CIMSS Satellite Blog, CIMSS

Convective snow squalls in the Upper Midwest

By Scott Bachmeier • 2 April 2016

A vigorous clipper-type shortwave moved rapidly southeastward across the Upper Midwest on 02 April 2016; there were widespread convective elements associated with this system as seen in GOES-13 Visible (0.63 µm) images (above), which produced moderate to heavy snowfall at times (and even thundersnow) creating brief white-out conditions (time-lapse video from the... Read More

GOES-13 Visible (0.63 µm) images, with hourly surface weather symbols [click to play animation]

A vigorous clipper-type shortwave moved rapidly southeastward across the Upper Midwest on 02 April 2016; there were widespread convective elements associated with this system as seen in GOES-13 Visible (0.63 µm) images (above), which produced moderate to heavy snowfall at times (and even thundersnow) creating brief white-out conditions (time-lapse video from the AOSS rooftop camera in Madison, Wisconsin). A sequence of visible images from the polar-orbiting MODIS, VIIRS, and AVHRR instruments (below) provided another detailed view of these convective elements. This disturbance produced strong winds and accumulating snowfall; more information can also be found here from the NWS Chicago.

MODIS, VIIRS, and AVHRR visible images [click to enlarge]

A pronounced warm/dry signature of middle-tropospheric subsidence (yellow color enhancement) was evident on GOES-13 Water Vapor (6.5 µm) images (below), which appeared to be along or just ahead of the areas of stronger wind gusts at the surface.

GOES-13 Water Vapor (6.5 µm) images with hourly wind gusts in knots [click to play animation]

This area of middle-tropospheric subsidence was located along the leading edge of a strong (110-120 knot) 500 hPa jet, as indicated by the NAM40 model isotachs (below).

GOES-13 Water Vapor (6.5 µm) images with METAR surface reports, surface fronts, and NAM40 500 hPa wind isotachs [click to play animation]

The convective elements were relatively shallow, with cloud-top infrared brightness temperatures only in the -20 to -30º C range (cyan to darker blue color enhancement) as seen in 4-km resolution GOES-13 Infrared Window (10.7 µm) images (below) and also in 1-km resolution MODIS, VIIRS, and AVHRR infrared images.

GOES-13 Infrared Window (10.7 µm) images, with hourly surface weather symbols [click to play animation]

The 24-hour snowfall amounts ending at 12 UTC on 02 and 03 April are shown below, from the NOHRSC site. There was a narrow swath of snowfall in excess of 3 inches just north of the track of the surface low (surface analyses), from northeast Minnesota across Wisconsin to southwest Lower Michigan.

24-hour snowfall amounts (in inches) ending at 12 UTC on 02 and 03 April [click to enlarge]

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Eruption of the Mount Pavlof volcano in Alaska

By Scott Bachmeier • 28 March 2016

A major eruption of the Mount Pavlof volcano on the Alaska Peninsula began shortly before 0000 UTC on 28 March, or 4:00 pm on 27 March Alaska time (AVO report), as detected by a thermal anomaly (or “hot spot”, yellow to red color enhancement) on Himawari-8 AHI Shortwave Infrared (3.9 µm) images... Read More

Himawari-8 AHI Shortwave Infrared (3.9 µm) images [click to play animation]

A major eruption of the Mount Pavlof volcano on the Alaska Peninsula began shortly before 0000 UTC on 28 March, or 4:00 pm on 27 March Alaska time (AVO report), as detected by a thermal anomaly (or “hot spot”, yellow to red color enhancement) on Himawari-8 AHI Shortwave Infrared (3.9 µm) images (above). The hot spot decreased in size and intensity toward the later hours of the day, signaling a lull in the volcanic eruption.

