768
NOUS41 KWBC 151345 AAF
PNSWSH
SERVICE CHANGE NOTICE 26-48 UPDATED
NATIONAL WEATHER SERVICE HEADQUARTERS SILVER SPRING MD
945 AM EDT THU OCT 15 2026
TO: SUBSCRIBERS:
-NOAA WEATHER WIRE SERVICE
-EMERGENCY MANAGERS WEATHER INFORMATION NETWORK
-NOAAPORT
OTHER NWS PARTNERS, USERS AND EMPLOYEES
FROM: DAVID MICHAUD, DIRECTOR
NWS CENTRAL OPERATIONS
SUBJECT: UPDATED: IMPLEMENTATION OF THE RAPID REFRESH FORECAST
SYSTEM (RRFS) AND RRFS ENSEMBLE FORECAST SYSTEM (REFS):
EFFECTIVE NOVEMBER 3, 2026
UPDATED TO REFLECT CHANGES TO INSTANTANEOUS PRECIPITATION TYPE
POST PROCESSING AND PRODUCT DISTRIBUTION.
THE RRFS AND REFS WILL REPLACE NAM, HREF, SREF, AND HIRESW. A
FULL LIST OF PRODUCTS BEING RETIRED IS AVAILABLE IN SCN 26-47.
THE RRFS AND REFS PRODUCTION IMPLEMENTATION AND THE RETIREMENT
OF THE LEGACY MODELS WILL OCCUR ON THE SAME DAY. IN THE EVENT
THAT THE IMPLEMENTATION DATE IS DECLARED A CRITICAL WEATHER DAY
(CWD), AN ENHANCED CAUTION EVENT, OR OTHER SIGNIFICANT WEATHER
IS OCCURRING OR IS ANTICIPATED TO OCCUR, IMPLEMENTATION OF THIS
CHANGE WILL TAKE PLACE AT 1200 UTC ON THE NEXT WEEKDAY NOT
DECLARED A CWD AND WHEN NO SIGNIFICANT WEATHER IS OCCURRING.
A REAL-TIME PARALLEL FEED OF RRFS AND REFS HAS BEEN AVAILABLE
SINCE AUGUST 12, 2026, ON NOMADS FOR BOTH NCEP WEB SERVICES AND
NOAAPORT OUTPUT HERE:
PRE-IMPLEMENTATION DATA LOCATION STARTING AUGUST 12, 2026:
HTTPS://NOMADS.NCEP.NOAA.GOV/PUB/DATA/NCCF/COM/RRFS/PARA/
HTTPS://NOMADS.NCEP.NOAA.GOV/PUB/DATA/NCCF/COM/REFS/PARA/
HTTPS://NOMADS.NCEP.NOAA.GOV/PUB/DATA/NCCF/COM/PARA/NOAAPORT/RRF
S/
HTTPS://NOMADS.NCEP.NOAA.GOV/PUB/DATA/NCCF/COM/PARA/NOAAPORT/REF
S/
POST-IMPLEMENTATION DATA LOCATION NOVEMBER 3, 2026:
HTTPS://NOMADS.NCEP.NOAA.GOV/PUB/DATA/NCCF/COM/RRFS/PROD/
HTTPS://NOMADS.NCEP.NOAA.GOV/PUB/DATA/NCCF/COM/REFS/PROD/
NEW CHANGES AS OF OCT 15, 2026
UPDATED TO REFLECT ADJUSTMENTS TO POST-PROCESSING AND PRODUCT
AVAILABILITY WITHIN RRFS AND REFS, PRIMARILY REPLACING A MODEL-
GENERATED, MICROPHYSICS-BASED INSTANTANEOUS PRECIPITATION TYPE
PRODUCT WITH A DIAGNOSED THERMODYNAMIC-BASED PRECIPITATION TYPE
CALCULATION, AND ALSO REMOVING ACCUMULATIONS OF FREEZING RAIN
AND FROZEN RAIN (SLEET) AS OUTPUT PRODUCTS. THESE CHANGES ARE
IN RESPONSE TO AN OVER-FORECASTING OF FREEZING RAIN AND UNDER-
FORECASTING OF SLEET WITHIN RRFS/REFS.
