. However, while taking a numerical weather prediction course taught by his graduate advisor, Dr. Gary Lackmann, Sawyer became intrigued by some of the new microphysical parameterization schemes in WRF-ARW and their potential to improve orographic precipitation forecasts.

Thus, as fate would have it, he found himself revisiting his meteorological “Achilles’ heel”—microphysics. Since then, Sawyer has developed a deep enthusiasm for cloud microphysics and is eager to apply his expertise toward CW3E’s mission of advancing the science and prediction of extreme hydrological events.