Rapid Refresh (RAP) and High-Resolution Rapid Refresh (HRRR) Forum

News and Updates on RAP and HRRR

Posted By: Curtis Alexander
Date: 5-May-16 0357Z

Hello. Updates here on 2 topics: 1) Current plans for coincident NCEP implementation of HRRRv2 and RAPv3 are for this to be accomplished in late June 2016. HRRRv2 (and RAPv3) details are found in http://rapidrefresh.noaa.gov/hrrr/ These changes include significant improvements in the physical parameterizations, largely responsible for removal of a previous warm/dry bias in the warm season, and all-season overall radar and other data assimilation improvements. At NCEP, HRRRv2 will run out to 18h every hour, an extension from 15h for HRRRv1. And RAPv3 will run out to 21h every hour, an extension from 18h in RAPv2. 2) Further advanced versions of the experimental HRRRX and RAPX are now in real-time testing at ESRL/GSD and graphics are available from http://rapidrefresh.noaa.gov/RAP and http://rapidrefresh.noaa.gov/HRRR These include: a) Extension of HRRRX out to 36h running every 3h. At the other initial times not evenly divisible by 3, HRRRX will run to 18h. Example with 36h HRRRX for 18z init time is here: http://rapidrefresh.noaa.gov/HRRR/Welcome.cgi?dsKey=hrrr_jet&domain=full&run_time=03+May+2016+-+18Z b) HRRR(X) Time-Lagged Ensemble (HRRR-TLE, pronounced “hurtle”) products are in ongoing development for heavy rainfall, snowfall (now out of season), severe weather and aviation parameters with graphics available at http://rapidrefresh.noaa.gov/hrrrtle/ c) HRRRX-Alaska. A 3km HRRR is now run experimentally every 3h at 3km resolution covering all of Alaska except the westernmost Aleutians. Special display domains are available for Anchorange/Cook Inlet, Juneau, and Fairbanks with graphics available at http://rapidrefresh.noaa.gov/alaska/ d) HRRR Ensemble. A test version of a formal HRRR ensemble, with initial condition perturbations and 3-km EnKF data assimilation, is running until mid June. The hourly data assimilation utilizes 20-40 3km HRRR members. Ensemble forecasts of 3-18 members out to 0600 UTC are initialized at 0000, 0300, 1200, 1500, and 1800 UTC. The initial HRRR Ensemble (HRRRE) runs over a sub-CONUS domain affordable with current computer resources. Graphics are available at http://rapidrefresh.noaa.gov/HRRRE/ Some version of all of these HRRR extensions have been discussed between ESRL and NCEP, but there are no specific plans yet on possible implementations or final configurations. Comments are welcome on the a, b, c, and d extensions. Stan Benjamin, Curtis Alexander, David Dowell, Trevor Alcott and many others in GSD Earth Modeling Branch.

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