Shelf Cloud Over Sugar Grove, Illinois

September 10, 2014

SugarGroveShelfWatermark (1)

Photographer: Jodi Mair
Summary Author: Jodi Mair

The photo above shows a nasty looking storm cloud overtaking an abandoned farmstead near Sugar Grove, Illinois. This is a shelf cloud -- it's detached from the parent cloud (top). A 48 mph (42 knots) wind gust was recorded a few minutes after this picture was snapped. Note that the highest winds usually occur just after the gust front passes. At this location, this storm wasn't deemed severe since a severe thunderstorm is defined by the U.S. National Weather Service as having large hail, at least 1.0 in (2.54 cm) in diameter, and/or damaging winds, at least 57 mph (50 knots). Nonetheless, when clouds such as this are seen on the plains it's time to seek cover. It should be mentioned that elsewhere in Illinois, to the northeast and southwest of Sugar Grove, severe weather was observed. Photo taken about 5:42 p.m. June 21, 2014.

Photo details: Camera Model: Canon EOS REBEL T2i; Lens: EF-S18-55mm f/3.5-5.6 IS II; Focal Length: 18.0mm; Focus Distance: 1.45m; Aperture: f/5.6; Exposure Time: 0.033 s (1/30); ISO equiv: 800; Software: Adobe Photoshop Elements 9.0 Windows.