The IEM produces a number of RASTER images meant for GIS use. These RASTERs are typically provided on the IEM website as 8 bit PNG images. This means there are 256 slots available for a binned value to be placed. This page attempts to document these RASTER images and provide the lookup table of PNG index to an actual value. Click on the item in the "Label" column to get the lookup table below.

LabelDescriptionUnits
composite_eetThis is a composite of 8bit Echo Tops (EET)kft
composite_n0qThis is a composite of 8bit Reflectivity (N0Q)dBZ
composite_n0rThis is a composite of Reflectivity (N0R)dBZ
mrms_a2mNCEP MRMS 2 minute interval precipitation accumulation.mm
mrms_lcrefNCEP MRMS 2 minute lowest elevation composite reflectivity.dBZ
mrms_p1hNCEP MRMS 1 Hour Accumulated Precipitation.mm
mrms_p24hNCEP MRMS 24 Hour Accumulated Precipitation.mm
mrms_p48hNCEP MRMS 48 Hour Accumulated Precipitationmm
mrms_p72hNCEP MRMS 72 Hour Accumulated Precipitation.mm

Programatic Access to this RASTER source

The IEM generated RASTERs are stored in a programatic way that should allow for easy scripted download of the archive. This section documents the URL format template used with the time shown in UTC. The string format modifiers below are pythonic strftime values.

https://mesonet.agron.iastate.edu/archive/data/%Y/%m/%d/GIS/uscomp/n0r_%Y%m%d%H%M.png

A general web service also exists to convert these RASTERs to netCDF "on-the-fly". The URL format is like so:

https://mesonet.agron.iastate.edu/cgi-bin/request/raster2netcdf.py?dstr=%Y%m%d%H%M&prod=composite_n0r

Try the netCDF Conversion!

Lookup Table for composite_n0r

Would it help you to have the information below in a different format? Please contact us if so!
Color IndexValue (dBZ)RedGreen BlueHEX
0Missing000#000000
1-30000#000000
2-25000#000000
3-20000#000000
4-15000#000000
5-10000#000000
6-5000#000000
700236236#00ecec
851160246#01a0f6
91000246#0000f6
101502550#00ff00
112002000#00c800
122501440#009000
13302552550#ffff00
14352311920#e7c000
15402551440#ff9000
164525500#ff0000
175021400#d60000
185519200#c00000
19602550255#ff00ff
206515385201#9955c9
2170255255255#ffffff