GOES-16 (left) and GOES-17 (right) Band 2 (0.64 µm) Visible imagery, 2140 UTC on 8 June 2020 through 0130 UTC 9 June 2020

 

Strong convection developed over Nebraska late in the afternoon of June 8th (SPC Storm reports are here).  Mesoscale domains from both GOES-16 and GOES-17 viewed this developing convection, enabling fine spatial and temporal-scale viewing of the convection.  (Past Mesoscale domain sectors can be searched at this website; this website shows locations in the past year.)

 

The stereoscopic mp4 animation (created using geo2grid and ffmpeg;  a similar blog post on this technique is here) above captures the convective development near 2200 UTC on the 8th, and follows the storm evolution through sunset.  To view the imagery in three dimensions, cross your eyes until three images are present, and focus on the image in the middle.

A 2-panel comparison of GOES-17 and GOES-16 Visible images during the period 2230-0208 UTC is shown below, with time-matched plots of SPC Storm Reports. The images are displayed in the native projection of each satellite.

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Two other animations (mp4s with imagery every minute from the mesoscale sector), courtesy of Tim Schmit, NOAA/STAR, show the evolution over Nebraska on this day. This one shows the GOES-17 visible imagery from sun-rise through late afternoon; stable wave clouds are evolve into the strong convection noted above. A second animation shows the evolution of the Convection RGB from 2100 UTC on 8 June through 0159 UTC on 9 June. This event is also featured in the CIRA Image of the day (link).

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1-minute Mesoscale Domain Sector GOES-16 “Red” Visible (0.64 µm) images (above) revealed low-level vortices that were pivoting around the analyzed center of Tropical Storm Cristobal as it approached the coast of Louisiana on 07 June 2020, making landfall at 2200 UTC. Wind gusts were as high as 57 mph in Louisiana and 64 mph in Mississippi.

GOES-16 Visible images with overlays of GLM Flash Extent Density (below) indicated that there was very little satellite-detected lightning associated with Cristobal.

GOES-16 “Clean” Infrared Window (10.35 µm) images (below) showed numerous cloud-top infrared brightness temperatures as cold as -70 to -77ºC (darker shades of red) within some of the convective bands.

GOES-16 Longwave Infrared Window (11.2 µm) images with plots of Derived Motion Winds (below) showed the broad low-, mid- and upper-level circulation of the tropical storm.

Rich tropical moisture was being transported northward across the Gulf of Mexico by Cristobal — the Blended Total Precipitable Water (TPW) and Percent of Normal TPW product (below) portrayed a large area with TPW values in the 2.5-3.0 inch range, which represented departures of 175-200% of normal. This led to areas of flash flooding along parts of the Gulf Coast, with some locations receiving 4-8 inches of rainfall.

The MIMIC TPW product during the period 03-07 June (below) provided a larger-scale view of the origins of the tropical moisture associated with Cristobal.

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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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