An Air Algerie Flight AH5017 crashed less than an hour after taking off from Ouagadougou, Burkina Faso (the southern asterisk in the animation above). Contact was lost at 0155 UTC (Press Report) and wreckage was found southeast of the Gossi, Mali (the northern asterisk in the animation above). Cloud-top IR Brightness Temperatures in the Mesoscale Convective System through which the plane flew were as cold as -78º C.

Suomi NPP was flying over Mali and Burkina Faso at 0152 UTC on 24 July and provided high-resolution infrared and Day/Night Band imagery along the flight path. The toggle below, of the VIIRS 11.45 µm infrared and 0.70 µm Day/Night Band (Imagery courtesy of William Straka, UW CIMSS) shows the convective storm. The bright lights of Ouagadougou are evident, as well as lightning streaks within the storm. (Click for zoomed-in versions of 11.45 µm and Day Night Band images)

============================= Added 28 July 2014 =========================

The image above includes the light flare from the actual plane crash, circled in red. Suomi NPP was passing over the crash site between 1:55:00 and 1:55:30 UTC on 24 July 2014 (Link, navigation computed from Two Line Element files). The animation below shows Day/Night Band imagery (also courtesy of William Straka, UW CIMSS) from before the crash (21 July), the time of the crash on the 24th, and after the crash (25 July).

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Arkansas and surrounding states experiences strong convectively-forced winds on July 23 2014 (SPC Storm Reports for the day are shown below). The visible imagery, above, shows the merging of two convective systems: one is moving south-southeastward through eastern Kansas and one is building southwestward from the lower Ohio River Valley into northern Arkansas. (Mesoscale Discussions for this event were issued from SPC at 1656 UTC, 1827 UTC and 2001 UTC on the 23rd).

Analyses from the GOES-13 Sounder (above) showed the atmosphere into which the convective features were building to be very unstable. A large area with Lifted Indices around -10 (light red) is present; values exceed -12 (purple) at 1800 UTC. GOES Sounder DPI Analyses of CAPE (Convective Available Potential Energy, below) (from this site) likewise show strong instability at the start of the day. Convection is initially at both ends of the area of most unstable air; by 1900 UTC, the end of the animation, it has overspread the entire region of instability.

The GOES-13 Infrared Imagery, above, likewise shows the convective systems from Kansas and from the lower Ohio Valley merging over Arkansas.

Suomi-NPP VIIRS data were available over Arkansas on two successive passes on 23 July, at 1829 UTC and 2010 UTC, and these high-resolution infrared images show the quick development and vigor of the convection. The high resolution allowed for the detection of very cold cloud tops at 2010 UTC; minimum values were near -88ºC! Coldest GOES-13 10.7 Brightness Temperatures at 2015 UTC (not shown) were -78ºC.

The storms produced considerable lightning as well, as shown in the animation below that overlays hourly lightning strikes on top of the Suomi NPP 11.35 µm imagery: there were 5800 strikes (400 positive) in the hour ending at 1800 UTC, and 12000 strikes (800 positive) in the hour ending at 2000 UTC!

NOAA/CIMSS ProbSevere showed values from 80-95% at the leading edge of the convection as it moved southward through Arkansas. In this event, satellite data were not available as one of the ProbSevere predictors because of the widespread cirrus shield. MRMS Mesh was generally in the 3/4″ to 1-1/2″ range; that combines with model CAPE values exceeding 4000 and generous shear lead to the high ProbSevere values.

Overshooting Tops, such as those apparent in the 11.35 µm imagery from Suomi NPP, above, can be detected automatically in GOES-13 10.7 µm imagery. The animation of auto-detected overshooting tops, below, from this site, shows a peak in convective intensity (as measured by the number of overshoots) between 2000 and 2100 UTC on the 23rd. This image shows the daily sum of detected overshoots. There is good spatial correlation between that image and the storm reports.

