Heavy rain event in southeastern South Dakota
A line of training thunderstorms produced heavy rainfall in parts of southeastern South Dakota on the evening of 27 August 2015, with the highest rainfall amount being 7.52 inches just southwest of Sioux Falls (Public Information Statement). 4-km resolution GOES-13 (GOES-East) 10.7 µm Infrared images (above; click to play animation) showed the development and motion of the storms that moved through the Sioux Falls (KFSD) area. The coldest cloud-top IR brightness temperature was -68º C (darker black color enhancement) just to the northwest of Sioux Falls on the 0115 UTC (8:15 PM local time) image. However, because of parallax resulting from the large satellite viewing angle, the actual location of that tall, cold cloud top would have been just to the southeast of Sioux Falls (the yellow + symbol on this image).A comparison of 1-km resolution POES AVHRR Visible (0.86 µm) and Infrared (12.0 µm) images at 2330 UTC or 6:30 PM local time (below) showed the developing convective storms in greater detail. The coldest cloud-top IR brightness temperature was -73º C with the westernmost cluster of thunderstorms.
A closer view of the GOES-13 Infrared images with METAR surface reports is shown below. Note that Sioux Falls had a peak wind gust of 32 knots (37 mph). The Blended Total Precipitable Water (TPW) Percent of Normal product (below; click to play animation) showed TPW values as high as 199% of normal just to the north-northeast of Sioux Falls at 0442 UTC (11:42 PM local time).
Check out the rainfall on the west side of Sioux Falls. Almost an inch of rain fell in 10 minutes! pic.twitter.com/OYavFY67pp
— NWS Sioux Falls (@NWSSiouxFalls) August 28, 2015
How unprecedented was the rain? At a SDSU automated rain gauge at Sertoma Park, it measured 2.73″ of rain within 25 minutes! Wow! — NWS Sioux Falls (@NWSSiouxFalls) August 28, 2015
At the same gauge at Sertoma Park, it recorded 0.71″ of rain within 5 minutes! That’s a lot of water!
— NWS Sioux Falls (@NWSSiouxFalls) August 28, 2015
Updated precip total map – thanks to NWS FSD for additional data. #sdwx #siouxfalls pic.twitter.com/fc9qHqZZ2y — Dennis Todey (@sdclimatologist) August 28, 2015
Wondering how much rain you received last night? Here is a map of rainfall reports we received. pic.twitter.com/rqUF6AVYdf
— NWS Sioux Falls (@NWSSiouxFalls) August 29, 2015