Severe thunderstorms in southwest Missouri

July 19th, 2018 |

GOES-16

GOES-16 “Red” Visible (0.64 µm), with hourly surface plots plotted in cyan/yellow and SPC storm reports plotted in red [click to play MP4 animation | Animated GIF]

1-minute Mesoscale Domain Sector GOES-16 (GOES-East) “Red” Visible (0.64 µm) images (above) showed the rapid intensification of thunderstorms over far southwestern Missouri during the early evening hours on 19 July 2018. Surface outflow boundaries from these storms produced damaging winds (SPC storm reports), including gusts to 45 knots (52 mph) at Branson West at 2355 UTC (text) and 55 knots (63 mph) at Branson (plot | text) at 0025 UTC — and strong winds capsized a boat on Table Rock Lake (located about midway between Branson West Airport KFWB and Branson Airport KBBG, map), resulting in 17 fatalities.

The overshooting tops of these intensifying storms began to penetrate the anvil debris of pre-existing convection after about 2330 UTC in the Monett KHFJ area, with an above-anvil cirrus plume becoming evident after 0000 UTC. The 0025 UTC image showed yet another new cell which had recently developed immediately northeast of Branson; its overshooting tops began rapidly penetrating the anvil debris of the aforementioned storms at 0018 UTC.

The corresponding GOES-16 “Clean” Infrared Window (10.3 µm) images (below) revealed cloud-top infrared brightness temperatures cooling to the -75 to -79ºC range (shades of light gray to white) with these thunderstorms, significantly colder than the -68.5ºC tropopause temperature on the 00 UTC Springfield MO rawinsonde report (plot | text).

GOES-16 "Clean" Infrared Window (10.3 µm), with hourly surface plots plotted in cyan/yellow and SPC storm reports plotted in dark blue [click to play MP4 animation | Animated GIF]

GOES-16 “Clean” Infrared Window (10.3 µm), with hourly surface plots plotted in cyan/yellow and SPC storm reports plotted in purple [click to play MP4 animation | Animated GIF]

Tornado outbreak in Iowa

July 19th, 2018 |

GOES-16 Upper-level Water Vapor (6.2 µm, top left), Mid-level Water Vapor (6.9 µm, top right), Low-level Water Vapor (7.3 µm, bottom left) and

GOES-16 Upper-level Water Vapor (6.2 µm, top left), Mid-level Water Vapor (6.9 µm, top right), Low-level Water Vapor (7.3 µm, bottom left) and “Red” Visible (0.64 µm, bottom right) images [click to play MP4 animation]

GOES-16 (GOES-East) Upper-level Water Vapor (6.2 µm), Mid-level Water Vapor (6.9 µm), Low-level Water Vapor (7.3 µm) and “Red” Visible (0.64 µm) images (above) revealed the well-defined signature of a mid-tropospheric lobe of vorticity moving from southeastern South Dakota across Iowa during the day on 19 July 2018 — this feature provided synoptic-scale forcing for ascent which aided in the development of severe thunderstorms in central and eastern Iowa. A number of tornadoes were reported, along with some large hail and damaging winds (SPC storm reports).

GOES-16

GOES-16 “Red” Visible (0.64 µm) images, with SPC storm reports plotted in red [click to play MP4 animation]

A closer look using 1-minute Mesoscale Domain Sector GOES-16 “Red” Visible (0.64 µm) images (above) showed the line of thunderstorms as they developed in advance of an approaching cold/occluded front (surface analyses). Two larger storms were dominant, which produced tornadoes causing significant damage and injuries in Pella KPEA and Marshalltown KMIWabove-anvil cirrus plumes were evident with both of these supercells. In addition, early in the animation a few orphan anvils could be seen along the southern end of the line (southeast and east of Des Moines KDSM).

The corresponding GOES-16 “Clean” Infrared Window (10.3 µm) images (below) showed cloud-top infrared brightness temperatures of -65ºC to -70ºC with the larger Pella storm, and around -55ºC with the smaller Marshalltown storm to the north.

GOES-16

GOES-16 “Clean” Infrared Window (10.3 µm) images, with SPC storm reports plotted in red [click to play MP4 animation]

GOES-16

GOES-16 “Clean” Infrared Window (10.3 µm) image, with ProbSevere contour and parameters [click to enlarge]

The NOAA/CIMSS ProbSevere model (viewed using RealEarth) had a ProbTor value of 74% at 2055 UTC for the Pella storm (above) and 83% at 2130 UTC for the Marshalltown storm (below). GOES-derived Cloud-top glaciation rate (from infrared imagery) is one of the predictors used in the model.

GOES-16 Infrared image, with ProbSevere parameters [click to enlarge]

GOES-16 “Clean” Infrared Window (10.3 µm) image, with ProbSevere contour and parameters [click to enlarge]

ProbSevere time series plots for the Pella and Marshalltown cells are shown below. They indicated that the Pella storm was long-lived, persisting past 0300 UTC — and that ProbTor ramped up quickly and then down quickly, bracketing the time of the tornado in Marshalltown.

NOAA/CIMSS ProbHail (Green), ProbWind (Blue) and ProbTor (Red) for the cell that produced the Pella IA tornado. [click to enlarge]

NOAA/CIMSS ProbHail (Green), ProbWind (Blue) and ProbTor (Red) for the cell that produced the Pella IA tornado [click to enlarge]

NOAA/CIMSS ProbHail (Green), ProbWind (Blue) and ProbTor (Red) for the cell that produced the Marshalltown IA tornado [click to enlarge]

A toggle between 375-meter resolution Suomi NPP VIIRS Visible (0.64 µm) and Infrared Window (11.45 µm) images at 1946 UTC (below) provided a look at the early stage of development of tornado-producing convection.

Suomi NPP VIIRS Visible (0.64 µm) and Infrared Window (11.45 µm) images, with plots of SPC tornado reports within +/- 30 minutes of the images [click to enlarge]

Suomi NPP VIIRS Visible (0.64 µm) and Infrared Window (11.45 µm) images, with plots of SPC tornado reports within +/- 30 minutes of the images [click to enlarge]

Additional satellite imagery and analysis of this event can be found on the Satellite Liaison Blog.