[gradsusr] Sample Script to Plot Radar Swath in GrADS for a Derecho Event.

Andrew Revering andy at f5data.com
Mon Jul 25 23:36:15 EDT 2022

I think what you're shooting for is to store the max value over the run.
I would do it with something like this:

'define maxvalue = if(reflectivity,>,maxvalue,reflectivity,maxvalue)'

I believe this IF/Then statement may be OpenGrads formatting, but the idea
is if the current hour's reflectivity value is greater than what's stored
in the variable you create called maxvalue, then store the current
reflectivity value, otherwise keep maxvalue.
Done in an iteration over the run, this will keep replacing the value for a
data point with the highest value in the run up to this point.

Depending on how your scripts are designed, if you need to store that, then
run another script for the next hour, you can save the maxvalue to an .nc
file, then open it up for comparison for the next forecast hour to do the
next image. Then after doing the statement above, you re-save the .nc file
with the updated maxvalue(s).

Or if it's all in one script, you don't need to read/write a NC file. But
this should get you started.

Andrew Revering
Convective Development, Inc.
dba F5Weather
Minneapolis, MN USA

[image: GeoTrack]
notified with GeoTrack
[image: 36]

On Sun, Jul 24, 2022 at 3:45 PM Brian Bernard <brian.brianbernard at gmail.com>

> Hello,
> Can anyone provide a sample script or advice on how I would plot in GrADS
> a radar swath (say from WRF) of multiple radar composite images on one plot.
> Say for example, at 15 hour of a WRF simulation, I'd plot all 15 hours on
> one image. Then at the final hour, for example 30, I'd plot all 30 hours on
> one plot.
> The website, HOPwrf shows exactly what I want to do with WRF ARW composite
> reflectivity. http://hopwrf.hopkinsschools.org/HopAheadWRF/index_1.html.
> Tom Hultquist calls it Max Run Composite Reflectivity.
> Thank you to anyone who can offer advice,
> Brian Bernard
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