WunderBlog Archive » Category 6™

Category 6 has moved! See the latest from Dr. Jeff Masters and Bob Henson here.

Midwest Cleans up 2013's Biggest Severe Weather Outbreak; Floods Kill 17 in Sardinia

By: Dr. Jeff Masters, 3:59 PM GMT on November 19, 2013

Damage surveys continue in the Midwest U.S. after a stunning and violent late-season severe weather outbreak swept through on Sunday, killing at least eight people and leaving widespread significant damage. Two violent EF-4 tornadoes and one strong EF-3 tornado hit Illinois, killing six, making Sunday Illinois' deadliest November day for tornadoes in its history. The most widespread damage from Sunday's outbreak occurred in the town of Washington (population 16,000), about 140 miles southwest of Chicago, where a violent EF-4 tornado destroyed or heavily damaged 250 - 500 homes and an apartment complex. NOAA's Storm Prediction Center logged 85 preliminary tornado reports from Sunday, along with 455 reports of high wind gusts and 32 reports of hail. Seventeen of the wind gusts were in excess of 74 mph (hurricane strength.) The grand total of 572 severe weather reports (filtered to remove duplicates) for the day were the most of any day of 2013, surpassing the 538 total reports from June 13. The 85 preliminary tornado reports is also the highest for any day of 2013, surpassing the 62 reports from January 29.

Figure 1. An aerial view of Washington, Illinois on Sunday, Nov. 17, 2013, after a tornado tore through the area. (Photo by Tasos Katopodis/Getty Images)

Video 1. View from a tugboat on the Ohio River of the EF-3 tornado that hit Brookport, Illinois, killing three people. It is difficult to see as it was shot through the windshield of the tugboat, but you can see evidence of the circulation in the distance. The most impressive part of the video is watching the rain finally reach the boat at around 3:00, as a rain-wrapped circulation crosses the river in front, heading towards the town of Brookport. Looking at the orientation of the town along the river, these guys were looking directly into the circulation, and the rain curtains overtaking their boat is likely the Rear Flank Downdraft (RFD) moving over them.  Thanks go to TWC's Sarah Dillingham for the link and the commentary.

Sunday's November tornado outbreak: how rare?
Sunday's outbreak will probably rank as the second to fourth most prolific November tornado outbreak since 1950. But what was really remarkable about the outbreak was how far north it extended. With three confirmed tornadoes on Sunday, Michigan has increased its total number November tornadoes observed since 1950 by 50%, from six to nine. Prior to Sunday, Indiana had recorded 57 November tornadoes. That total increased by 26 on Sunday, which was the 3rd busiest day for tornadoes in Indiana history (the record: 37 tornadoes on June 2, 1990.) Seven confirmed tornadoes occurred in the 23-county region of Northeast Illinois and Northwest Indiana serviced by the Chicago NWS. Prior to Sunday’s tornado outbreak, there had been just twelve November tornadoes in this region since accurate tornado records began in 1950. The 101 tornado warnings issued in Illinois on Sunday represented 52% of all November tornado warnings issued in the state since 1986. The two EF-4 tornadoes that struck Illinois were the 2nd and 4th most northerly EF-4s ever recorded in the U.S. during the month of November, according to data from the Tornado History Project. Prior to Sunday, only twenty EF-4s had occurred in the U.S. in November dating back to 1950. Also notable is the fact that the intensity and areal extent of this severe weather outbreak resulted in widespread damage over a huge area, making it possible that this will be the first November severe weather outbreak in history to exceed $1 billion in damages. November severe weather outbreaks are rare enough and our database poor enough that we cannot make any definitive statements on how climate change may be affecting them, but one would expect to see cold-season severe weather events become increasingly common farther to the north in a warming climate.

Here is a list of the largest November tornado outbreaks since 1950:

95 tornadoes: November 21–23, 1992, Texas to Mississippi and into the Ohio Valley. The most intense and largest November outbreak on record in U.S. history. Produced violent tornadoes from Texas to Mississippi and into the Ohio Valley, including six F4s and two extremely long-track tornadoes, 160 miles and 128 miles.
75 tornadoes: November 9–11, 2002, Southeast U.S. and Ohio Valley. Very large and deadly outbreak produced multiple killer tornadoes across the Ohio Valley and Southeastern United States. A violent F4 hit Van Wert, Ohio, killing four people. Deadly F3 also hit Mossy Grove, Tennessee, killing seven.
67 tornadoes: November 23–24, 2001, Southeast U.S. Thirteen people killed.
50 tornadoes: November 15, 2005, Central and Southeast U.S. One person killed.
50 tornadoes: November 15 - 16, 1987, Oklahoma, Texas, and Mississippi.

Wunderground weather historian Christopher C. Burt has more detail on November tornado history in his latest post.

Figure 2. MODIS image of Extratropical Storm Cleopatra/Ruven off the coast of Sardinia, taken at approximately 15:30 UTC (10:30 am EST) November 19, 2013. Image credit: NASA.

Extreme flooding kills 17 in Sardinia, Italy
Slow-moving and powerful Extratropical Storm Cleopatra (called Ruven by the Free University of Berlin) dumped prodigious rains over the Mediterranean island of Sardinia on Monday, triggering floods that have killed at least seventeen people. According to media reports, the storm dumped as much as 450 mm (17.72") of rain in just 24 hours on the Italian island. The storm brought sustained winds of 38 mph, gusting to 56 mph, to Cagliari, Sardinia, on Monday.

Figure 3. MODIS image of Subtropical Storm Melissa, taken at approximately 13:30 UTC (8:30 am EST) November 19, 2013. Image credit: NASA.

Subtropical Storm Melissa no threat to land
Subtropical Storm Melissa, the 13th Atlantic named storm of 2013, is slowly transitioning to a tropical storm as it heads north over the Central North Atlantic, far from land. Ocean temperatures are near 25°C, which is barely warm enough to support a tropical storm, but wind shear is a moderate 10 - 20 knots, which may allow Melissa to become fully tropical by Wednesday morning. Wind shear is expected to rise to the high range on Wednesday as ocean temperatures plummet to 20°C (68°F) and dry air sharply increases. These conditions should cause Melissa to rapidly deteriorate on Wednesday. Satellite loops show that Melissa has a large circulation, but only limited heavy thunderstorm activity near the center. Melissa will not be a threat to any land areas.

Jeff Masters

Severe Weather Tornado Flood

The views of the author are his/her own and do not necessarily represent the position of The Weather Company or its parent, IBM.