Experimental User-Defined Forecasts

A new experimental feature has been added to our homepage, the User-Defined Area Forecast (UDAF).  It is accessible on the left-hand menu under the "Forecasts" subheader, or via the link below:


This new forecast feature leverages the gridded forecast database that we issue.  Traditionally, the forecasts are accessible on our home page by clicking on the map on the front page, or by entering a location in the "City, St" box in the top left corner of the screen.  In these scenarios, the forecast is basically from a 2.5 x 2.5 km grid box.  Some areas, such as larger cities, encompass a larger geographical area.  In the example below, entering "Springfield, IL" as the location returns the forecast for a grid box centered near the main post office, and does not include the entire city.  However, the user-defined forecast page allows you to select an area that encompasses all of Springfield and nearby areas:

Example of current grid size box:  Example of a user-defined grid size box:
Example of traditional "point-and-click" coverage area, when requesting Springfield as the forecast point Example of User-Defined Area Forecast selection box


The forecast is presented in a way that is similar to the traditional presentation, with the addition of a table beneath the forecast icons:

Example of output of User-Defined Area Forecast

This table shows the range of each observed forecast element. In uniform conditions, the ranges may be the same over the entire forecast area (for example, the daytime temperatures in the table below). The table includes observed temperatures, the Probability of Precipitation (PoP), the forecast amount of rain (QPF, which means "Quantitative Precipitation Forecast"), the sky cover (ranging from 0% to 100%), wind direction and speed, and the expected weather types.  The forecast area can be redefined after the forecast is displayed by adjusting the corners on the displayed map. It can also be defined to narrow the forecast area by elevation, although this is more designed for areas with more significant terrain than central and southeast Illinois.

Example of table in user-defined area forecast

The NWS is conducting a survey as to the usefulness of this product.  To participate, visit the following link:



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