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Precipitation Service Explained

ETI precipitation gauge at JHR in northwest Wyoming.

Synoptic’s Weather API Precipitation Service is a powerful and flexible tool, processing raw precipitation data from station networks and serving it in a uniform format through Weather API. Precipitation is reported from hundreds of networks with different reporting conventions and precipitation sensor types. For example, precipitation may be reported in 15 minute accumulations, hourly accumulations, accumulation since local midnight, or continuous accumulation over the calendar year or water year (precip_accum). Across our data providers, precipitation is reported in more than 20 different forms (see Station Variables that include precip).

The large variety of precipitation measurement types (i.e. precipitation variables) makes it challenging for users to compare precipitation amounts over geographic areas with stations reporting a variety of variable types. Finding precipitation totals for a defined time period and collection of stations requires tailoring the precipitation processing to each station’s specific variable type, and accounting for events such as station resets. Synoptic’s Precipitation Service eliminates these variable-specific complications for the user, providing access to derived precipitation data that can be easily integrated into downstream applications.

Real-time precipitation data is processed and stored in Synoptic’s derived precipitation database. We have dedicated years to developing robust QC methods to remove outlier data, such as physically implausible dips and spikes. Through the Precipitation Service, we enable flexible retrieval of both current and historical data over time periods and intervals defined by the user. The result is access to real-time, quality-controlled, and consistently formatted precipitation data reported by more than 60,000 stations, all from a single API retrieval endpoint.

Basic Precipitation

Basic derived precipitation is provided for single or multiple stations via the Time Series Service by adding precip=1 to the request. This will replace any raw precipitation variables with two derived variables, precip_intervals and precip_accumulated. precip_intervals represent precipitation received in the intervals between consecutive observations. precip_accumulated is the cumulative sum of the interval values for the requested time period. This essentially standardizes the returned precipitation data for any network and request period. Basic precipitation is also available in csv output for individual stations. Note that basic precipitation intervals and accumulations are only provided at the reporting frequency of the station. For custom user-defined time intervals and totals, the advanced precipitation features must be used.

Advanced Precipitation

Advanced derived precipitation is provided with the Precipitation Service (the /precip endpoint). Please see our pricing page for access options. This service allows for user-defined “modes” (pmode) including:

  • totals: accumulation totals over a defined period between start and end.

  • intervals: precipitation between start and end, reported in time intervals defined as integer hours (e.g. 1,3,6,…), hour, day, week, month or year.

  • last: precipitation intervals over defined periods prior to a specified end time (current or historic).

Requests can include multiple station networks over broad geographic regions and time periods, where all results are returned with uniform format. The Precipitation Service accepts the same station selection parameters available to other web services, such as state, county, network, radius and bbox. Example request patterns may include:

  • Daily precipitation for all precipitation-measuring stations in California for the 2020-21 water year.

  • 1-yr, 5-yr and 10-yr precipitation totals for all stations in the entire SNOTEL network.

  • Precipitation totals over the past hour for all RAWS stations in a radius from a defined lat/lon coordinate.

  • Precipitation totals for the 1,3,6,12,24,48 and 72-hr periods prior to the current request time, for any network or geographic area.

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