[R] National Weather Service Data

[Roy Mendelssohn - NOAA Federal]

Hi Philip:

Results look correct to me.  This might help you:

https://www.cpc.ncep.noaa.gov/products/wesley/wgrib2/default_inv.html

-Roy


> On Jul 6, 2020, at 9:29 AM, Philip <herd_dog using cox.net> wrote:
> 
> I am trying to access National Weather Service forecasting data through the rNOMADS package.  I’m not sure if the Weather Service software – grib2 – loaded correctly.  Second, some of the examples in the rNOMADS documentation seem to run correctly but I’m not sure what the output means.  Any anvise would be greatly appreciated.
> 
> 1 - I tried to load the wgrib2 software from instructions in the following website:
> 
>    https://bovineaerospace.wordpress.com/2015/04/26/how-to-install-rnomads-with-grib-file-support-on-windows/
> 
> 2 – the instructions say that if it loaded correctly I should get a laundry list similar to what is below from the command: >system(“wgrib2”).
> 
> 
> 
> The list I get looks different.  Below is the first 20 or so entries.  How can I check to see if the wgrib2 loaded correctly?
> 
> wgrib2 v0.1.9.9 9/2013 Wesley Ebisuzaki, Reinoud Bokhorst, Jaakko Hyvätti, Dusan Jovic, Kristian Nilssen, Karl Pfeiffer, Pablo Romero, Manfred Schwarb, Arlindo da Silva, Niklas Sondell, Sergey Varlamov
> -0xSec           inv  X      Hex dump of section X (0..8)
> -MM              inv         reference time MM
> -N_ens           inv         number of ensemble members
> -RT              inv         type of reference Time
> -S               inv         simple inventory with minutes and seconds (subject to change)
> -Sec0            inv         contents of section0
> -Sec3            inv         contents of section 3 (Grid Definition Section)
> -Sec4            inv         Sec 4 values (Product definition section)
> -Sec5            inv         Sec 5 values (Data representation section)
> -Sec6            inv         show bit-map section
> -Sec_len         inv         length of various grib sections
> -T               inv         reference time YYYYMMDDHHMMSS
> -V               inv         diagnostic output
> -VT              inv         verf time = reference_time + forecast_time (YYYYMMDDHHMMSS)
> -YY              inv         reference time YYYY
> 
> 3 – As I said, some of the documentation examples work and for some I get error messages.  Below is an example of one that seemed to work but I don’t understand the output.
> 
> #GribInfo - page 20
> urlsOut <- CrawlModels(abbrev="gfs_0p50",depth=2)
> ModelParameters <- ParseModelPage(urlsOut[2])#[1] is most recent model
> MyPred <- ModelParameters$pred[grep("06$",ModelParameters$pred)]
>   Levels <- c("2_m_above_ground","800_mb")
>   Variables <- c("TMP","RH")
>   GribInfo <- GribGrab(urlsOut[2],MyPred,Levels,Variables)
> GribInv <- GribInfo(GribInfo[[1]]$file.name,"grib2")
> 
> The command GribInv$inventory returns:
> 
> $inventory
> [1] "1:0:d=2020070606:TMP:800 mb:6 hour fcst:"                "2:148450:d=2020070606:RH:800 mb:6 hour fcst:"           
> [3] "3:414132:d=2020070606:TMP:2 m above ground:6 hour fcst:" "4:571266:d=2020070606:RH:2 m above ground:6 hour fcst:" 
> 
> This is supposed to be temperature and relative humidity 2 meters above the ground and at 800 milibars for 2020 – July 6 – at ZULU time 0600.  But I have no idea what the numbers 414132 – second line – mean.
> 
> Any advise would be greatly appreciated.
> 
> Philip Heinrich
> 
> From: stephen sefick 
> Sent: Thursday, July 2, 2020 3:20 PM
> To: Philip 
> Cc: r-help 
> Subject: Re: [R] National Weather Service Data
> 
> I am unfamiliar with Rnomads. Could you provide a minimal reproducable example? You are more likely to receive help this way.
> 
> 
> On Thu, Jul 2, 2020, 18:06 Philip <herd_dog using cox.net> wrote:
> 
>  Is anyone out there familiar with rNOMADS?  It is a package to get into National Weather Service forecasting data with R?
> 
>  I'm not sure the Weather Service software named wgrib2 loaded correctly because some of the stuff won't run and I can't make much sense out of some of the output.
> 
>  Thanks.
>          [[alternative HTML version deleted]]
> 
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> 
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Roy Mendelssohn
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Environmental Research Division
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