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30-second imagery of severe thunderstorms across the Mid-South and Deep South

Overlapping 1-minute Mesoscale Domain Sectors from GOES-16 (GOES-East) provided imagery at 30-second intervals during an outbreak of severe thunderstorms (SPC Storm Reports) across parts of the Mid-South and Deep South on 09 December 2023. “Red” Visible (0.64 µm) and “Clean” Infrared Window (10.3 µm) images (above) included time-matched plots of SPC Storm Reports for a  thunderstorm that produced a... Read More

30-second GOES-16 “Red” Visible (0.64 µm, top) and “Clean” Infrared Window (10.3 µm, bottom) images, with time-matched (+/- 3 minutes) plots of SPC Storm Reports, from 1900 UTC to 2013 UTC on 09 December [click to play animated GIF | MP4]

Overlapping 1-minute Mesoscale Domain Sectors from GOES-16 (GOES-East) provided imagery at 30-second intervals during an outbreak of severe thunderstorms (SPC Storm Reports) across parts of the Mid-South and Deep South on 09 December 2023. “Red” Visible (0.64 µm) and “Clean” Infrared Window (10.3 µm) images (above) included time-matched plots of SPC Storm Reports for a  thunderstorm that produced a EF3-rated tornado which was responsible for 3 deaths and 62 injuries in the Clarksville, Tennessee (KCKV) area. The coldest cloud-top 10.3 µm infrared  brightness temperatures were in the -60 to -65ºC range (darker red enhancement).

1-minute GOES-16 Visible and Infrared images with/without an overlay of GLM Flash Extent Density (below) showed pulses of cold overshooting tops (brighter white infrared pixels) and brief lightning jumps associated with the Clarksville supercell thunderstorm as it moved across Montgomery County in Tennessee into Todd County in Kentucky.

1-minute GOES-16 “Red” Visible (0.64 µm, top) and “Clean” Infrared Window (10.3 µm, bottom) images, with/without an overlay of GLM Flash Extent Density, from 1900 UTC to 2045 UTC on 09 December [click to play animated GIF | MP4]

30-second GOES-16 Infrared images (below) showed a later thunderstorm that produced a EF2-rated tornado which was responsible for an additional 3 fatalities in Madison, Tennessee (just north of Nashville KBNA).

30-second GOES-16 “Clean” Infrared Window (10.3 µm) images, with time-matched (+/- 3 minutes) plots of SPC Storm Reports, from 2200 UTC to 2320 UTC on 09 December [click to play animated GIF | MP4]

1-minute GOES-16 Infrared images with/without an overlay of GLM Flash Extent Density (below) showed lightning activity associated with the thunderstorm that produced the Madison tornado (in Davidson County) — as with the Clarksville storm, pulses of cold overshooting tops and brief lightning jumps were observed as the tornadic thunderstorm progressed across the area.

1-minute GOES-16 “Clean” Infrared Window (10.3 µm) images, with/without an overlay of GLM Flash Extent Density, from 2130 UTC to 2330 UTC on 09 December [click to play animated GIF | MP4]

Cursor sampling of 2-km resolution GOES-16 10.3 µm brightness temperature along with the operational Cloud Top Temperature and CLAVR-x Cloud Top Height derived products for the Clarksville TN tornadic thunderstorm and the Madison TN tornadic thunderstorm (below) indicated that Cloud Top Temperatures were in the -65 to -66°C range, with Cloud Top Heights in the 43000-45000 ft range (the CLAVR-x Cloud Top Height product was shown here, since its 2-km resolution was superior to the legacy 10-km resolution Cloud Top Height product currently available in AWIPS).

Cursor sample of GOES-16 10.3 µm brightness temperature, Cloud Top Temperature derived product and CLAVR-x Cloud Top Height derived product for the Clarksville TN tornadic thunderstorm at 1932 UTC on 09 December [click to enlarge]


Cursor sample of GOES-16 10.3 µm brightness temperature, Cloud Top Temperature derived product and CLAVR-x Cloud Top Height derived product for the Madison TN tornadic thunderstorm at 2201 UTC on 09 December [click to enlarge]

Those GOES-16 Cloud Top Temperature and Cloud Top Height values were a bit colder/higher than the Most Unstable air parcel Maximum Parcel Level (MU MPL) calculated using rawinsonde data from Nashville, Tennessee rawinsonde data at 1200 UTC on 09 December, shown below (source). Unfortunately, a 0000 UTC / 10 December Nashville rawinsonde report was not available.