1) RRFS AND REFS ENSEMBLE MEMBER PRODUCT UPDATES:
- REMOVED FREEZING RAIN (FRZR) AND FROZEN RAIN (FROZR)
ACCUMULATION FIELDS FROM NOMADS OUTPUT FILES:
RRFS.TCCZ.2DFLD.{RESKM}.FFFF.{DOM}.GRIB2
RRFS.TCCZ.2DFLD.{RESKM}.SUBH.FFFF.{DOM}.GRIB2
RRFS.TCCZ.13KM.FFFF.NA.GRIB2
RRFS.TCCZ.M00?.2DFLDNOMADS.{RESKM}.FFFF.{DOM}.GRIB2
- MODIFIED COMPONENT FIELDS OF INSTANTANEOUS PRECIPITATION TYPE
(CSNOW, CICEP, CFRZR, CRAIN) ACROSS ABOVE LISTED PRIMARY 2D
NOMADS FILES.
2) REFS ENSEMBLE PRODUCT UPDATES:
- REMOVED FREEZING RAIN ACCUMULATION (FRZR) PROBABILITIES FROM:
REFS.TCCZ.PROB.FFF.${DOM}.GRIB2
- REMOVED DUPLICATE SURFACE HEIGHT RECORD (HGT:SFC) FROM:
REFS.TCCZ.SPRD.FFF.${DOM}.GRIB2
- MODIFIED COMPOSITE REFLECTIVITY (REFC) AND 1 KM RADAR
REFLECTIVITY (REFD) CALCULATIONS IN PROBABILITY-MATCHED MEAN
(PMMN) PRODUCTS TO IGNORE NEGATIVE REFLECTIVITY VALUES,
ELIMINATING ARTIFACTS IN NEGATIVE REFLECTIVITY RANGES:
REFS.TCCZ.PMMN.FFF.${DOM}.GRIB2
WHERE {DOM} IS THE DOMAIN, {RESKM} IS THE RESOLUTION IN KM
3) ADDITION OF FIREWX DOMAIN LOCATION FILE TO NOMADS:
UNDER RRFS/V1.0
FIREWX.YYYYMMDD/CC/INPUT/RRFS.TCCZ.FIREWXNEST_CENTER_LATLON
PREVIOUSLY ISSUED SUMMARY:
THE DEVELOPMENT OF THE RRFS AND REFS WAS A COORDINATED EFFORT
BETWEEN THE OFFICE OF MODELING AND DEVELOPMENT AND NOAA'S OFFICE
OF OCEANIC AND ATMOSPHERIC RESEARCH (OAR), SPECIFICALLY THE
GLOBAL SYSTEMS LABORATORY, AND A WIDE-RANGING NETWORK OF
PARTNERS. THIS COLLABORATION INCLUDED OTHER NWS ENTITIES,
ACADEMIC INSTITUTIONS, OTHER FEDERAL AGENCIES, AND INTERNATIONAL
PARTNERS.
1) RRFS MODELING SYSTEM
THIS TRANSITION TO RRFS WILL PROVIDE AN HOURLY UPDATED MODELING
SYSTEM COVERING THE NORTH AMERICA REGION AT 3 KM HORIZONTAL GRID
SPACING, WHICH, COMBINED WITH THE ASSOCIATED MODEL RETIREMENTS,
WILL GREATLY UNIFY AND SIMPLIFY THE "CONVECTIVE SCALE"
(APPROXIMATELY 3 KM GRID SPACING) SUITE OF REGIONAL MODELS
WITHIN THE NWS OPERATIONAL MODELING SUITE.
