No new tornado deaths yesterday; Super Typhoon Songda hits Category 5

The tornado onslaught of 2011 continued over the Midwest yesterday, as dozens of tornadoes touched down, primarily in Missouri, Illinois, Indiana, and Arkansas. NOAA's Storm Prediction Center logged 81 preliminary reports of tornadoes in eleven states. Even California got into the action, with a tornado near Chico causing minor damage. Mercifully, no deaths were reported from yesterday's tornadoes. Too many thunderstorms formed too close to each other to allow strong or violent tornadoes to grow, as the many thunderstorms interfered with each others' organization. The preliminary tornado count for the 5-day outbreak that began Saturday is 243. Preliminary tornado reports are an overestimate, since some storms get counted multiple times. These over-counts were 35% - 40% in the case of the April 14 - 16 tornado outbreak and April 25 - 28 Super outbreak, so we can expect that the May 21 - 25, 2011 outbreak will end up with close to 150 tornadoes. This would rank as the third largest tornado outbreak in history, giving 2011 the three largest tornado outbreaks of all-time. Prior to 2011, NOAA rated the April 3 - 4, 1974 Super Outbreak as the largest tornado outbreak of all-time, with 148 tornadoes. According to a list of tornado outbreaks maintained by Wikipedia, only two other tornado outbreaks have had as many as 150 twisters prior to 2011--the May 2004 outbreak (385), and the May 2003 outbreak (401). However, these outbreaks occurred over an eight-day and eleven-day period, respectively, and were not due to a single storm system.


Figure 1. Satellite image taken at 23:32 UTC (7:32pm EDT) May 25, 2011, showing a line of tornadic thunderstorms over the Midwest. Image credit: NASA/GSFC.


Figure 2. Tornado near Fariview, Oklahoma, on May 24, 2011. Image credit: Mike Theiss, www.ExtremeNature.com.


Video 1. "We are in the tornado!" is all this poor guy caught in a car during a tornado can say, while buildings fly apart around him. He is very lucky to have survived. Video shot in Navarro County, Texas on May 24, 2011.

The death toll from Tuesday's tornadoes over Oklahoma, Arkansas, and Kansas is now 16, which would bring the death toll from this year's tornadoes to 506, according to yesterday's NOAA tornado statistic update. This makes 2011 the deadliest year for tornadoes in the U.S. since 1953, when 519 people died. That year, three heavily populated cities received direct hits by violent tornadoes. Waco, Texas (114 killed), Flint, Michigan (115 killed), and Worcester, Massachusetts (90 killed) all were hit by violent F-4 or F-5 tornadoes. A similar bad tornado year occurred in 1936, when violent tornadoes hit Tupelo Mississippi (216 killed), and Gainesville, Georgia (203 killed.)

Only a "Slight Risk" day for severe weather today
The Storm Prediction Center has placed portions of twenty states, from Alabama to Vermont, in their "Slight Risk" region for severe weather potential. The slow-moving low pressure system responsible for all the tornado activity this week is weakening, and the primary severe weather threat today is from large hail and damaging straight-line thunderstorm winds. However, there are still likely to be tornadoes today, and I expect we'll see a dozen or so twisters touch down from some of the stronger thunderstorms that develop.


Figure 3. Severe weather threat for Wednesday, May 25, 2011.

Links
Here is an interactive hi-res satellite image showing Joplin before and after the tornado. Some non-interactive images are here.

The New York Times has an interactive tornado fatality map showing how this year's killer tornadoes have mostly clustered over the Southeast U.S., with the glaring exception of the Joplin, Missouri tornado.

NOAA's Visualization Laboratory has an impressive animation of the satellite imagery during the month of April, showing the locations of all the tornadoes as they happened.


Figure 4. Satellite image of Super Typhoon Songda.

Super Typhoon Songda the first Category 5 tropical cyclone of 2011
The first typhoon of 2011 is also the globe's first Category 5 tropical cyclone of the year. Super Typhoon Songda intensified dramatically over the past 24 hours in an environment of light wind shear and warm sea surface temperatures of 30°C, to reach Category 5 status with top sustained winds of 160 mph. Tropical Cyclone Yasi, which devastated Queensland, Australia in early February, was the globe's previous strongest tropical cyclone of 2011, with 155 mph winds.

Fortunately, Songda is expected to miss making a direct hit on the Philippines, though evacuations have been ordered in low-lying areas. Satellite-estimated rainfall for the coming 24-hour period is predicted to be less than 4 inches along the northeast coast of the Philippines' Luzon Island, which should not cause major flooding problems. Songda is expected to turn northwards and threaten the island of Okinawa on Saturday. Sea surface temperatures decline rapidly north of the Philippines, and Songda is expected to weaken significantly before reaching Okinawa, where sea surface temperatures are approximately 26°C. Wind shear will also increase to high levels by Saturday, and Songda should be at most a Category 2 typhoon by the time it reaches Okinawa.

Jeff Masters