A beautiful cloud-free day over Wisconsin

October 5th, 2010 |
MODIS "color balanced" Red/Green/Blue (RGB) image

MODIS "color balanced" Red/Green/Blue (RGB) image

It’s not often that the entire state of Wisconsin is “cloud-free” — but the MODIS “color balanced” Red/Green/Blue (RGB) image (above; courtesy of Sam Batzli, SSEC / WisconsinView Project) shows a beautiful example of Wisconsin and adjacent areas on 05 October 2010. Note that we used quotation marks around the term “cloud free”: there was in fact a small smoke plume seen drifting northward from a fire that was burning in the far northwestern part of the state. Otherwise, the vast diversity of vegetation across the region was quite evident by their differences in appearance on the image — from the golden orange hues of Autumn tree leaf colors in northern Wisconsin and the Upper Peninsula of Michigan, to the tan-colored fields of harvested corn across parts of southern Wisconsin, northern Illinois, northeastern Iowa, and southeastern Minnesota.

Also of interest are the bright cyan-colored areas of water over far southern Lake Michigan and also over far northern Lake Superior — these were signatures of  algae blooms. MODIS Sea Surface Temperature values on this day ranged from the upper 40s F in western Lake Superior to the middle 60s F in southern Lake Michigan (below).

MODIS Sea Surface Temperature product

MODIS Sea Surface Temperature product

Back to the smoke plume seen in the MODIS image above: a comparison of AWIPS images of the 4-km resolution GOES-13 3.9 µm shortwave IR and the corresponding 1-km resolution MODIS 3.7 µm shortwave IR images (below) demonstrated the importance of spatial resolution for determining the exact location of small-scale features such as actively burning fires. The fire “hot spot” was significantly hotter on the MODIS image (48.5º C, orange color enhancement) than on the GOES-13 image (28.5º C, darker gray color enhancement).

GOES-13 3.9 µm shortwave IR + MODIS 3.7 µm shortwave IR images

GOES-13 3.9 µm shortwave IR + MODIS 3.7 µm shortwave IR images

===== 07 OCTOBER UPDATE =====

Yet another cloud-free day over Wisconsin two days later on 07 October, allowing a nice comparison of the changing Autumn tree colors (below).

MODIS true color images (05 October and 07 October 2010)

MODIS true color images (05 October and 07 October 2010)

Severe thunderstorms in Arizona

October 5th, 2010 |
GOES-11 (left), GOES-15 (center), and GOES-13 (right) visible images

GOES-11 (left), GOES-15 (center), and GOES-13 (right) visible images

Multiple rounds of severe thunderstorms moved northward across southern Arizona on 05 October 2010, producing hail as large as 2.5 inches in diameter, wind gusts as high as 75 mph, and rainfall in excess of 2 inches at some locations (SPC Storm Reports). According to a Phoenix Public Information Statement, the 2.5 inch diameter hail was some of the largest hail ever reported in Arizona.

A 3-panel comparison of visible channel images from GOES-11, GOES-15, and GOES-13 (above; also available as a QuickTime movie) showed the large clusters of convection, some of which moved through the Phoenix area (station identifier PHX). After 18:30 UTC, the GOES-11 satellite was placed into Rapid Scan Operations (RSO) mode, allowing images as frequently as every 5-7 minutes (in contrast to the standard operational 15-minute image interval on GOES-15 and GOES-13).

AWIPS images of the MODIS 0.65 µm visible channel and 11.0 µm IR Window channel (below) showed a closer view of the storms at 21:01 UTC (3:01 pm local time). MODIS cloud top IR brightness temperatures were as cold as -61º C (darker red color enhancement). Cloud-to-ground lightning strikes, severe reports of hail and wind, and surface METAR reports are also overlaid on the MODIS images.

MODIS 0.65 µm visible and 11.0 µm IR Window images

MODIS 0.65 µm visible and 11.0 µm IR Window images

An AWIPS image of the POES AVHRR Cloud Top Temperature (CTT) product (below) displayed a minimum CTT value of -63º C just southeast of Chandler/Williams Air Force Base (station identifier KIWA) at 21:23 UTC (3:23 pm local time).

POES AVHRR Cloud Top Temperature product

POES AVHRR Cloud Top Temperature product