It is interesting to note on a comparison of the 0000 UTC Himawari-8 and GOES-15 Shortwave Infrared (3.9 um) images the large difference in the magnitude of the thermal anomaly — even though the viewing angle was larger for Himawari-8, the superior spatial resolution (2 km at nadir, compared to 4 km with GOES-15) detected a hot spot with an Infrared Brightness Temperature (IR BT) that was 36.6 K warmer (below). The Infrared channels on the GOES-R ABI instrument will also have a 2 km spatial resolution.

Himawari-8 AHI (left) and GOES-15 Imager (right) 3.9 µm Shortwave Infrared images [click to enlarge]

With the aid of reflected light from the Moon (in the Waxing Gibbous phase, at 75% of Full), a nighttime view using the Suomi NPP VIIRS Day/Night Band (0.7 µm) from the SSEC RealEarth site (below) revealed the bright glow of the eruption, along with the darker (compared to adjacent meteorological clouds) volcanic ash cloud streaming northeastward. The corresponding VIIRS Shortwave Infrared (3.74 µm) image showed the dark black hot spot of the volcano summit.

Suomi NPP VIIRS Shortwave Infrared (3.74 µm) and Day/Night Band (0.7 µm) image [click to enlarge]

The volcanic ash cloud continued moving in a northeastward direction, as seen in a sequence of GOES-15 Infrared Window (10.7 µm) and either Terra/Aqua MODIS or Suomi NPP VIIRS retrieved Volcanic Ash Height products from the NOAA/CIMSS Volcanic Could Monitoring site (below).

GOES-15 Infrared (10.7 µm) images, with Terra/Aqua MODIS and Suomi NPP VIIRS Ash Height products [click to play animation]

Due to the oblique satellite view angle, the shadow cast by the tall volcanic ash cloud was easily seen on the following early morning (Alaska time) Himawari-8 AHI Visible (0.64 µm) images (below). A closer view (courtesy of Dan Lindsey, RAMMB/CIRA) revealed overshooting tops and gravity waves propagating downwind of the eruption site.

Himawari-8 AHI Visible (0.64 um) images (click to play animation]

A few select Pilot reports (PIREPs) are shown below, plotted on GOES-15 Infrared Window (10.7 µm) and Aqua MODIS Ash Height derived products. Numerous flights were canceled as the ash cloud eventually began to drift over Western and Interior Alaska (media report).

GOES-15 Infrared Window (10.7 um) image, with METAR surface reports and Pilot reports [click to enlarge]

GOES-15 Infrared Window (10.7 µm) image, with METAR surface reports and Pilot reports [click to enlarge]

Aqua MODIS Ash Height product, with METAR surface reports and Pilot reports [click to enlarge]

GOES-15 Infrared Window (10.7 um), with METAR surface reports and Pilot reports [click to enlarge]

GOES-15 Infrared Window (10.7 µm), with METAR surface reports and Pilot reports [click to enlarge]

A comparison of Suomi NPP VIIRS Shortwave Infrared (3.74 µm), Day/Night Band (0.7 µm), and true-color Red/Green/Blue (RGB) images (below) showed the volcanic hot spot and the brown to tan colored ash cloud at 2141 UTC on 28 March. Significant ash fall (as much as 2/3 of an inch) was experienced at the village of Nelson Lagoon, located 55 miles northeast of Pavlof (media report).

Suomi NPP VIIRS Shortwave Infrared (3.74 µm), Day/Night Band (0.7 µm), and true-color RGB images [click to enlarge]

A comparison of the 3 Himawari-8 AHI Water Vapor bands (7.3 µm, 6.9 µm and 6.2 µm) covering the first 14 hours of the eruption from 0000 to 1400 UTC is shown below. Note that the volcanic plume was best seen on the 7.3 µm images, which indicated that it began to move over the coast of Western Alaska after around 0600 UTC; this is due to the fact that the 7.3 µm band is not only a “water vapor absorption” band, but is also sensitive to high levels of SO2 loading in the atmosphere (as was pointed out in this blog post).

