This web-based GIS application allows the dynamic overlay of current precipitation products for Iowa. Observations from automated stations can be overlayed with NEXRAD WSR-88D estimations.

Data Sources:

Currently, automated precipitation observations from the ASOS, AWOS and SchoolNet Networks are included in the application. NEXRAD estimations are generated by combining and gridding the 7 NEXRAD sites with Iowa coverage onto a 2km grid. The grids are updated every 15 minutes. Currently, I do not have an automated way to import the timestamps into the mapserver application. Hopefully, I can figure something out in the future.

The observations are updated a little after the top of the hour. For example, if you were looking at the image at :31 after, the 1 hour observed total would be valid for the previous hour. Updates usually occur at about :07 after.

Notes:

The NEXRAD Storm Total (STP) grid is somewhat problematic, since individual sites will reset the STP values at different times. For a wide spread rainfall event, the STP grid should be okay. As with any dataset, discretion should be used.

The projection of the NEXRAD image onto the mapserver application is not completely true. Care was taken to line up geographic locations, but spatial errors exist toward the edge of the image. These errors should not exceed 0.5 km, which is well within the uncertainty of NEXRAD grid itself.