Plot of Nashville, Tennessee rawinsonde data at 1200 UTC on 09 December [click to enlarge]

A larger-scale view of 30-second GOES-16 Infrared imagery is shown below, spanning the ~13-hour period from 1900 UTC on 09 December to 0752 UTC on 10 December — which depicted more of the nighttime SPC Storm Reports across parts of northern Mississippi, Alabama and Georgia.

30-second GOES-16 “Clean” Infrared Window (10.3 µm) images, with time-matched (+/- 3 minutes) plots of SPC Storm Reports, from 1900 UTC to 0752 UTC on 10 December [click to play MP4 animation]

Many of these severe thunderstorms were developing within a corridor of moisture and instability ahead of an advancing cold front, as seen in 5-minute GOES-16 Visible images combined with Total Precipitable Water and Lifted Index / CAPE Derived Stability Indices in cloud-free skies (below).

5-minute GOES-16 Visible images, combined with Total Precipitable Water, Lifted Index and CAPE derived products (in cloud-free skies) [click to play animated GIF | MP4]

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Cyclone Jasper in the Coral Sea

Target Sector (2.5-minute interval) JMA Himawari-9 AHI Clean Infrared Window (10.4 µm) images (above) showed the gradual development of a ragged eye with Cyclone Jasper as the storm moved southward across the Coral Sea on 07 December 2023. Intermittent convective bursts within the eyewall contained a few overshooting tops that exhibited infrared brightness temperatures around -90ºC (yellow... Read More

JMA Himawari-9 Clean Infrared Window (10.4 µm) images, from 0002 UTC on 07 December to 0602 UTC on 08 December [click to play animated GIF | MP4]

Target Sector (2.5-minute interval) JMA Himawari-9 AHI Clean Infrared Window (10.4 µm) images (above) showed the gradual development of a ragged eye with Cyclone Jasper as the storm moved southward across the Coral Sea on 07 December 2023. Intermittent convective bursts within the eyewall contained a few overshooting tops that exhibited infrared brightness temperatures around -90ºC (yellow pixels embedded within dark purple areas).

DMSP-17 SSMIS Microwave (85 GHz) image at 0816 UTC on 07 December [click to enlarge]

The partially-fragmented structure of the eyewall was evident in a DMSP-17 SSMIS Microwave image at 0816 UTC (source) (above) and a RCM-1 Synthetic Aperture Radar wind speed image at 0807 UTC (source) (below).

RCM-1 Synthetic Aperture Radar wind speed image at 0807 UTC on 07 December [click to enlarge]

Himawari-9 Infrared Window (11.2 µm) images from the CIMSS Tropical Cyclones site (below) showed that Jasper was moving through an environment of low deep-layer wind shear — which, in addition to its motion across warm water (SST | OHC) favored continued intensification.

JMA Himawari-9 Infrared Window (11.2 µm) images, with contours and streamlines of deep-layer wind shear at 1500 UTC on 07 December [click to enlarge]


DMSP-17 SSMIS Microwave (85 GHz) image at 1927 UTC on 07 December [click to enlarge]

Jasper was upgraded to Category 3 intensity at 1800 UTC (JTWC discussion) — and a DMSP-17 SSMIS Microwave image at 1927 UTC (above) as well as a RCM-3 SAR wind speed image at 1914 UTC (below) displayed a more organized eyewall structure.

RCM-3 Synthetic Aperture Radar wind speed image at 1914 UTC on 07 December [click to enlarge]

Jasper was subsequently upgraded to a Category 4 storm at 0000 UTC on 08 December (SATCON), as the satellite presentation of the eye improved in Himawari-9 Infrared images — and mesovortices within the eye were revealed in Visible images (below).

