Recurrent Large-Scale Environments Enable 24-Hour Predictability for High-Impact MCS Events in Northern South America

{"The preprint demonstrates that MCS events in the Orinoco-Amazon basin are not isolated local phenomena but expressions of repeatable large-scale configurations. Researchers mapped the Mocoa environment onto a specific SOM node characterized by favorable upper-level circulation and ER-wave forcing. This regime accounted for a disproportionate share of extreme precipitation events across the 2001-2021 record, shifting emphasis from purely stochastic local triggers to monitorable upstream signals.","Methodologically, the study combined an MCS tracking dataset with equatorial Rossby wave diagnostics and ERA5 fields before applying SOM clustering to isolate nine recurrent states. The Mocoa case aligned with a configuration that occurs multiple times per season, providing a statistical basis for regime-based forecasting. This approach directly addresses the lead-time gap that left emergency responders without actionable warnings during the 2017 disaster.","Original coverage of the preprint understated its relevance to operational forecasting systems. The identification of 24-hour precursors originating over the Guiana Highlands suggests that current global models already resolve the necessary scales but lack regime-aware post-processing. Integration of SOM diagnostics into existing frameworks could extend skillful MCS guidance from hours to multiple days, particularly for flood-prone Andean foothills where topography amplifies rainfall.","Next steps include testing the nine-regime classification in real-time hindcasts with ECMWF and GFS output over the next two wet seasons. If verification shows skill above current convective-permitting ensembles for events exceeding 100 mm day-1, national meteorological services in Colombia and Venezuela could adopt the method for targeted early-warning bulletins."}