Ying, I've answer your questions in green below.
Thanks for weighing in John.
Is the CBRFC hourly QPE from MPE (radar+hourly gauges?), and 6h QPE from the "Daily QC program" (mountain mapper, w/o radar, using 6h gauges and SNOTEL?)
Yes
I summed up the CBRFC hourly QPEs we received into 6h ending at 00Z 5 Mar and it looks like your plot on the left, while the plot made directly from the CBRFC 6h QPE looks like your plot on the right. Would you say that for CBRFC the 6h QPE is more accurate than the sum from hourly QPEs?
Yes we believe it to be more accurate (but of course not necessarily "correct") because we are able to include the information from SNOTEL
The 6 hourly ConUS Stage IV/URMA uses 6h QPEs from NW/CN/CB/MBRFCs, and hourly QPEs from the other 8 ConUS RFCs. What about the higher precip in the southern area of your 6h MPE plot/my plot of sum of hourly QPEs - is it 'real'? Came from radar?
This higher amount did NOT come from radar. In fact, given beam blockage and masking out data that is above the freezing level, there is no radar data for that area. (Attached is our current radar mask image in MPE.) You can see that we are not even using the Grand Junction, KGJX, (and Cedar City, KICX) radar at this time. The higher amount in this area also comes from not having SNOTEL information in MPE. In this case, a valley location received precipitation that was high relative to climatology. However, the near by SNOTEL data did not receive as much precip as a percent of climatology. Therefore when MPE gridded up the Gage Only field using climatology, the higher elevation area ended up with amounts that are most likely too high. In this case, the Meeker Gage, EEO, received about .2 inches of precip over the 6 hour period. This is about 12% of it's March climatology. The higher elevations March climatology is over 5 inches. 12% of 5 inches is .6 inches of precip. The near by Burro Mountain SNOTEL, BURC2, recieved about .17 inches of precip for the same 6hr period. This is about 5% of it's March monthly climatology. Being able to use this percentage of climatology in the higher elevations would have allowed MPE to have a more "realistic" estimate of around .25 inches of precip in that area for that time period. Sorry this answer got kind of long winded but hope this helps.