GOES-16 (GOES-East) “Clean” Infrared Window (10.3 µm) images (above) showed Willa during the 48 hours that it rapidly intensified (ADT | SATCON) from a Tropical Storm at 15 UTC on 20 October to a Category 5 Hurricane at 15 UTC on 22 October 2018. Willa  — which became the third Category 5 hurricane of the 2018 season in the northeast Pacific basin (east of 180º longitude) — formed and had been moving over very warm water, with Sea Surface Temperatures of 29-30ºC. Deep-layer wind shear was also light during the 15 hour period lead up to Category 5 intensity.

Suomi NPP VIIRS Day/Night Band (0.7 µm) and Infrared Window (11.45 µm) images (below; courtesy of William Straka, CIMSS) showed Category 4 Willa off the west coast of Mexico at 0852 UTC on 22 October. The Moon was in the Waxing Gibbous phase (at 95% of Full), providing ample illumination for a “visible image at night” using the VIIRS Day/Night Band. Intricate cloud-top gravity waves were seen propagating radially outward from the storm center.

1-minute Mesoscale Domain Sector GOES-16 “Red” Visible (0.64 µm) and “Clean” Infrared Window images (below) revealed the small eye of the Category 5 hurricane after sunrise, with multiple convective bursts that erupted along the western edge of the eyewall. A continuous series of storm-top waves could be seen propagating radially outward away from the eye on Visible imagery. However, the eye eventually became cloud-filled as Willa began to undergo an eyewall replacement cycle — the formation of a larger-diameter outer eyewall was evident on the MIMIC-TC product — and weaken to a Category 4 intensity.

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

GOES-17 “Red” Visible (0.64 µm) images (below) provided a more direct view of the storm, since the satellite was positioned over the Equator at 89.5º W longitude while in its post-launch testing location.

October 23 is the last full day, for a while, to use GOES-16 and GOES-17 data to produce stereoscopic imagery. GOES-17 is set to cease data transmission on 24 October around 1500 UTC as it starts its motion towards its operational GOES-West position of 137.2º W Longitude. The animation below, starting at 1307 UTC on 23 October, (click here for an animated gif) shows the occasional appearance of an eye within the storm center on 23 October as it approached the coast. To view the image in three dimensions, cross your eyes until 3 images are apparent, then focus on the image in the middle.

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Thanks go out to Jason Alumbaugh from NWS Marquette, who sent the following in an email:

“Previous shift here at NWS Marquette passed along interesting feature on satellite last night. Origin of the feature is approx. 49.23 N and 91.00 W (just west of CWDV – Upsala in Ontario) but eventually the plume spread as far south as south central Upper Michigan and northeast Wisconsin (IMT to MNM). Our meteorologists said it looked like a fire and called Environment Canada overnight but they had not heard of anything reported.”

Taking a look at the initial daytime formation of the plume on 20 October 2018, a very subtle signature could be seen at times in GOES-16 (GOES-East) “Red” Visible (0.64 µm) images, but the plume was more obvious in the Near-Infrared “Snow/Ice” (1.61 µm), Near-Infrared “Cloud Particle Size” (2.24 µm) and Shortwave Infrared (3.9 µm) imagery (above). Emissions from an industrial source (likely a power plant, or perhaps the Domtar paper mill?) acted as cloud condensation nuclei, causing a higher concentration of smaller supercooled cloud droplets downwind of the plume source — and this plume of smaller particles was more reflective and thus appeared brighter in the 1.61/2.24 µm images and warmer (darker gray) in the 3.9 µm images.

Color-enhanced 3.9 µm Shortwave Infrared imagery (below) showed the transition from a warmer (darker red) plume during the day — due to enhanced reflection of incoming solar radiation — to a colder (darker blue) plume at night.

The higher spatial resolution of MODIS and VIIRS imagery from the polar-orbiting Terra/Aqua and NOAA-20/Suomi NPP satellites offered alternative views of the plume. A comparison of Suomi NPP VIIRS Visible (0.64 µm), Day/Night Band (0.7 µm), Near-Infrared “Snow/Ice” (1.61 µm), Shortwave Infrared (3.74 µm) and Infrared Window (11.45 µm) images (below) showed the early stage of the plume during the day on 20 October — as was seen with GOES-16, the plume signature was most obvious in the 1.61 µm Snow/Ice and 3.74 µm Shortwave Infrared imagery.

