There are many outlets that can deliver a forecast, and multiple factors that take place when formulating these. This leaves the general public with forecasts for different spans of time that could change regularly, some that measure a few days and others that measure a season. From discovering a 15 day forecast to questioning how the winter will be across the country; the use of forecasting models, previous climatology data or probability would take effect to generate an outlook for future weather conditions. The difference between a seasonal outlook and extended range forecasts will be discussed, while each sound similar — they are conveyed to the public differently.
An outlook appears like this and is directed from a government agency like NOAA:
Photo: Three Month Outlook for precipitation over the winter months in the United States. This image was generated on November 21, 2019. (Image courtesy of NOAA)
This map shows the probability of precipitation across the United States that gives an outlook into expected precipitation. A map depicting a seasonal outlook will be general in nature and not suggest a definitive forecast, since this amount of time that is forecasted covers a broad range which in this case is December to February. These outlooks consider global factors that can affect weather systems and their path towards the country. For example, ENSO or El Nino Southern Oscillation, will determine if sea surface temperatures over the Pacific Ocean are higher or lower than average. Phases of warmer than average or colder than average sea surface temperatures can have an effect on temperature, precipitation or dryness for a given region. In turn, this factors into a seasonal outlook.
An extended range forecast appears like this from a weather application from a website:
Photo: Current forecast provided by Wunderground for New York City, NY. (Image retrieved on December 1, 2019 from Wunderground.)
This depicts a local forecast for an extended period of time, but still within a term that is in closer range. For instance, extended forecasts are usually in the form of 7-day or 10-day forecasts, but in some cases up to 15-day. In the closest range of 1-3 days, we see the most accuracy and the further the forecast extends, the more vulnerable they are to changes. The amount of forecasting models that run a forecast extending up to 15 days are slim, and even though they exist, a forecast that is extending beyond 5 days could begin to lose confidence. These forecasts can change over the course of a few hours and are usually automatically generated based on the latest forecasting model runs.
Each of these forecasts depict a prediction of the future but in different spans of time. Seasonal outlooks will give a probability of a given variable, over a longer portion of time which will not provide a definitive forecast for your region. Over the course of time, you may expect a larger amount of precipitation than average for these months, but since this map extends over three months, you still have the chance of seeing normal days with less than average precipitation. Extended range forecasts do provide a look at an extended period of time, but within the course of one to two weeks, which is still in a relatively near-term. Each forecast can have future changes, and it’s best to ensure that you are looking at the most updated version of a forecast to be up to date with what is happening in your area.
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©2019 Meteorologist Jason Maska