|OVF Hungarian Hydrological Forecasting Service|
About HHFS hydrological forecast
At certain gauges close to the spring or gauges on high altitudes water level rising usually occurs within a short time. Consequently, hydrological regime at these gauges is defined by the performance of the meteorological models, mainly precipitation forecast. Since uncertainties of both precipitation and hydrological forecasts can increase significantly with lead time, hydrological forecasts with several days lead time can contain higher uncertainties than the average uncertainties indicated by the error interval and thus they are rather intented to draw attention to the possibility of the predicted hydrological situation.
In order to highlight the uncertainties of precipitation forecasts, lead time of hydrological foreacasts is divided into two parts. The first part (marked with light grey color) presents shorter lead time hydrological forecasts caused by meteorological events occured in the past period. In the second part (marked with dark grey color) longer lead time hydrological forecasts are presented which mainly rely on meteorological forecasts, thus their accuracy strongly depends on the performance of the meterological forecast model. The proportion of the two parts basically depends on the concentration and propagation times at the given gauge.
For gauges situated in backwater reaches another significant error source can be the artificial water regime resulted from the unknown working program of power plants.
Observed and forecasted water level values might exceed alert levels or the HHW level, or they might decrease under the LLW level. In order to draw attention to these superventions these levels are marked with certain colours.
Alert levels indicated by the color of stations refeer to the actual water regime, therefore they can differ from enacted alert levels used during flood defence.