RT Journal Article T1 A new moisture tagging capability in the Weather Research and Forecasting model: formulation, validation and application to the 2014 Great Lake-effect snowstorm A1 Insua Costa, Damián A1 Míguez Macho, Gonzalo AB A new moisture tagging tool, usually known as water vapor tracer (WVT) method or online Eulerianmethod, has been implemented into the Weather Research and Forecasting (WRF) regional meteorologicalmodel, enabling it for precise studies on atmospheric moisture sources and pathways.We present here the methodand its formulation, along with details of the implementation into WRF. We perform an in-depth validation witha 1-month long simulation over North America at 20 km resolution, tagging all possible moisture sources: lateralboundaries, continental, maritime or lake surfaces and initial atmospheric conditions. We estimate errors as themoisture or precipitation amounts that cannot be traced back to any source. Validation results indicate that themethod exhibits high precision, with errors considerably lower than 1% during the entire simulation period,for both precipitation and total precipitable water. We apply the method to the Great Lake-effect snowstorm ofNovember 2014, aiming at quantifying the contribution of lake evaporation to the large snow accumulationsobserved in the event. We perform simulations in a nested domain at 5 km resolution with the tagging technique,demonstrating that about 30–50% of precipitation in the regions immediately downwind, originated fromevaporated moisture in the Great Lakes. This contribution increases to between 50 and 60% of the snow waterequivalent in the most severely affected areas, which suggests that evaporative fluxes from the lakes havea fundamental role in producing the most extreme accumulations in these episodes, resulting in the highestsocioeconomic impacts. PB Copernicus Publications SN 2190-4979 YR 2018 FD 2018 LK http://hdl.handle.net/10347/22802 UL http://hdl.handle.net/10347/22802 LA eng NO Insua-Costa, D. and Miguez-Macho, G.: A new moisture tagging capability in the Weather Research and Forecasting model: formulation, validation and application to the 2014 Great Lake-effect snowstorm, Earth Syst. Dynam., 9, 167–185, https://doi.org/10.5194/esd-9-167-2018, 2018 NO Funding for this work came from the European Commission FP7 (EartH2Observe) and the Spanish Ministerio de Economía y Competitividad (CGL2017-89859-R and CGL2013-45932-R), and from contributions by the CRETUS Strategic Partnership (AGRUP2015/02) DS Minerva RD 24 abr 2026