A Nebraska thunderstorm and a Wyoming wildfire, as viewed by GOES-15, GOES-17 and GOES-16

August 29th, 2018 |
Visible images from GOES-15 (0.63 µm, left), GOES-17 (0.64 µm, center) and GOES-16 (0.64 µm, right), with SPC storm reports plotted in red [click to play animation | MP4]

Visible images from GOES-15 (0.63 µm, left), GOES-17 (0.64 µm, center) and GOES-16 (0.64 µm, right), with SPC storm reports plotted in red [click to play animation | MP4]

* GOES-17 images shown here are preliminary and non-operational *

A comparison of Visible images from GOES-15 (GOES-West), GOES-17 and GOES-16 (GOES-East) (above) showed an isolated thunderstorm that developed in the Nebraska Panhandle late in the day on 29 August 2018. The storm produced hail (SPC storm reports), and also exhibited an Above Anvil Cirrus Plume. The images are displayed in the native projection of each satellite, with no re-mapping.

One other feature that was seen north of the thunderstorm was smoke which was being transported eastward from the Britania Mountain Fire in southeastern Wyoming. The smoke was more apparent on the GOES-17 and GOES-16 images as forward scattering increased toward sunset.

Shortwave Infrared imagery from the 3 satellites revealed important differences affecting fire detection: namely spatial resolution and viewing angle. The 3.9 µm detector on the GOES-15 Imager has a spatial resolution of 4 km (at satellite sub-point), compared to 2 km for the GOES-16/17 ABI. Given that the fire was burning in rugged mountain terrain, the view angle from each satellite had an impact on the resulting bire brightness temperature values. For example, the first indication of very hot (red-enhanced) pixels was at 1527 UTC from GOES-16/17, vs 1715 UTC from GOES-15; at the end of the day, the very hot fire pixels were no longer seen with GOES-15 after 2300 UTC, but continued to show up in GOES-17 imagery until 0042 UTC and in GOES-16 imagery until 0122 UTC.

Shortwave Infrared images from GOES-15 (3.9 µm, left), GOES-17 (3.9 µm, center) and GOES-16 (3.9 µm, right) [click to play animation | MP4]

Shortwave Infrared images from GOES-15 (3.9 µm, left), GOES-17 (3.9 µm, center) and GOES-16 (3.9 µm, right) [click to play animation | MP4]

Severe thunderstorms in Wisconsin

August 28th, 2018 |

GOES-16

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

Thunderstorms produced a variety of severe weather (SPC storm reports) as they moved eastward across the Upper Midwest on 28 August 2018. 1-minute Mesoscale Domain Sector GOES-16 (GOES-East) “Red” Visible (0.64 µm) images (above) and “Clean” Infrared Window (10.3 µm) images (below) showed the development and progression of the severe convection across central Wisconsin.

GOES-16

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

Toggles beween Visible and Infrared images from Terra MODIS (1715 UTC), Aqua MODIS (1855 UTC) and Suomi NPP VIIRS (1945 UTC) are shown below.

Terra MODIS Visible (0.65 µm) and Infrared Window (11.0 µm) images, with plots of SPC storm reports [click to enlarge]

Terra MODIS Visible (0.65 µm) and Infrared Window (11.0 µm) images, with plots of SPC storm reports [click to enlarge]

Aqua MODIS Visible (0.65 µm) and Infrared Window (11.0 µm) images, with plots of SPC storm reports [click to enlarge]

Aqua MODIS Visible (0.65 µm) and Infrared Window (11.0 µm) images, with plots of SPC storm reports [click to enlarge]

Suomi NPP VIIRS Visible (0.64 µm) and Infrared Window (11.45 µm) images, with plots of SPC storm reports [click to enlarge]

Suomi NPP VIIRS Visible (0.64 µm) and Infrared Window (11.45 µm) images, with plots of SPC storm reports [click to enlarge]

These storms also brought heavy rain, which resulted in flooding that closed Interstate 90/94 near Mauston (about halfway between Madison and Fort McCoy) — that area received about 10 inches of rainfall in a 48-hour period (below). Amtrack trains were also forced to stop overnight near that same area, due to flooded tracks.

24-hour precipitation ending at 12 UTC on 28 August and 29 August [click to enlarge]

24-hour precipitation ending at 12 UTC on 28 August and 29 August [click to enlarge]

Hail-producing thunderstorm in South Dakota

August 26th, 2018 |
Visible images from GOES-15 (0.63 µm, left), GOES-17 (0.64 µm, center) and GOES-16 (0.64 µm, right) [click to play animation | MP4]

Visible images from GOES-15 (0.63 µm, left), GOES-17 (0.64 µm, center) and GOES-16 (0.64 µm, right), with SPC storm reports plotted in yellow [click to play animation | MP4]

 * GOES-17 images shown here are preliminary and non-operational *

A comparison of Visible images from GOES-15 (GOES-West), GOES-17 and GOES-16 (GOES-East) (above) showed a severe thunderstorm that developed ahead of an advancing cold front (surface analyses) in central South Dakota late in the day on 26 August 2018. This storm produced hail as large as 4.0 inches in diameter (SPC storm reports), and also exhibited an above anvil cirrus plume (AACP) which is a signature often associated with severe thunderstorms.

