The eruption of Mt. Shisaldin late in the day on 15 September (Blog Post) was accompanied by lightning. Shishaldin’s latitude is 54.75^oN, very near the northern edge of the GOES-18 Geostationary Lightning Mapper’s (GLM’s) field of view, as shown in this Quick Guide; although most of Alaska is not sampled by the GLM instrument, parts of the Aleutians are, including the land surrounding Shishaldin. The toggle below shows the SO₂ RGB at 0220 UTC and 1-minute Flash Extent Density at 0219 UTC on 16 September 2023. This case is a good reminder that GLM can give lightning information, even in Alaska!

Similarly, GLM observed lightning at 0151 and 0152 UTC 0n 16 September 2023, as shown below.

GLM imagery for this blog post was created using CSPP’s Gridded GLM software that operates on Level 2 LFCA files; resultant GLMF files were then placed into AWIPS.

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GOES-18 (GOES-West) SO2 RGB images (above) showed the eastward drift of a volcanic cloud produced by an explosive eruption of Mount Shishaldin that began around 0150 UTC on 16 September 2023. Trace amounts of ash fall were observed at False Pass from 0200-0430 UTC.

GOES-18 True Color RGB images from the CSPP GeoSphere site (below) helped to highlight the ash-laden volcanic cloud (light shades of tan) moving east from the summit of Shishaldin.

GOES-18 “Red” Visible (0.64 µm) images (below) include plots of GLM Group points — which revealed 2 brief periods of satellite-detected volcanic lightning activity near the summit of Shishaldin shortly after the eruption onset. Station PAKF is False Pass, where some light ash fall was observed.

Lots of lightning from the ongoing eruption of Shishaldin Volcano in western Alaska. pic.twitter.com/hYVBEQ0vhA

— Brian Brettschneider (@Climatologist49) September 16, 2023

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Hurricane Lee, moving northward off the east coast of the United States, is generating a large cirrus shield (see the ABI Band 4 image below) at high levels over New England, as also shown in the Air mass RGB shown above. The corrugated features in the cirrus are well-known predictors of aircraft turbulence, and pilot reports of observations are common within the field of cirrus (as shown in these blog posts). Additionally, the CIMSS Turbulence product, a prediction developed using Machine Learning and ABI Channels 8 (Upper-level water vapor, 6.19 µm) and 13 (Clean window infrared, 10.3 µm), along with GFS thermondynamic fields, shows a high probability of turbulence in the region where turbulence is observed. CIMSS turbulence probability fields are also available online here. A training recording (mp4) on the product is here.

For the latest on Hurricane Lee, refer to the National Hurricane Center (USA, Canada). Information is also available at the NWS Forecast Offices in Boston, Portland (Gray Maine), and Caribou.

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Many thanks to Professor Rick DiMaio at Lewis University for focusing our attention on this event!

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1-minute Mesoscale Domain Sector GOES-16 (GOES-East) “Red” Visible (0.64 µm) images (above) showed Category 1 Hurricane Lee as it moved northward between Buoy 41048 and Bermuda (station identifier TXKF) on 14 September 2023. As shown in the plot below, the highest wind gust at Buoy 41048 was 41.0 m/s (79.7 knots, or 97.7 mph) at 2010 UTC (data transmission from the buoy ceased after 2310 UTC). The strong winds from Lee produced wave heights to 32 ft — and produced upwelling that cooled the water temperature several degrees.

In 1-minute GOES-16 “Clean” Infrared Window (10.3 µm) images (below), the coldest cloud tops exhibited infrared brightness temperatures around -80ºC (brighter shades of white embedded within darker black regions).

Analyses of deep-layer wind shear from the CIMSS Tropical Cyclones site (below) showed that Lee was moving into an environment of increasingly unfavorable shear as it gained latitude — which was acting to suppress the development of deep convection and the maintenance of a well-defined eye.

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