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]

Tornado in Luzerne County, Pennsylvania

June 14th, 2018 |

GOES-16 ABI Band 2 (Red Visible, 0.64 µm) over northeastern Pennsylvania. Luzerne County is outlined in Yellow, and Wilkes-Barre’s location is highlighted as a yellow box (Click to animate)

A confirmed tornado struck Wilkes-Barre in Luzerne County in northeastern Pennsylvania shortly after sunset on 13 June 2018 (at about 0215 UTC). Visible imagery, above, shows the line of thunderstorms approaching the region before sunset. This video, from Citizens Voice Reporter Nico Rossi, shows some of the damage.

NOAA/CIMSS ProbTor captured the tornadic cell very well (Click this link for a discussion that includes infrared satellite animations). Click here for real-time access to ProbTor.

1-minute Mesoscale Sector GOES-16 Band 13 (Clean Infrared Window, 10.3 µm) images with plots of SPC storm reports are shown below. The Wilkes-Barre PA tornado is plotted as a red T on the 0200 UTC image.

GOES-16 Band 13 (Clean Infrared Window, 10.3 µm) images, with SPC storm reports plotted in red [click to animate]

GOES-16 Band 13 (Clean Infrared Window, 10.3 µm) images, with SPC storm reports plotted in red [click to animate]

Below is a 1-km resolution Terra MODIS Band 31 (Infrared Window, 11.0 µm) image from shortly after the Luzerne County tornado, showing the line of convection that had developed in advance of a cold front. The 2 overlapping SPC storm reports (listed as damaging winds, with report times of 2008 and 2015 UTC) for the Wilkes-Barre event are in the center of the image. The minimum cloud-top infrared brightness temperature was -66ºC.

Terra MODIS Band 31 (Infrared Window, 11.0 µm) image, with plots of cumulative SPC storm reports and the 03 UTC position of the surface cold front [click to enlarge]

Terra MODIS Band 31 (Infrared Window, 11.0 µm) image, with plots of cumulative SPC storm reports and the 03 UTC position of the surface cold front [click to enlarge]

Mesoscale Convective System in the Plains

June 11th, 2018 |

GOES-16

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

A Mesoscale Convective System (MCS) developed over eastern Nebraska early in the evening on 11 June 2018, then propagated southward across the Plains during the subsequent overnight hours. GOES-16 (GOES-East) “Clean” Infrared Window (10.3 µm) images with plots of SPC storm reports are shown above; a Mesoscale Sector was positioned over the region, providing images at 1-minute intervals.

A closer look over Kansas using Infrared imagery from polar-orbiting satellites (below) revealed some very cold cloud-top infrared brightness temperatures, which included -87ºC on MODIS, -90ºC on VIIRS and -92ºC on AVHRR.

POES AVHRR, Terra/Aqua MODIS and Suomi NPP VIIRS Infrared images, with plots of SPC storm reports [click to enlarge]

Metop-B AVHRR, Terra/Aqua MODIS and Suomi NPP VIIRS Infrared images, with plots of SPC storm reports [click to enlarge]

The coldest air temperature on 00 UTC rawinsonde data from Dodge City and Topeka, Kansas (below) was -69.5ºC (at altitudes of 14.6 km/49,900 feet at Dodge City, and 17.6 km/57,700 feet at Topeka) — so in theory air parcels and cloud material within a vigorous overshooting top could have ascended a few km (or thousands of feet) beyond those altitudes to exhibit an infrared brightness temperature of -92ºC.

Plots of rawinsonde data from Dodge City and Topeka, Kansas [click to enlarge]

Plots of rawinsonde data from Dodge City and Topeka, Kansas [click to enlarge]

A toggle between re-mapped versions of the GOES-16 ABI and Metop-B AVHRR Infrared imagery over Kansas at the time of the very cold cloud-top infrared brightness temperature (below) revealed 2 important points: (1) with improved spatial resolution (1 km for AVHRR, vs 2 km *at satellite sub-point* for ABI) the instrument detectors sensed much colder temperatures (-92.6ºC with AVHRR vs -81.2ºC with ABI), and (2) due to parallax. the GOES-16 image features are displaced to the northwest. In addition to the isolated cold overshooting top in south-central Kansas, note the pronounced “Enhanced-V” storm top signature in far northeastern Kansas.

Comparison of GOES-16 ABI and Metop-B AVHRR Infrared images [click to enlarge]

Comparison of GOES-16 ABI and Metop-B AVHRR Infrared images [click to enlarge]

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Cape Newenham, Alaska bow shock waves

June 10th, 2018 |

GOES-15 Visible (0.63 µm) images, with hourly plots of wind barbs [click to play animation]

GOES-15 Visible (0.63 µm) images, with hourly plots of wind barbs [click to play animation]

GOES-15 (GOES-West) Visible (0.63 µm) images (above) showed patches of fog and low stratus moving southwestward off Southwest Alaska and across the adjacent offshore waters of the Bering Sea on 10 June 2018.

A closer look using 250-meter resolution Terra/Aqua MODIS and 375-meter resolution Suomi NPP VIIRS true-color Red-Green-Blue (RGB) images from RealEarth (below) revealed a packet of “bow shock waves” created as the shallow fog/stratus interacted with the relatively rugged terrain of the narrow Cape Newenham land feature (Google Maps). Other examples of similar bow shock wave cloud features have been documented here, here and here.

Terra MODIS, Aqua MODIS and Suomi NPP VIIRS true-color RGB images [click to enlarge]

Terra MODIS, Aqua MODIS and Suomi NPP VIIRS true-color RGB images [click to enlarge]

A 30-meter resolution Landsat-8 false-color RGB image (below) provided a more detailed view of the bow shock wave structure. Snow cover (cyan) could be seen on some of the higher-elevation land features.

Landsat-8 false-color RGB image [click to enlarge]

Landsat-8 false-color RGB image [click to enlarge]

A time series plot of Cape Newenham surface observations (below) showed the fluctuations in visibility as northerly winds brought patches of fog over the site.

Time series plot of Cape Newenham surface observations [click to enlarge]

Time series plot of Cape Newenham surface observations [click to enlarge]