Severe thunderstorms in the Southern Plains

October 10th, 2021 |

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

1–minute Mesoscale Domain Sector GOES-16 (GOES-East) “Red” Visible (0.64 µm) images (above) include time-matched plots of SPC Storm Reports produced by supercell thunderstorms that moved eastward across Oklahoma and Texas late in the day on 10 October 2021. These storms developed along and ahead of a strong cold front — and in Texas the hazy signature of post-frontal blowing dust was evident immediately behind the western edge of the convective cloud line.

GOES-16 “Clean” Infrared Window (10.35 µm) images (below) revealed pulsing overshooting tops that exhibited infrared brightness temperatures in the -70 to -75ºC range (shades of white embedded within dark black pixels).

GOES-16 “Clean” Infrared Window (10.35 µm) images, with SPC Storm Reports plotted in cyan [click to play animation | MP4]

SIFT investigations of an EF-3 tornado that hit Boscobel WI

August 13th, 2021 |
GOES-16 ABI Band 13 (“Clean Window”) Infrared imagery (10.3 µm), 2100-2159 UTC on 7 August 2021 (Click to animate)

An EF-3 tornado moved through the southwest Wisconsin town of Boscobel, in Grant County, late in the afternoon of 7 August 2021 (Preliminary Storm Summary from WFO ARX). The tornado was on the ground from 4:29 to 4:56 PM CDT, or 2129 – 2156 UTC. How did the ABI imagery and GLM data change over this time? The Satellite Information Familiarization Tool (SIFT) can be used to investigate this. Gridded GLM data that can be imported into SIFT (a two-week rolling archive is available) is available at this website. ABI Radiance data can be acquired from NOAA CLASS or from the Amazon Cloud.

The GOES-16 ABI Clean Window animation from 2100 to 2159 UTC, bracketing the times that the tornado, linked to the image above, shows very strong upper-level difluence (consider how the cirrus shield spreads south in the hour of the animation!); one might infer cyclonic motion in the fields as well.

SIFT allows for the identification of regions that can then be investigated. The toggle below shows a polygon that has been defined. Subsequent plots will focus on this region surrounding the storm tops associated with the tornadic storm.

SIFT display of GOES-16 Clean Window (10.3 µm) at 2124 and 2157 UTC on 7 August 2021. The transparent red box defines a region being investigated.

How do the cloud-top brightness temperatures evolve in that region? One way to describe that is a simple bar-graph showing the distribution of temperatures, shown below. There are three distinct cold temperature events: around 2130 UTC, around 2138 UTC, around 2148 UTC. (Recall the tornado is on the ground fron 2129-2156) The time-scale of the changes is such that only 1-minute imagery will be able to capture it accurately.

Distribution of 10.3 µm brightness temperatures within a defined polygon as shown above; 2124-2159 UTC on 7 August 2021

How do the lightning observations evolve in the storm? SIFT will display many different GLM parameters: Average and Minimum Flash Areas, Total Energy, Group (and Flash) Extent and Centroid Densities, Group and Flash Areas. Some are displayed below, again within the confines of the polygon defined above. The first plot compares Average Flash Area (along a constant x axis) and Total Optical Energy (along a varying y axis). The distribution in the plot seems to change during the time when the tornado is on the ground.

GLM Average Flash Area v. GLM Total Energy within the defined polygon, 2124, 2127, 2134, 2140, 2149 and 2151 UTC.

SIFT also allows direct comparisons between ABI and GLM data, as shown below: Flash Extent Density is compared to Band 13 (10.3 µm) brightness temperatures at discrete times within the tornado’s lifecycle.

GLM Flash Extent Density vs. G16 ABI Band 13 (10.3 µm) Brightness Temperature within a predefined polygon, 2124, 2127, 2134, 2140, 2149, 2151 UTC

For more information on SIFT, including download instructions for linux, MacOS and Windows, refer to the SIFT website.

Severe weather over northeast Illinois

August 9th, 2021 |
GOES-16 “Red”Visible (0.64 µm) Imagery, 1900 UTC 9 August – 0040 UTC 10 August 2021

Severe thunderstorms developed over northeast Illinois late in the afternoon on 9 August, and a series of tornadoes resulted. Storm Reports (from the Storm Prediction Center) are shown below. The mp4 animation above (click here for a large animated gif) shows 1-minute GOES-16 Mesoscale Sector 2 visible imagery (0.64 µm) from 1900 UTC on 9 August through 0040 UTC on 10 August. The active convection is apparent.

SPC Storm Reports from 9 August 2021 (Click to view site at SPC)

Part of the region hit by severe weather is in a persistent drought, as shown below (an image from this website). Rains that accompanied the severe weather provided some drought relief. (Click here for hourly CMORPH2 precipitation estimates from RealEarth)

Drought Intensity over the Midwestern United States, 3 August 2021 (Click to enlarge). Portions of southeast Wisconsin and northeast Illinois are under Severe Drought (Orange Enhancement)

RCM3 (RADARSAT Constellation Mission 3) Synthetic Aperture Radar (SAR) winds from a 2340 UTC overpass on 9 August (from this site) show a wind feature over Lake Michigan associated with the convection. These wind estimates might be affected by ice within the glaciated clouds

RCM3 SAR esimates of wind speed, 2340 UTC on 9 August 2021 (Click to enlarge)

Severe thunderstorms in northern Minnesota

July 26th, 2021 |
GOES-16 “Red” Visible (0.64 µm) images (top) and “Clean” Infrared Window (10.35 µm) images (bottom), with plots of SPC Storm Reports [click to play animation | MP4]

GOES-16 “Red” Visible (0.64 µm) images (top) and “Clean” Infrared Window (10.35 µm) images (bottom), with plots of SPC Storm Reports [click to play animation | MP4]

1–minute Mesoscale Domain Sector GOES-16 (GOES-East) “Red” Visible (0.64 µm) images and “Clean” Infrared Window (10.35 µm) images (above) include time-matched plots of SPC Storm Reports produced by supercell thunderstorms that moved east-southeastward across northern Minnesota during the afternoon and early evening hours on 26 July 2021. Severe reports included a tornado at 2213 UTC and hail as large as to 3.0 inches in diameter at 2334 UTC. These storms developed near and north of a warm/stationary frontal boundary (surface analyses).