Altocumulus castellanus clouds (ACCAS) unexpectedly developed in southern Wisconsin yesterday morning, producing beautiful cloud features and eventually a severe thunderstorm. ACCAS form due to mid-level instability and manifest in towering billows that can often produce pileus clouds as they burst through a more stable layer.The rooftop cameras of the UW-AOSS building caught... Read More

1-minute Mesoscale Domain Sector GOES-19 (GOES-East) Infrared images (above) included plots of 1-minute GLM Flash Points (which are parallax-corrected to correspond to their surface locations) — and showed an increase in thunderstorm coverage and lightning activity across southeastern Wisconsin late in the day on 15 April 2026.Unfortunately, one lightning-related fatality occurred south of... Read More

While Chicago O’Hare recently retook the crown of the country’s busiest airport in terms of number of flights, Atlanta’s Hartsfield-Jackson International Airport (ATL) continues to have the largest number of passengers. A great number of those ATL passengers were significantly inconvenienced on the evening of 6 March 2026 as a... Read More

The early morning hours of 21 February 2026 brought some intense tropical convection to the vicinity of the Samoan Islands. Radar coverage is lacking in this part of the world so satellites remain the best way to monitor storms in this region for potential safety hazards. A good first stop... Read More