Flash flooding in southern Wisconsin

August 20th, 2018 |

GOES-16 “Red” Visible (0.64 µm) images [click to play MP4 animation]

1-minute Mesoscale Domain Sector GOES-16 “Red” Visible (0.64 µm) images (above) showed multiple bands 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. As much as 15.33 inches of rain was reported in Cross Plains (Local Storm Reports) — 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). There was also an EF-0 tornado at Delavan. Animations of radar base reflectivity and storm total precipitation (courtesy of Pete Pokrandt, UW-AOS) showed that the combination of slow overall motion, cell mergers and a pivoting of precipitation bands played a role in producing the heavy rainfall.

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 [click to play 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 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 product [click to play MP4 animation]

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]

Wildfires in British Columbia

August 17th, 2018 |

GOES-16

GOES-16 “Red” Visible (0.64 µm, left) and Shortwave Infrared (3.9 µm, right) images [click to play MP4 animation]

A 2-panel comparison of GOES-16 (GOES-East) “Red” Visible (0.64 µm) and Shortwave Infrared (3.9 µm) images (above) showed the smoke plumes and thermal anomalies or “hot spots” (darker black to red pixels) associated with a flare-up of wildfires in western British Columbia on 17 August 2018.

A sequence of Shortwave Infrared (3.7 µm) images from Terra / Aqua MODIS and Suomi NPP / NOAA-20 VIIRS (below) revealed the diurnal changes in areal coverage and intensity of the thermal signature of the fires.

Shortwave Infrared (3.7 µm) images from Terra / Aqua MODIS and Suomi NPP / NOAA-20 VIIRS [click to enlarge]

Shortwave Infrared (3.7 µm) images from Terra / Aqua MODIS and Suomi NPP / NOAA-20 VIIRS [click to enlarge]

Toggles between Visible and Shortwave Infrared images from Terra MODIS (1912 UTC), NOAA-20 VIIRS (1950 UTC) ans Suomi NPP VIIRS (2129 UTC) are shown below (note: the NOAA-20 images are incorrectly labeled as Suomi NPP). It is interesting to note the impact that the smoke plume had on the air temperature at Quesnel (CYQZ) — because the smoke layer was optically dense enough (VIIRS True Color image) to significantly reduce incoming solar radiation, the temperature was as much as 14-18ºF (8-10ºC) cooler than Prince George (CYXS) to the north and Williams Lake (CYWL) to the south.

Terra MODIS Visible (0.65 µm) and Shortwave Infrared (3.7 µm) images [click to enlarge]

Terra MODIS Visible (0.65 µm) and Shortwave Infrared (3.7 µm) images at 1912 UTC [click to enlarge]

NOAA-20 VIIRS Visible (0.64 µm) and Shortwave Infrared (3.74 µm) images [click to enlarge]

NOAA-20 VIIRS Visible (0.64 µm) and Shortwave Infrared (3.74 µm) images at 1950 UTC [click to enlarge]

Suomi NPP VIIRS Visible (0.64 µm) and Shortwave Infrared (3.74 µm) images at 2129 UTC [click to enlarge]

Suomi NPP VIIRS Visible (0.64 µm) and Shortwave Infrared (3.74 µm) images at 2129 UTC [click to enlarge]

Farther to the east in Alberta, thick smoke caused very poor air quality in cities like Edmonton and Grande Prairie (photo 1 | photo 2). Daily composites of Suomi NPP VIIRS True Color RGB images from 11 August to 17 August (below) revealed the transport of smoke across British Columbia, Alberta and Saskatchewan.

Daily composites of Suomi NPP VIIRS True Color RGB images (with VIIRS fire detections in red), 11-17 August [click to play MP4 | Animated GIF]

Daily composites of Suomi NPP VIIRS True Color RGB images (with VIIRS fire detections in red), 11-17 August [click to play MP4 | Animated GIF]

A time series of surface reports from Edmonton, Alberta covering the period 14-17 August (below) showed that smoke restricted the surface visibility there to 1.5 miles on 15 August and 17 August.

