AWIPS images of the GOES 10.7 µm IR channel (above) showed the development of severe thunderstorms across parts of Colorado, Wyoming, Nebraska, and Kansas on 22 May 2008 (see also: CIRA RAMMB Satellite Case Study). According to the SPC storm reports, a number of tornadoes were produced by these storms (one tornado-related fatality was reported near Greely, Colorado), along with large hail (up to 2.75 inches in diameter near Windsor, Colorado and 3.00 inches in diameter near Grinnell, Kansas).

A closer view using the 1-km resolution MODIS 11.0 µm IR channel (above) from around 17:57 UTC (11:57 am local time) revealed a rather diffuse “enhanced-v” signature just east/northeast of Fort Collins, Colorado (station identifier KFNL). This storm went on to produce tornadoes and large hail in southeastern Wyoming, with one tornado doing extensive damage in the Laramie area.

Another MODIS IR image from around 19:34 UTC (1:34 pm local time) displayed impressive detail in the overshooting top structure of the storms developing over western Kansas and far southwestern Nebraska (below), with the coldest cloud top brightness temperatures in the -70º to -80º C range (black to while enhancement).

The GOES sounder derived Convective Available Potential Energy (CAPE) product (below) indicated that the pre-convective environment across northeastern Colorado during the morning hours was becoming unstable, with CAPE values in the 2000-4000 J kg-1 range (yellow to red enhancement) at 16:00 UTC (10 am local time). The air mass south of the warm front and east of the dryline (from southern Kansas into Texas) was also very unstable, with CAPE values in some areas over 4000 J kg-1 (purple enhancement).

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A comparison of Aqua MODIS true color images from 05 March 2008 and 17 May 2008 (above) showed the “browning” of vegetation across Southern California after the Spring season rains (90-day total rainfall | 90-day percent of normal rainfall) had ended. A significant amount of snowmelt was also evident during that period over the southern Sierra Nevada mountains (as well as over the higher elevations of smaller ranges such as the San Gabriel, San Bernardino, and San Jacinto Mountains). The images (courtesy of Liam Gumley, CIMSS) were created in Google Earth using publicly available data from the SSEC MODIS Today website.

Even though the MODIS true color images above suggested an overall dry-down of the vegetation across the region, a comparison of AWIPS images of the MODIS Normalized Difference Vegetation Index (NDVI) and visible channel (below) indicated that many areas of southern California still exhibited a NDVI value as high as 0.5-0.6 on 20 May 2008. A National Public Radio story pointed out that the rapid growth of non-native plant species across parts of southern California could actually be a warning sign of an increased potential for future wildfire activity (once that vegetation continued to dry out over the upcoming Summer and Fall months).

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AWIPS images of the water vapor  satellite composite (above) showed the evolution of a wide variety of synoptic-scale features across the Northern Hemisphere at 3-hour intervals during the 19 May – 20 May 2008 period. Of particular interest was the water vapor signatures associated with an occluding cyclone over the North Atlantic Ocean (located south of Iceland and west of the British Isles). A closer view using Meteosat-9 images of the 6.2 µm water vapor channel at 15-minute intervals (below) revealed a great deal of interesting mesoscale structure as bands of moist and dry air wrapped into the occluding cyclone as it began to fill .

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Comparisons of the 1-km resolution MODIS fog/stratus product with the 4-km resolution GOES fog/stratus product help to underscore the improved ability to detect subtle features using higher spatial resolution satellite data. AWIPS images of the MODIS and GOES-11 fog/stratus products (plus topography) covering the Monterey and Fresno, California regions on 19 May 2008 (above) showed a patch of fog over Monterey (KMRY), Watsonville (KWVI), and Salinas (KSNS), with a narrow finger of fog that extended southeastward into the Salinas River Valley.

Farther inland over central California, the MODIS fog/stratus product imagery revealed a noisy “false fog/stratus signal” over parts of the San Joaquin Valley, due to the high emissivity of desert soils that covered the non-agricultural portions of the valley (the contrasting patchwork of green agricultural fields versus brown to gray non-agricultural areas was very evident on 250-m resolution MODIS true color imagery from the previous day) — regions with a lower MODIS Normalized Difference Vegetation Index (NDVI) generally corresponded with regions that exhibited a more pronounced “false fog/stratus signal” (below).

Images centered off the coast of Southern California and Baja California on 20 May 2008 (below) revealed several ship tracks in the marine stratocumulus cloud deck that was offshore. Once again, such small-scale features showed up with greater clarity on the MODIS fog/stratus product imagery. These comparisons give a bit of a preview of the types of improved products that will be available using the Advanced Baseline Imager (ABI) instrument on the upcoming GOES-R satellite (scheduled to be launched in 2014), which will offer IR imagery and products at a 2-km spatial resolution (at 5-minute intervals on a routine basis).

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