Overlapping 1-minute Mesoscale Domain Sectors provided 30-second interval GOES-16 (GOES-East) “Red” Visible (0.64 µm) images (above) — which showed thunderstorms that produced tornadoes, large hail (up to 4.4 inches in diameter) and damaging winds (SPC Storm Reports) across western Oklahoma on 30 April 2024. Pulses of overshooting tops and evidence of Above-Anvil Cirrus Plumes (reference | VISIT training | blog posts) were apparent in the Visible imagery.

A longer animation of 30-second GOES-16 “Clean” Infrared Window (10.3 µm) images (below) extended a few hours past sunset. The coldest overshooting top infrared brightness temperatures were in the -75 to -78ºC range (brighter shades of white).

Small Radiance Anomaly along the Focal Plane Array

An anomaly that’s immediately obvious is a “flicker” between Infrared images from the 2 Mesoscale Sectors (which was also evident in full bit depth AWIPS imagery). This oscillation is also seen in a McIDAS-X “radiance” animation of alternating Meso Sectors — where radiance values of 120 to 10 are mapped to brightness values from 0 to 255. This anomaly was due to combining 1-minute images from the upper portion of Meso 1 with 1-minute images from the lower portion of Meso 2 (figure) to create 30-second imagery; as the GOES ABI scans each Mesoscale Sector, a swath-to-swath discontinuity is mainly caused by the difference in detector response at the ends of the focal plane array (FPA) — depending on the location in the ABI field of regard (thanks to Tim Schmit, NOAA/NESDIS for tracking down the explanation for this image anomaly, which came from F. Yu, GOES Calibration Working Group). In general, the magnitude of these differences are less than 0.1 K @300 K (although for an extremely cold scene, the brightness temperature difference may be larger than 1 K). These difference values are within the ABI design specification.
Note that brightness temperature discontinuities can sometimes be seen between ABI horizontal scan swaths, if the scene is very cold. One such ABI Band 13 example was seen with Hurricane Zeta (from this blog post). In addition, here’s an example from Zeta showing a scan swath discontinuity from 3 GOES-16 sectors (Full Disk, CONUS and Mesoscale).

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Farther to the north, 30-second GOES-16 Visible images centered over southern Kansas (below) also displayed pulses of overshooting tops and signatures of Above-Anvil Cirrus Plumes.

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12 days after its powerful eruption on 17 April, 10-minute JMA Himawari-9 AHI Infrared Window (10.4 µm) images (above) showed another explosive eruption of Mount Ruang in Indonesia on 29 April 2024. The coldest cloud-top infrared brightness temperatures reached -90ºC (internal yellow pixels) at 1850 UTC, shortly after eruption onset. Note that the volcanic umbrella cloud exhibited concentric cloud-top gravity waves from about 1900-2100 UTC. At the surface, volcanic ash (VA) was reported at Menado (station identifier WAMM: text | plot) beginning at 0000 UTC on 30 April, which restricted the visibility to 3-4 miles.

The volcanic umbrella cloud-top gravity waves were more apparent in higher-resolution Himawari-9 Red Visible (0.64 µm) images (below).

A toggle between Himawari-9 Visible and Infrared images at 2150 UTC on 29 April (below) showed that the primary volcanic plume (which reached heights above that of the broader umbrella cloud) exhibited warmer infrared brightness temperatures — indicating that it had penetrated the local tropopause and extended into the lower stratosphere.

A plot of rawinsonde data from Menado, Indonesia at 0000 UTC on 30 April is shown below.

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Himawari-9 imagery below compares a zoomed-out version of upper-level water vapor (Band 8, 6.25 µm) and the window channel (Band 13, 10.4 µm) that is also shown above. The zoomed-out version reveals some similarities is size in the evolution of the eruption cloud to that of surrounding tropical convection occurring at the same time. The Band 13 imagery does show that the eruptive cloud penetrates higher into the atmosphere than typical tropical convection (as discussed above).

Himawari-9 SO₂ RGB imagery (created using Geo2Grid), below, certainly distinguishes between the eruptive cloud of Ruang (whose edges become tinged in shades of orange to pink, suggesting a mixture of SO₂ and Ash), and the developing cumulonimbus to the northwest.

