CIMSS Satellite Blog

Severe thunderstorms developed across parts of Montana on 16 June 2007, producing heavy rainfall (2-6 inches), large hail (up to 3 inches in diameter), damaging winds (gusting to 89 mph), and isolated tornadoes (SPC storm reports). GOES-11 10.7µm InfraRed (IR) imagery (above; Java animation) indicated cloud top brightness temperature values were as cold as -68º C (dark red enhancement) with these storms.

A closer view using GOES-11 visible channel imagery (above; Java animation) shows the storms in the Billings (KBIL) and Glasgow (KGGW) regions. Of particular interest was the northernmost Glasgow storm, whose northwest-to-southeast track deviated from that of the other eastward or northeastward-moving areas of convection over eastern Montana that day. Also note that the southernmost Billings storm exhibited a well-defined anvil plume after about 00:00 UTC on 17 June — this anvil plume was quite apparent in the visible imagery, but did not seem to exhibit much of a signal in the IR imagery (below).

The large hail (driven by strong winds) from the northernmost Glasgow storm produced extensive damage to the wheat, alfalfa, and corn crops in that region — Tanja Fransen (WCM, NWS Glasgow) alerted us to the fact that the northwest-to-southeast oriented hail damage swath was clearly evident on Aqua MODIS true color imagery on 20 June, 4 days following the storm (below). A Java image fader applet allows a comparison between the MODIS images on 10 June (before the storm) and 20 June (after the storm), further highlighting hail damage swath. NWS Glasgow measured the damage swath to be about 285 miles long, and up to 12 miles wide (NWS public information statement).

A series of low-level convective outflow boundaries was seen moving off the coast of Cuba on 08 June 2007. GOES-12 visible imagery (above; Java animation) shows the narrow convex cloud bands as they propagated across the offshore waters; note how new convection was seen to develop where adjacent outflow boundaries intersected.

An outbreak of severe thunderstorms developed across the Upper Midwest states on 07 June 2007 — SPC storm reports showed widespread tornadoes (including the EF-3 Langlade WI tornado), large hail, and damaging winds over much of the region. GOES-12 visible channel (above; Java animation) revealed a large area of boundary layer wave clouds that developed during the morning hours over a good deal of western Wisconsin and extreme northeastern Iowa and southeastern Minnesota.

GOES-12 10.7µm IR images (below; Java animation) depicted cloud top brightness temperatures as cold as -69º C / -92º F (dark red enhancement) as the storms intensified during the afternoon. The dynamics associated with this severe weather outbreak were quite strong, with very fast jet stream winds at the 500 hPa and 250 hPa pressure levels. The 1-km resolution MODIS water vapor imagery indicated a broad area of potential clear air turbulence downwind of the Rocky Mountains, with the characteristic “herringbone signature” extending as far eastward as western Kansas.

CIMSS employee Derrick Herndon was chasing these storms in central Wisconsin, and took a photo of some very large hail on the ground in Wisconsin Rapids (below). The largest hail listed on the SPC storm reports for that day was 4.25 inches in diameter at Wisconsin Rapids.

An interesting feature seen on MODIS false color imagery (below) was the southwest-to-northeast oriented swaths of wet ground left in the wake of rainfall from storms moving across portions of northeastern Iowa and southeastern Minnesota. Note the cooler temperatures (60s and 70s F) at locations within the rainfall swaths. The larger rain swath was still evident on the following day, with surface temperature at Preston, Minnesota (station identifier KFKA) remaining 2-3 degrees cooler than surrounding sites.

2 days later (09 June), the long-track tornado damage path across northeastern Wisconsin was evident on consecutive passes of the Terra MODIS (below) and Aqua MODIS satellites (courtesy of the Environmental Remote Sensing Center).