GOES-16 (GOES-East) Red Visible (0.64 µm) images (above) revealed the development of Horizontal Convective Roll (HCR) clouds — a signature often associated with blowing snow — across parts of North Dakota, South Dakota, Minnesota and Wisconsin on 4th December 2024. Strong northwesterly winds in the wake of an arctic cold front were gusting in excess of 40 knots at several locations (including a peak gust of 57 knots or 66 mph in northeastern North Dakota), with blowing snow restricting the surface visibility to near zero at times. Periods of localized blizzard conditions prompted the issuance of several Snow Squall Warnings, with some of those warnings covering portions of Interstates 29 and 94 in North Dakota and Minnesota. Note that the HCRs were highly concentrated within the lower elevations of the Red River Valley along the North Dakota / Minnesota border.

Blowing Snow RGB images from GOES-19 (Preliminary/Non-operational) — created using Geo2Grid — provided a more detailed view of the widespread HCR clouds (below). Existing snow cover appeared as darker shades of red in the RGB imagery, while bare ground appeared as brighter shades of green; supercooled water droplet clouds appeared as brighter shades of white.

VERY poor visibility inside horizontal convective roll snow bands near Grand Forks, North Dakota, this afternoon. Visibility at times ~100yds.

Just W GF @NWSGrandForks #NDwx pic.twitter.com/uLaYAdMIF4

— Kyle J Gillett (@wxkylegillett) December 4, 2024

View only this post Read Less

Cuba’s largest power plant went offline around 0700 UTC on 4th December 2024 (media report), which led to a collapse of the power grid across much of the island. A toggle between VIIRS Day/Night Band images from Suomi-NPP and NOAA-20 (above) provided a before/after view of nighttime city light emissions across Cuba — there was a notable decrease in city lights evident in the later NOAA-20 (mislabeled as NPP) Day/Night Band image.

View only this post Read Less

1-minute Mesoscale Domain Sector GOES-16 (GOES-East) Clean Infrared Window (10.3 µm) images (above) showed a lake effect snow (LES) band that intensified over far eastern Lake Erie, shortly before moving inland across western New York after sunset on 30th November 2024. Intermittent lightning activity was seen immediately inland as the LES band moved across Interstate 90 between Buffalo (KBUF) and Dunkirk (KDKK), with several GLM Flash Points appearing.

A similar animation of GOES-16 Infrared images included overlays of both GLM Flash Extent Density and Flash Points (below). Note the slight northward displacement of the Flash Extent Density pixels compared to the Flash Points — this is because commonly-used Gridded GLM products (such as Flash Extent Density, Minimum Flash Area and Total Optical Energy) are not corrected for parallax, as the GLM Flash Points are.

A stepped sequence of 6 times with GLM observations (2329 UTC/2339 UTC/2345 UTC/0005 UTC/0008 UTC/0051 UTC) is shown below, to provide an easier examination of the displacement between GLM Flash Extent Density and GLM Flash Points. Much of this satellite-detected lightning activity was occurring near Lackawanna (south of Buffalo), where thundersnow was observed.

Constant thundersnow in Lackawanna!! pic.twitter.com/t9K7uzQ2ru

— BuffaloWeather (@weather_buffalo) December 1, 2024

View only this post Read Less

Cold air over the Great Lakes (see the plot of 850-mb temperature from RAOB stations at 1200 UTC below; note the similarity in temperatures and wind speeds over the Great Lakes states) means Lake Effect Snow. The animation above (source) shows snow bands over western lower Michigan and also downwind of Lake St. Clair, and in a single band over Lake Erie. An interesting aspect to this animation (to your blogger, at least), is the distance before the radar detection of snow occurs is pretty large over Lake Michigan, but the band development is almost immediate over Lake St. Clair and just a bit slower over Lake Erie. In addition, lake-effect band development over Lake Ontario is a bit slower than over Erie. Why?

---

Day Cloud Phase Distinction RGB Imagery from near Noon, below, shows that the bands over Lakes Erie and St. Clair are likely glaciating almost immediately (this is based on the color — yellowish/green — of the RGB in those bands) compared to non-glaciated clouds (cyan or reddish in the RGB) over western Michigan with the lake-effect there. The atmospheric motions one might infer from the cloud and radar motions is from Lake Michigan (where moisture is added to the lower troposphere) across southern Michigan. Once the air re-emerges over Lake Erie, the moisture added over Lake Michigan means an atmosphere more pre-conditioned to the development of clouds.

GOES-East Low-level water vapor infrared imagery, below, at 1200 UTC, shows little variability in that field. This suggests that moisture being added to the atmosphere is confined to the lowest part of the atmosphere, below what is detected by the 7.3 µm band. The weighting function for KDTX (that is, White Lake Michigan near Detroit), below, shows information at 7.3 µm is predominantly from the 600-700 mb (assuming clear skies, an admittedly dubious assumption). The GeoXO (the follow-on to the GOES-R series of satellites, scheduled to launch in the mid-2030s) satellite will detect radiation at 5.15 µm, a wavelength that allows moisture detection at even lower levels than bands on GOES-16/GOES-18; perhaps that channel will detect the moistening caused by Lake Michigan that allows Lake Effect Bands to develop more rapidly over downwind lakes, given a suitable trajectory.

For those (correctly!) wondering if lake surface temperatures might drive the difference in band development, consider the temperature analysis below for 28 November 2024 (source). Michigan and Erie temperatures are very similar.

View only this post Read Less