Report: Estimation of Extreme Precipitation Thresholds for the Issuance of Meteorological Notices in Peru

Luis Alfaro Lozano | Senamhi - Servicio Nacional De Meteorologia e hidrologia del Perú

** Original report is in Spanish **


  • Sets out to identify thresholds using climatological criteria to establish criterion for classifying the recurrence hazard of meteorological events
  • States that communicating around extreme precipitation events is one of the most important responsibilities of SENAMHI
  • States that the lower this probability OR the longer its return period, the less likely it is that the affected populations are less prepared to cope with their effect
  • Uses a practical and internationally recognized method, without knowing the probability distribution of a series of daily precipitation data, to establish a common criterion for determining the "rarity" of the amount of precipitation accumulated in 24 hours and thus determine extreme rainfall thresholds
  • Considers the following indices: IPCC extreme event definitions, ETCCDI (expert team on climate change detection and indices), and STARDEX (Statistical and Regional Dynamic Downscaling of Extremes for European Regions)
    • Uses these indices to establish and characterize extreme rains
    • Sets the criterion for "daily rain" (accumulated rainfall in 24 hours) at greater than 0.1mm (RR>0.1 mm), in order to take into account the behavior of precipitation in the Peruvian coast



  • States that this classification is not intended to provide rainfall intensity thresholds and their specific impacts with respect to specific economic activities
  • States that it is more a classification of "abundance" than of intensity aimed at helping us to have a common criterion when classifying the total accumulated in 24 hours, rather than evaluating the intensity of precipitation, although indirectly it does
  • States these values ​​can be referred to impacts when we have more elements of what they mean according to the issues to be addressed
  • States—regarding the use of the 75th percentile—that precipitation values below this threshold should be considered as usual