GOES-13 10.7 µm IR images

Clusters of severe thunderstorms developed across parts of northeastern Nebraska and southeastern South Dakota ahead of a warm frontal boundary that was advancing northward across the region on 22 September 2010. These severe thunderstorms produced a number of reports of large hail and damaging winds. AWIPS images of GOES-13 10.7 µm IR data (above) showed that cloud top IR brightness temperatures were as cold as around -70º C (dark black enhancement) at times.

The corresponding GOES-13 3.9 µm shortwave IR images (below) revealed that a few interesting “darker plumes” developed on the cloud tops of some of the southernmost storms — this darker appearance was a signature of smaller ice crystal particles that were being ejected above the anvil top by some of the stronger thunderstorm updrafts. These smaller ice crystals were better reflectors of incident solar radiation, making them show up as warmer (darker) features on the shortwave IR images.

GOES-13 3.9 µm shortwave IR images

These darker anvil top plumes were also very evident at 16:33 UTC on 1-km resolution MODIS 3.7 µm shortwave IR imagery (below).

MODIS 3.7 µm shortwave IR image

A closer view using 1-km resolution POES AVHRR 10.8 µm IR imagery at 18:56 UTC (below) displayed a well-defined “enhanced-v” signature in southeastern South Dakota (with the coldest cloud top IR brightness temperature value of -82º C, violet color enhancement) — and a large number of hail reports associated with this storm as it tracked through the area, including a report of 3.5 inch diameter hail near Vermillion, South Dakota.

POES AVHRR 10.8 µm IR image (with hail reports)

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GOES-15 1-minute interval (SRSO) 0.63 µm visible channel images

21 September 2010 was the final day of the GOES-15 Post Launch Science Test — and the satellite was placed into Super Rapid Scan Operations (SRSO) mode to provide images as frequently as every 1 minute over the Upper Midwest region. A set of SRSO 0.63 µm visible images  (above) showed the evolution of clusters of severe thunderstorms with overshooting tops that were producing large hail and damaging winds across parts of Iowa, northern Illinois, and southern Wisconsin during the 20-22 UTC time frame (SPC Storm Reports).

The full set of 1-minute interval SRSO 0.63 µm visible, 10.7 µm IR, and 6.5 µm water vapor images (from 12:45 UTC to 23:45 UTC on 21 September) are available as either QuickTime movies or as Animated GIF files (below).

GOES-15 1-minute interval (SRSO) 0.63 µm visible images

GOES-15 1-minute interval (SRSO) 10.7 µm IR images

GOES-15 1-minute interval (SRSO) 6.5 µm water vapor images

In addition to the severe convection, there were a number of small agricultural fires burning  across parts of northern Arkansas into the Boothill of Missouri region and extreme southern Illinois. A comparison of GOES-15 3.9 µm shortwave IR images at 1-minute intervals (below; top panels) vs the “normal” operational 15-minute interval (below; bottom panels) demonstrates the improved ability to monitor the temporal variability of such small and often short-lived fires (which were denoted by the hotter yellow to red pixels).

GOES-15 3.9 µm shortwave IR images: 1-minute interval (top) vs 15-minute interval (bottom)

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GOES-15 SRSO 0.63 µm visible channel images

As part of the GOES-15 Post Launch Science Test, the satellite was placed into Super Rapid Scan Operations (SRSO) mode on 20 September 2010, providing images as frequently as every 1 minute during certain intervals of the day. McIDAS images of GOES-15 0.63 µm visible channel data (above) showed the evolution of stratus clouds along and just offshore of the southern California coast.

Satellite imagery at such a temporal scale gives a preview of what will be available in the GOES-R era, when 30-second interval SRSO image sectors will be available on a routine basis.

The location of the marine status clouds had an important impact on the daily high temperature at any given site. For example, on the GOES-15 visible image (below) you can see why Los Angeles International Airport (LAX) had a daily high  temperature of only 69º F (21 º C), while just a few miles further inland, downtotown Los Angels had a high temperature that day of 80º F (27º C).

GOES-15 visible image, with locations of Airport (A) and Downtown (D)

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GOES-11 0.65 µm visible channel images

A persistent ridge of high pressure aloft was keeping the interior of Alaska unusually cloud-free, as was evident on McIDAS images of GOES-11 0.65 µm visible channel data on 19 September 2010 (above). Temperatures at many stations across the region had been averaging about 10 degrees F above normal during the previous week, with many daily high temperatures in the 60s and 70s F. On this particular day, the high temperatures ranged from 70º F (21º C) at Holy Cross (in the clear skies of the interior of southwestern Alaska) to only 37º F (+3º C) at Barter Island (beneath the stratus clouds along the northeast Arctic Coast).

The visible images showed that low stratus clouds and fog were attempting to work their way inland (southward) across the Arctic Slope region of northern Alaska. Widespread stratus clouds also covered much of the Gulf of Alaska, and was affecting some of the coastal regions in the far southern portions of the state. In addition, a smoke plume from a wildfire could also be seen drifting southwestward across the interior of Alaska later in the day.

AVHRR visible image + Cloud Type, Cloud Top Temperature, and Cloud Top Height products

AWIPS images of the 1-km resolution POES AVHRR visible channel data along with the corresponding Cloud Type, Cloud Top Temperature, and Cloud Top Height products (above) demonstrated how the various cloud features could be further characterized according to their type (for example, fog vs. supercooled clouds vs. cirrus clouds) along with the temperature and height of their tops.

AVHRR visible image + Cloud Type, Cloud Top Temperature, and Cloud Top Height products

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