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1-minute Mesoscale Domain Sector GOES-16 (GOES-East) Visible/Infrared Sandwich RGB images (above) showed thunderstorms that produced tornadoes, large hail and damaging winds (SPC Storm Reports) across eastern Nebraska and western Iowa on 26 April 2024.

1-minute GOES-16 Visible/Infrared Sandwich RGB images with an overlay of GLM Flash Extent Density (below) showed the lightning activity associated with this convection — which included some notable lightning jumps as tornadic thunderstorms moved through the Omaha area (producing the EF3-rated Elkhorn tornado) beginning about 2040 UTC.

A larger-scale view using 1-minute GOES-16 “Clean” Infrared Window (10.3 µm) images (below) also showed the storms that affected western and central Iowa after sunset. The coldest infrared brightness temperatures of thunderstorm overshooting tops were around -60ºC (darker black enhancement).

Cursor samples displayed a few select Tornado Local Storm Reports across eastern Nebraska and western Iowa from 1955-2305 UTC on 26 April (above) and across western and central Iowa from 0025-0159 UTC on 27 April (below).

A larger-scale view of 1-minute GOES-16 Infrared images that included an overlay of GLM Flash Extent Density is shown below.

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High Pressure over the Great Lakes on 25 April meant a spectacular true-color view of the 5 Great Lakes (apologies to Lake Champlain) by the VIIRS instruments on NOAA-20. A similar view was recorded at 1755 UTC by Suomi-NPP, shown below.

Clear skies also meant a determination of Lake Surface Temperatures, shown below (compare these to Monday, although note the scale here is 32 to 59^oF v. 32 to 50^oF on Monday). Relatively cool waters persist in eastern Lake Erie, Lake Superior is uniformly cold (37 to 38^oF), and a curious warm ring has developed over southern Lake Michigan, 10^oF warmer at its center than the surrounding lake waters!

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AWIPS-ready JPSS Tiles are created from data downloaded at the Direct Broadcast antenna at CIMSS (processed by CSPP software) and are available from an LDM feed at CIMSS. Data are also available as imagery at this ftp site, and here.

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Sometimes, warm water observations occur because of the reflection of solar radiation (although that should be accounted for in ACSPO algorithms as sunglint location can be calculated). In this case you don’t see glint in the True Color, and the I04 imagery (shorwave infrared, at 3.74 µm) doesn’t show spectacular warmth. The GOES-16 Land Surface Temperature does show a warm eddy moving westward across the Lake however, at fairly high speed! That earns this post the “What the heck is this?” tag!

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Has this type of warm-water feature appeared in Lake Michigan before? The answer is yes: such isolated warm water features are often associated with areas of very light winds — usually beneath the center of high pressure at the surface — which allows the relatively calm water surface to warm more rapidly. These areas of light winds will exhibit a darker appearance in Visible imagery — or in this case on 25 April, Near-Infrared imagery (above). The warmest VIIRS Sea Surface Temperature value was 52.73ºF, near the apparent center of the surface high pressure (judging by the model surface wind barbs). Details of 2 similar Lake Michigan events are available in previous blog posts here and here.

Although it was about 6 hours earlier than the NOAA-20 VIIRS images, an overpass of RCM-3 provided Synthetic Aperture Radar (SAR) imagery (source) which displayed lighter wind speeds (darker shades of blue) in southern Lake Michigan (below).

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The animation below shows GOES-16 Hourly Land Surface Temperature fields from 1400 UTC 25 April 2024 through 0200 UTC 26 April 2024. That important central Lake Michigan observation appears to be part of the Great Lakes Observing System (link). A curious aspect of the in situ observations is that they are cooler than the sensed surface temperature as the warm lens of water moves through (up through 1900 UTC), but at 2000 and 2100 UTC, the buoy temperatures are warmer than the satellite-derived product.

Data from the Spotter Buoy are available here. Data include observed significant wave heights and pressure, and Lake Temperatures. The monthly temperature trace is shown below, highlighting the intense character of this feature. (Daily and Weekly traces are also available). Data from Buoy 45214 are also available at the NDBC site: here are plots of water temperature and significant wave height.

Significant wave heights during this time were minimal — generally less than 1 foot. The barometric pressure at the buoy started falling around 1500 UTC. (Direct wind observations at the buoy site are not available).

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