[gradsusr] Plot NCEP Stage IV precip data

[Thomas W. Collow]

Hello,

Does anyone have any experience plotting NCEP stage 4 precipitation data in GrADS.  My problem lies in generating the correct information in the contol file, particularly the xdef and ydef parameters because I can't figure out what the proper grid spacing should be.  This is what I have so far using wgrib. 

dset  ^ST4.%y4%m2%d2%h2.01h
index ^stage4.idx
options yrev template
undef 9.999E+20
title NCEP Stage IV Precipitation (hourly)

dtype grib 240

pdef 1121 881 nps 400.5 1600.5 255 4.763

xdef 1121 linear -119.023 0.04763
ydef 881 linear 23.117 0.04763

TDEF 25 linear 00Z10may2010 1hr
ZDEF 1 levels 0

VARS 1
APCP 0 61,1,0 Accumulated Precipitation (kg/m^2)
ENDVARS

This gets me all undefined values in GrADS.  Does anyone have any experience with this?  Thanks in advance

Tom