GOES-13 6.5 µm water vapor images (click image to play animation)

An intense winter storm impacted a great deal of the eastern US on 26 December – 27 December 2010, producing blizzard conditions along much of the East Coast (with Blizzard Warnings issued from Virginia to Maine), total snowfall amounts as high as 32.0 inches at Rahway, New Jersey, and significant accumulations as far south as Mississippi, Alabama, and Georgia (HPC storm summary). AWIPS images of 4-km resolution GOES-13 6.5 µm water vapor channel data (above) showed that the storm exhibited a very well-defined dry slot (yellow to orange color enhancement) and comma head structure during the course of its development. Cloud-to-ground lightning strikes could be seen along the periphery of the dry slot, with isolated strikes noted over New Jersey and also Long Island, New York (where thundersnow was reported). An excellent summary of the storm can be found on the AccuWeather WeatherMatrix Blog.

On a series of 1-km resolution POES AVHRR 0.63 µm and MODIS 0.65 µm visible images (below) the shadowing and texture of a number of convective bands could be seen, which were responsible for enhancing snowfall rates. On a longer series of 1-km resolution POES AVHRR and MODIS IR images, IR cloud top brightness temperatures as cold as -40 to -50º C were evident along the East Coast of the US.

POES AVHRR 0.63 µm and MODIS 0.65 µm visible images

Night-time images of 4-km resolution GOES-13 3.9 µm shortwave IR images suggested the presence of a warm “eye-like” signature at the center of the storm, but the subsequent daytime 1-km resolution GOES-13 0.63 µm visible images showed that the presence of extensive low-level cloudiness prevented a well-defined “eye structure” from being seen (below).

GOES-13 3.9 µm shortwave IR and 0.63 µm visible images (click to play)

Once the bulk of the cloudiness had cleared in the wake of the storm by the afternoon on 27 December, a comparison of a 1-km resolution MODIS 0.65 µm visible channel image with the corresponding MODIS false-color Red/Green/Blue (RGB) image (created using the 0.65 µm visible channel as the Red and the 2.1 µm “snow/ice” channel as the Blue and Green components of the image) revealed that a rather large “snow hole” remained from central Pennsylvania to northern Virginia (below). Inland snow cover appeared as darker shades of red on the RGB image, in contrast to bare ground (cyan) and supercooled water droplet clouds (lighter shades of white).

MODIS 0.65 µm visible + MODIS false-color Red/Green/Blue (RGB) image

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GOES-13 0.63 µm visible images

We received the following in an email from Mike Sporer (NOAA/NESDIS):

I saw this in a Goes-13 visible loop. There appears to be a "dark cloud" originating near the volcano Popocatepetl. But I have never seen a volcanic plume appear dark in a visible image before. The "dark cloud" also appears in IR4 at a temperature similar to nearby mid clouds but IR2 shows no hot spot signature of volcanic activity. Could it be that Popocatepetl burped a huge cloud of gas that is absorbing in the visible spectrum?

Taking a closer look using McIDAS images of GOES-13 0.63 µm visible channel data (above), a large dark plume feature can be seen moving southward and then southwestward, just to the east and south of the summit of the Popocatepetl volcano (denoted by the red “V” on the images) on 19 December 2010. It is interesting to note that part of the northern (trailing) edge of the dark plume appeared to slow down and then separate from the main body of the plume around 17 UTC — the turning of the surface winds from northerly to southerly at Puebla (the observing station just to the east) may have had something to do with this plume behavior.

MODIS Red/Green/Blue (RGB) image created using channels 01/04/03

MODIS Red/Green/Blue (RGB) image created using channels 07/02/01

The plume feature also appeared very dark on MODIS Red/Green/Blue (RGB) images at 17:35 UTC (above) — and on AWIPS images of POES AVHRR data at 19:45 UTC (below) the plume exhibited IR brightness temperatures around 12-15º C, which corresponded to altitudes between 9307-10,656 feet or 2838-3249 meters on the Mexico City MMMX rawinsonde plot).

POES AVHRR 0.86 µm visible and 12.0 µm IR images

As it turns out, this plume was not volcanic in nature, but rather was a result of a large fire from an explosion on the Nueva Teapa oil pipeline near San Marten Texmelucan in the state of Puebla (news article 1 | news article 2). Several hours earlier, a pronounced “hot spot” (yellow to red color enhancement) could be seen on a 1-km resolution MODIS 3.7 µm shortwave IR image at 08:10 UTC (below). The maximum IR brightness temperature  within the hot spot feature at that time was 322 K (49º C).

MODIS 3.7 µm shortwave IR image

Thanks to Mike for the heads-up on this very interesting satellite feature!

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GOES-13 6.5 µm "water vapor channel" images

A large and intense cyclone produced widespread heavy snowfall and blizzard conditions across much of the Upper Midwest region on 11 December – 12 December 2010. AWIPS images of 4-km resolution GOES-3 6.5 µm “water vapor channel” data (above) showed the evolution of several important storm features, including a well defined dry slot, deformation zone, and Trough of Warm Air Aloft (TROWAL). The highest snowfall totals with this storm included 26.0 inches at Winona Dam, Minnesota and 23.0 inches at Osceola, Wisconsin.

A closer view using AWIPS images of 1-km resolution MODIS 11.0 µm IR and POES AVHRR 10.8 µm IR data (below) revealed the presence of widespread convective elements are various points in the storm’s life, with many exhibiting cloud top IR brightness temperatures as cold as -65º C (darker red color enhancement).

MODIS 11.0 µm IR and POES AVHRR 10.8 µm IR images

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.

During the afternoon hours on 12 December, 1-km resolution MODIS false-color Red/Green/Blue (RGB) images created using the 0.65 µm “visible channel” and the 2.1 µm near-IR “snow/ice channel” (below) displayed the extent of some of the resulting snow cover — snow on the ground showed up as varying shades of darker red, in contrast to supercooled water droplet clouds which were the brighter features on the image.

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

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MODIS 0.65 µm visible image + MODIS false-color Red/Green/Blue (RGB) image

A comparison of AWIPS images of MODIS 0.65 µm visible channel data and a MODIS false-color Red/Green/Blue (RGB) image (created using the MODIS 0.65 µm visible and the 2.1 µm snow/ice channel images) revealed a swath of snow cover from southwestern Virginia all the way to extreme eastern North Carolina on the morning of 05 December 2010 (above).

Storm total snowfall amounts were as high as 3.0 inches with this event, which occurred on 04 December. While only two first-order stations (Greensboro KGSO and Raleigh KRDU) reported 1 inch of snow on the ground at 12 UTC on the morning of 05 December, the MODIS imagery showed that snow cover (which appeared as shades of red on the false-color RGB image) still remained across a number of counties to the east and southeast.

Better detail of the swath of snow cover across North Carolina can be seen using a 250-meter resolution MODIS true-color RGB image from the SSEC MODIS Today site (below; viewed using Google Earth).

250-meter resolution MODIS true-color Red/Green/Blue (RGB) image

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