GOES-16 (GOES-East) “Red” Visible (0.64 µm) images (above) showed the cyclonic circulation of a Mesoscale Convective Vortex (MCV) in the Hill Country of Texas (east of San Angelo, KSJT) on 12 May 2020. The animation begins with 5-minute CONUS sector images, then transitions to 1-minute images as a Mesoscale Domain Sector is positioned over the area at 1529 UTC. As the MCV approached a cluster of ongoing convection, a few tornadoes were reported, likely due to the MCV enhancing low-level wind shear (SPC Mesoscale Discussion).

A more subtle signature of the MCV circulation was also evident in GOES-16 Low-level Water Vapor (7.34 µm) images (below).

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GOES-16 (GOES-East) Mid-level Water Vapor (6.9 µm) images (above) showed the circulation associated with a midlatitude cyclone that moved southeastward from southern Canada across the Upper Midwest on 09 May 2020. This system brought a variety of precipitation to the region, including snow with several inches of accumulation in parts of North Dakota and Minnesota.

Anomalously strong winds were associated with this storm, which produced peak wind gusts of 60 mph or higher in North Dakota and South Dakota — hourly surface winds with gusts are plotted on GOES-16 Water Vapor images (below).

GOES-16 Day Cloud Phase Distinction RGB images (below) revealed the northwest-to-southeast oriented swath of fresh snowfall (brighter shades of green) from eastern Saskatchewan ad western Manitoba into north-central North Dakota. The edges of the snow swath began to rapidly melt during the day, due to the warming power of the early May sun.

===== 10 May Update =====

As the surface low’s occluded front moved across southern Wisconsin on the morning of 10 May, GOES-16 Day Cloud Phase Distinction RGB images (above) provided a nice depiction of of the brief period of dynamic cooling and transition from rain to snow as glaciated cloud tops (shades of green) blossomed over the Madison (KMSN) area.

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JMA Himawari-8 True Color Red-Green-Blue (RGB) images created using Geo2Grid (above) showed a cloud of dust moving southeastward off the coast of Victoria and New South Wales, Australia on 08 May 20120.

A more subtle signature of the airborne dust (shades of pink) was seen in a longer animation of Himawari-8 Dust RGB images (below), which included nighttime periods prior to and after the True Color image sequence.

The dust cloud was also apparent in a Suomi NPP VIIRS True Color RGB image as viewed using RealEarth (below).

Thick and large haze cloud coming of Australia , it could be dust (AEs are low) but cannot rule out resuspended ash from last summer’s fires. pic.twitter.com/Hcwz55oufi

— Santiago Gassó (@SanGasso) May 8, 2020

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As a follow-on to this blog post, we will examine the period following convective initiation and take a closer look at the isolated supercell thunderstorm as it produced a long swath of large hail across far northern Texas on 07 May 2020. 1-minute Mesoscale Domain Sector GOES-16 (GOES-East) “Red” Visible (0.64 µm) images with plots of time-matched SPC Storm Reports (above) revealed pulsing overshooting tops as the storm produced hail as large as 3.25 inches in diameter.

In the corresponding GOES-16 “Clean” Infrared Window (10.35 µm) images (below), the pulsing overshooting tops exhibited infrared brightness temperatures in the -70 to -80ºC range (black to white enhancement).

In a plot of 00 UTC rawinsonde data from Amarillo, Texas (below) the tropopause temperature was -61.7ºC at the 192 hPa (12.4 km) level — warming was seen directly above the tropopause, but then air temperatures cooled to the -60 to -70ºC range within the 122-100 hPa (15.2-16.3 km) layer. Judging from their infrared brightness temperatures, the overshooting tops likely penetrated into those higher levels.

Slightly longer animations of full-bit-depth GOES-16 Visible and Infrared images from AWIPS (below) showed the storm-top features in better detail. One low-level feature of interest was the brief formation of inflow feeder bands along the southwest flank of the storm during the 0015-0035 time period (rocking animation). The gradual north-northwestward flow of hazy, more humid boundary layer air was also apparent (which likely aided and helped to sustain convective development).

A prominent and long-lived Above-Anvil Cirrus Plume (AACP) was seen with this severe thunderstorm — a toggle between GOES-16 Visible and Infrared images at 0105 UTC is shown below. The AACP appeared to exhibit colder infrared brightness temperatures, in agreement with the Amarillo rawinsonde profile at the highest altitudes.

GOES-16 Visible images with and without an overlay of GLM Flash Extent Density (below) showed how electrically active the storm was. The lighting activity began at 2134 UTC, 1 minute after the cloud-top infrared brightness temperature first became -60ºC or colder.

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GOES-17 also viewed the storm development, albeit at a 10-minute time increment because west Texas sits outside of GOES-17’s ‘CONUS’ domain. GOES-17’s more oblique view from the allows the satellite to see more structure on the western flank of the system, particularly beneath the cirrus shield! (Click here for a faster animation)

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