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Tropical Storm Ophelia makes landfall in North Carolina

By Scott Bachmeier •

GOES-16 “Red” Visible (0.64 µm) and “Clean” Infrared Window (10.3 µm) images, from 1700-2250 UTC on 22 September [click to play animated GIF | MP4]

1-minute Mesoscale Domain Sector GOES-16 (GOES-East) “Red” Visible (0.64 µm) and “Clean” Infrared Window (10.3 µm) images (above) showed Ophelia for a few hours after it became a Tropical Storm at 1800 UTC on 22 September 2023. The low-level circulation center (LLCC) was initially exposed, but deep convection just to the west began to increase in coverage and intensity as it wrapped around and soon obscured the LLCC. Ophelia was becoming better organized as it traversed the warm water (Sea Surface Temperature | Ocean Heat Content) of the Gulf Stream.

1-minute GOES-16 Infrared images with/without an overlay of GLM Flash Extent Density (below) indicated that lightning activity began to increase around 1900 UTC, as smaller-scale pulses of embedded convection started to exhibit cloud-top infrared brightness temperatures around -70ºC. A notable lightning jump was evident from 1925-1945 UTC.

GOES-16 “Clean” Infrared Window (10.3 µm) images, with/without an overlay of GLM Flash Extent Density, from 1700-2259 UTC on 22 September [click to play animated GIF | MP4]

A closer look at the aforementioned lightning jump is shown below, using 5-minute GOES-16 Infrared images and GLM Flash Extent Density — a brief pulse of convection with cold overshooting tops (brightness temperatures around -70ºC, brighter shades of white embedded within darker black regions) occurred from 1916-1931 UTC, with the Flash Extent Density then ramping up from 1926-1946 UTC (reaching a peak at 1936 UTC).

GOES-16 “Clean” Infrared Window (10.3 µm) images, with/without an overlay of GLM Flash Extent Density, from 1911-1951 UTC on 22 September [click to play animated GIF | MP4]


GOES-16 Infrared (10.3 µm), CLAVR-x Cloud Top Height and Operational Cloud Top Height derived products at 1921 UTC [click to enlarge]

In comparisons of GOES-16 Infrared (10.3 µm), CLAVR-x Cloud Top Height (CTH) and Operational CTH derived products at 1921 UTC (above) and 1926 UTC (below), it can be seen that the CIMSS-derived CLAVR-x CTH (having a 2-km resolution) was far superior to the Operational CTH (having a 10-km resolution, as is currently available in AWIPS) in terms of determining both the areal coverage and the magnitude of cloud heights associated with the cold overshooting tops that immediately preceded the lightning jump. In fact, at 1926 UTC, the CLAVR-x CTH value was nearly 10 kft higher than the Operational CTH (57384 ft vs 47687 ft).

GOES-16 Infrared (10.3 µm), CLAVR-x Cloud Top Height and Operational Cloud Top Height derived products at 1926 UTC [click to enlarge]

Several hours later, a closer look at 1-minute GOES-16 Infrared images with/without an overlay of GLM Flash Extent Density (below) showed Ophelia approaching the coast of North Carolina, making landfall at 1020 UTC or 6:20 AM EDT on 23 September (producing strong winds and heavy rainfall). The center of Ophelia passed between Buoy 41037 to the southwest (which recorded a peak wind gust of 72 knots) and Buoy CLKN7 to the northeast (which recorded a peak wind gust of 67 knots).

GOES-16 “Clean” Infrared Window (10.3 µm) images, with/without an overlay of GLM Flash Extent Density, from 0500-1100 UTC on 23 September [click to play animated GIF | MP4]

Hourly MIMIC Total Precipitable Water images (below) depicted the tropical moisture that was transported inland across the Mid-Atlantic states, resulting in heavy rainfall and flooding.

MIMIC Total Precipitable Water product, from 0800 UTC on 23 September to 0100 UTC on 24 September [click to play animated GIF | MP4]

Categories: CLAVR-x, GLM, GOES-16, Heavy rain / flooding, Lightning, Tropical cyclones