IEM Daily Feature
Thursday, 30 September 2021

HRRR Postage Stamps

Posted: 30 Sep 2021 05:36 AM

The High Resolution Rapid Refresh (HRRR) weather forecast model is run by the NWS each hour and produces at least an eighteen hour forecast. Instead of looking at just a single deterministic forecast model run, weather forecasters like to look at ensembles of forecasts to provide probabilities and other statistical measures of forecast likelihood. Since the HRRR model is run every hour with at least hourly output available, one can create a time-lagged ensemble by stitching together the recent runs and looking at each run's forecast at a given valid time. The featured map does this stitching in "postage stamps" format with the top left box showing the actual RADAR mosaic presentation at 4 AM this morning and fifteen other boxes showing the most recent fifteen hourly runs of the HRRR model with that given run's forecast valid at 4 AM shown. While not explicitly forecast, the HRRR model produces a post-processed field that is meant to replicate a RADAR presentation. There's actually significant rainfall in the state this morning and each of the forecast runs shown some amount of storminess at this time. Consistency with the weather forecast over time from a given model provides forecasters with increased confidence that the forecast may be right! You can generate your own HRRR postage stamp plots for a location of your choice and historical date of your choice on this website! The plot takes a number of seconds to generate, so please be patient running the IEM Autoplot 221!

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Tags:   hrrr