The corresponding 4-km resolution GOES-15 Infrared (10.7 µm) images (below) revealed that cloud-top IR brightness temperatures quickly cooled from -23º C at 2130 UTC to -42º C at 2200 UTC.There was a 30-minute gap in GOES-15 coverage from 2100 to 2130 UTC (due to a full disk scan), but a comparison of 1-km resolution NOAA-19 AVHRR Visible (0.63 µm) and Infrared (10.8 µm) caught the very early growth of the tornado-producing storm at 2115 UTC (below). The cloud-top IR brightness temperatures were as cold as -23º C at that time, indicating a high probability that cloud glaciation had begun. A timely overpass of the Suomi NPP satellite allowed a comparison of 375-meter resolution VIIRS Visible (0.64 µm) and Infrared (11.45 µm) images during the time that the tornado was srill on the ground (below). Once again, the strong slant of the storms due to increasing wind speeds aloft allowed the western/southwestern sides of the thunderstorm clouds to be brightly illuminated on the visible image. The coldest cloud-top IR brightness temperature was -51º C (yellow color enhancement), which was just shy of the -53º C tropopause temperature reported on the Oakland rawinsonde report at 12 UTC. A VIIRS true-color image of the storm visualized using RealEarth is shown below. The actual satellite overpass time was around 2151 UTC. GOES-15 sounder Lifted Index (LI) derived product images (below) showed the pockets of post-frontal instability over central California — LI values less than -4 C were seen (yellow color enhancement).
Since the first operational geostationary weather satellites (SMS-1 and SMS-2) were relatively new back in 1975, the CIMSS Regional Assimilation System (CRAS) model was utilized to generate synthetic Infrared (IR) satellite images to provide a general idea of what the satellite imagery might have looked like for this intense storm. The 48-hour sequence of synthetic CRAS IR images (below) shows the evolution of the model-derived cloud features at 1-hour intervals.Additional information about this Edmond Fitzgerald storm can be seen on this website and this lecture, as well as the NWS Marquette and this journal article.
A strong storm of similar character developed over the Upper Midwest and Great Lakes region on 9-11 November 1998. GOES-8 (GOES-East) Infrared (10.7 µm) and Water Vapor (6.7 µm) images of this 1998 storm are shown below (and are also available as YouTube videos). This storm set all-time minimum barometric pressure records for the state of Minnesota, with 962 mb (28.43″) recorded at Albert Lea and Austin in southern Minnesota. On the cold side of the storm, up to 12.5 inches of snow fell at Sioux Falls in southeastern South Dakota. Wind gusts were as high as 64 mph in Minnesota and 94 mph in Wisconsin.
A comparison of 1-km resolution POES AVHRR Visible (0.86 µm) and Infrared (12.0 µm) images at 2330 UTC or 6:30 PM local time (below) showed the developing convective storms in greater detail. The coldest cloud-top IR brightness temperature was -73º C with the westernmost cluster of thunderstorms.A closer view of the GOES-13 Infrared images with METAR surface reports is shown below. Note that Sioux Falls had a peak wind gust of 32 knots (37 mph). The Blended Total Precipitable Water (TPW) Percent of Normal product (below; click to play animation) showed TPW values as high as 199% of normal just to the north-northeast of Sioux Falls at 0442 UTC (11:42 PM local time).
Check out the rainfall on the west side of Sioux Falls. Almost an inch of rain fell in 10 minutes! pic.twitter.com/OYavFY67pp
— NWS Sioux Falls (@NWSSiouxFalls) August 28, 2015
How unprecedented was the rain? At a SDSU automated rain gauge at Sertoma Park, it measured 2.73″ of rain within 25 minutes! Wow! — NWS Sioux Falls (@NWSSiouxFalls) August 28, 2015
At the same gauge at Sertoma Park, it recorded 0.71″ of rain within 5 minutes! That’s a lot of water!
— NWS Sioux Falls (@NWSSiouxFalls) August 28, 2015
Wondering how much rain you received last night? Here is a map of rainfall reports we received. pic.twitter.com/rqUF6AVYdf
— NWS Sioux Falls (@NWSSiouxFalls) August 29, 2015
GOES-13 sounder Convective Available Potential Energy (CAPE) derived product images (above; click to play animation) showed a large cluster of of severe thunderstorms that developed in eastern Kansas and moved southeastward across southern Missouri into northern Arkansas during the day on 14 July 2015. Due to strong surface heating and ample low-level moisture ahead of the storms, the atmosphere became quite unstable with GOES sounder CAPE values reaching the 5800-6000 J/kg range (lighter violet color enhancement) by 16 UTC. A long swath of damaging winds (SPC storm reports) was produced by these storms.
The visible and infrared images below show snapshots of this severe convective cluster at 3 different times, using high-resolution data from instruments on polar-orbiting satellites: Terra MODIS at 1657 UTC, Suomi NPP VIIRS at 1851 UTC, and POES AVHRR at 1916 UTC. The coldest cloud-top IR brightness temperatures were -83º C on the MODIS image, -86º C on the VIIRS image, and -87º C on the AVHRR image.