1-minute Mesoscale Domain Sector GOES-18 (GOES-West) Infrared and Visible images (above) included plots of GLM Flash Points — which showed an area of convection that produced thundersnow and 1/4 mile visibility at Grant, New Mexico (KGNT) and prompted the issuance of a Special Weather Statement which mention of a snow squall affecting areas that included a portion of I-40 east of Grant late in the day on 08 January 2026.

A larger-scale view of 1-minute GOES-18 Infrared images (below) extended past sunset — when convection with lightning produced more thundersnow at Double Eagle II (KAEG) just NW of Albuquerque International Airport (KABQ). A Special Weather Statement was issued at 0035 UTC (image | text) as this thunderstorm began to produce accumulating graupel — graupel (GR) was later reported at KABQ, beginning at 0104 UTC (METARs). A Severe Thunderstorm Warning was then issued for that storm as it produced 1.00-inch diameter hail at 0100 UTC.

In a toggle between the GOES-18 Infrared image at 0050 UTC that included GLM Flash Points with/without an overlay of GLM Flash Extent Density (below), note that the 2 GLM Flash Points are parallax-corrected (to match their location at the surface), while the GLM Flash Extent Density gridded product is *not* parallax-corrected (and therefore exhibited a slight NNE displacement in GOES-18 imagery).

The coldest cloud-top infrared brightness temperatures of the thunderstorm in the vicinity of Albuquerque — around -50ºC — were just below the Most Unstable (MU) air parcel’s Equilibrium Level (EL), according to a plot of rawinsonde data from KABQ (below).

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VIIRS Infrared images from Suomi-NPP and NOAA-21 (above) showed widespread ice leads in the Chukchi Sea during the 3-day period from 06-08 January 2026. A combination of ocean currents and wind stress influenced the motion and evolution of these ice leads.

Surface analyses (below) showed a tighter pressure gradient across the Chukchi Sea early in the 3-day period, as high pressure was approaching from the Siberian Sea — which would have induced a stronger northerly flow across the VIIRS image domain displayed above. As the core of this high pressure settled over eastern Siberia on 08 January, the pressure gradient relaxed across much of the Chukchi Sea, with a lighter westerly flow likely becoming more prominent toward the end of the period.

Daily results using an AI-based sea ice lead detection method covering the entire Arctic Ocean are shown below; the Chukchi Sea is located near the bottom center of the images.

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1-minute Mesoscale Domain Sector GOES-19 (GOES-East) Water Vapor and Visible images (above) included plots of Pilot Reports (PIREPs) of Moderate to occasionally Severe turbulence — several of which were in the vicinity of mountain waves over parts of eastern Colorado on 05 January 2026. It was notable that in the area where mountain waves were very apparent in Water Vapor images (immediately downwind of the high terrain of the Rocky Mountains), there were no clouds seen in the corresponding Visible images.

Cursor samples of 2 PIREPs of Moderate to Severe turbulence are shown below. In the immediate vicinity of the earlier 1939 UTC PIREP, the distinct signature of mountain waves — adjacent bands of warm/dry subsiding air (shades of yellow) and cool/moist rising air (shades of blue) — was evident in the Water Vapor image.

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A common sight on calm nights and early mornings is radiation fog: as the surface cools at night, the air above the ground cools as well. The absolute moisture content of the air remains the same, but since the temperature is dropping less water vapor can be contained in equilibrium and thus the relative humidity goes up. If the temperature cools enough, it will reach the dew point and fog will form.

But what happens when you throw a dense city into the mix? Cities are warmer than the surrounding land for a number of reasons. First and foremost, the building materials like concrete and asphalt that are prevalent in cities are better at absorbing the sun’s energy than vegetation is. The vertical dimension of cities also matters: the perpendicular surfaces of tall buildings strongly absorb the sun’s rays when the sun is low in the sky and the rest of the landscape is absorbing very little, and the infrared radiation that is emitted outward by one building is often absorbed by a different building right next door. Thus, cities retain their heat at night in a phenomenon known as the urban heat island, or UHI.

On the morning of 5 January 2026, widespread areas of radiation fog were visible over the southeastern continental United States, as large scale nocturnal cooling took place over the Carolinas and Georgia. This can be seen in the Day Cloud Phase Distinction RGB from the GOES-19 geostationary satellite as large regions of cyan clouds. Note how the clouds seem to follow terrain, which is expected for fogs. This particular loop spans the period from before to after sunrise, and (as one can guess from the name) the Day Cloud Phase Distinction product is a daytime only product, so it really only the end of the loop that can be interpreted in this way.

However, something interesting happens when you zoom in on Atlanta, Georgia. While the population of the city of Atlanta proper is relatively small (fewer than 500,000 people), it is the heart of the nation’s 8th largest metropolitan area, ranking it ahead of the Philadelphia, Phoenix, or Boston metros. With so much development, it has a well-pronounced UHI. Let’s look at the same product, zoomed into the Atlanta metro. This map shows the Interstate highways, and the center of the image where the highways all converge is the heart of Atlanta.

Note the gap in the fog right in the heart of the city. This is because the urban heat island kept the temperature of the central core of the city from cooling enough to allow fog to form. In the regions further out, however, the UHI was weaker. Out there, the air cooled more and condensation was able to take place. Sometimes, if you want to avoid the fog, all you have to do is head downtown.

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