[gradsusr] Total Snow Accumulation with GFS .25 Degree

[Jeff Chabot]

Hello GrADS Users,

I have been struggling to plot total snow accumulations with GFS .25 degree
for the past week or so.  I know GFS does the following with precip accum:
0-3hr;0-6hr,6-9hr; 6-12hr, etc and I am trying to workaround that
alternating precip totals.

I was able to get this equation to work for total liquid precip, but I
can't get it to work with snow:

if t=1|t=2
'display 'precip'
else
'display sum(precip,t-1,t+0) - sum(precip,t-1,t-1)'
endif

Where:
precip = apcpsfc/25.4 (for inches) and t = time steps from 1 to 129.

When I try to convert this to snow, I either get snow totals off the charts
100+ inches or I get rolling precip that moves and does not accumulate.  I
am using a 10:1 ratio with csnowsfc to detect snow where 1 is snow, 0 is no
snow.

I started with the equation above:

if t=1|t=2
'display 'asnow'
else
'define preciptot = sum(precip,t-1,t+0) - sum(precip,t-1,t-1)'
'display preciptot * 10'
endif

Where:
asnow = apcpsfc * csnowsfc * 10.

The above equation shows a 10:1 ratio for all of the precip.  Once I
attempt to multiply by * csnowsfc (in the else section), I lose total
precip and instead see moving precip over time.  I tried it in the sum
equations multiplying precip * csnowsfc; then just in the display preciptot
* csnowsfc * 10.  I even tried to use the same sum equation for precip
substituting precip for csnowsfc, but none of these attempts worked to show
total snow accumulations from t=1 to 129. I just can't get it to work with
GFS.  All other models like nam, hrrr, use a nice simple sum equation:
'display sum(asnow,t=1,t='t')'.

Any help here would be really appreciative.

Sincerely,

Jeff C
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