The effect of heavy precipitation on rivers in Illinois

April 21st, 2013 |
Total observed precipitation during the 07-21 April 2013 period

Total observed precipitation during the 07-21 April 2013 period

The middle part of April 2013 brought periods of very heavy rainfall to portions of Illinois and the Upper Midwest region, with many areas receiving 5-7 inches of rainfall. A map of the 14-day total observed precipitation during the 07-21 April period (above) shows the widespread distribution of the heavy rainfall, which was 4-5 inches above normal and 300-400% of normal at many locations for this time of the year. Additional information can be found at the NWS Chicago and NWS Lincoln sites.

The effect of this heavy rainfall was very apparent in a before (05 April) and after (21 April) comparison of 250-meter resolution MODIS false-color Red/Green/Blue (RGB) images from the SSEC MODIS Today site (below) — obvious changes can be seen in the width of sections of the Illinois River (which runs fron northeast through southwest across the center of the images) and many of its tributaries. 138 river gauges were reporting moderate to major flooding levels on 21 April.

MODIS false-color Red/Green/Blue (RGB) images from 05 April and 21 April 2013

MODIS false-color Red/Green/Blue (RGB) images from 05 April and 21 April 2013

AWIPS image comparisons of the standard 0.64/0.65 µm visible channel with the corresponding 0.86 µm visible channel from the VIIRS and MODIS instruments (below) show that the 0.86 µm imagery can be useful for helping to monitor the areal coverage of significant water inundation following heavy rainfall events such as this. Rivers, lakes, and flooded areas show up as darker features on the 0.86 µm images.

Suomi NPP VIIRS 0.64 µm visible and 0.86 µm visible channel images

Suomi NPP VIIRS 0.64 µm visible and 0.86 µm visible channel images

MODIS 0.65 µm (Band 1) visible channel and 0.86 µm (Band 2) visible channel images

MODIS 0.65 µm (Band 1) visible channel and 0.86 µm (Band 2) visible channel images

Precipitation variability across the Upper Midwest region

June 21st, 2012 |
MODIS true-color image, Sea Surface Temperature product, and 0.65 µm visible channel image

MODIS true-color image, Sea Surface Temperature product, and 0.65 µm visible channel image

AWIPS comparisons of a 250-meter resolution MODIS true-color Red/Green/Blue (RGB) image at 16:46 UTC on 21 June 2012 with the corresponding 1-km resolution MODIS Sea Surface Temperature product and 0.65 µm visible channel image (above) revealed the vivid signature of iron and/or copper rich runoff sediment in the near-shore waters of western Lake Superior following the historic heavy rainfall event of 19 June20 June 2012 (for more details on this event, see the Duluth National Weather Service).

A “before” (21 May 2012) and “after” (21 June 2012) true color image from the SSEC MODIS Today site (below) showed the dramatic change in appearance of the western Lake Superior near-shore waters.

MODIS true-color images (21 May 2012 and 21 June 2012)

MODIS true-color images (21 May 2012 and 21 June 2012)

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7-day total precipitation, percent of normal, and departure from normal

7-day total precipitation, percent of normal, and departure from normal

Maps of the total 7-day precipitation, percent of normal precipitation, and precipitation departure from normal (above) highlighted the extreme nature of the event in the Duluth region, but also showed the large amount of variability in precipitation across other portions of the Upper Midwest states during this period.

In particular, note the large southwest-to-northeast oriented swath across northeastern Nebraska, northwestern Iowa, southeastern South Dakota, and southwestern Minnesota (below): in this highly agricultural area, the stress on the crops within this rain-free swath was apparent on MODIS 0.65 µm visible imagery (lighter gray where the vegetation was less healthy), the MODIS Land Surface Temperature (LST) product (LST values in the upper 80s to mid 90s F, surrounded by LST values in the 70s F), and the Normalized Difference Vegetation Index (NDVI values as low as 0.43 in southwestern Minnesota, surrounded by NDVI values of 0.7 to 0.8 to the north and to the south where ample rainfall had been occurring).

