Basin Streamflow Forecast

Mitigate flooding risks and effectively manage your hydro facility with high-resolution, regularly updated forecasts projecting 7 days into the future.​​​​​


  • Site-specific meteorological observations

  • Site-specific streamflow observations

  • Third party off-site observations (temperature, precipitation, streamflow, snow depth)

Forecast Components

  • Hosted, client-specific forecast website
  • Local and regional weather and streamflow observations and forecasts
  • Custom data files (XLS, CSV, XML, etc.)
  • Observed snow conditions
  • Monthly forecast verification report (PDF document)
  • 4 daily forecast updates switching to hourly updates during flood conditions*
  • Forecast of hourly flows for up to 168 hours

Methods and Technology

  • Customized numerical weather prediction (NWP) model
  • High resolution, customized hydrology model
  • Deterministic forecasts with uncertainty estimates

Product Highlights

  • Delivery method: Fast, reliable, and user-friendly forecasts are hosted on a secure, client-specific website and include graphics, tables, and data files of current weather, snowpack and streamflow conditions, and weather and streamflow forecasts.
  • Running verification: Vaisala will show our forecast against actual meteorological and hydrological conditions for the previous 31 days and deliver verification reports at the end of each month.
  • Superior customer service: Vaisala's hydro scientists and customer support staff have years of experience in operational hydro forecasting and are dedicated to providing the best and most customized customer experience available.

More On Our Methodology

Vaisala uses physically-based, fully-distributed modeling techniques to produce the Short-Range forecast.

The meteorological weather inputs to the forecast are created by using a mesoscale atmospheric NWP (Numerical Weather Prediction) model to downscale global meteorological forecasts from the NOAA National Centers for Environmental Prediction (NCEP) Global Forecast System (GFS). Forecasts based on the European Center for Medium Range Weather Forecasting (ECMWF) can also be made available.

Vaisala's hydrologic model simulates the land surface water balance (including snowpack and soil moisture) and translates the weather forecast inputs into streamflow forecast outputs. The hydrology model is calibrated to hourly or sub-daily streamflow values and typically uses meteorological information from publically available sources, and optional data provided by the client, to help estimate the watershed conditions at the time of the forecast.

Customer Requirements

Client inputs are desirable, but not required. While local weather data and streamflow data at your location will greatly improve the forecast quality, if customer-sourced observations are not available, Vaisala will attempt to locate publically available data to meet the forecast needs.

* Hydrologic forecasts are accompanied by precipitation, temperature, wind, and radiation forecasts at multiple locations in and around your watershed.

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Key Benefits

Flood prevention
Our customized weather and streamflow prediction models, coupled with a rapid, reliable, web-based forecast delivery system, provide enough advanced warning to manage flood events by allowing time for reservoir drawdown via power generation rather than spill.
Improve daily water management, baseload projections, and maintenance planning
By supplying the necessary information to optimize water and energy planning, the Basin Streamflow forecast allows users to avoid costly and dangerous spills as well as prevent dry-season shortfalls. For run-of-the-river hydropower operations, the forecast also provides forewarning of shifts in streamflow that may disrupt generation, allowing operators time to bring alternative energy sources online.
Accurate, up-to-date, customized forecasts for the best decision support
The Basin Streamflow forecast projects seven days into the future and updates four times daily, increasing to hourly updates during flooding events. This forecast is delivered by Vaisala 3TIER Services and uses proven, mesoscale atmospheric modeling techniques customized for your watershed and a high-resolution, distributed hydrologic model that simulates the land-surface water balance to determine streamflow.​