5-minute CONUS Sector GOES-19 (Preliminary/Non-operational) True Color RGB and Blowing Snow RGB images created using Geo2Grid (above) displayed a small patch of radiation fog over Lake Mendota that slowly dissipated during the morning hours on 25th December 2024 (the Blowing Snow RGB is a modified version of the Day Snow-Fog RGB, which uses higher spatial resolution Band 2 imagery in place of Band 3 as the Red component). Much of Lake Mendota was still ice-free (although some ice growth had occurred along parts of the shoreline) — but nocturnal radiational cooling allowed the surface air temperature at nearby airports to reach minimum values of 9ºF at Middleton (KC29) and 10ºF at Madison (KMSN). The Lake Mendota fog did briefly move inland across the southern and western edges of the lake.

5-minute GOES-16 (GOES-East) Visible images (below) showed the fog dissipating over the western half of Lake Mendota as surface air temperatures began to warm after sunrise.

UW-SSEC/AOS north-facing rooftop camera images (below) revealed multiple incursions of the Lake Mendota fog into the University of Wisconsin – Madison campus, located just south of the lake (both before and after sunrise).

Thanks to Tim Schmit (NOAA/NESDIS/STAR) for bringing this interesting case to our attention (and also taking ground truth photo1 and photo2 of the fog on campus).

Local #fog advection https://t.co/K4d9vjINEK; ?@NOAASatellites? #GOES16 Madison #WIwx ?@UWSSEC? ?@UWCIMSS? pic.twitter.com/njAjw4T97w

— Tim Schmit (@GOESguy) December 25, 2024

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5-minute CONUS Sector GOES-18 (GOES-West) Shortwave Infrared (3.9 µm) and Fire Mask derived product images (above) displayed a pronounced thermal signature associated with an eruption in the Halema’uma’u crater (located within the Kilauea summit caldera) on the Big Island of Hawai’i, which began around 1220 UTC (2:20 AM HST) on 23rd December 2024. Yellow pixels in the Fire Mask product denoted 3.9 µm brightness temperatures that had reached 137.88ºC — the saturation temperature of GOES-18 ABI Band 7 detectors — which first occurred at 1251 UTC, about 30 minutes after eruption onset.

Since the Kilauea eruption began during the nighttime hours, its thermal signature was also apparent in GOES-18 Near-Infrared 0.86 µm, 1.61 µm and 2.24 µm spectral bands (below).

GOES-18 True Color RGB images from the CSPP GeoSphere site (below) showed the southwest transport of volcanic fog (vog) — a mixture of SO₂, CO₂ and water vapor — from the Kilauea eruption site.

GOES-18 SO2 RGB images from RealEarth (below) confirmed the presence of SO2 (lighter shades of cyan) within the vog plume that was drifting southwest from Kilauea — the cluster of dark blue pixels denoted the thermal anomaly associated with the eruption site.

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CSPP Geosphere imagery, above, (link for the latest animation) shows extensive snowcover over Wisconsin in the wake of the season’s first large-scale snowfall on 19-20 December. WFO MKX shows reported accumulations below (from their weather story). Note that Lake Winnebago south of Green Bay is ice-covered, but various other lakes (Mendota/Monona, Green Lake, Lake Geneva) in Wisconsin have not yet frozen.

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10-minute JMA Himawari-9 AHI “Red” Visible (0.64 µm), Shortwave Infrared (3.9 µm) and “Clean” Infrared Window (10.4 µm) images (above) showed the formation of a pyrocumulonimbus (pyroCb) cloud that was spawned by a bushfire in Grampians National Park in far southeast Australia on 20th December 2024. The pyroCb cloud exhibited cloud-top 10.4 µm infrared brightness temperatures (IRBTs) of -40ºC and colder (denoted by the shades of blue) — attaining a minimum IRBT of -44º C at 0530 UTC (the air temperature at an altitude around 10 km, according to rawinsonde data from Melbourne: plot | text). The pyroCb cloud eventually drifted southeast over Melbourne Airport (YMML).

Himawari-9 True Color RGB images created using Geo2Grid (below) displayed the broad smoke plume that was being transported east-southeastward from the Grampians bushfire — along with the high-altitude pyroCb cloud that cast a shadow upon the smoke layer below.

A NOAA-20 (mislabeled as NPP) VIIRS Day/Night Band (0.7 µm) image valid at 0450 UTC (below) provided another view of the pyroCb cloud shortly after its formation.

As a surface trough of low pressure was moving east-northeastward across the state of Victoria (surface analyses), strong S-SW winds behind the trough axis (surface observations at Melbourne and Avalon) helped to intensify the Grampians fire complex — and the pyroCb cloud developed just after the trough passed through the area. Himawari-9 Fire Temperature RGB images (below) revealed (1) the rapid northward run of the Grampians bushfire following the ~0400 UTC trough passage, (2) the pyroCb formation shortly after the time of the trough passage, and (3) the northeastward surge of cooler air (darker shades of purple over cloud-free land surfaces) in the wake of the trough passage. Note that in the Himawari-9 True Color RGB images shown above, the trough passage also initiated a northward transport of boundary layer smoke from the bushfire source region.

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