GOES-13 10.7 µm IR channel images (click to play animation)

AWIPS images of 4-km resolution GOES-13 10.7 µm IR channel data with overlays of SPC storm reports (above; click image to play animation; also available as an MP4 movie file) showed the growth of a large mesoscale convective system (MCS) that formed over eastern Colorado late in the day on 04 June 2014 and became very intense as it moved east-southeastward across Kansas during the overnight hours on 05 June 2014.  Although severe weather reports were not as widespread after daybreak on 05 June, the MCS still produced large hail and damaging winds across Missouri into the Mississippi River Valley (SPC storm reports: 04 June | 05 June). Note the cluster of high wind reports across northeastern Kansas into northwestern Missouri after about 12:00 UTC — these were due to the formation of a “wake low” in the rear portion of the exiting MCS.

At 08:46 UTC (3:46 AM local time), a comparison of 375-meter resolution Suomi NPP VIIRS 11.45 µm IR channel and 750-meter resolution Day/Night Band images (below) revealed cloud-top IR brightness temperatures as cold as -90º C (darker violet color enhancement), along with subtle cloud-top gravity waves propagating radially outward away from the central core of intense overshooting tops. On the Day/Night Band (DNB) image, numerous bright white streaks indicated portions of the cloud top that were illuminated by intense lightning activity. Although the Moon was in the Waxing Gibbous phase at nearly 50% of full, it had set a few hours earlier, limiting its “visible image at night” capability. Another item of interest on the DNB image was the presence of larger bands of mesospheric airglow waves propagating southwestward away from the storm, seen over southwestern Kansas into far northeastern New Mexico.

Suomi NPP VIIRS 11.45 µm IR channel and 0.7 µm Day/Night Band images

Via Twitter, the NWS CWSU in Oakland provided the corresponding 08:45 UTC GOES-13 IR image with overlays of radar-based VIL, echo tops, and lightning (below). Note that the maximum radar-based echo top was 63,000 feet.

GOES-13 IR image with overlays of VIL, lightning, and echo tops (courtesy of NWS CWSU Oakland)

Not surprisingly, there were numerous overshooting tops (OT) and thermal couplets (TC) associated with this severe MCS, as seen in this animation (where OT detections are blue, and TC detection are red). Icons of Automated Overshooting Top Detections (green) are plotted on GOES-13 10.7 µm IR channel images (below; click image to play animation; also available as an MP4 movie file). Of particular interest was the image at 10:00 UTC or 5:00 AM local time, when a report of hail of 3.0 inches in diameter and estimated winds of 60-70 mph beneath a cluster of overshooting top detection icons (the easternmost storm in central Kansas). Jim LaDue of the NWS WDTB in Norman OK provided this image showing Maximum Expected Size of Hail (MESH) of 2.0 inches for that particular supercell thunderstorm.

GOES-13 10.7 µm IR images, with Automated Overshooting Top Detection icons (click to play animation)

1-km resolution GOES-13 0.63 µm visible channel images after sunrise (below; click image to play animation; also available as an MP4 movie file) revealed a vivid display of transverse banding along the northwestern periphery of the MCS (primarily over Nebraska). This transverse banding is a satellite signature indicating a high potential for turbulence.

GOES-13 0.63 µm visible channel images (click to play animation)

A comparison of GOES-13 1-km resolution 0.63 µm visible channel and 4-km resolution 10.7 µm IR channel images at 12:30 UTC (below) showed that portions of the transverse banding signature were resolved differently by the 2 different images.

GOES-13 0.63 µm visible channel and 10.7 µm IR channel images at 12:30 UTC

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GOES-15 0.63 µm visible channel images (click to play animation)

On 02 June 2014, McIDAS images of 1-km resolution GOES-15 0.63 µm visible channel data (above; click image to play animation) revealed the presence of a cyclonic mesoscale vortex in the vicinity of Point Reyes along the California coast, which appeared to be playing a role in enhancing the inland penetration of marine fog/stratus into areas such as the San Francisco Bay region just south of the mesovortex.

An AWIPS image of 375-meter resolution (projected onto a 1-km AWIPS grid) Suomi NPP VIIRS 0.64 µm visible channel data at 21:07 UTC (below) included overlays of surface station and buoy reports, along with MADIS 1-hour satellite-derived atmospheric motion vectors within the 1050-900 mb layer at 21 UTC. The satellite cloud-tracked winds appeared to be picking up on the cyclonic circulation of the mesovortex. At this particular time, winds at San Francisco (station identifier KSFO) were southwesterly gusting to 23 knots.

Suomi NPP VIIRS 0.64 µm visible channel image, with surface and buoy observations and 1-hour MADIS satellite winds

A time series of surface observation at San Francisco International Airport (below) showed the increase in layered stratus clouds (with ceilings of 1000 to 1500 feet) after the southwesterly winds began to increase around 19 UTC.

Time series of surface observations at San Francisco International Airport

AWIPS images of the GOES-R Cloud Thickness product — with the GOES-R algorithm for Fog and Low Stratus products applied to GOES-15 data — indicated that the thickness of the stratus clouds moving inland across the San Francisco Bay area was only about 500 feet (below; click image to play animation). The thicker stratus clouds with depths of 1000-3000 feet remained off the coast of California.

GOES-15 Cloud Thickness product (click to play animation)

The corresponding GOES-15 Marginal Visual Flight Rules (MVFR) product (below; click image to play animation) showed that MVFR probability values were generally below 50-60% in the San Francisco Bay area, with much higher probabilities existing within the offshore marine boundary layer stratus cloud field.

