GOES-16 ABI Band 13 (10.3 µm) infrared imagery, 1901 6 June 2020 – 0656 7 June 2020 (Click to play mp4 animation)

 

Portions of the High Plains and intermountain states experienced a climatologically rare Derecho event oni 6-7 June 2020. (Here is a preliminary write-up on this event from the National Weather Service in Rapid City SD;  the forecast office in Boulder discussed the event here.). The GOES-16 Clean window infrared (10.3 µm) animation, above, (Click here for the same animation as an animated gif) shows rapid development over western South Dakota late in the afternoon of 6 June. The swath of wind reports is shown in this graphic from the Storm Prediction Center.

Several satellite-based thermodynamic estimates keyed in on South Dakota as a region where instability was noteworthy. The GOES-16 All-Sky Convective Available Potential Energy (available here), shown below from 2026 UTC on 6 June when values were greatest, for example, showed a persistent corridor of instability across South Dakota.

NUCAPS estimates of 700-500 mb lapse rates, below (from this site), show pronounced instability upstream of South Dakota at 1945 UTC, when Suomi-NPP overflew the region. (Most of the soundings used to produce the lapse rate information were from successful infrared retrievals as shown in this graphic).

Surface moisture had pooled over western South Dakota. That is shown in the plot below of surface dewpoints showing very unusual (for South Dakota) mid-60s dewpoints! Further evidence of the unusual moisture amounts over the high Plains (for early June) is in this sounding from Rapid City at 0000 UTC on 7 June (source); Precipitable Water is at 1.2″! This value is unusual for the location and time of year, as shown here (Source).

GOES-17 Full-Disk imagery (at 10-minute time-steps) captured an oblique view of the developing convection. (The ‘PACUS’ sector with 5-minute imagery terminates in west-central South Dakota so is not used here; A GOES-17 Mesoscale sector was not in place for this event, although a GOES-16 one was).

1-minute Mesoscale Domain Sector GOES-16 “Red” Visible images with time-matched plots of SPC Storm Reports are shown below.

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GOES-16 Airmass RGB, 1400 UTC on 2 June 2020 to 1640 UTC on 3 June 2020

Severe weather occurred over the upper Midwest on 2 June 2020, and a derecho occurred over the mid-Atlantic States on 3 June 2020. These two events were linked, and the animation above shows the system moving and redeveloping from Minnesota on 2 June 202 eastward to Pennsylvania on 3 June 2020. How was this animation created?

geo2grid is a software packaged developed at CIMSS. It is designed to produce high-quality full-resolution imagery from archived (or real-time) GOES-16/GOES-17 Level-1b imagery. This blog post (a follow-up to this one) will outline how to use the software package to create imagery.  Note that geo2grid runs on CentOS6-compatible Linux.  There is no Windows version.  Here are the steps used to create the imagery above.

