The morning of 5 March 2026 saw widespread fog over the Midwestern United States. The following animation shows the Day Cloud Phase Distinction RGB product from GOES-19 with some surface observations overlaid on top. The surface observations show just how widespread the fog was. The standard meteorological chart code uses two horizontal parallel lines to denote mist and three such lines for fog. The visibility at a station (in miles) is shown by the number in the lower-right of each plot. In northwestern Illinois, for example, visibilities were between 2 and 3 miles, while in Chicago it was 1.5 miles and in Milwaukee it was as low as a quarter of a mile. Many of the lcoations across the map are also showing conditions at or very close to saturation, with numerous places have dew points at the same value as the temperature or just a degree or two apart.

The day cloud phase distinction product does well in discriminating between liquid (cyan) and ice (orange-yellow) clouds. A similar product, the Day Snow/Fog RGB, is another tool for identifying low clouds and fog from satellite. Here, teh frozen surface areas (lake ice or snow) show up as red with the flog as various shades of gray or yellow-gray.

An additional data source worth monitoring are the aircraft profiles. Many commercial aircraft provide observations of temperature and winds as they take off and land, while a small subset also provide water vapor. This smaller selection of temperature + water vapor observations (less than 10% of the total) is publicly available in real time, although there’s not a lot of places to easily access the data. Fortunately, a weather enthusiast has made a page to produce Skew-T plots of recent aircraft profiles, which can be found here. Here’s a plot of the observations from a flight into Chicago’s Midway Airport at 9:58 AM (1558 UTC) this morning. Note how the layer between the surface and the nocturnal inversion is fully saturated. Unlike radiosondes, where the disposable sensors often struggle to record full saturation, the aircraft-based sensors can be engineered to greater precision since they’ll be reused for thousands of profiles over their lifespan.

The low visibilities over the past day did have some adverse impacts on aviation. A plane scheduled to fly from Chicago O’Hare to Bloomington-Normal in central Illinois made it as far as the vicinity of its destination before having to divert all the way to Madison, Wisconsin, due to the low visibilities. The flight track, from FlightAware, is seen here:

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A total lunar eclipse occurred on 03 March 2026, with totality beginning at 1104 UTC and ending at 1202 UTC (source). A sequence of VIIRS Day/Night Band images (acquired by the VIIRS Direct Broadcast ground station at SSEC/CIMSS) viewed using RealEarth (above) showed how the land surface and clouds were brightly illuminated by the Full Moon across much of eastern North America around 0644 UTC (prior to the beginning of the eclipse) — with illumination gradually diminishing across western North America and the eastern Pacific by about 1029 UTC (about 40 minutes into the partial phase of the eclipse).

A composite of NOAA-20 Day/Night Band image swaths from the VIIRS Today site is shown below.

An AWIPS view of three consecutive Suomi-NPP VIIRS Day/Night Band images centered over Alaska (below) included an image within the period of totality (around 1144 UTC — the brighter city lights of Anchorage and Fairbanks along with those of oil drilling operations along the northern coast of Alaska near Deadhorse and Prudhoe Bay were apparent in that otherwise dark image; the subtle glow of WNW-ESE oriented stripes of aurora borealis also appeared in the image). The sublunar longitude at mid-eclipse was at 170°37′ W longitude.

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5-minute CONUS Sector GOES-19 (GOES-East) Visible images (above) included plots of surface wind barbs — which showed a general easterly to southeasterly flow in the vicinity of Lake Erie, as high pressure was moving east of the Great Lakes (surface analyses) on 02 March 2026. A number of new ice leads opened across the eastern portion of the lake, while other leads that were already present were seen to grow in length and/or width.

A faster animation of GOES-19 True Color RGB images from the CSPP GeoSphere site (below) helped to emphasize the west-southwestward drift of ice in Lake Erie (as well as the northward drift of ice within the far southern part of Lake Huron).

A closer look at GOES-19 True Color RGB imagery over Lake St. Clair (below) revealed an abrupt ice fracture that opened in the southeast portion of the lake — which pushed a large amount of ice westward (and even forced a few small ice floes to travel down the north end of the Detroit River).

RCM-2 Synthetic Aperture Radar (SAR) Normalized Radar Cross Section (NRCS) imagery (below) provided a very detailed view of the Lake Erie and Lake St. Clair ice structure — including pre-existing ice leads — prior to sunrise.