GOES-15 Marginal Visual Flight Rules (MVFR) Probability product (click to play animation)

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MTSAT-2 0.63 µm visible channel and 10.8 µm IR channel images at 08:32 UTC

A comparison of McIDAS images of MTSAT-2 0.63 µm visible channel and 10.8 µm IR channel data at 08:32 UTC on 30 May 2014 (above) showed the volcanic cloud from the first in a series of eruptions of the Sangeang Api volcano in Indonesia (aircraft photos). The coldest cloud-top IR brightness temperature at that time was -74.5º C; note that the tall volcanic cloud was casting a large shadow toward the east-southeast in the visible image.

An animation of MTSAT-2 10.8 µm IR images (below; click image to play animation; also available as an MP4 movie file) revealed that there were a number of smaller eruptions that followed the initial, larger eruption.

MTSAT-2 10.8 µm IR channel images (click to play animation)

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MTSAT-2 false-color RGB images (click to play animation)

The NOAA/CIMSS Volcanic Cloud Monitoring MTSAT-2 false-color Red/Green/Blue (RGB) images (above; click image to play animation) showed the southeastward spread of volcanic ash cloud from the first 2 eruptions, while the Volcanic Ash Height product (below; click image to play animation) indicated that the ash may have reached altitudes of at least 12-14 km. Pilot reports in the vicinity placed the height of the volcanic cloud at 65,000 feet or 19.8 km.

NOAA/CIMSS Volcanic Ash Height product (click to play animation)

Night-time McIDAS-V images of Suomi NPP VIIRS 11.45 µm IR, 3.9 µm shortwave IR, and 0.7 µm Day/Night Band (DNB) images of one of the secondary eruptions at 17:43 UTC on 30 May (below; courtesy of William Straka, SSEC) showed a cloud-top IR brightness temperature as cold as -77º C, along with the yellow-enhanced “hot spot” on the shortwave IR and the bright glow on the DNB image from the hot volcano vent and lava flows.

Suomi NPP VIIRS 11.45 µm IR, 3.9 µm shortwave IR, and 0.7 µm Day/Night Band images

A composite of Suomi NPP VIIRS true-color RGB images from 31 May, viewed using the SSEC RealEarth web map server (below) showed the widespread extent of the volcanic ash cloud from the ongoing eruption.

Suomi NPP VIIRS true-color RGB image composite

Due to the southeastward drift of the primary volcanic ash plume toward Australia, flights were cancelled at the Darwin airport. MTSAT-2 visible and IR images with polygons of Volcanic Ash Advisories are shown below (click image to play animation).

MTSAT-2 visible and IR images, with Volcanic Ash Advisory polygons

===== 01 June Update =====

A comparison of Suomi NPP VIIRS true-color images from 31 May and 01 June (below) showed that while the eruption was still ongoing, the amount of ash output had dramatically decreased.

Suomi NPP VIIRS true-color images

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GOES-13 10.7 µm IR channel images (click to play animation)

An isolated severe thunderstorm developed over the northern portion of the Black Hills of South Dakota around 18 UTC (Noon local time) on 27 May 2014, and moved southeastward producing hail as large as 2.75 inches in diameter and a tornado (SPC storm reports), as well as up to 3 inches of heavy rainfall. 4-km resolution GOES-13 10.7 µm IR channel images (above; click image play animation) showed the cold cloud-top IR brightness temperatures associated with the storm (which reached a minimum of -59º C at 21:40 UTC). Convective initiation was aided by convergence of a surface cold frontal boundary with the topography of the Black Hills, as seen here.

A comparison of 375-meter resolution Suomi NPP VIIRS 0.64 µm visible channel and 11.45 µm IR channel images at 19:38 UTC (below) revealed a minimum cloud-top IR brightness temperature of -68º C. Subsequent cumulus cloud development is seen to be suppressed in the stable outflow region in the wake of the storm.

Suomi NPP VIIRS 0.64 µm visible channel and 11.45 µm IR channel images

A comparison of the VIIRS IR image with the closest available GOES-13 IR image (below) demonstrated the advantage of higher spatial resolution of polar-orbiting satellite imagery, as well as the lack of parallax error associated with the geostationary-orbit GOES imagery. The coldest cloud-top IR brightness temperature on the GOES-13 image was -57º C, compared to -68º C on the VIIRS image.

GOES-13 10.7 µm IR channel and Suomi NPP VIIRS 11.45 µm IR channel images

The NOAA/CIMSS ProbSevere model identified this storm as a potential producer of severe weather. The animation below shows the evolution of the MRMS radar signal with ProbSevere overlain from 1812 UTC through 2000 UTC. The Radar object that is highlighted has strong satellite growth rate (observed at 1725 UTC), MUCAPE of 1750 J/kg and Effective Shear of ~19 knots. At 1810 UTC, when MESH values are 0.53″, ProbSevere is 18%; four minutes later at 1814 UTC MESH increased to 0.94″ and ProbSevere increased to 69%. The National Weather Service issued the first warning at 1905 UTC and severe hail (1.5″ in diameter) occurred at 1910 UTC (when MESH was 1.64″ and ProbSevere was 94% and less than an hour after ProbSevere increased above 50%).

NOAA/CIMSS ProbSevere over South Dakota, times as indicated (Click to enlarge)

ProbSevere later in the day, after 2200 UTC, continues to track the hail-producing storm in far southwestern South Dakota. Although ProbSevere is designed to show when the first severe reports might occur, it does continue to provide useful information. In time, as below at 2222 UTC, the satellite growth parameters are replaced by ‘Mature Storm’ as a reminder that this tracked feature is not new.

Annotated NOAA/CIMSS ProbSevere over South Dakota, times as indicated (Click to animate)

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