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Wind Gust Aggregations from Timeline API

Jason Cook

May 09, 2022 18:23

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Hello,

Is there documentation on how wind gust is aggregated over time periods and weather stations? Is it safe to assume that the 'windgust' column reported is the maximum value for the time period and the maximum value of each weather stations used?

Sample Return:

• ['days'][0]['windgust'] = 34.4 mph
• 7 weather stations returned
• 6 weather stations have a quality = 100 (1 station quality = 0)
• 'useCount' is 0 for all stations

Sample Request:

https://weather.visualcrossing.com/VisualCrossingWebServices/rest/services/timeline/Jacksonville%2C%20Florida/2022-04-26/2022-04-26?unitGroup=us&elements=windgust%2Cwindspeed%2Cwindspeedmax%2Cwindspeedmean%2Cstations%2Csource&include=days%2Cevents%2Calerts&key={key}&contentType=json

Does the 34.4mph represent an overall max or an interpolation?

 

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5 comments

• 
  Support Agent May 09, 2022 21:22 Official comment

  Thank you for your question. 34.4 mph represents the maximum of the hourly values for the wind gust. The hourly values are interpolated from the surrounding stations. Using the query builder (https://www.visualcrossing.com/weather/weather-data-services), we can see there are 6 official stations nearby:

  

  In this case, the distance to each is fairly similar and so all will have an impact on the interpolated value. We do weight the distance by the square of the distance so the closer stations have significantly higher weighting. 

  If you are interested in modifying which station is used, you can either use the station ID directly (such as "stn:KJAX" for the location). Or you can reduce the maximum distance and maximum count of stations considered using the maximum distance and maximum station count fields (see https://www.visualcrossing.com/resources/documentation/weather-api/timeline-weather-api/)

  Regards

  Visual Crossing Support

   

• 0
  
  Jason Cook May 10, 2022 13:04

  Thank you for the response and great explanation. The maximum of hourly values that are used in the calculation reflect the maximum wind gust during the hour?
  
  The end goal is to obtain the maximum wind gust near a specific location on a given day. If the max value during an hour is used, limiting the max station count to 1 should achieve this.

   

  -Thank you, Jason

• 0
  
  Support Agent May 11, 2022 20:39

  Hi Jason -

  this is absolutely correct.

  You find additional definitions of the measures under https://www.visualcrossing.com/resources/documentation/weather-data/what-forecast-weather-measures-are-available/

  Best regards

  Visual Crossing Team

• 0
  
  Jason Cook May 17, 2022 14:12

  Thank you again for the comment. Can you suggest the API and parameters that are needed to get the maximum wind gust at a location given my attempts below? As a baseline I used the history API at a 2 minute aggregate assuming this has to contain the maximum wind gust for a day.

   

  The history API at with a 2 minute aggregate and the top 2 values shown yields the top value at 21.9 mph.

  
  https://weather.visualcrossing.com/VisualCrossingWebServices/rest/services/weatherdata/history?startDateTime=2022-04-26T00%3A00%3A00&endDateTime=2022-04-27T00%3A00%3A00&location=Jacksonville%2C+Florida&key={key}&unitGroup=us&contentType=json&maxStations=1&collectStationContribution=True&aggregateMinutes=2
                    datetimeStr  windgust
  2022-04-26T17:40:00-04:00      21.9
  2022-04-26T15:26:00-04:00      20.8
  
  The history API at hourly and daily aggregates produces only null values.
  
  

  https://weather.visualcrossing.com/VisualCrossingWebServices/rest/services/weatherdata/history?startDateTime=2022-04-26T00%3A00%3A00&endDateTime=2022-04-27T00%3A00%3A00&location=Jacksonville%2C+Florida&key={key}&unitGroup=us&contentType=json&maxStations=1&collectStationContribution=True&aggregateHours=24
  [
      {'datetimeStr': '2022-04-26T00:00:00-04:00', 'wgust': None}, 
      {'datetimeStr': '2022-04-27T00:00:00-04:00', 'wgust': None}
  ]

  
  https://weather.visualcrossing.com/VisualCrossingWebServices/rest/services/weatherdata/history?startDateTime=2022-04-26T00%3A00%3A00&endDateTime=2022-04-27T00%3A00%3A00&location=Jacksonville%2C+Florida&key={key}&unitGroup=us&contentType=json&maxStations=1&collectStationContribution=True&aggregateHours=1
  [
      {'datetimeStr': '2022-04-26T00:00:00-04:00', 'wgust': None},
      {'datetimeStr': '2022-04-26T01:00:00-04:00', 'wgust': None},
      ...
      {'datetimeStr': '2022-04-26T23:00:00-04:00', 'wgust': None},
      {'datetimeStr': '2022-04-27T00:00:00-04:00', 'wgust': None}
  ]

   

  The timeline API yields a windgust value of 15.9 mph, which is 5 mph less than the maximum value from the history API at a 2 minute aggreate.

  https://weather.visualcrossing.com/VisualCrossingWebServices/rest/services/timeline/Jacksonville%2C%20Florida/2022-04-26?unitGroup=us&elements=windgust&include=days&key={key}&maxStations=1&contentType=json
  [{'windgust': 15.9}]
  
  

   

  Thank you again,

  Jason

• 0
  
  Support Agent May 18, 2022 13:38

  Thank you for your question. When you use the  aggregateMinutes=2 parameter, your request will become a 'subhourly' query. Subhourly queries will add additional weather stations to the result (see https://www.visualcrossing.com/resources/documentation/weather-api/requesting-sub-hourly-weather-data-using-the-weather-api/).

  The stations used in sub-hourly include personal weather stations and other local weather stations the provide more localized, and often more frequent, observations. However these stations are not officially recognized stations and so may not conform to the recommendations for weather station configuration. The history and timeline hourly results only includes data for official weather stations and remote data sources such as radar and satellite data. 

  The '21.9mph' result gust will be measurement from a sub-hourly station. 

  The null value for the wind gust in hourly history indicates that no nearby official weather station exceeded the wing gust criteria. A wind gust requires the measured short term wind speed to be significantly more than mean wind speed. Typically, the wind speed should be 10 knots more (11mph or 18kph). When the wind gust does not meet these criteria, a null/empty value is returned (see https://www.visualcrossing.com/resources/documentation/weather-data/weather-data-documentation/)

  The timeline API matches the history API 'null' if you request only data from weather stations, not remote sources such as satellite using the 'obs' include parameter:

  https://weather.visualcrossing.com/VisualCrossingWebServices/rest/services/timeline/Jacksonville%2C%20Florida/2022-04-26?unitGroup=us&key=YOUR_API_KEY&contentType=json&include=days%2Cobs&elements=windgust&maxStations=1

  Regards

  Visual Crossing Support