JMA Himawari-9 Red Visible (0.64 µm, left) and Clean Infrared Window (10.4 µm, right) images, from 2232 UTC on 07 December to 0732 UTC on 08 December [click to play animated GIF | MP4]

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Water Vapor imagery sensng the surface of Hawai`i

A sequence of 5-minute CONUS Sector GOES-18 (GOES-West) Lower-level Water Vapor (7.3 µm), Mid-level Water Vapor (6.9 µm), and Upper-level Water Vapor (6.2 µm) images (above) revealed the diurnal cycle of nighttime cooling and daytime warming at the summits of Mauna Kea and Mauna Loa on the Big Island of Hawai’i on 06 December 2023. This case is another... Read More

GOES-18 Low-level Water Vapor (7.3 µm), Mid-level Water Vapor (6.9 µm), and Upper-level Water Vapor (6.2 µm) images, from 0001 UTC on 06 December to 0101 UTC on 07 December  [click to play animated GIF | MP4]

A sequence of 5-minute CONUS Sector GOES-18 (GOES-West) Lower-level Water Vapor (7.3 µm), Mid-level Water Vapor (6.9 µm), and Upper-level Water Vapor (6.2 µm) images (above) revealed the diurnal cycle of nighttime cooling and daytime warming at the summits of Mauna Kea and Mauna Loa on the Big Island of Hawai’i on 06 December 2023. This case is another example which helps to underscore the fact that Water Vapor spectral bands are essentially Infrared bands, which — in the absence of clouds, and in a dry atmosphere — can sometimes sense surface features.

The presence of very dry air within most of the middle/upper troposphere over Hawai’i on 06 December had the effect of shifting the water vapor weighting functions to lower altitudes, as seen on plots for the 3 ABI Water Vapor spectral  bands calculated using rawinsonde data from Hilo PHTO (below). This allowed thermal radiation from the higher terrain of Mauna Kea and Mauna Loa to pass upward — with minimal attenuation — through what little high-altitude moisture was present, and reach the 7.3 µm / 6.9 µm / 6.2 µm detectors on the GOES-18 ABI instrument. The 2 mountain summits extend upward to near the 600 hPa pressure level — close to the level of peak weighting function contributions for Water Vapor spectral bands 09 and 10 — and to an altitude where there was still a contribution from the Band 08 weighting function, as calculated using the Hilo soundings.

Plots of weighting functions for GOES-18 Water Vapor spectral bands 08 (light brown), 09 (cyan) and 10 (dark brown), calculated using Hilo (PHTO) rawnsonde data at 0000 UTC on 06 December 2023 [click to enlarge]
Plots of weighting functions for GOES-18 Water Vapor spectral bands 08 (light brown), 09 (cyan) and 10 (dark brown), calculated using Hilo (PHTO) rawnsonde data at 1200 UTC on 06 December 2023 [click to enlarge]
Plots of weighting functions for GOES-18 Water Vapor spectral bands 08 (light brown), 09 (cyan) and 10 (dark brown), calculated using Hilo (PHTO) rawnsonde data at 0000 UTC on 07 December 2023 [click to enlarge]

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Wet weather in the Pacific Northwest

Hourly GOES-18 Hemispheric views, above, from 2140 UTC on 1 December to 2040 UTC on 4 December, (from the CSPP Geosphere site) show the development of a strong system in the Gulf of Alaska. This system is tapping into an airstream rich in moisture that augurs for a wet period along the... Read More

True Color (daytime) and Night Microphysics RGB (nighttime) hourly from 2140 UTC on 1 December through 2040 UTC on 4 December 2023

Hourly GOES-18 Hemispheric views, above, from 2140 UTC on 1 December to 2040 UTC on 4 December, (from the CSPP Geosphere site) show the development of a strong system in the Gulf of Alaska. This system is tapping into an airstream rich in moisture that augurs for a wet period along the Pacific Northwest coast. Flood watches and have been issued from western Washington and Oregon. MIMIC Total Precipitable Water fields in December ending at 1500 UTC on 4 December, below, show that some of the moisture in the North Pacific may have been part of the Kona Low that drenched Hawai’i last week.

MIMIC Total Precipitable Water, 0000 UTC 1 December – 1500 UTC 4 December 2023 (Click to enlarge)

Airmass RGB imagery from GOES-18, below (from this OSPO site), shows the well-developed cyclone with the characteristic orange signal in the airmass RGB denoting air with a large Potential Vorticity signal (as confirmed in this cross-section from1800 UTC on 4 December, take from this site).

GOES-18 Airmass RGB, 1220 UTC 4 December – 2110 UTC 4 December 2023 (click to enlarge)

For more information on this event, refer to the websites of the National Weather Service Offices in Seattle, Portand and Medford.

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