anchor.diff:                  {
                       "meteoGroupStationId": "3002",
                       "meteoGroupStationName": "Baltasound",
  -                    "observedAt": "2017-03-04T00:00:00Z"
  +                    "observedAt": "2017-03-05T06:00:00Z"
  +                }
  +            ],
  +            "maxPrecipitationAmountInMillimeters": 2.1,
  +            "maxPrecipitationAmountObservations": [
  +                {
  +                    "meteoGroupStationId": "43081",
  +                    "meteoGroupStationName": "Baskervilles",
  +                    "observedAt": "2017-03-05T06:00:00Z"
                   }
               ]
             },
  
positive.code:    + the highest value of all reported `maxAirTemperatureInCelsius` within that period (`PT12H`)
   + for max wind speed calculation `PT0S` period is used
   + for max wind gusts speed calculation `PT1H` period is used
   
negative.code:                 {
                      "meteoGroupStationId": "3002",
                      "meteoGroupStationName": "Baltasound",
                      "observedAt": "2017-03-04T06:00:00Z"
                  }
              ],
              "maxPrecipitationAmountInMillimeters": 1.5,
              "maxPrecipitationAmountObservations": [
                  {
                      "meteoGroupStationId": "3002",
                      "meteoGroupStationName": "Baltasound",
                      "observedAt": "2017-03-04T06:00:00Z"
                  }
              ]
            },
  