MODIS 0.65 µm visible image, Land Surface Temperature product, and Normalized Difference Vegetation Index product

MODIS 0.65 µm visible image, Land Surface Temperature product, and Normalized Difference Vegetation Index product

Large algae bloom in Lake Erie

October 9th, 2011 |
MODIS true color and false color images

MODIS true color and false color images

A previous blog post discussed the sediment features seen in southern Lake Michigan in early October of 2011. However, looking a bit farther to the east over Lake Erie several days later, a 09 October 2011 comparison of 250-meter resolution MODIS true color and false color Red/Green/Blue (RGB) images from the SSEC MODIS Today site (above) showed a notable contrast between the two lakes: large green colored features covered much of western Lake Erie, compared to the cyan colored sediment that was seen in southern Lake Michigan (as well as southern Lake Huron).

According to the NASA Earth Observatory site, this is one of the worst algae blooms in Lake Erie in decades, brought about in part due to large amounts of runoff into the lake following a period of above-normal precipitation. The thickest portions of the algae bloom appear brighter green in the false color images, similar to the way that dense vegetation does.

A comparison of the consecutive Terra (16:52 UTC) and Aqua (18:33 UTC) MODIS true color images (below, viewed using Google Earth) seemed to suggest a slight northward movement of the algae features during the 91 minutes between the two images.

Terra (16:52 UTC) and Aqua (18:33 UTC) MODIS true color images

Terra (16:52 UTC) and Aqua (18:33 UTC) MODIS true color images

An animation of GOES-15 0.63 µm visible channel images (below) confirmed the gradual northward movement to the algae bloom features over western Lake Erie during the day. Surface winds were generally light out of the south across the region, so most of this motion was likely driven by lake currents.

GOES-15 0.63 µm visible channel images

GOES-15 0.63 µm visible channel images

Sediment features in southern Lake Michigan

October 3rd, 2011 |
MODIS true color images: 02 October (left) and 03 October (right)

MODIS true color images: 02 October (left) and 03 October (right)

As was highlighted in news stories posted by the National Weather Service forecast offices at Chicago and Milwaukee, a large amount of sediment was seen in southern Lake Michigan following a strong wind event which produced very large waves. A comparison of 250-meter resolution MODIS true color Red/Green/Blue (RGB) images from the SSEC MODIS Today site (above) showed one particularly large sediment feature protruding northward from the southeastern part of Lake Michigan on 02 October and 03 October 2011.

A comparison of AWIPS images of 1-km resolution MODIS 0.65 µm visible channel data with the corresponding 1-km resolution MODIS Sea Surface Temperature (SST) product on 03 October (below) showed that while the prominent sediment feature was embedded within a larger scale area of warmer waters (SST values in the lower 60s F, darker red color enhancement) in the far southern part of the lake, there was not necessarily a 1:1 correspondence between the sediment pattern and the sea surface temperature pattern.

MODIS 0.65 µm visible channel image + MODIS Sea Surface Temperature product

MODIS 0.65 µm visible channel image + MODIS Sea Surface Temperature product

GOES-13 0.63 µm visible channel imagery (below; click image to play animation) indicated that the prominent sediment feature was moving slowly northward early in the day on 03 October — however, once the northwesterly winds reported by the mid-lake buoy began to increase and gust to 16 knots later in the day, the northward motion of the sediment feature appeared to slow somewhat.

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

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

===== 06 October Update =====

A sequence of daily 250-meter resolution MODIS true color RGB images from 02, 03, 04, 05, and 06 October (below) show the changes in shape and location of the large sediment feature in the southeastern part of Lake Michigan.

MODIS true color images from 02, 03, 04, 05, and 06 October

MODIS true color images from 02, 03, 04, 05, and 06 October

In addition, daily 15-minute interval GOES-15 0.63 µm visible channel images from that same period (below; click image to play 5-day animation) further show how the sediment patterns were transported and morphed by the Lake Michigan water currents.

GOES-15 0.63 µm visible channel images (click image to play 5-day animation)

GOES-15 0.63 µm visible channel images (click image to play 5-day animation)