True-color imagery over Lakes Erie/Ontario shows a white patch backed into extreme eastern Lake Erie, and also in Lake Ontario at the mouth of the Niagara River. White patches also exist over inland portions of New York, between Fredonia and Houghton. Are these white regions clouds or snow? Visible imagery, (I01 imagery at 0.64 µm) shown below in a toggle with near-infrared imagery at 1.61 (I03 VIIRS data), shows highly reflective regions in the visible that are absorbing (rather than reflecting) energy at 1.61 µm. The snow over western New York between Fredonia and Houghton is dark in the I03 imagery — and the reflective signal over Lakes Erie and Ontario south of Buffalo and at the mouth of the Niagara River is much diminished or missing altogether. This is likely ice, or snow on top of ice.

VIIRS False-Color imagery (in reality, the Day Land Cloud RGB), shows the cyan color expected with ice features in that small corner of Lake Erie, over the remnant snow over western New York and also in the outflow from the Niagara River.

A screengrab from the webcam at Fort Niagara on Lake Ontario (here) shows the near-shore ice (revealed by the webcam to be drifting to the east).

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True Color imagery from the 1755 UTC overpass over all the Great Lakes, below, shows that ice is confined to the small patch over eastern Lake Erie, over parts of the North Channel of Lake Huron, extreme eastern Lake Superior where that lake drains into the St Mary’s River, and some of the bays along the western Lake Superior shore, such as Black Bay.

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One of the reasons ice is flowing down the Niagara River: The Buffalo Ice Boom has been removed (press release). A screen capture from a Buffalo webcam showing the Niagara River is below, and I thank Michael Fries, MIC at WFO BUF for this information.

Thanks to Rick DiMaio for initially alerting us to this feature.

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The Direct Broadcast Processing System (DBPS) at SSEC/CIMSS now has a website (http://erb-dbps.ssec.wisc.edu/browser/MADISON/) that serves up VIIRS imagery and products that become available very quickly. As I type this at 2011 UTC, for example, NOAA-21 data from the 1937 UTC overpass is available. The animation below shows 3 different true-color scenes (produced with polar2grid) over the midwestern United States. The greening of Spring has reached into southern Illinois, but snow-cover is still widespread over the Upper Peninsula of Michigan and much of Canada. Lakes in Minnesota still have ice cover, but those in Wisconsin are clear of ice.

Imagery from a variety of VIIRS channels, including the Day Night Band, are routinely produced. Satellites providing imagery also include Metop-B and Metop-C, NOAA-18 and NOAA-19, GCOM-W1 and Aqua. Microwave imagery is available, at 36.5 and 89 GHz (both horizontal and vertical polarities) as shown in the toggle below. In addition, level 2 products from MIRS can be accessed (Total Precipitable Water, Rain Rate, and microwave brightness temperatures at 31, 89, 157, 165, 183 and 191 GHz!)

Perhaps you noticed the clear skies over the Great Lakes above and asked yourself: “I fancy a swim; I wonder what the Lake Surface Temperatures are?” AWIPS-ready tiles produced at CIMSS (by polar2grid) and displayed in AWIPS, below, show the answer. Lake Superior and most of Lake Huron have surface temperatures in the mid-30s (^oF); Lake Michigan is a bit warmer, closer to 40^oF, except along the far southern shore, where waters are just a bit warmer. Only western Lake Erie is uniformly “warm” with temperatures in the upper-40s to around 50. Enjoy your swim there. Lake Surface Temperatures are not yet at the DBPS site, but their implementation is planned.

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VIIRS imagery is also available at the eosdb url: https://ftp.ssec.wisc.edu/pub/eosdb/; the latency at that site is not as quick as at the DBPS site because the DBPS site incorporates only data from the Direct Broadcast antenna at CIMSS, whereas the eosdb site incorporates data from other Direct Broadcast sites, and it waits (typically up to 30 minutes) until those data are present before processing. Imagery at the eosdb site covers larger regions at the expense of latency. The NOAA-20 true-color imagery below, for example, includes information over South America that did not originate from the Madison downlink. This image of NOAA-20 orbits over North American on 16 April (source) includes a (very large) circle from which the CIMSS Direct Broadcast antenna can acquire data, but you’ll note it does not extend into South America.

DBPS websites are available for other Direct Broadcast antennas as well, as noted in this blog post.

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Target Sector (2.5-minute interval) JMA Himawari-9 AHI Red Visible (0.64 µm) and Clean Infrared Window (10.4 µm) images (above) showed Cyclone Errol as it was rapidly intensifying off the northern coast of Western Australia on 15-16 April 2025. About 2 hours after the end of the above animation, Errol peaked at 140 kts — Category 5 intensity — at 1200 UTC (SATCON). Errol exhibited a pinhole eye during the time period shown — a feature frequently observed with rapidly-intensifying tropical cyclones. Cloud-top infrared brightness temperatures in the eyewall region of Errol were in the -80s C (shades of violet to purple).

A NOAA-20 VIIRS Day/Night Band image valid at 0503 UTC (below) provided a higher-resolution view of the 10-mile diameter pinhole eye.

A Sentinel-1A Synthetic Aperture Radar (SAR) image (source) at 1610 UTC (below) sensed a maximum radial wind velocity of 124.8 knots in the northeast quadrant of Errol.

Factors favoring Errol’s rapid intensification included very warm water that the storm was traversing, and an environment of low deep-layer wind shear (below). Sea Surface Temperature and Wind Shear images were sourced from the CIMSS Tropical Cyclones site.

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Instrument issues at the weather station in Pago Pago (related to Hydrogen generation) means that balloon launches occur only once every other day, at 0000 UTC on odd days. The sounding for 15 April/0000 UTC (1 PM Samoa Standard time on 14 April) is shown below.

Two different JPSS satellites overflew the Samoan Islands just after 0000 UTC on 15 April 2025, and two profiles were created just west of Tutuila, as shown below.

The toggle below compares the two NUCAPS soundings shown in the image above to the 0000 UTC rawinsonde from Pago Pago. There is, overall, agreement, although (of course), the NUCAPS soundings are very much smoother.

At 1200 UTC, no rawinsonde was launched. But NUCAPS profiles were available at around 1200 and 1300 UTC as shown in the animations below.

If you compare the 0000 UTC NUCAPS profiles to those sensed around 1200-1300 UTC, what changes do you see, and how might those changes have been sensed by a rawinsonde if it had been launched. The later profiles all show dryer conditions at mid-latitudes (precipitable water values have dropped by about 0.4″). Temperatures above 700 mb are very similar in the two profiles, but the later profile is a bit cooler between the surface and 850 mb

The information change in the 12h between NUCAPS profiles (note also that there was a NUCAPS profile at around 0900 UTC!) can help you decide what a full-resolution sounding (made by a radiosonde) might have looked like.

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