NWS/NCEP Office Note 388 - GRIB / NCEP output grid information - available at http://www.nco.ncep.noaa.gov/pmb/docs/on388/download/
Updated November 2002
RUC grids are available from two sources:
There are three sections to this document:
Information on GRIB available at these web sites:
ftp://ftp.ncep.noaa.gov/pub/nws/nmc/docs/gribed1/
http://www.unidata.ucar.edu
The Rapid Update Cycle (RUC) output is available on the National Weather Service's TG file server. For more information on the TG server, see
Type in the following:
ftp
open tgftp.nws.noaa.gov
account: anonymous
password: your email address
Once you're in:
cd /SL.us008001/ST.opnl to get to a directory for all NCEP operational cycles for the last day.
Next, cd MT.ruc_CY.hh where hh is the hour of the initial time. There is a separate directory for each hourly cycle. From this point, for instance, cd MT.ruc_CY.12 for the 1200 UTC cycle. Sorry, you're not quite there yet; still two more subdirectory levels to go:
cd RD.yyyymmdd where yyyy is the year, and mmdd is the month/date of month.
cd PT.grid_DF.gr1
The entire path for grids is /SL.us008001/ST.opnl/MT.ruc_CY.hh/RD.yyyymmdd/PT.grid_DF.gr1
Different types of grids (20km/40km fields in each file listed here ) are then in different directories. All of these files are in GRIB format:
File name convention
fh.hhhh_tl.press.gr.#### where #### is the file name extension as listed above, e.g., sgrib20 hhhh is the forecast projection hour (or 'anal' for analysis)
The entire path for BUFR sounding data is /SL.us008001/ST.opnl/MT.ruc_CY.hh/RD.yyyymmdd/PT.sndn_DF.buf
The RUC is also available from the National Weather Service via the Family of Services. This is a service which must be subscribed to for a fee. Some current subscribers include WSI, Kavouras, and Accu-Weather. This service is maintained by the Office of Systems Operations (OSO). NCEP puts the proper headers on the GRIB files and sends it to the National Weather Service Telecommunications Gateway. There, a switching directory maintained by OSO directs it to the proper location.
These files are created every three hours (8 times per day). Separate files are created for the analysis , and forecasts outputs at 1,2,3,6,9,12 hours. The grid is a 93 X 65 80 km Lambert-Conformal grid. Only points within the RUC grid domain are given values. Each file contains the following (exceptions are noted):
Isobaric levels: (37 levels) every 25 mb 1000 - 100 mb
height
temperature
relative humidity
u and v wind components
Mean sea level
pressure (MAPS reduction method, Benjamin and Miller 1990, Monthly Weather Review)
Tropopause level
pressure
potential temperature
u and v wind components
Maximum wind level
pressure
u and v wind components
Freezing level
pressure
height
relative humidity
Layers near ground (0-30 mb, 60-90 mb, 150-180 mb above ground)
relative humidity
u and v wind components
temperature
Surface
10 m u and v wind components
2 m relative humidity
2 m temperature
1 hr accumulation non-convective precipitation (fcst files only)
1 hr accumulation convective precipitation (fcst files only)
1 hr accumulation total precipitation (fcst files only)
3 hr accumulation non-convective precipitation
(3,6,9,12 hr fcst files only)
3 hr accumulation convective precipitation
(3,6,9,12 hr fcst files only)
3 hr accumulation total precipitation
(3,6,9,12 hr fcst files only)
instantaneous precipitation rate (fcst files only)