Previous blog posts (example) have documented how to create imagery from the VIIRS instrument, and this one is another example. For example, if you receive a request for VIIRS imagery such as this one: “If you have time to try a case, you could pick Feb 1, 2022 near North Pole Point for 11 um channel” — how do you proceed? A first step is to determine the day/time of the data, and that’s achieved by looking at orbits over the Arctic, at this website. That website also has an archive, and the archive for Arctic passes on 1 February 2022 is here. The image shows NOAA-20 passing over Greenland, the Arctic Ocean, and then moving over eastern Russia between 1455 and 1510 UTC on 1 February 2022. Now you know the times to request.

NOAA CLASS is the data repository that stores VIIRS imagery from NOAA-20 and Suomi-NPP. Go to the website, an log in (register if you have not already), and choose JPSS VIIRS SDRs (Operational Sensor Data Records) as shown below. Choosing those data and clicking >>GO to the right of the drop-down menu bar will move you to a new data-selection menu, where you will select the day/time of the data (1 February 2022, 14:55 Start time, 15:10 end time), and the band (I chose SVI05 — the 11.45 µm Imager channel, with 375-m resolution, that is: VIIRS Imagery Band 05 SDR (SVI05) (public 02/07/2012) ), and the satellite (NOAA-20). Geolocation data must also be selected, and Polar2Grid will expect the GITCO files. Choose them ( VIIRS Image Bands SDR Ellipsoid Terrain Corrected Geolocation (GITCO) (public 02/07/2012)) as well. It is very important, however, that your User Preferences are configured so that the data are disaggregated! Click on User Preferences, and make that selection. The User Preferences page should include information as shown here.

The steps above will produce 12 matches — 6 files of SVI05 and 6 GITCO files. Submit your order and wait for the email notification that the files are ready. While you are waiting, if you’ve not done so already, download the Polar2Grid software from CIMSS CSPP Site (CSPP: Community Satellite Processing Package; note that a free registration might be required). Expand the downloaded (compressed tar) file into an empty directory, and enter this unix command: export POLAR2GRID_HOME=/directory/where/the/expanded/file/sits.

NOAA CLASS will send an email once the data are staged and ready for you. Download those data, and then enter this command:

sh ./polar2grid.sh viirs_sdr gtiff -p i05 -g polar_canada -f /directory/holding/downloaded/SVI05Data/SVI05* /directory/holding/downloaded/GITCOdata/GITCO*

That code takes the viirs_sdr and GITCO data pointed to by the -f flag and creates a geotiff of i05 (11.45) imagery. Because these data are near the Pole, I’ve specified a grid (‘-g polar_canada’) to be used (a full list of pre-defined grids is here, part of the Polar2Grid online documentation). The command will stitch together the data in the 6 different files, and you’ll see an image at full resolution, as shown above. I also used software to add coastlines and lat/lon (‘grid’) lines.

sh ./add_coastlines.sh --add-grid --grid-D 10 10 --grid-d 10 10 --add-coastlines noaa20_viirs_i05_20220201_145336_polar_canada.tif

View only this post Read Less

1-minute Mesoscale Domain Sector GOES-16 (GOES-East) “Clean” Infrared Window (10.35 µm) images (above) include time-matched SPC Storm Reports — and showed the widespread severe weather produced by thunderstorms (many of which were associated with a squall line that developed ahead of a cold front) moving eastward across the Mid-South and Deep South on 30 March 2022.

The corresponding 1-minute GOES-16 “Red” Visible (0.64µm) images (below) showed these storms during the period leading up to sunset on 30 March.

View only this post Read Less

Severe weather occurred over the Deep South on 31 March (see this blog post); NOAA’s Storm Prediction Center (SPC) showed a Moderate Risk of severe weather over a region centered on Alabama; the toggle above shows the Moderate Risk in combination with the Tornadic Probailities. Here are the storm reports for this event. The overlap between the risk area and severe weather is here (or here at the SPC website); the overlap between the risk area and observed tornadoes is shown below (and here at the SPC website).

Observed tornadoes and SPC Risk from 1630 UTC on 30 March 2022 (Click to enlarge)

This blog post discussed output from Polar Hyperspetral modeling and how it could be used the day before. The animation below shows the Significant Tornado Potential parameter forecast at 2100 UTC on 30 March from initializations at 1200, 1400, 1700, 1800 and 2000 UTC (that is, 90, 7-, 4-, 3- and 1-hour forecasts). The areal extent of the maximum STP values is decreasing with time. Storm Reports from 30 March suggest that tornadic activity after 2100 UTC was in Mississippi and Louisiana. In addition, the largest values of STP did not extend to the into the northern part of the Moderate Risk.

In addition to being in the local AWIPS at CIMSS, in preparation for the Hazardous Weather Testbed, model output is also available at this link. The 00-h through 08-h forecast Lifted Index and Significant Tornado Parameter for this event, initialized at 2100 UTC, are shown below. The forecast shows that although the thermodynamic forcing might be dropping — as measured by the Lifted Index — the low-level wind field is becoming more favorable, as measured by the increase of STP as the system moves into Alabama.

---

Which polar orbiters provide data to this modeling effort? Both Metop-B and Metop-C, as well as Suomi-NPP and NOAA-20. A 2100 UTC model initialization will include data from the afternoon passes of Suomi-NPP and NOAA-20 (it generally takes at most an hour for the polar orbiting data to be incorporated into the Data Fusion initializations). You can view orbital paths from the Metop satellites, and from JPSS, at this website.

View only this post Read Less

As part of the Hazardous Weather Testbed this year at the Storm Prediction Center, CIMSS will be demonstrating forecast model output initialized with hyperspectral data from Polar Orbiters that is fused with ABI data; this methodology takes advantage of (for example) the high spectral resolution of CrIS on NOAA-20 and the high spatial and temporal resolution of the ABI on GOES-16. (See this blog post). Preliminary storm reports for 29-30 March 2022 are shown above, scattered severe weather occurred over the southern Plains. What did the PHSnMWnABI data look like for this event, specifically for the severe weather in northwestern Arkansas reported around 0909 UTC?

The toggle above compares two estimates of instability, one using just thermodynamics (Convective Available Potential Energy — CAPE), one incorporating model wind fields as well (STP). This 11-hour forecast was a bit fast, bringing the largest tornado threat into northwestern Arkansas by 0700 UTC (in reality, per the SPC, severe weather occurred shortly after 0900 UTC). The toggle below compares 11-h forecast of CAPE to the initial field (i.e., 00-h) of CAPE at 0700 UTC and the GOES-16 Band 13 infrared (10.3 µm) satellite imagery at 0700 UTC. The initial field certainly shows enhanced instability lagging behind the coldest cloud tops!

ProbSevere (version 3), as shown at this website, will also be demonstrated at HWT this year. The readout below, from 0701 UTC, shows the strongest convection lagging the predicted region of strongest instability.

ProbSevere version 3 at 0916 UTC shows a maximum over the severe storm near Springdale, AR. The ProbSevere readout (from this website) for that radar object, shows a maximum value at 0910 UTC.

---

Use the model forecast fields to better identify the regions of risk in the 3-12 hour timeframe, and then use observation-based products to hone in on exactly where the biggest threat exists.

View only this post Read Less