Derecho from the Midwest to the Mid-South

June 28th, 2018 |

GOES-16

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

GOES-16 (GOES-East) “Red” Visible (0.64 µm) images (above) showed a large Mesoscale Convective System (MCS) which produced a long-lived path of large hail and damaging winds from eastern Nebraska to western Tennessee on 28 June 2018. The length and duration of damaging wind events (SPC storm reports) qualified this event as a derecho.

The corresponding GOES-16 “Clean” Infrared Window (10.3 µm) images (below) revealed cold cloud-top infrared brightness temperatures that occasionally reached -80ºC (violet enhancement).

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

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

A closer look at the MCS using 375-meter resolution Suomi NPP VIIRS Infrared Window (11.45 µm) images (below) showed cloud-top gravity waves on the 1844 UTC image, propagating radially outward from the primary area of overshooting tops; cloud-top infrared brightness temperatures were as cold as -86ºC (violet enhancement).

Suomi NPP VIIRS Infrared Window (11.45 µm) images, with SPC storm reports plotted during the 3 hours preceding the 1844 UTC image [click to enlarge]

Suomi NPP VIIRS Infrared Window (11.45 µm) images, with plots of SPC storm reports during the 3 hours preceding the 1844 UTC image [click to enlarge]

Severe thunderstorms in the Southeast US

June 25th, 2018 |

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 (GOES-East) “Clean” Infrared Window (10.3 µm) images (above) showed the development of thunderstorms which produced small hail and widespread damaging winds (SPC storm reports) across the Southeast US on 25 June 2018.

A closer view of the storms was provided by GOES-16 “Red” Visible (0.64 µm) images (below).

GOES-16

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

A toggle between an 1854 UTC Aqua MODIS Infrared Window (11.0 µm) image and the corresponding Total Precipitable Water derived product (below) showed that abundant moisture was in place across the region — as pointed out by a SPC Mesoscale Discussion, TPW values in excess of 2.0 inches (50 mm, violet enhancement) suggested that wet microbursts were likely with any thunderstorms that developed.

Aqua MODIS Infrared Window (11.0 µm) image and Total Precipitable Water derived product, with plots of SPC storm reports [click to enlarge]

Aqua MODIS Infrared Window (11.0 µm) image and Total Precipitable Water derived product, with plots of SPC storm reports [click to enlarge]



Severe thunderstorms in Kansas and Oklahoma

June 23rd, 2018 |

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 (GOES-East) “Clean” Infrared Window (10.3 µm) images (above) showed the development of a number of Mesoscale Convective System (MCS) features across the southern Plains (with a focus on Kansas and Oklahoma) after sunset on 23 June 2018. A Mesoscale Domain Sector was positioned over that region, providing images at 1-minute intervals; SPC storm reports are plotted in cyan.

A toggle between Suomi NPP VIIRS Day/Night Band (0.7 µm) and Infrared Window (11.45 µm) images at 0748 UTC or 2:48 am CDT (below) showed two MCS features — one with its core in north-central Oklahoma and another over eastern Oklahoma. Features exhibited by the northern storm included numerous bright lightning streaks on the Day/Night Band image, with one cluster located over an area of damaging wind reports. The minimum cloud-top infrared brightness temperature associated with this storm was -86ºC (violet enhancement). Over Kansas, packets of gravity waves could be seen on both images, propagating radially outward from the storm core along the cloud top. The combination of lightning and damaging winds (which downed power poles) led to power outages that lasted into the next evening (map | provider listing) across parts of Oklahoma.

With the MCS over eastern Oklahoma, a large cluster of bright lightning streaks was co-located with the overshooting top (which had a minimum cloud-top infrared brightness temperature of -80ºC) — and a distinct above-anvil cirrus plume could be seen flowing east-southeastward from the overshooting top.

Suomi NPP VIIRS Day/Night Band (0.7 µm) and Infrared Window (11.45 µm) images, with SPC storm reports of damaging winds plotted in cyan [click to enlarge]

Suomi NPP VIIRS Day/Night Band (0.7 µm) and Infrared Window (11.45 µm) images, with SPC storm reports of damaging winds plotted in cyan [click to enlarge]

About 48 minutes later, a 0836 UTC overpass of the NOAA-20 satellite provided similar VIIRS Day/Night Band and Infrared Window images (below). However, in that relatively short amount of time the Moon had moved to a position low on the western horizon, providing much less illumination of the cloud tops for the Day/Night Band image. Another striking difference was the presence of long black or dark gray “post-saturation recovery streaks” downstream of bright clusters of lightning in north-central Oklahoma — as the VIIRS instrument scanned across-track (from northwest to southeast), the Day/Night Band optical detectors became saturated by the brightness of the intense lightning activity. The minimum cloud-top infrared brightness temperature in eastern Oklahoma was -86ºC.

NOAA-20 VIIRS Day/Night Band (0.7 µm) and Infrared Window (11.45 µm) images [click to enlarge]

NOAA-20 VIIRS Day/Night Band (0.7 µm) and Infrared Window (11.45 µm) images [click to enlarge]

Large hail in north central Colorado

June 18th, 2018 |

GOES-16

GOES-16 “Red” Visible (0.64 µm, left) and “Clean” Infrared Window (10.3 µm, right) images, with plots of SPC storm reports [click to play MP4 animation]

Severe thunderstorms developed  over the Front Range of Colorado during the late afternoon and early evening of 18 June 2018. One of the GOES-16 (GOES-East) Mesoscale Domain Sectors positioned over that region provided 1-minute data — shown above is a comparison of “Red” Visible (0.64 µm) and “Clean” Infrared Window (10.3 µm) images of these storms as they produced large hail (up to 3 inches in diameter) across parts of the Front Range Urban Corridor. SPC storm reports are plotted on the images.