Himawari-8 AHI Water Vapor 7.3 µm (left), 6.9 µm (center) and 6.2 µm (right) images [click to play animation]

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Large grass fire in Oklahoma and Kansas

By Scott Bachmeier • 23 March 2016

A grass fire (now referred to as the “Anderson Creek fire”) was first reported in western Woods County, Oklahoma around 2245 UTC or 5:45 PM local time on 22 March 2016. “Hot spot” signatures (yellow to red to black pixels) on GOES-13 Shortwave Infrared (3.9 µm) images (above) showed that the fire... Read More

GOES-13 Shortwave Infrared (3.9 µm) images, with surface reports [click to play animation]

A grass fire (now referred to as the “Anderson Creek fire”) was first reported in western Woods County, Oklahoma around 2245 UTC or 5:45 PM local time on 22 March 2016. “Hot spot” signatures (yellow to red to black pixels) on GOES-13 Shortwave Infrared (3.9 µm) images (above) showed that the fire proceeded to make a very fast run to the north during the overnight hours, crossing over the Kansas border into Comanche and Barber Counties. The fire eventually jumped Highway 160 — which runs west-to-east across the northern portion of those 2 counties (highways are plotted in violet) — forcing it to be closed for several hours. As of the afternoon of 23 March, the fire was reported to have burned at least 72,000 acres; on that evening, the mayor of Medicine Lodge, Kansas (station identifier KP28) called for a voluntary evacuation as the fire began to approach the edge of the town. Note that GOES-13 (GOES-East) had been placed into Rapid Scan Operations (RSO) mode specifically to monitor the extremely critical fire risk, and was providing images as frequently as every 5-7 minutes.

A nighttime comparison of Suomi NPP VIIRS Day/Night Band (0.7 µm) and Shortwave Infrared (3.74 µm) images at 0823 UTC or 3:23 AM local time (below) showed the hot spots and the bright glow of the large and very hot fire.

Suomi NPP VIIRS Day/Night Band (0.7 µm) and Shortwave Infrared (3.74 µm) images {click to enlarge]

A sequence of Shortwave Infrared images from POES AVHRR, Terra/Aqua MODIS, and Suomi NPP VIIRS (below) provided higher-resolution snapshots of the rapid northward progression of the fire during the overnight hours (aided by strong southerly winds), followed by an east/northeastward expansion during the subsequent daylight hours (driven by a switch to strong southwesterly winds after the passage of a dryline).

POES AVHRR (3.7 µm), Terra/Aqua MODIS (3.7 µm), and Suomi NPP VIIRS (3.74 µm) Shortwave Infrared images [click to enlarge]

GOES-13 Visible (0.63 µm) images (below) revealed a large increase in smoke produced by the fire during the day on 23 March. This smoke was drawn cyclonically northeastward then northward around the circulation of a storm system that was deepening over western Kansas. Afternoon wind gusts were as high as 61 mph in Newton, Kansas. Downstream of the fire source region, smoke reduced the surface visibility to 4 miles at Hutchinson, Kansas (station identifier KHUT) at 21 UTC or 4 PM local time, and Wichita (station identifier KICT) reported a visibility of 1.75 miles at 00 UTC or 7 PM local time; ash falling from the smoke aloft caused the surface air quality in Wichita to briefly deteriorate to unhealthy levels.

GOES-13 Visible (0.63 µm) images, with surface reports [click to play animation]

In the early afternoon at 1748 UTC or 12:48 PM local time, a pilot report near the northern flank of the fire (below) indicated that the tops of the smoke towers were already rising to altitudes of 8000 to 11000 feet above ground level.

GOES-13 Visible (0.63 µm) image, with surface reports and a pilot report of smoke altitude [click to enlarge]

It is of interest to note that a similar (albeit smaller) grass fire spread rapidly northward from Oklahoma into Kansas, one county to the west and about one month earlier: the Buffalo fire. That event had the benefit of Super Rapid Scan Operations of GOES-14, which provided imagery at 1-minute intervals. The ABI instrument on the GOES-R satellite will be capable of providing 1-minute images over 2 pre-defined mesoscale sectors.

