CDO

Dear CDO users,

I have a GRIB file containing 3-hourly total precipitation data (attached below). I want to select the 3-hourly data for a specified day (in this case for 12/29/2015) and store it in a new GRIB file.

I used the following cdo command to do it:

cdo -selday,20151229 fcst_phy2m.061_tprat.reg_tl319.2015120100_2015123121 fcst_phy2m_20151229

However, when I use grib_ls to look into the newly created GRIB file, I noticed it selected the final 3 hours of the previous day (20151228) and didn’t select the final 3-hours of the day I want (20151229).

Does anyone know why this might be happening? Or if there is an alternative to using cdo -selday? Thank you!