1-minute Mesoscale Domain Sector GOES-16 (GOES-East) images showed clusters of severe thunderstorms that developed in the vicinity of the North Carolina / South Carolina border on 20 April 2024 — “Red” Visible (0.64 µm) and “Clean” Infrared Window (10.3 µm) images (above) included time-matched plots of preliminary/filtered SPC Storm Reports for these thunderstorms, which produced wind gusts as high as 90 mph and hail as large as 4.00 inches in South Carolina, and hail that was possibly as large as 4.50 inches in diameter in Lumberton, North Carolina (KLBT) at or around 2122 UTC (a toggle between the GOES-16 Visible and Infrared images at 2122 UTC is shown below, which portrayed a distinct overshooting top in the vicinity of that hail report). The coldest cloud-top 10.3 µm infrared  brightness temperatures were around -70ºC (darker black enhancement) — according to a plot of 1200 UTC Greensboro NC rawinsonde data, that -70ºC cloud-top infrared brightness temperature represented a small overshoot of the local tropopause (which was -65.5ºC at 185 hPa or 12.5 km).

 

1-minute GOES-16 Visible images combined with CAPE and Lifted Index Derived Stability Indices in cloud-free skies (above) indicated that an axis of instability existed in the general vicinity of a diffuse quasi-stationary frontal boundary, which was situated south of the developing thunderstorms. However, these severe thunderstorms were developing within a corridor of enhanced moisture that was located just north of the front, as seen in GOES-16 Visible images combined with the Total Precipitable Water derived product (below).

1-minute GOES-16 Visible images with/without an overlay of GLM Flash Extent Density (below) showed the lightning activity associated with these thunderstorms, which included periodic brief lightning jumps.

Today’s 4.5 inch #Hail in #LumbertonNC is just the 13th(1950-2022) recorded hail stone over 4 inches in NC. https://t.co/4V2yc9yBUd@NCSCO @NWSWilmingtonNC @wxbrad @katcampbellwx pic.twitter.com/DR1H30HdXw

— SERCC (@SERCC) April 21, 2024

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1-minute Mesoscale Domain Sector GOES-18 (GOES-West) “Red” Visible (0.64 µm) and “Clean” Infrared Window (10.3 µm) images (above) showed a mountain wave cloud over southcentral Alaska — beneath which a landspout tornado developed in the Chugach Mountains just southwest of Anchorage (PANC) at 0413 UTC on 20 April 2024 (8:13 PM local time on 19 April).

Taking parallax into account (source), a cursor sample of GOES-18 “Clean” Infrared Window (10.3 µm) brightness temperature, Cloud Top Temperature and Cloud Top Height derived products over the approximate location of the landspout at 0413 UTC on 20 April is shown below.

With an infrared brightness temperature and Cloud Top Temperature value around -60ºC along with a Cloud Top Height value around 35000 ft (10.7 km), the top of this mountain wave cloud appeared to have reached the tropopause, as indicated by a plot of Anchorage rawinsonde data at 0000 UTC on 20 April (below).

Landspout tornado spotted near Rusty Point on April 19th!
These events, while not rare, go mostly unnoticed due to our topographically diverse area.
Credit to Geremy Clarion who captured these pictures.

For more info on this, and other phenomena, visit https://t.co/47Wd2ixxi5 pic.twitter.com/SuZtuW9Vrg

— NWS Anchorage (@NWSAnchorage) April 25, 2024

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The animation below from the CSPP Geosphere website (direct link to animation) shows regions of low clouds, some of which develop in the vertical, and some of which do not (see annotated image underneath the animation). Is there a product that can be used to discriminate between these two regions?

GOES-18 Total Precipitable Water fields, below, might help you understand why development occurs in some places (where there’s more moisture) and doesn’t occur in others (where there’s not quite so much moisture). In the color enhancement below, blue/green regions are relatively dry — 1.4 to 1.6 inches of TPW — and yellow and orange regions are not as dry: 1.8 to 2.0″ of TPW. Total Precipitable Water is a clear-sky product; high clouds that are masking the fields are generally moving south to north, and low clouds (including those that occasionally develop in the vertical) are moving towards the northwest. The low clouds are mostly static (as far as vertical growth is concerned) in regions that are diagnosed as dryer in the TPW fields.

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Use Level 2 Products from GOES-R to better understand and anticipate how the atmosphere will evolve in the near term.

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There are many GOES loops showing the moon’s shadow from the total solar eclipse on April 8, 2024 (UW/CIMSS; CIRA; Satellite Liaison; NOAA). Time compositing, in this case selecting the minimum brightness, shows the shadow from several times in a single frame.

2017 and 2024 Comparisons

The size of the Moon’s shadow on the Earth during the total solar eclipses were very different between 2017 and 2024. We use ABI band 3 (0.86 um), since the land background tends to be bright (due to reflection off vegetation), hence giving more contrast with the dark shadow.

A similar (mp4) loop as above, but with the years annotated on the images.

Similar to above, but with 5 min ABI imagery….

A direct link to the above animation.

Full Disk

The above image is a composite of 21 images, from 16:30 to 19:50 UTC (image start times). The composite consists of selecting the darkest pixel. Note that a special enhancement was applied to each image before the compositing. The dark regions from the Moon’s shadow are clearly evident. Note that less clouds are apparent in the composite, since the minimum values were chosen over time.

A larger version (11,000 x 11,000) of the above FD image, without labels.

Another Full Disk composite, but hourly, and of the CIMSS Natural color composite image.

CONUS + Meso-scale

A research request was submitted to satellite operators to have an ABI meso-scale sector “follow” the shadow, from Mexico to Canada. This special schedule was scanned. The time compositing procedure was applied to the 1-min meso-scale sectors, as well the 5-min CONUS sectors. This consisted of over 100 images, between 17:51 and 19:59 UTC. The dark regions from the Moon’s shadow is evident. A toggle (animated gif) between the composited image and the predicted path.

CONUS + Meso-scale — Following the shadow

A direct link to the above mp4 animation.

GOES-18 and -16 ABI

The above loop, as an animated gif. Note how GOES-18 better depicts the Moon’s shadow during the earlier times.

H/T

Thanks to those investigating / scheduling the meso’s on April 8th, including the NOAA NESDIS User Services team. Fun fact, the meso research request was initially submitted on May 3, 2023. Thanks to many from UW/CIMSS/SSEC helping with this blog post. Thanks also for the Eclipse Predictions by Fred Espenak, NASA’s GSFC. McIDAS-X was used for image generation. Thanks to the satellite operators, SDM, PRO, SAB and the NWS as well as UW/CIMSS (especially M. Gunshor and J. Nelson) and the SSEC Data Services. More on the ABI and the GOES-R series. T. Schmit works for NOAA/NESDIS/STAR and is stationed in Madison, WI.

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