A nighttime comparison of Suomi NPP VIIRS Day/Night Band (0.7 µm), Shortwave Infrared (3.74 µm), Infrared Window (11.45 µm) and Fog/stratus Brightness Temperature Difference (11.45-3.74 µm) images (below) revealed signatures of the plume at 0716 UTC or 2:16 am CDT on 21 October, after it had traveled nearly 350 miles from the Ontario source to the Green Bay, Wisconsin area. Cloud-top 11.45 µm infrared brightness temperatures of the plume and the surrounding supercooled clouds were generally in the -13º to -16ºC range.

A sequence of nighttime Fog/stratus BTD images from Terra/Aqua MODIS and NOAA-20/Suomi NPP VIIRS (below) showed the plume moving southeastward across the Upper Peninsula of Michigan into northeastern Wisconsin. BTD values associated with the plume were in the 3-5ºC range (darker shades of red). [Note: the NOAA-20 VIIRS images are incorrectly labeled as Suomi NPP]

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Aerolineas Argentinas Flight 1303 encountered severe turbulence while flying from Miami, Florida to Buenos Aires, Argentina on 18 October 2018 (media report). The flight track (above) and flight log data indicated that the aircraft rapidly gained then lost over 2000 feet in altitude around 1823 UTC while over far western Brazil.

GOES-16 (GOES-East) “Clean” Infrared Window (10.3 µm) images (below) showed a cluster of rapidly-developing thunderstorms at that location and time (within the red circle) — cloud-top infrared brightness temperatures were colder than -80ºC (shades of violet).

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With a large dome of high pressure centered over Iowa/Missouri/Illinois (above), the stage was set for a night of strong radiational cooling across much of the Upper Midwest on 17/18 October 2018. Minimum temperatures were generally in the 20-40ºF range, with the coldest being 15ºF at Champion in the Upper Peninsula of Michigan.

An animation of 5-minute GOES-16 (GOES-East) “Clean” Infrared Window (10.3 µm) images (below) suggested a lack of clouds across most of the region, except for some patchy mid/high-level clouds drifting slowly northward from Nebraska/Wyoming across western South Dakota and far southeastern Montana. However, a close inspection of the imagery revealed the subtle appearance of “motion” across northern/eastern North Dakota into eastern South Dakota and far western Minnesota. This was noted by Carl Jones (NWS Grand Forks), who further pointed out “strong winds just above the surface (45 kt at 900ft per KMVX VWP) mixing down a huge warm tongue at 900mb along with downslope influences”. A comparison of the GOES-16 Infrared images with topography showed the slightly higher elevation of the Coteau du Missouri (elevation around 2000 feet) across southwestern North Dakota and western South Dakota along with the more narrow Coteau des Prairies in northeastern South Dakota and southwestern Minnesota — and a subtle “downslope warming” effect could be seen on the Infrared images (warmer temperatures are darker shades of blue with the applied enhancement).

The same effect was evident on hourly images of the GOES-16 Land Surface Temperature product (below). However, with the Land Surface Temperature product enhancement, warmer temperatures appear as lighter shades of cyan.

Similarly, a sequence of higher spatial resolution Infrared Window images from Terra/Aqua MODIS (11.0 µm) and NOAA-20/Suomi NPP VIIRS (11.45 µm) (below) showed the slow propagation of the downslope warming. The lack of fog or low clouds was confirmed via this comparison of VIIRS Infrared Window and “Fog product” Brightness Temperature Difference at 0903 UTC; no airports were reporting any clouds or a surface visibility less than 10 miles.

12 UTC NAM40 winds and isotachs at a height of 0.5 km above ground level (below) verified the presence of broad southwesterly flow off the Coteau du Missouri and the Coteaus des Prairies, with subtle warming (darker shades of blue) immediately downwind.

Plots of 12 UTC rawinsonde data from Bismarck, North Dakota and Aberdeen, South Dakota (below) showed strong low-level temperature inversions that morning — and at the top of those temperature inversions, southwesterly winds of 27 knots at a height of 1056 feet over Bismarck and 26 knots at 728 feet over Aberdeen.

 

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