Fog/stratus over Lake Michigan

June 30th, 2018 |

GOES-16

GOES-16 “Red” Visible (0.64 µm) images, with hourly plots of surface reports [click to play animation | MP4]

As a warm and very humid air mass (surface analyses) moved northward across the relatively cool waters of Lake Michigan on 30 June 2018, GOES-16 (GOES-East) “Red” Visible (0.64 µm) images (above) revealed complex interactions of the resulting fog/stratus with coastlines and islands — features such as “bow shock waves” and internal reflections of waves off the northern end of the lake could be seen.

A 30-meter resolution Landsat-8 false-color Red-Green-Blue (RGB) image viewed using RealEarth (below) provided a very detailed view of the fog/stratus structure over the northern end of the lake.

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

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

The Aqua MODIS Sea Surface Temperature product at 1734 UTC (below) showed SST values in the middle 60s to around 70ºF across the southern end of Lake Michigan (the southern lake buoy reported a water temperature of 66ºF), transitioning to SST values around 60ºF mid-lake. The northern lake buoy reported a water temperature of 54ºF — much colder than the surface air dew points that were in the low to middle 70s F, which explained the more widespread coverage of lake fog/stratus farther north.

Aqua MODIS Sea Surface Temperature product, with plots of surface and buoy reports [click to enlarge]

Aqua MODIS Sea Surface Temperature product, with plots of surface and buoy reports [click to enlarge]

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]

Severe thunderstorms in Montana and South Dakota

June 28th, 2018 |

GOES-16

GOES-16 “Red” Visible (0.64 µm) images, with SPC storm reports plotted in red; Carter County, Montana and Harding County, South Dakota are outlined in blue [click to play MP4 animation]

1-minute Mesoscale Domain Sector GOES-16 (GOES-East) “Red” Visible (0.64 µm) images (above) showed thunderstorms which produced large hail and tornadoes in far southeastern Montana and far northwestern South Dakota (SPC storm reports | NWS Billings | NWS Rapid City) on 28 June 2018. The pulsing nature of the parent storm’s overshooting tops was very apparent in the animation.

The corresponding GOES-16 “Clean” Infrared Window (10.3 µm) images (below) revealed cloud-top infrared brightness temperatures in the -70 to -75ºC range (black to light gray enhancement) associated with some of the overshooting tops (for example, at 0233 UTC).

GOES-16 "Clean" Infrared Window (10.3 µm) images, with SPC storm reports plotted in red; Carter County, Montana and Harding County, South Dakota are outlined in blue [click to play MP4 animation]

GOES-16 “Clean” Infrared Window (10.3 µm) images, with SPC storm reports plotted in red; Carter County, Montana and Harding County, South Dakota are outlined in blue [click to play MP4 animation]

These overshooting top infrared brightness temperatures were 5-10ºC colder than the -65.3ºC tropopause temperature on 00 UTC Rapid City SD rawinsonde data (below).

Plot of rawinsonde data from Rapid City SD [click to enlarge]

Plot of rawinsonde data from Rapid City SD [click to enlarge]

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]