IEM Provided NCEP HRRR Forecated Simulated Reflectivity

Latest HRRR 1 Hour Forecast

Since 2003, the IEM has been providing GIS web services providing NEXRAD composite and single site products. A common feature request made is for forecasted reflectivity to be made as well. Thanks to some simulated reflectivity products from the NCEP HRRR Model, this is now possible.

Quick Overview

Tile Map Service (TMS)

You can call the TMS with either model initialization time explicit set or latest run processed by the IEM. For the explicit time set, the URL form looks like so:
The important parts here are hrrr::REFD-F0000-201707140100 which equates to HRRR model reflectivity for forecast minute 0000 (needs to be 4 characters) for model initialization on 14 July 2017 at 01 UTC. Whew, that's a mouthful! HRRR forecasts are available every 15 minutes between initialization and forecast hour 18. Again, this F**** value is in minutes, not hours!

You can also specify 0 as the model initialization time, of which the last run processed by the IEM will be picked. For example:

Web Map Service (WMS)

There is also a standard WMS located at:
The individual forecast hours have individual LAYERS defined like so refd_0000 where 0000 is the forecast time in minutes


  1. How soon is the latest run made available?
    At :40 minutes after the hour, a process starts that looks for the HRRR run initialized for the previous hour. This processing takes about 10 minutes, so at for example 01:50 UTC, the 00 UTC run should be available.
  2. What color index to reflectivity value scale is used for the RASTERS?
    These images should match the IEM N0Q Composites.
  3. What exact dataset is being shown here?
    This is the production NCEP HRRR "REFD" variable, "1000 m above ground" simulated RADAR reflectivity.
  4. Am I free to use this service for lucrative commercial interests?
    You betcha, but don't sue us and also send us feedback on how things can be improved for better usage.