River Forecasts Versus Hydrologic Outlooks

As the National Weather Service begins to issue deterministic river forecasts, we wish to remind residents of the region that the probabilistic outlooks issued on Friday April 3rd are still valid for the upcoming flood. Deterministic River Forecasts are issued for the next 7 days, are updated daily, and provide the best forecast to the public and flood fighters. The Probabilistic Outlooks are designed to show the greatest threat during the next few months. These outlooks are usually issued the last Thursday of each month, and are valid for the next 3 to 4 months. The exception is the Devils Lake Outlook, which is usually for the next 6 months.

As an example, the NWS 7 day, deterministic forecast calls for the Red River at Fargo is for a rise to between 38 and 40 feet sometime in mid April. While this is a specific forecast, there is still a 50 percent chance the Red River will rise to at least 41.7 feet during the next few weeks.

Click here for an article on the Science of River Forecast, written by Chauncy Schultz, meteorologist intern with the NWS in Grand Forks. It is an excellent example on how the technology has changed the past decade or so. A more in depth article, Probabilistic Outlooks V. Deterministic Forecasts is available (in PDF format) by clicking here.

Your NOAA's NWS is charged with the protection of life and property by the timely issuance of outlooks, watches and warnings. Residents of the Red River Valley are advised to pay close attention to radio, T.V. or your favorite source of weather information for the latest outlooks, watches and warnings.


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