271
NOUS41 KWBC 221735
PNSWSH
SERVICE CHANGE NOTICE 26-87
NATIONAL WEATHER SERVICE HEADQUARTERS SILVER SPRING MD
135 PM EDT TUE SEP 22 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: UPGRADE OF CURRENT ICING PRODUCT (CIP) TO CIP VERSION 2
(CIP2): EFFECTIVE ON OR ABOUT OCTOBER 22, 2026
EFFECTIVE OCTOBER 22, 2026, BEGINNING AT 1200 COORDINATED
UNIVERSAL TIME (UTC), THE NATIONAL CENTERS FOR ENVIRONMENTAL
PREDICTION (NCEP) WILL UPGRADE THE CURRENT ICING PRODUCT (CIP)
TO VERSION 2 (CIP2).
THE CIP IS A NUMERICAL WEATHER PREDICTION (NWP) BASED ALGORITHM
THAT ASSESSES THE STATE OF THE ATMOSPHERE FOR CONDITIONS RELATED
TO IN-FLIGHT ICING OVER CONUS AND ADJACENT COASTAL WATERS. THE
CIP COMBINES SENSOR AND NEAR-TERM HIGH-RESOLUTION MODEL OUTPUT
TO PROVIDE AN HOURLY, THREE-DIMENSIONAL DIAGNOSIS OF THE ICING
ENVIRONMENT. THE OBSERVATIONAL DATA USED BY CIP INCLUDE MRMS
REFLECTIVITY, METARS, PIREPS, FIVE SATELLITE CHANNELS, AND
GLOBAL LIGHTNING. CIP CURRENTLY OUTPUTS THREE PARAMETERS: ICING
PROBABILITY, ICING SEVERITY, AND POTENTIAL FOR SUPERCOOLED LARGE
DROPLETS (SLD). COMMON VALUES FOR ICING PROBABILITIES MAY RANGE
FROM 0-1 (0-100%). ICING SEVERITY IS A DERIVATIVE OF THE ICING
PROBABILITY AND THE NWP GENERATED PRECIPITATION CONDITIONS
ARRIVING AT A CATEGORICAL INDEX ENCOMPASSING FIVE CATEGORIES:
NONE, TRACE, LIGHT, MODERATE, AND SEVERE. SLD IS A NON-
CALIBRATED PARAMETER AND AS SUCH, IT IS NOT A PROBABILITY AND
DOES NOT HAVE ASSOCIATED UNITS. HOWEVER, HIGHER VALUES ARE
INDICATIVE OF INCREASING POTENTIAL FOR THE PRESENCE OF SLD
CONDITIONS.
SUMMARY OF CHANGES
(A) CIP2 WILL USE THE 3-KM HRRR IN PLACE OF THE 13-KM RAP
(B) CIP2 INCLUDES TWO ADDITIONAL GOES-19 SATELLITE CHANNELS, 5
(SNOW/ICE) AND 6 (CLOUD PARTICLE SIZE)
(C) THE LIQUID WATER CONTENT (LWC) PARAMETER IN THE HRRR WILL BE
USED IN PLACE OF THE TOTAL WATER CONTENT (TWC)
(D) GEOSTATIONARY LIGHTNING MAPPER (GLM) WILL BE USED IN PLACE
OF NATIONAL LIGHTNING DETECTION NETWORK (NLDN) VAISALA DATA.
3 KM CIP2 GRIB2 FILES WILL BE NEWLY ADDED TO THE NOAA
OPERATIONAL MODEL ARCHIVE AND DISTRIBUTION SYSTEM (NOMADS) WITH
THE FOLLOWING DETAILS:
- FILENAME FORMAT: CIP.THHZ.3KM.GRIB2
- 60 VERTICAL LEVELS EVERY 500 FT FROM 500 FT TO 30,000 FT
- ICING SEVERITY:
1. GRIB2 CODE TABLE IS 4.228
2. GRIB2 CATEGORY 19 AND PARAMETER NUMBER 37 (ICESEV)
- ICING PROBABILITY:
1. GRIB2 CATEGORY 19 AND PARAMETER NUMBER 233 (ICPRB)
- SUPERCOOLED LARGE DROPLETS:
1. GRIB2 CATEGORY 19 AND PARAMETER NUMBER 217 (SIPD)
- JPEG2000 COMPRESSION WITH BITMAP OVER LAND MASK, NO BITMAP
OTHERWISE
- FILE SIZE: APPROXIMATELY 60 MB/CYCLE, BUT VARIES THROUGHOUT
THE YEAR
13-KM CIP2 GRIB2 FILES WILL BE AVAILABLE OVER THE SBN TO REPLACE
THE RAP-BASED 13-KM CIP1. SBN CHANGES INCLUDE:
- MODIFICATION OF WMO HEADER SITE ID FROM KWBC TO KWBB
- COMPLEX3 PACKING WITH NO BITMAP
- ICING SEVERITY PARAMETER NUMBER CHANGED TO 37 FROM 234 THAT
INCLUDES THE REPLACEMENT OF HEAVYTO SEVERE .
- GRIB2 CODE TABLE IS 4.228
(E) NOMADS LINK TO ACCESS CIP2 GRIB2 FILES CONTAINING NON-WMO
HEADED PRODUCTS DURING THE 30-DAY PARALLEL:
- HTTPS://NOMADS.NCEP.NOAA.GOV/PUB/DATA/NCCF/COM/CIP/PARA
NOMADS LINK TO ACCESS CIP2 GRIB2 FILES CONTAINING NON-WMO HEADED
PRODUCTS POST IMPLEMENTATION:
- HTTPS://NOMADS.NCEP.NOAA.GOV/PUB/DATA/NCCF/COM/CIP/PROD
CIP1 TO BE REMOVED:
HTTPS://TGFTP.NWS.NOAA.GOV/SL.US008001/DC.AVSPT/DS.CIP20/PT.GRID
_DF.GR2/ WITH FILENAME PATTERN: SN.*.BIN
FTP://TGFTP.NWS.NOAA.GOV/SL.US008001/DC.AVSPT/DS.CIP20/PT.GRID_D
F.GR2/ WITH FILENAME PATTERN: SN.*.BIN
IN THE EVENT THAT THE IMPLEMENTATION DATE IS DECLARED A CRITICAL
WEATHER DAY (CWD), AN ENHANCED CAUTION EVENT (ECE), 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.
PLEASE SUBMIT COMMENTS, QUESTIONS, OR REQUESTS PERTAINING TO
THIS IMPLEMENTATION TO:
ROBERT HEPPER
AVIATION WEATHER CENTER (AWC)
ROBERT.HEPPER@NOAA.GOV
FOR QUESTIONS ABOUT THE DATAFLOW ASPECTS, PLEASE CONTACT:
MARGARET CURTIS
NWS CENTRAL OPERATIONS HPC DATAFLOW TEAM LEAD
NCEP.PMB.DATAFLOW@NOAA.GOV
NATIONAL SERVICE CHANGE NOTICES ARE ONLINE AT:
HTTPS://WWW.WEATHER.GOV/NOTIFICATION/
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