Snow and Ice (Graupel, e.g.) is tough... CCR wants to know "Did it snow? How Much? Is there any on the ground? How Much?" etc.... Now, the 'caveat' here is this: We're all volunteers... we don't do a thing to endanger our life or limb... and we report as best we can.... Having said that, let me suggest the following:
The way I understand it the only place you use trace is in Rain and Melted Snow to the nearest hundredth inch. A few observed snowflakes or moisture on/or inside gauge but under .001 would be a trace and qualify. NA value is for unknown.
Best way is never use NA in this block. Report what you see, what's in the gauge: Zero, T or some value. Use NA only if you didn't take a 'gauge' measurement. NA virtually mandates a 'multiple day report'... "some snow, rain, ice today but I made No Attempt to measure it"... next day's report would be in error, technically you should submit a 'multiple day" instead of "today's" Precip. Follow me? Many of us will use a zero here, and for total snow, even throughout the summer... indicating "No frozen Precip."
New Snowfall section:
Accumulation of new snow in inches to the nearest tenth would be 0 because they are asking for nearest tenth.
Melted value from core to the nearest hundredth would be 0 because they are asking for nearest hundredth.
Accumulation: NA (No Attempt) tells them nothing. 0 says it didn't snow. T says 'one or more snowflakes fell, but I've less then a tenth inch" T (or even zero, depending on what you add in "comments") here also means "It snowed, but melted before I could measure it.. total liquid is included above"....
Core: NA or actual value, which can be zero, or T. If you don't core you use NA, or even T if there's just a 'trace' of accumulation, whether you cored or not... there's still 'snow' on the ground that will melt someday,... If you have no snow accumulation at all, use zero. If depth varies across your location, You might, e.g., take 3+ measurements and report 'average' depth here. Your core value is 'some percentage' (average) of whatever group of measurements you 'melted'.. so to speak...
Total Snow and Ice on Ground at Observation Time:
Depth of total snow and ice (new and old) in inches to the nearest half inch and if less than 1/2, it would be 0.
Melted value from core to the nearest hundredth if less than 1 hundredth it would also be 0.
CCR would, ideally, like to have these figures at least weekly, mostly in the more 'snow prone" areas.. The amout of 'water' runoff availability is important. And Snow cover has that. Many of us report the 'totals' daily.... and that's the best way, in truth. Others report that total every few days. If not 'measuring'.. then you use NA,.... but if it's obvious you have less than 0.5" I'd suggest keep using "T" for the duration... which indicates "Snow Cover Present, but thin"... if you will,...
Depth would be T if < 0.5" not zero. Zero is 'no total snow" or "NA.. didn't measure (No Attempt)"
If you have 1" on 'half the ground surface" and bare ground on the other half... then your total snow on ground would be 0.5"... average, right? and your core sample would be " melted core times 50%" ... assuming one sample from the '1 inch' area.
FINALLY... use the 'comments' section to explain...
here's the deal... as a comment reader for CCR... we see mention of "snow", but "NA". We then 'flag' the report for further follow up by Coordinators, or QC. If a station 2 miles from you reports something totally different, you get flagged.. in all likely hood... so use the comments! Explain what you see, how you did it, etc... this enables CCR QC, or you local coordinators, the NWS, other data users, to evaluate and give you feedback if necessary! You can also ask questions about such things, as this thread, in the "Comments" and we should catch it, and refer it to the appropriate CCR staff. In Comments, tell us you saw 'wild turkeys'... first robin... you're going on vacation for a few days (then we'll watch for a "Multiple day report" when you return) Tell us you had 'hail' and submitted a hail report.. Tell us you submitted a "significant" report, eg.... The comments are very important... very.