===== 24 March Update =====

Anderson Creek Fire perimeter map [click to enlarge]

A map of the Anderson Creek Fire perimeter (above) was issued by the Oklahoma Forestry Services at 1642 UTC or 11:42 AM local time. At that time, an estimated 397,420 acres (621 square miles) had been burned — which makes it the largest wildfire on record for the state of Kansas.

A comparison of Suomi NPP VIIRS true-color and false-color Red/Green/Blue (RGB) images from the SSEC RealEarth site (below) showed the extent of the burn scar, with smoke plumes drifting south-southeastward from 2 small areas of fires that were still actively burning at 2106 UTC or 4:06 PM local time. As discussed above, it can be seen that the fire crossed (and forced the closure of) US Highway 160 between Coldwater and Medicine lodge, and came very close to the town of Medicine Lodge.

Suomi NPP VIIRS true-color and false-color images [click to enlarge]

===== 25 March Update =====

Suomi NPP VIIRS Day/Night Band (0.7 µm) image [click to enlarge]

With ample illumination from the Moon (in the Waning Gibbous phase, at 98% of Full), the contrast between the dark Anderson Creek fire burn scar and the lighter surrounding grassland was very apparent on a Suomi NPP VIIRS Day/Night Band (0.7 µm) image at 0742 UTC or 2:42 AM local time. This example demonstrates the “visible image at night” capability of the VIIRS Day/Night Band.

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2 West Pacific storms, as seen using 3 Himawari-8 water vapor bands

By Scott Bachmeier • 19 March 2016

The Himawari-8 AHI instrument has 3 water vapor bands, centered at 6.2 µm, 6.9 µm, and 7.3 µm. Images of these 3 water vapor bands (above; also available as a large 126 Mbyte animated GIF) showed the intensification of a mid-latitude cyclone as it moved east of Japan during the 17-19... Read More

Himawari-8 Water Vapor images: 6.2 µm (top), 6.9 µm (middle), and 7.3 µm (bottom) – [click to play MP4 animation]

The Himawari-8 AHI instrument has 3 water vapor bands, centered at 6.2 µm, 6.9 µm, and 7.3 µm. Images of these 3 water vapor bands (above; also available as a large 126 Mbyte animated GIF) showed the intensification of a mid-latitude cyclone as it moved east of Japan during the 17-19 March 2016 period. Surface analyses of this storm produced by the Ocean Prediction Center are shown below.

West Pacific surface analyses [click to play animation]

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Himawari-8 Water Wapor images: 7.3 µm (left), 6.9 µm (center), and 6.2 µm (right) – [click to play MP4 animation]

Several days earlier (during 14-16 March), another storm just off the coast of Japan rapidly intensified to hurricane force as it moved north-northeastward toward the southern tip of the Kamchatka Peninsula. A comparison of the three Himawari-8 AHI water vapor bands (above; also available as a large 109 Mbyte animated GIF) depicted varying aspects of the storm evolution. The corresponding Ocean Prediction Center surface analyses are shown below.

West Pacific surface analyses [click to play animation]

The GOES-R ABI instrument will have nearly identical water vapor bands; plots of their weighting functions (below, from this site) show that each of these 3 spectral bands senses radiation from different layers of the atmosphere. This example assumes a typical cold mid-latitude winter temperature/moisture vertical profile, with a satellite view angle (or “zenith angle”) of 45 degrees.

GOES-R ABI water vapor band weighting function plots

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Convective snow squalls in the Upper Midwest

Eruption of the Mount Pavlof volcano in Alaska

Large grass fire in Oklahoma and Kansas

2 West Pacific storms, as seen using 3 Himawari-8 water vapor bands

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