Severe thunderstorms in Wyoming and South Dakota

June 29th, 2018 |

GOES-16

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

1-minute Mesoscale Domain Sector GOES-16 (GOES-East) “Red” Visible (0.64 µm) images (above) showed the development of large clusters of thunderstorms that moved from northeastern Wyoming into South Dakota during the afternoon and evening hours on 29 June 2018. These storms produced a variety of severe weather (SPC storm reports | NWS Rapid City), including tornadoes, hail of 4.50 inches in diameter and damaging wind gusts of 90 mph.

The corresponding GOES-16 “Clean” Infrared Window (10.3 µm) images (below) indicated that the coldest cloud-top infrared brightness temperatures associated with the strongest overshooting tops were generally around -70ºC (black enhancement).

GOES-16

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

GOES-16 Mid-level Water Vapor (6.9 µm) images (below) revealed a shortwave trough which was moving eastward across the northern Rocky Mountains — the approach of this mid-tropospheric trough was bringing enhanced forcing for ascent to aid in the development of thunderstorms.

GOES-16 Mid-level Water Vapor (6.9 µm) images [click to play MP4 animation]

GOES-16 Mid-level Water Vapor (6.9 µm) images [click to play MP4 animation]

===== 30 June Update =====

A comparison of before/after Terra MODIS True Color Red-Green-Blue (RGB) images viewed using RealEarth (below) revealed a pair of crop/vegetation damage swaths — the first (oriented northwest to southeast) caused by storms early on 27 June, and the second (oriented approximately west to east) caused by the 29 June storms shown on the GOES-16 imagery above. One SPC storm report listed hail of 2.00 inches in diameter with winds gusting to 69 mph near Mission Ridge SD — wind-driven hail of that size can easily inflict significant damage to structures and vegetation.

Terra MODIS True-Color images on 26 June, 27 June and 30 June [click to enlarge]

Terra MODIS True Color RGB images on 26 June, 27 June and 30 June [click to enlarge]

===== 02 July Update =====

Aqua MODIS True Color RGB image [click to enlarge]

Aqua MODIS True Color RGB image [click to enlarge]

An Aqua MODIS True Color RGB image on 02 July (above) provided a cloud-free view of the segmented west-to-east 29 June hail/wind damage path across western/central South Dakota — NWS Aberdeen noted that the storm producing this damage traveled more than 420 miles. In addition, the hazy signature of smoke being transported northeastward (from wildfires in Colorado) was apparent at the bottom center of the image. These hail/wind damage swaths (as well as the wildfire smoke aloft) were also evident in GOES-16 Natural Color RGB imagery.

Looking at the corresponding Aqua MODIS Visible (0.65 µm) image, Normalized Difference Vegetation Index (NDVI) product and Land Surface Temperature (LST) product (below), the hail/wind damage swaths were characterized by NDVI values in the 0.2-0.4 range (compared to adjacent healthy vegetation values of 0.7-0.8) and LST values  warmer than 100-110ºF (adjacent healthy vegetation LST values were generally in the 80s F). The lowest NDVI values were observed in parts of Sully and Hughes Counties, within the northwest-to-southeast 27 June damage path — there were reports of extensive crop devastation and wildlife casualties in that area (media story).

Aqua MODIS Visible (0.65 µm) image and Normalized Difference Vegetation Index (NDVI) and Land Surface Temperature (LST) products [click to enlarge]

Aqua MODIS Visible (0.65 µm) image, Normalized Difference Vegetation Index (NDVI) product and Land Surface Temperature (LST) product [click to enlarge]

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