GOES-14 remained in Super Rapid Scan Operations for GOES-R (SRSO-R) mode on 25 May 2015, providing 1-minute 0.63 µm visible channel imagery of severe thunderstorms that produced widespread damaging winds, large hail, and tornadoes  (SPC storm reports) across much of Texas (above; also available as an MP4 movie file). One fatality and four injuries were reported at 2104 UTC in Pettibone, Texas (denoted by the asterisk in this GOES-14 visible/IR comparison).

The animation below (YouTube 1080p HD version; also available as an MP4 movie file) is centered a bit farther north, to cover storms that developed in Oklahoma. The enhancement is also tailored to help highlight the thunderstorm overshooting tops and storm-top gravity wave features.

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After nearly 33 years of inactivity, a comparison of GOES-13 0.63 µm visible channel and 3.9 µm shortwave IR channel images (above; click to play animation; also available as an MP4 movie file) showed that the Wolf Volcano in the Galapagos Islands began to erupt sometime between 0645 and 0715 UTC on 25 May 2015. A large thermal anomaly or “hot spot” (red-enhanced pixels) was quite apparent, along with what appeared to be a brief post-eruption “shock wave” (warmer, darker gray enhancement) propagating radially outward from the eruption site on the 0715 and 0745 UTC shortwave IR images. Two plumes of volcanic cloud could be seen: a small one at a lower altitude propagating northeastward, and a second larger plume at a higher altitude moving south-southwestward.

With the arrival of daylight at 1215 UTC, a portion of the volcanic cloud could be seen at times (although identification was difficult with widespread meteorological clouds present in the area).

An Aqua MODIS false-color Red/Gren/Blue (RGB) image at 0800 UTC (below; courtesy of Michael Pavolonis, NOAA/NESDIS/CIMSS) displayed a signal of SO2 (green enhancement) along the edges of the larger volcanic cloud as it was moving southward.

GOES-13 10.7 µm IR channel images (below; click to play animation; also available as an MP4 movie file) indicated that the coldest cloud-top IR brightness temperature of -65º C appeared at 1015 UTC with the larger plume moving south-southwestward.

According to the nearby San Cristobal rawinsonde report at 12 UTC, the altitude of the -65º C temperature was around 14 km, at the 157 hPa pressure level. The tropopause for this sounding was coded to be at 16.1 km or 109.0 hPa, where the air temperature was -80.7º C.

The latest advisories issued by the Washington Volcanic Ash Advisory Center can be found here.

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Singapore Airlines Flight SQ836 was en route to Shanghai from Singapore on 23 May 2015 when it lost power from both engines at an altitude of 39,000 feet over the South China Sea, not far south-southeast of Hong Kong (Aviation Herald). The aircraft lost about 13,000 feet in altitude (above) before the engines were successfully re-started. The violet portion of the flight path denotes the period when no ADS-B data were received, from 1246 to 1311 UTC.

Himawari-8 AHI 11.2 um IR channel images (above; click image to play animation; also available as an MP4 movie file) and 6.2 um water vapor channel images (below; click image to play animation; also available as an MP4 movie file) showed a broken line of vigorous deep convection to the north of where the engine power loss first occurred (approximately within the yellow circle; VHHH is the airport identifier for Hong Kong). On the IR imagery, the coldest cloud-top brightness temperatures were in the -80 to -90 C range (shades of violet), and anvil debris could be seen drifting south-southwestward.  This convective cloud debris may have contributed to a phenomenon known as ice crystal icing, which affected the engines of the aircraft.

 

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GOES-14 remained in Super Rapid Scan Operations for GOES-R (SRSO-R) demonstration mode on 21 May 2015, providing 1-minute images for much of the eastern US (see this blog post) — and another interesting feature was seen over eastern Tennessee that was rather perplexing. Since this easily qualified for the “What the heck is this?” blog category, we thought it might be fun to have a contest of sorts and invite readers to submit their wild guesses and/or educated explanations. We will post more imagery later in the day on 22 May as to our explanation — but in the meantime, leave a comment on the blog (comments are moderated, so they will not appear until approved), or send your thoughts to our Twitter account.

—– 22 May Update —–

Thanks to all who submitted their suggestions here and on Twitter of an explanation of the “What the heck is this” feature; Here is our best guess:

The first step in trying to understand what might be causing this interesting feature was to examine 4-panel images showing imagery from other GOES channels (or spectral bands): in this case, the 3.9 µm “shortwave IR” channel, the 6.5 µm “water vapor” channel, and the 10.7 µm “IR window channel” (above; click image to play animation). The 3.9 µm IR brightness temperatures of cloud features were in the +20 to +25º range, while the 10.7 µm IR brightness temperatures were in the +3 to +5º C range — the significantly warmer shortwave IR temperatures indicates that the clouds were comprised of liquid or supercooled cloud droplets. Otherwise, no significant clues were seen on the IR (or the water vapor) images.

However, the METAR surface reports offer an important clue: a rain shower moved from southwest to northeast through the region during the preceding overnight hours with the passage of a weak low pressure system (surface analyses), with Knoxville (station identifier KTYS) receiving 0.23″ and Oak Ridge (KOQT) receiving 0.10″ of rainfall (radar-estimated 24-hour precipitation). Therefore, one plausible explanation of the feature seen on visible imagery is that it was a shallow pool of stable, rain-cooled air near the surface that was spreading out and flowing downslope (westward) into the Great Valley of East Tennessee during the morning and early afternoon hours.

While the outer edges of this rain-cooled stable air feature remained generally cloud-free, the inner core exhibited a good deal of cloud development (including what appeared to be a more dense northwest-to-southeast oriented cloud band through the middle). An overlay of hourly RTMA surface winds (below; click image to play animation) indicated that there was convergence within the feature (to the lee of higher terrain within the Cumberland Plateau), which along with daytime heating of the moist soil would have helped to promote such shallow cloud development.

For clouds within expanding the rain-cooled boundary at 1534 UTC, the CLAVR-x POES AVHRR Cloud Type was liquid, with Cloud Top Height values of 1-3 km and Cloud Top Temperature values of +2 to +10º C (below).

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