Hourly/6-hourly Precipitation Analysis at NCEP/EMC

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Since 28 July 2020, Stage II has been discontinued and Stage IV output has been changed from GRIB1 to GRIB2 in format.

Additional information

(1) Background Information

Stage IV: Mosaicked from the regional multi-sensor analyses generated by the RFCs
Mosaicked into a national product at NCEP, from the regional hourly/6-hourly multi-sensor (radar+gauges) precipitation analyses produced by the 12 River Forecast Centers (RFCs) over CONUS. Some manual QC done at the RFCs. Mosaic done at NCEP within an hour of receiving any new hourly/6-hourly data from one or more RFC.

Precipitation RTMA

Precipitation URMA

Questions and Answers


(2) Dataset

The official NCO data (past 14 days): http://nomads.ncep.noaa.gov/pub/data/nccf/com/pcpanl/prod/pcpanl.yyyymmdd/
The NCAR archive: "https://data.eol.ucar.edu/dataset/21.087
The developer's backup data: "https://ftp.emc.ncep.noaa.gov/mmb/sref/st2n4.arch "https://ftp.emc.ncep.noaa.gov/mmb/sref/st4.dailyplot
The RFC files: "https://www.emc.ncep.noaa.gov/mmb/SREF/pcpanl/stage4/st3log/overview/yyyy/yyyymm/st3log.yyyymmdd

Other archive locations

(3) Images

(4) Precipitation Verification

(5) Contact

Jun.Du@noaa.gov (NCEP SREF)

Parallel testing (if any)

List of Upgrades

28 July 2020, pcpanl.v4.0.1/RTMA-URMA v2.8.2
Update presentation:
Additional information: https://www.emc.ncep.noaa.gov/users/verification/precip/rtma-urma.v2.8/
Latest update to implementation schedule: https://www.emc.ncep.noaa.gov/users/meg/rtma_urma_v2p8/

4 Dec 2018, pcpanl.v.3.1.0/URMA v2.7.1
Filling offshore data gaps in ConUS PCPURMA with 1) gauge QC'd MRMS 2) CMORPH.

Notes on this upgrade: https://docs.google.com/presentation/d/1IU2IXCvitN1zQ8joE20prr8z2MrucVdpe6uNKsCWtpg/edit?usp=sharing

Unofficial parallel runs starting 28 Nov 2017:
Parallel validations
The EMC URMA v2.7.0 parallel ftp page for non-precip fields, with links to the pcpurma: ftp://ftp.emc.ncep.noaa.gov/mmb/rtma/v2.7.0/urma/para/

13 Dec 2017, pcpanl.v.3.0.0, affecting: Stage IV/PCPURMA (RTMA/URMA v2.6)
Hourly URMA for ConUS and Puerto Rico (requirement from MDL/NBM)

Additional notes about this change

Official parallel output on para.nomads.ncep.noaa.gov:

Unofficial parallel runs, 26 Mar - 28 Nov 2017: ftp://ftp.emc.ncep.noaa.gov/mmb/precip/pcpanl.v3.0.0/

Missing MRMS logs (incomplete):

2 May 2017 (Stage IV/URMA) [pcpanl.v2.3.0, rtma/urma v2.5]

Official 30-day evaluation started at 18Z 16 Feb 2017.
Unofficial parallel runs: ftp://ftp.emc.ncep.noaa.gov/mmb/precip/pcpanl.v2.3.0/
Official NCO parallel output: http://para.nomads.ncep.noaa.gov/pub/data/nccf/com/pcpanl/para/
NWS Service Change Notice (SCN) for this change
Additional notes about this change

1 Mar 2016 (Stage IV/URMA)

    Stage IV mosaicking:
  1. Revised RFC domains map: filled in isolated “missing” pixels at RFC boundaries
  2. Source of 6-hourly Stage IV: if hourly QPE from a central/eastern RFC is missing, then the corresponding 6-hourly QPE for that RFC is used as the source of 6-hourly Stage IV
Additional notes about this change

6 Jan 2016 (Stage II/IV, RTMA/URMA)

  1. Stage IV mosaicking:
    • For grid points inside of an RFC's domain, if input from that RFC is late or missing, we will no longer use neighboring RFCs' data to fill in.
    • Areas outside of the RFC domains (except for Gulf of Mexico and the Atlantic) are set as no data/missing
    • Areas in the Gulf of Mexico and off the Atlantic Coast are filled in with data from the RFCs, as before
    • WGRFC domain expanded to part of Mexico
    • Coverage for the Great Lakes will come from specific RFCs assigned to the Lakes (currently it is the average of coverage from all neighboring RFCs)
    • For hourly Stage IV, CNRFC input is excluded (as is NWRFC, which does not provide hourly input)
  2. Stage II: gross error check of gauges (reports tossed above limit) increased from 1"/hr to 5"/hr
  3. Precipitation RTMA: Stage IV hourly is used as primary input for RTMA, supplemented by Stage II hourly

New RFC domain mask

Additional notes/examples about this upgrade

Parallel run output:
NCO parallel runs, 30 Oct 2015 -

14 Apr 2015 (Stage IV/URMA)
  1. Sources of 6-hourly mosaic QPE for Stage IV/URMA: currently the 6-hourly Stage IV is a mosaic of the 6-hourly QPEs from the 12 ConUS RFCs (the “quilt” approach). For this release, we adopted a “laminate-and-quilt” approach, i.e. based on each individual RFC’s practice of producing either hourly or 6-hourly as its base/primary analysis, we first produce 6-hourly totals from the eight Eastern/Central RFCs’ hourly QPEs, then combine these 6-hourly totals with the four Western RFCs’ (NWRFC, CNRFC, CBRFC, MBRFC) 6-hourly QPEs to arrive a 6-hourly ConUS QPE.
  2. Hourly Stage IV is re-made hourly (if there are new input) after valid time for the next 23 hours, then again at 1/3/5/7 days after valid time. The 6-hourly Stage IV/URMA is re-made hourly (if there are new input) for 42 hours after valid time; the four 6-hourlies covering a 12Z-12Z 24h period are also re-made on a fixed schedule (regardless of input) at 1/3/5/7 days after the ending 12Z (i.e. at the 12:33Z run); at which time the corresponding 24h totals are also re-made. The current day's 24h totals are made at 15:33/21:33/23:33Z run cycles.