The images are displayed in the native projection of each satellite, with no re-mapping. Note the important differences due to satellite scan strategy — the GOES-15 imager was initially performing a Full Disk scan, so imagery was only available every 30 minutes; the GOES-17 ABI was scanning at the standard “CONUS Sector” 5 minute interval; a GOES-16 ABI Mesoscale Domain Sector was providing images every 1 minute.

Flash flooding in southern Wisconsin

August 20th, 2018 |

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

1-minute Mesoscale Domain Sector GOES-16 “Red” Visible (0.64 µm) images (above) showed multiple clusters of convection which developed across far southern Wisconsin during the late afternoon and early evening hours on 20 August 2018, producing very heavy rainfall and flash flooding (with at least one fatality) that was focused in western Dane County (CoCoRaHS | AHPS). As much as 15.33 inches of rain was reported in Cross Plains (Local Storm Reports). which set a new record for 24-hour precipitation in the state of Wisconsin (the old record was 11.72 inches at Mellen in northern Wisconsin on 24 June 1946). Animations of radar base reflectivity and storm total precipitation (courtesy of Pete Pokrandt, UW-AOS) showed that the combination of slow overall motion — and a pivoting of precipitation bands, due to weak flow aloft within a deformation zone (300 hPa analysis) —  and cell mergers played a role in producing the heavy rainfall. There was also an EF-0 tornado at Delavan (NWS Milwaukee summary).

The corresponding 1-minute GOES-16 “Clean” Infrared Window (10.3 µm) imagery (below) showed that cloud-top brightness temperatures were generally in the -50º to -60ºC range with these initial areas of convection.

GOES-16 Infrared images [click to play animation]

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

A longer Infrared animation (below) with a different color enhancement (adapted for winter convection) better emphasized the colder cloud tops as convective development persisted into the subsequent overnight hours. Note the absence surface observations from Middleton KC29 after 03 UTC or 10 pm CDT — this was due to an extended power outage to that area and other parts of western Dane County.

GOES-16

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

GOES-16 Mid-level Water Vapor (6.9 µm) images (below) revealed the large circulation associated with an occluded low (surface analyses) over the lower Missouri River valley.

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]

The GOES-16 Total Precipitable Water derived product (below) showed that values of 1.3 to 1.5 inches were being advected northward toward the area.

Composite of GOES-16 Water Vapor (6.9 µm) imagery and Total Precipitable Water product [click to play MP4 animation]

Composite of GOES-16 Water Vapor (6.9 µm) imagery and Total Precipitable Water derived product [click to play MP4 animation]

With widespread cloudiness prevailing across much of the Upper Midwest, the CIMSS All-Sky Total Precipitable Water product (below) was helpful to better track the transport of moisture into the region — TPW values of 40-43 mm (1.6-1.7 inches) were seen feeding into southern Wisconsin within a TROWAL airstream around the northern edge of the occluded low pressure system (WPC discussion). The All-Sky products blend GOES ABI clear-sky retrievals with GFS background fields in cloudy regions; these products have been evaluated by the NWS Hazardous Weather Testbed (see here).

GOES-16 AllSky Total Precipitable Water product [click to play animation | MP4]

GOES-16 All-Sky Total Precipitable Water product [click to play animation | MP4]

The Aqua MODIS Total Precipitable Water product at 1943 UTC (below) showed TPW values of 40-45 mm (1.6-1.8 inch) on either side of the frontal boundary in northern Illinois.

Aqua MODIS Total Precipitable Water product [click to enlarge]

Aqua MODIS Total Precipitable Water product [click to enlarge]

One example of the hydrologic impact of the heavy rain was seen at the Pheasant Branch Creek USGS gauge (map), where nearly 11 inches of rainfall were recorded. A dramatic time-lapse video showed the rise of the normally-small creek as it inundated the adjacent multi-use path on 21 August.

Pheasant Branch Creek flows into the northwest corner of Lake Mendota, which crested at 852.3 feet on the morning of 22 August. This was the third highest lake elevation on record — and the highest level on record for so late in the calendar year. Portions of the University of Wisconsin – Madison campus adjacent to the lake experienced some impacts due to the high water, as shown on the map below. There were also several road closures in Madison due to high water.

Map of flood impacts for portions of the UW-Madison campus adjacent to the southwestern shoreline of Lake Mendota [click to enlarge]

Map of flood impacts for portions of the UW-Madison campus adjacent to the southwestern shoreline of Lake Mendota [click to enlarge]

Farther downstream on the Yahara River chain of lakes, Lake Waubesa reached its 100-year flood level on 22 August.