1. 1. geo2grid software can be downloaded as a g-zipped tarball from this link. (You may need to register — for free! — before downloading). Version 1.0.1 was released in March of 2020. You can also download documentation (always a good idea) as a pdf file from the download site, or you can access it online.  Once you have unzipped and untarred the software package, you’re ready to begin.  Your unix system must know where the software package sits, and that’s through this command: EXPORT GEO2GRID_HOME=/path/to/Geo2GridSoftwareLocation/
   2. Of course, you will also need data.  For Advanced Baseline Imager (ABI) data, geo2grid expects Radiance fields.  These can be accessed via NOAA CLASS, or via “The Cloud”, or from a GRB Receiving antenna.  (some data sources are listed here)  NOAA CLASS ABI L1b Radiances data (ordered under “GOES-R Series ABI Products (GRABIPRD) (partially restricted L1b and L2+ Data Products) ”  )  will have a file format that looks something like this:  OR_ABI-L1b-RadF-M6C08_G16_s20201542340169_e20201542349477_c20201542349544.nc ; that particular file listed is Full Disk (the ‘F’ in ‘RadF’) when GOES-16 was in Mode 6 (M6) scanning, and it contains Band 8 (C08);  the start time is Year 2020, Day 154 (June 2 2020) at 23:40:16.
   3. As noted in this blog post, you can specify which fraction of the domain to display. geo2grid also has a mapping routine if you want to define your own domain (i.e., not a satellite projection, or a subset of that satellite projection), and documentation is under ‘Utility Scripts’ at the geo2grid documentation site.  To define a domain near the Great Lakes, for example, I used this command:   $GEO2GRID_HOME/bin/p2g_grid_helper.sh PADERECHO -83.0 45.0 2000 -2000 1500 800 > $GEO2GRID_HOME/PADERECHO.conf ;  the shell scripts takes a grid name (PADERECHO in this case), a center longitude/latitude (83.0 degrees West, 45.0 Degrees North), x- and y- grid-spacing in meters (2 km for this case), and the number of points in the x- and y- directions.  These mapping instructions are placed in a configuration file;  cat $GEO2GRID_HOME/PADERECHO.conf will show this line in the file:  PADERECHO, proj4, +proj=lcc +datum=WGS84 +ellps=WGS84 +lat_0=45.00000 +lat_1=45.00000 +lon_0=-83.00000 +units=m +no_defs, 1500, 800, 2000.00000, -2000.00000, -104.24668deg, 50.40805deg .  It might take some trial and error using geo2grid to find the map domain that suits you best, but it is a simple matter to iterate to a solution.
   4. Next, run geo2grid.   The command I invoked (with small changes for each time) is here:  $GEO2GRID_HOME/bin/geo2grid.sh -r abi_l1b -w geotiff -p airmass -g PADERECHO --grid-configs $GEO2GRID_HOME/PADERECHO.conf --method nearest --cache-dir=$GEO2GRID_HOME/datacache/ -f /data-hdd/PADerecho/Day154/14/*1450*.nc   There are several flags included in this call, and they are explained in the documentation, but also here.
      • -r:  What kind of data are being read?  In this case, level-1b data from ABI
      • -w:  Output format (geotiff).  That is the only option for imagery
      • -p:  What imagery should be created?  In this case, airmass RGB.  To find out what can be computed given the data present, user the –list-products flag.  For the data I have downloaded, this returned C08, C10, C12, C13, C15, airmass:  I had downloaded to the specified directory the components necessary to compute the airmass RGB (plus band 15).  If you wanted to create imagery for all these channels in addition to the airmass RGB, -p airmass C08 C10 C12 C13 C15 would work.  (Note:  C15 is not actually needed in the computation of the airmass RGB).
      • -g:  to what grid should these data be interpolated?  The answer: the PADERECHO grid that is defined and specifed where –grid-configs points to:  $GEO2GRID_HOME/PADERECHO.conf;
      • –method:  what interpolation method should be used?  For this case, nearest neighbor is specified.
      • –cache-dir:  This is used to speed processing.  If you have multiple files being interpolated to the same grid, it speeds things to save the interpolation methods/points.  You have to specify the directory where this file will sit.
      • -f:  Where do the Radiance files sit?  In this example I have placed different times in separate directories.  I haven’t yet figured out how to use Geo2Grid that points to a directory where multiple times sit.
   5. geo2grid includes scripts (“add_coastlines.sh“;  for full documentation, see the ‘Utility Scripts’ section in the geo2grid documentation)  that will add maps to the imagery.  $GEO2GRID_HOME/bin/add_coastlines.sh --add-coastlines --coastlines-resolution=h --coastlines-level=4 GOES-16_ABI_RadF_airmass_20200602_152017_PADERECHO.tif  This command invoked only a few of the mapping additions, as described below.  For a full list, refer to the documentation.
      1. –add-coastlines ;  as you might expect this flag adds coastlines.  In the animation above, you’ll see that the coastlines include lakes.  You can also add borders, grids (lat/lon lines) and other features.
      2. –coastline-resolution=h ; I have asked for high resolution.
      3. –coastlines-level=4 ; This is the default level of detail in the lines.
      4. The .tif is the geotiff created from Geo2Grid.  When add_coastlines.sh is finished, the filename GOES-16_ABI_RadF_airmass_20200602_152017_PADERECHO.png is created.
   6. geo2grid does not annotate imagery.  I use ImageMagick for that.  (something like this:  convert GOES-16_ABI_RadF_airmass_20200603_163017_PADERECHO.png -gravity Northeast -fill white -pointsize 32 -annotate +8+40 "3 June 2020 1630 UTC" GOES-16_ABI_RadF_airmass_20200603_163017_PADERECHOannotate.png )

A challenge in scripting geo2grid is that the start time of the files is not constant.  For example, on 2 June, the 15:20 image starts at 15:20:17.1 (as shown above, the file name includes 152017) ; the 17:20 image starts at 17:20:16.9 and the created filenames include 172016.

The completed animation is shown above.

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GOES-16 (GOES-East) “Clean” Infrared Window (10.35 µm) images covering the 26-hour period from 1801 UTC on 03 June to 1956 UTC on 04 June 2020 (above) featured the merger of 2 Mesoscale Convective Systems over northwestern Missouri (beginning around 06 UTC). An animation of radar reflectivity is available here (credit: Pete Pokrandt, AOS).

To all of you asking us what this means/is. We basically have a back-building Mesoscale Convective System (MCS) from the east running into a forward propagating MCS from the west. It’s not out of the realm of possibility, but for us on shift we’ve never witnessed it in real-time. https://t.co/AIBLTz0cul

— NWS Kansas City (@NWSKansasCity) June 4, 2020

1-minute Mesoscale Domain Sector GOES-16 Infrared images from 0200-0800 UTC (below) include time-matched plots of SPC Storm Reports. Cloud-top infrared brightness temperatures reached -80ºC (violet pixels) around the time of the MCS merger.

With ample illumination from the Moon — in the Waxing Gibbous phase, at 93% of Full — a Suomi NPP VIIRS Day/Night Band (0.7 µm) image (below) shortly after the MCS merger revealed cloud-top gravity waves propagating outward from the center of the storm (along with numerous clusters of bright white pixels, highlighting areas of intense lightning activity):

As the merged MCS dissipated during the day on 04 June, a Mesoscale Convective Vortex became evident on GOES-16 “Red” Visible (0.64 µm) images (below), which then moved across southeastern Missouri, far southern Illinois and western Kentucky (helping to initiate new convective activity).

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GOES-16 (GOES-East) “Red” Visible (0.64 µm) images with time-matched plots of SPC Storm Reports (above) displayed a fast-moving derecho which moved southeastward across Pennsylvania and New Jersey on 03 June 2020. Winds gusted as high as 83 mph in Pennsylvania (at 1535 UTC)  and 93 mph in New Jersey (at 1719 UTC).

A sequence of GOES-16 Visible images – with and without an overlay of GLM Flash Extent Density – and “Clean” Infrared Window (10.35 µm) images (below) showed modest lightning activity and pulsing overshooting tops with cloud-top infrared brightness temperatures as cold as -75ºC (darker red enhancement).

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