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SUMMARY:Informal Seminar: Forecast asymmetries and fragile data flows: cha
 llenges and responsibilities for S2S services
DTSTART:20250603T130000Z
DTEND:20250603T140000Z
DTSTAMP:20260807T212100Z
UID:indico-event-481@events.ecmwf.int
DESCRIPTION:\nForecast skill is unevenly distributed across regions and sc
 ales\, with major implications for the design of sub-seasonal to seasonal 
 (S2S) services. A recent study (Keane et al.\, accepted) demonstrates a cl
 ear crossover in model skill at 5–7 days lead time: mid-latitudes favour
  short-term\, fine-scale forecasts\, while tropical regions exhibit higher
  skill at longer lead times and coarser spatial scales. This pattern holds
  for both traditional numerical models and machine learning systems (which
  surprised us)\, suggesting that it reflects fundamental atmospheric dynam
 ics rather than modelling artefacts.\nA companion study (Dunn-Sigouin et a
 l.\, accepted) shows that spatial aggregation improves forecast accuracy a
 nd extends usable lead time. This is especially true for daily rather than
  weekly accumulations. I will illustrate these findings using Storm Hans (
 2023)\, likely the most expensive weather-related disaster in Norwegian hi
 story\, to show how aggregation would have improved the usefulness of earl
 y warnings for extreme rainfall.\nTogether\, these papers point to a need 
 for region-specific forecast strategies. In tropical regions—especially 
 in Africa—this means investing both in improving short-term capabilities
  and in harnessing the relative strength of longer-range probabilistic for
 ecasts. Yet these efforts face growing headwinds. U.S. budget cuts have di
 srupted FEWS NET and threaten CHIRPS and key model data streams such as GF
 S and CFS\, on which many African meteorological services depend.\nIn this
  talk\, I will reflect on how these scientific and infrastructural challen
 ges intersect in practice\, as well as why ECMWF and European institutions
  may now be called upon to fill emerging global data gaps and support more
  equitable access to forecast information.\n\nhttps://events.ecmwf.int/eve
 nt/481/
LOCATION:Council Chamber
URL:https://events.ecmwf.int/event/481/
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