GOES-11 0.65 µm visible channel images

McIDAS images of GOES-11 0.65 µm visible channel data (above) showed hazy plumes of glacial silt blowing southwestward from the Alaska Panhandle region out over the adjacent offshore waters of the Gulf of Alaska on 17 November 2010. A NOAA-19 false-color Red/Green/Blue (RGB) image created using AVHRR channels 1, 2, and 4 (below) offered another view with a bit more contrast, making the plumes of airborne particulate matter somewhat easier to see.

NOAA-19 AVHRR false-color Red/Green/Blue (RGB) image

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MODIS 6.7 µm water vapor and GOES-13 6.5 µm water vapor images

An AWIPS image comparison of  MODIS 6.7 µm and GOES-13 6.5 µm “water vapor channel” data (above) demonstrated the advantage of improved spatial resolution for detecting the structure and areal coverage of mountain waves that were present over the Mid-Atlantic states on 17 November 2010. The spatial resolution of the MODIS water vapor image is 1 km, compared to 8 km for the GOES-13 water vapor image (note that the native resolution of the water vapor channel on GOES-13 is actually 4 km, but this image was viewed on the AWIPS “CONUS” scale, which downgrades the resolution to 8 km).

About 2 hours later, an AWIPS image of the POES AVHRR Cloud Top Height product (below) indicated that the tops of the mountain wave cloud bands at that time were generally in the 3-4 km range, which corresponded well to some of the altitudes of pilot reports of moderate turbulence (8,000-10,000 feet above ground level).

POES AVHRR Cloud Top Height product

As part of the CIMSS involvement in GOES-R Proving Ground activities, MODIS and POES AVHRR satellite images and products are currently being made available in an AWIPS format for interested NWS forecast offices to add to their local AWIPS workstations (via LDM subscription). For more information, see the MODIS Imagery in D-2D and AVHRR Imagery and Products in D-2D sites. VISIT training lessons are also available for these MODIS and AVHRR images and products.

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GOES-13 6.5 µm "water vapor channel" images + cloud-to-ground lightning strikes

A major winter storm impacted parts of the Upper Midwest region on 13 November 2010, producing snowfall amounts as high as 14 inches at Emmetsburg, Iowa, 12.0 inches at Maple Grove, Minnesota (NWS MPX story), and 11.0 inches at Hawthorne, Wisconsin (NWS DLH story).

AWIPS images of 4-km resolution GOES-13 6.5 µm “water vapor channel” data (above) revealed a pronounced middle-tropospheric dry slot wrapping into the eastern sector of the storm. Thundersnow was reported at a few locations — note that there were a few cloud-to-ground lightning strikes showing up near the leading edge of the dry slot (over western Iowa after 05:15 UTC, and then over southern Minnesota after 12:15 UTC).

The corresponding 4-km resolution GOES-13 10.7 µm “IR window channel” images (below) showed that the cloud top IR brightness temperatures were not particularly cold across the areas that received the heavy snow (generally in the -30 to -40º C range, dark blue to green color enhancement), though there were bands exhibiting much colder cloud tops (colder than -60º C, red color enhancement) farther to the east within the warm conveyor belt of the storm.

GOES-13 10.7 µm "IR window channel" images + cloud-to-ground lightning strikes

A more detailed view of the storm’s cloud structures could be seen by examining a series of 1-km resolution MODIS 11.0 µm and POES AVHRR 10.8 µm “IR window channel” images (below). An overlay of the 12 UTC HPC-analyzed surface fronts and surface pressure on the 11:16 UTC POES AVHRR IR image showed that the center of the storm system was located over central Iowa at that time.

MODIS 11.0 µm and POES AVHRR 10.8 µm "IR window channel" images

A 1-km resolution MODIS false-color Red/Green/Blue (RGB) image (below) showed the beginning portion of the heavy snow swath, which was stretching from southeastern Nebraska (where as much as 4.0 inches was reported at Gretna) into southwestern Iowa as the main cloud deck associated with the storm system began clear out over that region. In this false-color RGB image (created using the MODIS 0.65 µm “visible channel” image as the Red, and the MODIS 2.1 µm “snow/ice channel” image as the Green and Blue components), the deeper snow cover shows up as the darker red features.

MODIS false-color Red/Green/Blue (RGB) image

========== 15 NOVEMBER UPDATE ==========

There was enough of a break in the clouds on 15 November to get a nice view of the southern portion of the swath of snow cover that stretched from Iowa into southern Minnesota — on the comparison of MODIS false-color RGB images at 17:35 UTC and 19:17 UTC  (below), the snow cover again appears as the darker red feature (in contrast to the brighter supercooled water droplet clouds, and the lighter pink ice crystal clouds).

MODIS false-color Red/Green/Blue (RGB) images

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MODIS 0.65 µm "visible" channel and MODIS 2.1 µm "snow/ice" channel images

AWIPS images of MODIS 0.65 µm “visible channel” and 2.1 µm “snow/ice channel” data (above) revealed a long, narrow band of snow cover oriented from south to north across far northeastern Wyoming, far eastern Montana, and far western North Dakota at 19:42 UTC (12:42 pm local time) on 11 November 2010.   Both snow cover and clouds appear as brighter white features on the visible image, but the near-IR snow/ice channel image helps to discriminate between snow cover and clouds (since snow and ice are strong absorbers at the 2.1 µm wavelength,  they appear very dark on that particular image).    NOHRSC snow depth data indicated that as much as 5-6 inches of snow remained on the ground that morning, which explains the strong  signal on the MODIS snow/ice channel image.  According to National Weather Service local storm reports, total snowfall amounts during the preceding 24 hours in that particular area were as high as 17 inches at Hulett, Wyoming and 12 inches at Carlyle, Montana.

On a MODIS false-color Red/Green/Blue (RGB) image using the visible and snow/ice images (below), snow cover appears as varying shades of red, while water droplet clouds appear as brighter white features. Note the lack of first-order stations reporting snow depth within the area of the heavy snow swath — this highlights the value of using high spatial resolution satellite imagery for helping to determine the areal coverage of the snow on the ground.

MODIS false color Red/Green/Blue (RGB) image

The MODIS Land Surface Temperature (LST) product (below) indicated that LST values were being held in the mid 20s to low 30s F (violet to blue colors) within the snow band, while LST values across the adjacent bare ground areas were rising in the upper 40s to low 50s F (cyan to green colors). However, there was not quite that large of a contrast in instrument shelter air temperatures across that area.

MODIS Land Surface Temperature product + surface METAR reports

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