It was yet another active day for tornadoes, flooding, and severe thunderstorms in the Midwest on Thursday, with NOAA’s Storm Prediction Center (SPC) logging 16 preliminary tornado reports. Twisters touched down in Oklahoma, Arkansas, and Illinois. The tornadoes missed heavily populated areas for the most part, but seven people were injured in Arkansas in two separate tornadoes, and two other people were hurt by lightning. The severe weather forced organizers of the outdoor Wakarusa Music Festival north of Ozark, Arkansas to delay the start of the festival. The band “Widespread Panic” was one of the groups scheduled to perform, leading to an Associated Press headline from yesterday titled, “Nine hurt in Arkansas storm; Widespread Panic delayed.” Heavy rains from this week’s thunderstorms have pushed the Mississippi River to major flood stage at most places from Burlington Iowa to Quincy Illinois, and the river is expected to crest near major flood stage at St. Louis early next week. In Iowa, the Cedar River at Cedar Falls, the Iowa River at Marengo, and the Skunk River near Sigourney and at Augusta are also in major flood. The latest forecast from NOAA’s Storm Prediction Center calls for a “Moderate Risk” of severe weather today (Friday) over much of Oklahoma and Southwest Missouri, including Oklahoma City and Tulsa in Oklahoma, and Joplin, Missouri, with the potential for several strong EF-2 and EF-3 tornadoes.

Figure 1. Lightning strike from a severe thunderstorm near Guthrie, Oklahoma on May 30, 2013, as photographed by KFOR-TV. (AP Photo/KFOR-TV)

Figure 2. Severe weather outlook for Thursday, May 30, calls for a “Moderate Risk” of severe weather over much of Oklahoma and Southwest Missouri, including Oklahoma City and Tulsa in Oklahoma, and Joplin, Missouri. You can follow today’s severe weather outbreak from our Severe Weather page.

A mostly quiet year for violent tornadoes
After a very quiet March, April, and first half of May, the U.S. tornado season has become very active during the last half of May, and is beginning to catch up to normal. TWC’s tornado expert Dr. Greg Forbes has a preliminary count of 181 tornadoes for the month of May, through May 29, which is 35% below the 10-year average of 279 through May 29th. May 2012 had only 121 tornadoes. The 2013 tornado tally has risen significantly in the last half of May, due to 7 of the last 15 days having above-average numbers of tornadoes. Fortunately, we are well below-average for strong and violent EF-3, EF-4, and EF-5 tornadoes so far in 2013. According to NOAA, the U.S. has averaged 43 EF-3 or stronger tornadoes per year during the period 1954 – 2012. With tornado season nearly half over, only twelve EF-3 and EF-4 tornadoes have been recorded so far in 2013. An average year should have had at least twenty of these tornadoes by this point in the year. Here are the twelve EF-3 and stronger tornadoes so far in 2013, as detailed in Wikipedia’s excellent Tornadoes of 2013 page:

EF-5, May 20, Moore, Oklahoma. 24 deaths, 377 injuries, $2 billion in damage.
EF-4, May 28, Ottawa County, Kansas. Intensity based on mobile Doppler radar data. See the Capital Weather Gang’s description of this tornado.
EF-4, May 19, Shawnee, Oklahoma. 2 deaths, 6 injuries.
EF-4, May 15, Granbury, TX. 6 deaths, 24+ injuries.
EF-4, May 18, Rozel, Kansas.
EF-4, February 10, Hattiesburg, MS. 0 deaths, 82 injuries.
EF-3, Corning, KS, May 28.
EF-3, May 27, Lebanon – Esbon, KS. 1 injured. Wind gust of 175 mph measured by TIV2 intercept vehicle.
EF-3, May 15, Cleburne, TX. No deaths or injuries.
EF-3, January 30, Adairsville, GA. 1 death, 17 injuries, 363 buildings damaged or destroyed.
EF-3, April 11, Kemper County, AL. 1 death, 9 injuries.
EF-3, May 19, Luther – Carney, Oklahoma.

Figure 3. The annual number of EF-3 and stronger tornadoes, 1954 – 2012. The greatest number of these dangerous tornadoes was 131 in 1974, the year of the notorious “Super Outbreak.” The minimum was just 15, set in 1987. The average is 43 per year. Image credit: NOAA.

Video 1. Impressive 2-minute timelapse of the Bennington, Kansas wedge tornado of May 28, 2013, as filmed by the Aussie Storm Chasers. As discussed in an excellent blog post by Jason Samenow of the Capital Weather Gang, the violent EF-4 tornado stood still for nearly an hour, and had wind gusts as high as 264 mph at an altitude of 300 feet measured by Doppler on Wheels.

Remains of Hurricane Barbara bringing heavy rains to Mexico
Hurricane Barbara died on Thursday as it attempted to cross Mexico’s Isthmus of Tehuantepec into the southernmost Gulf of Mexico. While there is no low level circulation apparent on satellite loops this Friday morning, there is a bit of spin at middle levels of the atmosphere, and the remains of Barbara are kicking up some heavy thunderstorm activity over the southernmost Gulf of Mexico and adjacent land areas of Mexico. Wind shear is a high 20 knots in the region, and the area of disturbed weather is quite small, so I don’t expect any development to occur over the next few days. Wind shear is predicted to remain high over the Gulf of Mexico for the next six days, and none of the reliable computers models is calling for tropical cyclone development in the Atlantic during that period. Late next week, wind shear is predicted to drop, and there is a better chance for tropical cyclone development in the Gulf of Mexico or Western Caribbean. Both the GFS and ECMWF models suggest that a strong tropical disturbance with heavy rains may affect Mexico’s Yucatan Peninsula, Western Cuba, and the Southwest Florida by Friday next week.

Figure 4. Remains of Hurricane Barbara in the southernmost Gulf of Mexico as seen by MODIS at 12:05 pm EDT Thursday, May 30, 2013. Barbara had just been declared dead one hour prior to this photo. Image credit: NASA.

Saturday, June 1, is the first day of hurricane season, and I’ll post a quick look at what we might expect to see in June.

from:    http://www.wunderground.com/blog/JeffMasters/show.html