On the following day, a combined analysis of Ice Concentration and Level Ice Thickness (below) indicated that much of the Lake Erie ice was at 9-10 Tenths concentration (red), with a maximum thickness of 12-28 inches (cross-hatched).

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France has been experiencing record rainfall this winter. Last week (the final week of February 2026), the country ended a positively-biblical 40 day streak of consecutive days of rain, defined as an average of at least 1 mm of rain from all observing sites across continental France (about 80% of the size of Texas). The previous record was 32 days in 2023. Further details, for all francophone readers, are available from MétéoFrance. Some interesting highlights: since January 1st, Bordeaux received 321 mm (12.6 inches) of rain; they’d expect a total of 260 mm (10.2 inches) for the entire winter. Toulouse is in a similar situation, having received 203 mm (8.0 inches) so far in 2026 when they’d expect only 139 mm (5.5 inches) for the whole season. Across the country, this registered as the wettest February since 1959 with total accumulation more than twice the normal value.

Satellites are an excellent tool for monitoring not only the short-term weather conditions that lead to flooding, but also the longer-term extent of the floodwaters. The VIIRS Flood Mapping Product (quick guide here) provides one such look. Polar-orbiting satellites like those that host VIIRS are well-suited for flood observations because the higher resolution compared to geostationary enables a more detailed view of the extent of the flooding, while the slowly-evolving nature of floods means that the coarser temporal resolution of the polar-orbiting satellites is still adequate to capture the evolution of flooding events. The identification of floodwaters via satellite is conceptually very simple: surface water can be readily identified via satellite, and surface water in a location where water is not supposed to be implies a flood. There are some more challenging aspects to this, however, as clouds, surface snow, and terrain shadows can create regions of false positives and thus a flood detection algorithm needs to accommodate these and other issues.

Flooding products are available from SSEC’s Real Earth. Here is a link to the VIIRS 5 day composite flood product. This product is available once a day over the continents and selected island regions. The advantage of the 5 day composite is that it can help ameliorate the impact of clouds that would otherwise be in the way. The following animation shows the last two weeks of the VIIRS 5 day composite flood product over the Loire river valley in western France, a region famous for chateaux and vineyards. The colors on this product are representative of the fraction of a pixel that is covered by flooding waters: yellow is more than 40% and red is more than 80%. The rapid jump in the flood extent on the 24th is likely a result of the composite nature of this product with many of the preceding days featuring extensive cloud coverage.

Flood detection can be further enhanced with the inclusion of digital elevation models (DEMs). VIIRS observations can be used to calculate a percentage of a pixel that is covered by water. Assuming that the lowest portions of the pixel will be filled with water first, the higher resolution DEM can be used to downscale the macro-scale flooding information to more finely-detailed flood maps. SSEC is developing an experimental 30 m flood depth product that connects the areal coverage of the satellite to the DEM to produce highly-detailed observations of localized flooding. Here’s a sample image from that product, showing the Garonne and Dordogne rivers just downstream from Bordeaux, another famous winemaking region.

Different satellites can give an even more detailed view. Sentinel 2 is a European polar-orbiting satellite, analogous to the United States’ Landsat mission, designed for small-scale mapping and land classification. Among its bands include true-color red, green, and blue channels at 10 m spatial resolution. The downside of this high resolution is that the imager has a very narrow swath, and thus a given location doesn’t get an overpass every single day and clouds can further limit the number of usable views. An archive of Sentinel multispectral observations is available from the EU Copernicus Browser. Below is a slider that enables comparison between two different Sentinel 2 views of the Loire between Nantes and Angers: one from late January before significant flooding and another from late February when flooding is rampant. You can drag the bar back and forth to see how the environment changes between the two dates. It’s clear where the Loire has escaped its banks, and is especially evident in the middle of the image.

Finally, we can also look at the Normalized Difference Water Index (NDWI). Like its more famous cousin, the Normalized Difference Vegetation Index (NVDI), the NWDI takes the difference between the reflectance observed by two satellite bands and divides that by the sum of those bands. In this case, this is the difference between the green (560 nm) and the near IR (842 nm) bands. Water tends to be positive while vegetation and bare soil tends to be negative. Here is a comparison of the NDWI for the two dates, and here the impact of the flooding is obvious.

Fortunately, the amount of rainfall over France has lessened and waters appear to have started to recede.

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