Severe weather across southern Wisconsin

May 9th, 2018 |

GOES-16

GOES-16 “Red” Visible (0.64 µm, top) and “Clean” Infrared Window (10.3 µm, bottom) images, with airport identifiers plotted in yellow and SPC storm reports plotted in red [click to play MP4 animation]

Severe weather (SPC | NWS ARX | NWS MKX) occurred across far southern Wisconsin on the afternoon of 09 May 2018, as a surface low moved eastward across the area. 1-minute Mesoscale Domain Sector GOES-16 (GOES-East) “Red” Visible (0.64 µm) and “Clean” Infrared Window (10.3 µm) images (above) provided a view of the isolated thunderstorm that rapidly developed in far southwestern Wisconsin around 1800 UTC. The evolution of overshooting tops was seen in both Visible and Infrared imagery — cloud-top infrared brightness temperatures cooled into the -50 to -60 ºC range (orange to red enhancement). On the Visible imagery, rear inflow feeder bands could be seen on the southwestern flank of the storm leading up to the time that it produced 1.00-inch diameter hail near Madison at 2045 UTC. SPC storm reports are “parallax corrected” so as to be plotted at a height corresponding to the cloud-top features of the parent storm.

A comparison of Suomi NPP VIIRS Visible (0.64 µm) and Infrared Window (11.45 µm) images at 1923 UTC (below) showed the isolated thunderstorm as it was moving into northwestern Dane County. The rear inflow feeder bands were evident, and the minimum cloud-top infrared brightness temperature was -62 ºC.

Suomi NPP VIIRS Visible (0.64 µm) and Infrared Window (11.45 µm) images [click to enlarge]

Suomi NPP VIIRS Visible (0.64 µm) and Infrared Window (11.45 µm) images [click to enlarge]

GOES-16 Rayleigh-corrected pseudo true color Red-Green-Blue (RGB) images (below; courtesy of Pete Pokrandt, AOS) showed a large Mesoscale Convective Vortex (MCV) that moved through northern Illinois and Wisconsin during the early morning hours, along with the hazy signature of smoke from agricultural burning in the central Plains (which was being drawn northward across eastern Iowa ahead of the surface cold front).

GOES-16 Rayleigh-corrected RGB images [click to play YouTube video]

GOES-16 Rayleigh-corrected RGB images [click to play YouTube video]

Subtropical cyclone formation off the coast of Chile

May 9th, 2018 |

GOES-16

GOES-16 “Clean” Infrared Window (10.3 µm) images, with hourly plots of surface weather [click to play MP4 animation]

A very unusual subtropical cyclone formed off the coast of Chile during the 07-08 May 2018 period (Weather Channel | Weather Underground). The system transitioned from a typical cold core baroclinic mid-latitude cyclone to a shallow warm core cyclone with some deep convection around the center of circulation. GOES-16 (GOES-East) “Clean” Infrared Window (10.3 µm) images (above) showed the evolution from 06 May to 09 May. The surface report plotted in the lower right corner of the images is Concepción, Chile.

A Suomi NPP VIIRS True-color Red-Green-Blue (RGB) image viewed using RealEarth (below) depicted the circulation once it had drifted to a position northwest of Santiago, Chile at 1839 UTC on 08 May.

Suomi NPP VIIRS Ttue-color RGB image [click to enlarge]

Suomi NPP VIIRS Ttue-color RGB image [click to enlarge]

The hourly MIMIC Total Precipitable Water product (below) initially showed a long ribbon of subtropical moisture which was being transported ahead of a cold front into the baroclinic low on 05 May — then during the transition to a subtropical low, a small pocket of modest TPW migrated slowly northward  with the surface circulation.

MIMIC Total Precipitable Water product [click to play animation | MP4]

MIMIC Total Precipitable Water product [click to play animation | MP4]