CW3E Publication Notice

Advances in the Application and Utility of Subseasonal-to-Seasonal Predictions

December 6, 2021

CW3E researcher Dr. Mike DeFlorio, along with co-authors Dr. F. Martin Ralph (CW3E Director), Dr. Luca Delle Monache (CW3E Deputy Director), Dr. Duane E. Waliser (NASA JPL/CalTech; Chief Scientist of the Earth Science and Technology Directorate), Dr. Peter B. Gibson (NIWA), and Dr. Michael L. Anderson (California Department of Water Resources) recently contributed as co-authors to an article in BAMS titled “Advances in the Application and Utility of Subseasonal-to-Seasonal Predictions”. The contributions of DeFlorio, Ralph, Delle Monache, and Gibson were supported by the California Department of Water Resources Atmospheric River Program Phase II and the United States Army Corps of Engineers Forecast Informed Reservoir Operations Program Phase II.

The purpose of this BAMS article is to provide a detailed description of an international community of researchers who are partners with specific end users in advancing the utility of subseasonal-to-seasonal (S2S; 2-week to 6-month lead time) forecasts. Twelve case studies are presented in the article and span the end user sectors of water resource management, public health, agriculture, renewable energy and utilities, and emergency management and response. A key component of the case studies presented in this article is the collaboration and partnership between researchers and end users in co-generating S2S forecasts of relevant quantities of interest (e.g., atmospheric rivers, precipitation, ridging, temperature, etc.). The organization and coalescence of this broad community of international researchers and end users was facilitated by the World Weather Research Programme (WWRP) / World Climate Research Programme (WCRP) S2S Prediction Project Real-time Pilot Initiative (

Figure 5 from the article is included below. It provides an overview of the CW3E/NASA JPL contribution to this effort, which includes week-3 AR activity and weeks 3-4 ridging outlooks.

Figure 5: Water management in western U.S., showing: a) CW3E/JPL week 3 AR activity outlook. Forecast initialized September 21, 2020 and verified October 06-12, 2020. Top panel shows the forecasted number of AR days to occur during the week 3 verification period; middle panel shows the NCEP hindcast climatology of AR days during the October 06-12 week in the hindcast record; bottom panel shows the anomaly forecast field (top minus middle panels). Hindcast skill assessment provided in DeFlorio et al. (2019a,b); b) CW3E/JPL weeks 3-4 experimental ridging outlook. Forecast initialized on September 21, 2020 and verified October 05-19, 2020. Left column shows the occurrence frequency of each ridge type (bars) compared to climatology (horizontal line) for each of the model ensemble members. The top, middle, and bottom row display the North, South, and West ridge forecasts, respectively. If over 50% of the ensemble members predict more ridging than expected (for this time of year), then the right column maps indicate the likelihood of wetter or drier conditions based on how each ridge type typically influences precipitation. Methodology for calculating ridge types is provided in Gibson et al. (2020a); hindcast skill assessment is provided in Gibson et al. (2020b).

White, C.J., Domeisen, D.I.V., Acharya, N., Adefisan, E.A., Anderson, M.L., Aura, S., Balogun, A.A., Bertram, D., Bluhm, S., Brayshaw, D.J., Browell, J., Büeler, D., Charlton-Perez, A., Chourio, X., Christel, I., Coelho, C.A.S., DeFlorio, M.J., Delle Monache, L., Di Giuseppe, F., García-Solórzano, A.M., Gibson, P.B., Goddard, L., González Romero, C., Graham, R.J., Graham, R. M., Grams, C.M., Halford, A., Katty Huang, W.T., Jensen, K., Kilavi, M., Lawal, K.A., Lee, R.W., MacLeod, D., Manrique-Suñén, A., Martins, E.S.P.R., Maxwell, C.J., Merryfield, W.J., Muñoz, Á.G., Olaniyan, E., Otieno, G., Oyedepo, J.A., Palma, L., Pechlivanidis, I.G., Pons, D., Ralph, F.M., Reis, D.S., Jr., Remenyi, T.A., Risbey, J.S., Robertson, D.J.C., Robertson, A.W., Smith, S., Soret, A., Sun, T., Todd, M.C., Tozer, C.R., Vasconcelos, F.C., Jr., Vigo, I., Waliser, D.E., Wetterhall, F., & Wilson, R.G. (2021). Advances in the application and utility of subseasonal-to-seasonal predictions. Bulletin of the American Meteorological Society, 1(aop), 157.