Finally, CRiS/ATMS data can be used to generate soundings (NUCAPS Soundings) that are available in AWIPS II. The image below shows the spatial coverage of soundings at 2000 UTC on 23 July. The NUCAPS sounding from the easternmost column, third point south of the Oklahoma/Texas border, bottom, is shown at the bottom of the post. The boundary layer of this sounding is too cool and dry — the surface temperature is around 80º F and the surface dewpoint is in the mid-60s. Consequently, the MUCAPE is far too small (about 120 J per kilogram). If the sounding is edited so that surface values are closer to observations (it was 90º F with a 75º F dewpoint in Texarkana at this time) then MUCAPE values jump to near 5000. The sounding is also too dry; the precipitable water is 1.45″ vs. an actual value closer to 2″ at this time.

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The southerly flow of warm, moist air over the still-cold waters of Lake Superior on 21 July 2014 led to the formation of some interesting lake fog patterns, as seen in McIDAS images of GOES-13 0.63 µm visible channel data (above; click image to play animation; also available as an MP4 movie file). The images above are shown in their native GOES-13 satellite projection.

A similar animation of AWIPS images of re-mapped GOES-13 visible channel data with overlays of METAR surface reports and buoy reports (below; click image to play animation) showed that three of the northern Lake Superior buoys were reporting a water temperature of 38 to 39º F. As far north as Thunder Bay, Ontario (CYQT), air temperatures exceeded 90º F and the dew point exceeded 70º F.

A Terra MODIS Sea Surface Temperature (SST) product at 17:37 UTC (below) revealed that parts of the western half of Lake Superior exhibited SST values in the 40s F (cyan to blue color enhancement).

During the overnight hours preceding the images shown above, a Suomi NPP VIIRS IR brightness temperature difference “fog/stratus product” image at 07:43 UTC (below) showed a signal of widespread fog/stratus (yellow to red color enhancement) across much of the eastern half of Lake Superior.

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A large (approximately 50-mile diameter) “hole punch cloud” or “fall steak cloud” was seen over northwestern Wisconsin during the morning hours of 18 July 2014. An AWIPS 4-panel comparison of GOES-13 0.63 µm visible channel, 3.9 µm shortwave IR channel, 10.7 µm IR window channel, and 6.5 µm water vapor channel images (above; click image to play animation) showed that 10.7 µm IR cloud top brightness temperatures were not particularly cold with this feature (generally in the 0º C to -4º C range), and while 3.9 µm shortwave IR brightness temperatures warmed within the broad cloud deck surrounding the hole punch cloud after sunrise (due to reflection of solar radiation off of water cloud droplets), the center of the feature continued to exhibit colder (lighter gray enhancment) IR brightness temperatures which suggests cloud glaciation.

A comparison of CLAVR-x POES AVHRR Cloud Type, Cloud Top Height (CTH), and Cloud Top Temperature (CTT) products at 09:32 UTC or 4:32 am Central time (above) showed patches of water droplet clouds with CTH values in the 3-4 km range and CTT values in the 0º C to -4º C range.

A similar comparison at 12:05 UTC or 7:05 am Central time (below) revealed two areas of “cirrus” cloud type (orange color enhancement) exhibiting CTT values in the -35º to -40º C range (darker blue color enhancement) along the northern and southern periphery of the forming hole punch cloud.

These ranges of AVHRR Cloud Top Temperature and Cloud Top Height values agreed well with the regional rawinsonde data from Davenport IA (KDVN), Minneapolis MN (KMPX) and Green Bay WI (KGRB) shown below.

Terra MODIS visible and Cloud Phase products at 17:07 UTC or 12:07 pm Central time (below) indicated that a large area of glaciated ice cloud (salmon color enhancement) existed in the center portion of the hole punch cloud feature.

The cause of this large hole punch or fall streak cloud feature — and the other similar but smaller features seen across the region — was likely aircraft that had either ascended or descended through the cloud layer; particles in the aircraft exhaust acted as ice condensation nuclei, causing the process of cloud glaciation to begin.

GOES-15 imagery (above) shows the Hole Punch cloud from an oblique angle, and highlights how the region was overrun by smoke from wildfires in Canada. Smoke is most easily seen in visible satellite imagery when the sun is low in the sky, allowing for forward scatter. The smoke becomes less apparent in the imagery as the Sun rises. A similar animation for GOES-13 is below. Smoke is not quite so evident in this image because there is less forward scatter to GOES-13 over 75º W. Animations from both satellites show a hole punch cloud in Iowa as well.

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