AS A DETERMINISTIC SYSTEM RUNNING TO 84 H FOR THE 00/06/12/18
UTC CYCLES, AND TO 18 H FOR OTHER HOURLY CYCLES, THE RRFS WILL
FULLY RETIRE THE NORTH AMERICAN MESOSCALE (NAM), AND RETIRE THE
HIGH-RESOLUTION WINDOW (HIRESW) ASIDE FROM THE GUAM DOMAIN WHICH
WILL REMAIN. AS AN ENSEMBLE FORECAST SYSTEM RUNNING TO 60 H FOR
THE 00/06/12/18 UTC CYCLES, THE RRFS ENSEMBLE FORECAST SYSTEM
(REFS) WILL FULLY RETIRE THE HIGH-RESOLUTION ENSEMBLE FORECAST
(HREF) SYSTEM.
A) DETERMINISTIC FORECAST DETAILS
THE DETERMINISTIC RRFS RUNS OVER A FULL NORTH AMERICA (NA)
DOMAIN AT 3 KM GRID SPACING, AND PROVIDES SUBSET GRID OUTPUT AT
3 KM GRID SPACING FOR THE CONTIGUOUS UNITED STATES (CONUS) AND
ALASKA (AK), AND AT 2.5 KM GRID SPACING FOR HAWAII (HI) AND
PUERTO RICO (PR). IT ALSO PROVIDES NORTH AMERICA OUTPUT AT 13
KM GRID SPACING. THE RRFS ALSO PROVIDES OUTPUT FROM A SEPARATE
RELOCATABLE 1.5 KM RRFS FIRE WEATHER RUN, WITH OUTPUT PROVIDED
OVER A 5 X 5-DEGREE ROTATED LATITUDE LONGITUDE REGION.
DETERMINISTIC RRFS OUTPUT IS ORGANIZED AS FOLLOWS:
UNDER RRFS/V1.0
RRFS.YYYYMMDD/CC/RRFS.TCCZ.PRSLEV.3KM.FFFF.{CONUS|AK}.{GRIB2,GRI
B2.IDX}
RRFS.YYYYMMDD/CC/RRFS.TCCZ.PRSLEV.2P5KM.FFFF.{HI|PR}.{GRIB2,GRIB
2.IDX}
RRFS.YYYYMMDD/CC/RRFS.TCCZ.PRSLEV.13KM.FFFF.NA.{GRIB2,GRIB2.IDX}
RRFS.YYYYMMDD/CC/RRFS.TCCZ.2DFLD.3KM.FFFF.{CONUS|AK}.{GRIB2,GRIB
2.IDX}
RRFS.YYYYMMDD/CC/RRFS.TCCZ.2DFLD.2P5KM.FFFF.{HI|PR}.{GRIB2,GRIB2
.IDX}
RRFS.YYYYMMDD/CC/RRFS.TCCZ.2DFLD.3KM.SUBH.FFFF.{CONUS|AK}.{GRIB2
,GRIB2.IDX}
RRFS.YYYYMMDD/CC/RRFS.TCCZ.2DFLD.2P5KM.SUBH.FFFF.{HI|PR}.{GRIB2,
GRIB2.IDX}
RRFS.YYYYMMDD/CC/RRFS.TCCZ.2DFLD.13KM.FFFF.NA.{GRIB2,GRIB2.IDX}
RRFS.YYYYMMDD/CC/RRFS.TCCZ.2DFLD_AWIPSUBSET.3KM.FFFF.NA.{GRIB2,G
RIB2.IDX}
FIREWX.YYYYMMDD/CC/RRFS.TCCZ.PRSLEV.1P5KM.FFFF.FIREWX_LCC.{GRIB2
,GRIB2.IDX}
FIREWX.YYYYMMDD/CC/RRFS.TCCZ.2DFLD.1P5KM.FFFF.FIREWX_LCC.{GRIB2,
GRIB2.IDX}
RRFS.YYYYMMDD/CC/BUFRSND.TCCZ/BUFR.*.YYYYMMDDCC
RRFS.YYYYMMDD/CC/RRFS.TCCZ.CLASS1.BUFR
A FULL DESCRIPTION OF RRFS PRODUCTS INCLUDING VARIABLES AND
ENCODING IS AVAILABLE AT:
HTTPS://WWW.NCO.NCEP.NOAA.GOV/PMB/PRODUCTS/RRFS/
B) ENSEMBLE FORECAST DETAILS
THE RRFS PRODUCES FIVE ENSEMBLE FORECAST MEMBERS RUNNING TO 60 H
FOR THE 00/06/12/18 UTC CYCLES, OVER THE SAME NA REGION AS THE
DETERMINISTIC RRFS. THESE MEMBERS UTILIZE DIFFERENT INITIAL
CONDITIONS, LATERAL BOUNDARY CONDITIONS, AND MODEL PHYSICS
RELATIVE TO THE DETERMINISTIC FORECAST TO BETTER COVER THE RANGE
OF FORECAST POSSIBILITIES.