Time series of surface reports from Edmonton, Alberta during the period 14-17 August [click to enlarge]

Time series of surface reports from Edmonton, Alberta during the period 14-17 August [click to enlarge]

===== 19 August Update =====

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

GOES-17 Near-Infrared

GOES-17 Near-Infrared “Cloud Particle Size” (2.24 µm, left) and Shortwave Infrared (3.9 µm, right) images [click to play 81 Mbyte MP4 animation]

A 2-panel comparison of GOES-17 Near-Infrared “Cloud Particle Size” (2.24 µm) and Shortwave Infrared (3.9 µm) images during the 7-day period of 13-19 August (above) showed the diurnal changes in thermal signatures of the ongoing British Columbia wildfires. The nighttime thermal signatures seen on the 2.24 µm images (brighter white pixels) result from the fact that this spectral band is located close to the peak emitted radiance of very hot features such as active volcanoes or large fires (below).

Plots of Spectral Response Functions for ABI Bands 5, 6 and 7 [click to enlarge]

Plots of Spectral Response Functions for ABI Bands 5, 6 and 7 [click to enlarge]

Tornadoes in Wyoming

July 28th, 2018 |

GOES-16

GOES-16 “Red” Visible (0.64 µm) images, with hourly plots of surface observations (cyan/yellow) along with SPC storm reports and Interstate Highways (red) and State Highways (cyan) [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 a supercell thunderstorm that produced tornadoes, large hail and damaging winds (SPC storm reports) across parts of eastern Wyoming on 28 July 2018. A distinct above-anvil cirrus plume could be seen with this storm.

The corresponding GOES-16 “Clean” Infrared Window (10.3 µm) images (below) revealed that the dominant northern storm began to exhibit a well-defined “enhanced-V” signature (2051 UTC image) about an hour before it began to produce tornadoes. Minimum cloud-top infrared brightness temperatures were in the -60 to -65ºC range (darker shades of red) with the stronger pulses of overshooting tops.

GOES-16 "Clean" Infrared Window (10.3 µm) images, with hourly plots of surface observations (yellow) along with SPC storm reports (cyan) Interstate Highways (violet) and State Highways (cyan) [click to play MP4 animation]

GOES-16 “Clean” Infrared Window (10.3 µm) images, with hourly plots of surface observations (yellow) along with SPC storm reports (cyan) Interstate Highways (violet) and State Highways (cyan) [click to play MP4 animation]

A sequence of Infrared Window images from Suomi VIIRS (11.45 µm) and Aqua MODIS (11.0 µm) (below) showed minimum cloud-top infrared brightness temperatures rapidly cooling from the -40s to -72ºC as the dominant storm crossed Interstate 25.

Suomi NPP VIIRS and Aqua MODIS Infrared Window images [click to enlarge]

Infrared Window images from Suomi NPP VIIRS (11.45 µm) and Aqua MODIS (11.0 µm) [click to enlarge]

A comparison of the Terra and Aqua MODIS Total Precipitable Water product (below) indicated that TPW values increased from the 10-20 mm range to the 20-30 mm range in less than 2 hours.

Terra and Aqua MODIS Total Precipitable Water product [click to enlarge]

Terra and Aqua MODIS Total Precipitable Water product [click to enlarge]

Fog/stratus along the New England coast

July 24th, 2018 |

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

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

The GOES-16 (GOES-East) Total Precipitable Water product (above) showed a northerly/northwesterly flow of tropical moisture toward New England during the day on 24 July 2018, with TPW values in the 1.0 to 1.6 inch range moving toward the region. As this moist air moved over relatively cool water — as indicated by Aqua MODIS Sea Surface Temperature values generally in the 60s F on the previous day (below) — areas of marine boundary layer fog/stratus developed.

Aqua MODIS Sea Surface Temperature product from 23 July [click to enlarge]

Aqua MODIS Sea Surface Temperature product from 23 July [click to enlarge]

1-minue Mesoscale Domain Sector GOES-16 “Red” Visible (0.64 µm) images (below) revealed interesting patterns in the resulting marine layer fog/stratus — for example, bow shock waves along the eastern edges of Nantucket Island and Cape Cod, and narrow clear swaths to the lee of some of the smaller islands off the coast of Maine.

GOES-16

GOES-16 “Red” Visible (0.64 µm) images [click to play MP4 animation]