5-minute CONUS Sector GOES-19 (GOES-East) Visible images with an overlay of GLM Flash Extent Density (FED) and contours of LightningCast Probability (above) showed two isolated thunderstorms which passed over the eastern portion of Lake Murray (located in central South Carolina, just northwest of Columbia KCAE) during the late afternoon hours on 24 June 2025. GLM FED highlighted the presence of satellite-detected lightning activity with each of those two storms — and with the second storm, a lightning strike on the lake around 2043 UTC resulted in 20 injuries, with 12 of those being hospitalized (media report).

A sequence of GOES-19 Infrared and Visible images with LightningCast contours (plus Visible images with both LightningCast contours and GLM FED) is shown below. Note that the LightningCast Probability began to increase in advance of the appearance of FED pixels. The coldest cloud-top infrared brightness temperatures of the isolated thunderstorms were around -55 to -57ºC.

A time series plot of LightningCast Probability and GOES-19 GLM flash counts at Columbia Metropolitan Airport KCAE (below) showed how the LightningCast Probability dramatically ramped up after 1926 UTC, with GLM flash counts within a 10-mile radius of the airport beginning at 1956 UTC. The LightningCast values dipped briefly at 2021 UTC, as the first storm moved farther from the airport (and before the second storm began to produce GLM flash counts as it moved closer).

Cursor samples of LightningCast Probability near the eastern edge of Lake Murray — where the lightning-related injuries occurred — revealed values of 96% from 2026-2041 UTC (below).

For the storms that affected Lake Murray, lightning was first explicitly mentioned in a METAR report from Fairfield County Airport in Winnsboro at 2015 UTC (below).

View only this post Read Less

GOES-19 True Color imagery (from CSPP Geosphere) over the mid-Atlantic between 35^o and 40^oN Latitude, above, shows the circulation of Tropical Storm Andrea, a system that has been tracked for several days now. Overnight, convection developed over the storm, but that convection appears to have dissipated by mid-day on 24 June 2025. A longer (infrared) animation, below, shows an interesting interactions between two circulations. The more prominent of the two is apparent near 39^oN at the start of the animation, versus the harder-to-find circulation of what would become Andrea around 35^oN. Convection that develops around Andrea — that lead to the storm being named — might have been influenced by the more northerly circulation.

Andrea is in a hostile environment for a tropical storm as shown below (imagery from the CIMSS Tropical Weather Site). Shear is strong, and sea-surface temperatures are cooler than 25^oC.

MetopB and MetopC both sampled the storm on 24 June 2025, as shown in the slow toggle below (images taken from the manati website). The compact circulation is moving to the northeast, towards colder waters.

View only this post Read Less

A fast-moving thunderstorm complex raced across North Dakota and Minnesota in the late afternoon/evening/overnight on 20-21 June 2025, as shown above. GOES-19 band 13 (10.3 µm) imagery and derived stability (Lifted Index) show the development of notable instability with an alignment over North Dakota along the direction of convective movement. One very noteworthy aspect of the cold cloud-tops in GOES-19 is their very rapid movement across central North Dakota from about 0100-0500 UTC on 21 June. Mesoscale discussions from SPC on this complex are here, here, here, here, here, here, here, here, here and here (!! — there were a lot of them!). SPC Watch numbers 447, 448 and 449 covered this system.

This system caused numerous tornadoes and severe wind reports as shown below.

________________

Overlapping 1-minute Mesoscale Domain Sectors provided GOES-19 (GOES-East) imagery at 30-second intervals over much of the area affected by this severe convection; shown below is Infrared imagery of a large mesoscale convective system over western/central North Dakota and a pair of supercell thunderstorms in eastern North Dakota as they eventually merged and began to move eastward across northwestern Minnesota. Pulsing overshooting tops exhibited infrared brightness temperatures in the -75 to -79ºC range (brighter white pixels embedded within dark black areas) — which represented a significant overshoot of the Most Unstable (MU) air parcel’s Equilibrium Level (EL), according to rawinsonde data at Bismarck ND and Aberdeen SD.

The supercell thunderstorms that developed over eastern North Dakota produced several tornadoes, including an EF3-rated tornado near Enderlin shortly after 0400 UTC that was responsible for 3 fatalities (NWS Grand Forks damage survey) **NOTE: after further investigation, Enderlin tornado #1 was upgraded from an EF-3 to an EF-5; specific details are available here. This was the first EF5-rated tornado in the US since 20 May 2013 in Moore OK**. Hail as large as 3.00″ in diameter also was reported with these supercell thunderstorms. The highest wind gusts associated with this derecho event included 111 mph in eastern North Dakota and 106 mph in northwestern Minnesota.

View only this post Read Less

1-minute Mesoscale Domain Sector GOES-18 (GOES-West) “Clean” Infrared Window (10.3 µm) images and “Red” Visible (0.64 µm) images with an overlay of the FDCA Fire Mask derived product (above) showed that a wildfire southwest of Nenana, Alaska (METAR site PANN) produced two pyrocumulonimbus (pyroCb) clouds late in the day on 20 June 2025 . The pyroCb clouds exhibited cloud-top 10.3 µm infrared brightness temperatures (IRBTs) in the -40s C (denoted by shades of blue to cyan) — a necessary condition to be classified as a pyroCb — with the first pyroCb developing at 0027 UTC on 21 June, and the second pyroCb forming at 0226 UTC. These were the first confirmed pyroCbs in Alaska for the 2025 wildfire season.

Another wildfire just east of Healy Lake, Alaska later produced a larger pyroCb, developing at 0326 UTC (below).

The coldest cloud-top IRBT exhibited by the Healy Lake pyroCb was -57.12 C at 0607 UTC (below) — colder than the -43.66 C and -49.01 C IRBTs for the two pyroCbs produced by the wildfire southwest of Nenana.

View only this post Read Less