ENSEMBLE RRFS OUTPUT IS ORGANIZED AS FOLLOWS:
UNDER RRFS/V1.0
RRFSENS.YYYYMMDD/CC/M00#/RRFS.TCCZ.M00#.PRSLEVNOMADS.3KM.FFFF.{C
ONUS|AK}.{GRIB2,GRIB2.IDX}
RRFSENS.YYYYMMDD/CC/M00#/RRFS.TCCZ.M00#.2DFLDNOMADS.3KM.FFFF.{CO
NUS|AK}.{GRIB2,GRIB2.IDX}
RRFSENS.YYYYMMDD/CC/M00#/RRFS.TCCZ.M00#.PRSLEVNOMADS.2P5KM.FFFF.
{HI|PR}.{GRIB2,GRIB2.IDX}
RRFSENS.YYYYMMDD/CC/M00#/RRFS.TCCZ.M00#.2DFLDNOMADS.2P5KM.FFFF.{
HI|PR}.{GRIB2,GRIB2.IDX}
2) REFS MODELING SYSTEM
THE REFS IS AN ENSEMBLE PRODUCT GENERATION SYSTEM THAT COMBINES
THE FORECAST OUTPUT FROM THE CURRENT AND 6 H OLD CYCLES OF RRFS
DETERMINISTIC (SECTION 1A) AND ENSEMBLE (SECTION 1B) SYSTEMS TO
GENERATE ENSEMBLE PRODUCTS. FOR THE ALASKA AND CONUS REFS
DOMAINS, THE HRRR PROVIDES TWO ADDITIONAL MEMBERS (FROM CURRENT
AND 6 H OLD CYCLES).
THE REFS IS A REPLACEMENT FOR THE HIGH-RESOLUTION ENSEMBLE
FORECAST (HREF) SYSTEM, AND SHARES SIMILARITIES WITH THE HREF IN
TERMS OF PRODUCT TYPES. REFS DOES DIFFER FROM HREF IN TERMS OF
MEMBERSHIP, AND PRODUCES PRODUCTS TO 60 H, WHILE HREF GENERATES
PRODUCTS TO 48 H. ALSO, REFS GENERATES PRODUCTS FOR ALL DOMAINS
(CONUS, AK, HI, PR) FOR THE 00/06/12/18 UTC CYCLES, WHILE HREF
GENERATES PRODUCTS TWICE DAILY FOR NON-CONUS DOMAINS (AK AND PR
DOMAINS AT 06Z/18Z, AND HI AT 00Z/12Z).
REFS ENSEMBLE PRODUCT OUTPUT IS ORGANIZED AS FOLLOWS UNDER
REFS/V1.0:
REFS.YYYYMMDD/CC/ENSPROD/REFS.TCCZ.${TYPE}.FFF.${DOM}.{GRIB2,GRI
B2.IDX}
WHERE DOM IS THE DOMAIN (CONUS, AK, HI, PR)
AND WHERE TYPE IS THE PRODUCT TYPE LISTED AND DESCRIBED BELOW
MEAN: SIMPLE ENSEMBLE MEAN
SPRD: ENSEMBLE SPREAD
PMMN: PROBABILITY-MATCHED MEAN
LPMM: LOCALIZED PROBABILITY-MATCHED MEAN
AVRG: A COMBINATION OF THE PMMN AND MEAN FIELDS
PROB: PROBABILISTIC OUTPUT
EAS: ENSEMBLE AGREEMENT SCALE PROBABILISTIC OUTPUT
REFS.YYYYMMDD/CC/ENSPROD/REFS.TCCZ.FFRI.FFF.CONUS.{GRIB2,GRIB2.I
DX}
FFRI: FLASH FLOOD AND RECURRENCE INTERVAL EXCEEDANCE
PROBABILITIES (CONUS ONLY)
DETAILED INFORMATION ABOUT THE FILE CONTENTS INCLUDING VARIABLES
AND ENCODING IS AVAILABLE AT:
HTTPS://WWW.NCO.NCEP.NOAA.GOV/PMB/PRODUCTS/REFS/
3) CHANGES TO SBN/NOAAPORT DISSEMINATION
WHILE THE RRFS AND REFS RUN HOURLY AND PRODUCE OUTPUT FOR EACH
CYCLE AVAILABLE ON NOMADS, ONLY A SUBSET WILL BE DISSEMINATED
ACROSS THE SATELLITE BROADCAST NETWORK (SBN) AND NOAAPORT DUE TO
BANDWIDTH LIMITATIONS.
BELOW ARE THE DOMAINS AVAILABLE FOR EITHER THE RRFS OR REFS, THE
GRID SPACING, AND WMO HEADERS:
GEOGRAPHIC REGION GRID SPACING WMO HEADERS
----------------- ------------ -----------
AK (REFS) 3 KM A*[A-Q]*## KWDB
CONUS (REFS) 3 KM Y*[A-Q]*## KWDB
HI (REFS) 2.5 KM H*[A-Q]*## KWDB
PR (REFS) 2.5 KM P*[A-Q]*## KWDB
NA (RRFS) 3 KM Y*A*## KWDA
NA (RRFS) 13 KM Y*H*## KWDA
A DETAILED LISTING OF RRFS AND REFS WMO HEADERS (BY DOMAIN) TO
BE
ADDED OVER THE SBN/NOAAPORT CAN BE FOUND AT:
HTTPS://WWW.NCO.NCEP.NOAA.GOV/PMB/PRODUCTS/NOAAPORT/
NCEP URGES ALL USERS TO ENSURE THEIR DECODERS CAN HANDLE CHANGES
IN CONTENT ORDER, CHANGES IN THE SCALING FACTOR COMPONENT WITHIN
THE PRODUCT DEFINITION SECTION (PDS) OF THE GRIB FILES, AND
VOLUME CHANGES. THESE ELEMENTS MAY CHANGE WITH FUTURE NCEP MODEL
IMPLEMENTATIONS. NCEP WILL MAKE EVERY ATTEMPT TO ALERT USERS TO
THESE CHANGES BEFORE IMPLEMENTATION.
QUESTIONS CAN BE DIRECTED TO:
THE OFFICE OF MODELING AND DEVELOPMENT
RRFS FEEDBACK
RRFS.FEEDBACK@NOAA.GOV
FOR QUESTIONS ABOUT DATAFLOW ASPECTS OF THESE IMPLEMENTATIONS,
PLEASE CONTACT:
MARGARET CURTIS
NWS CENTRAL OPERATIONS HPC DATAFLOW TEAM LEAD
NCEP.PMB.DATAFLOW@NOAA.GOV
NATIONAL SERVICE CHANGE NOTICES ARE ONLINE AT:
WWW.WEATHER.GOV/NOTIFICATION/
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