WASHINGTON — Over the past few decades, tornadoes have been shifting — decreasing in Oklahoma, Texas and Kansas but spinning up more in states along the Mississippi River and farther east, a new study shows. Scientists aren’t quite certain why.
Tornado activity is increasing most in Mississippi, Arkansas, Tennessee, Louisiana, Alabama, Kentucky, Missouri, Illinois, Indiana, Wisconsin, Iowa and parts of Ohio and Michigan, according to a study in Wednesday’s journal Climate and Atmospheric Science. There has been a slight decrease in the Great Plains, with the biggest drop in central and eastern Texas. Even with the decline, Texas still gets the most tornadoes of any state.
The shift could be deadly because the area with increasing tornado activity is bigger and home to more people, said study lead author Victor Gensini, a professor of atmospheric sciences at Northern Illinois University. Also more people live in vulnerable mobile homes and tornadoes are more likely to happen at night in those places, he said.
Even though Texas, Kansas and Oklahoma get many more tornadoes, the four deadliest states for tornadoes are Alabama, Missouri, Tennessee and Arkansas, according to the National Oceanic and Atmospheric Administration.
“More folks are generally at risk because of that eastward shift,” Gensini said.
Because tornadoes sometimes go undercounted, especially in the past and in less populous areas, scientists don’t like to study trends by using counts of tornadoes. Gensini and tornado scientist Harold Brooks of the National Severe Storms Lab looked at “significant tornado parameters,” a measurement of the key ingredients of tornado conditions. It looks at differences between wind speed and direction at different altitudes, how unstable the air is and humidity. The more of those three ingredients, the more likely tornadoes will form.
The increases in this measurement mirrored slightly smaller increases found in number of twisters.
The study looked at changes since 1979. Everywhere east of the Mississippi, except the west coast of Florida, is seeing some increase in tornado activity. The biggest increase occurred in states bordering the Mississippi River.
Overall there is a slight increase in tornado activity, but it’s not too much and not nearly like what’s happening in the east, Gensini said.
Why is this happening?
“We don’t know,” Gensini said. “This is super consistent with climate change.”
As the Great Plains dry out, there’s less moisture to have the type of storms that spawn tornadoes, Gensini said. Tornadoes form along the “dry line” where there are more thunderstorms because there’s dry air to the west and moist air from the Gulf of Mexico to the east.
That dry line is moving east.
“This is what you would expect in a climate change scenario, we just have no way of confirming it at the moment,” Gensini said.
Gensini said unless there are specific detailed studies, he and others cannot say this is caused by global warming, just that it looks like what is expected.
Pennsylvania State University meteorology professor Paul Markowski, who wasn’t part of the research, praised the study as careful and well done.
The Associated Press Health & Science Department receives support from the Howard Hughes Medical Institute’s Department of Science Education. The AP is solely responsible for all content.
As the upper jet stream starts to react to the closing season, troughs will dig further into California, thus the surface lows should form in Colorado and Kansas, bringing with it the perfect setup for violent tornado outbreaks. This is the seventh year of prediction made here at TheWeatherSpace.com about the tornado season. All predictions have been accurate, including the tornado drought in the plains a couple years back. This year will not feature a death ridge.
A death ridge is when a ridge of high pressure sets up over the Western United States, owning to a northwest flow into the region with no upper divergence or colder air aloft to push supercells off. This has happened a couple times in the seven year prediction period done on this site.
This year, however, is not a death ridge, but one where a trough should set-up end April into May across the Western United States. Impulses riding that into the Great Plains will bring the perfect ingredients for tornadoes … and since the jet may be in perfect orientation for these events, outbreaks are likely …
The year 2014 has just begun, but the tropical cyclone seasons in both the Northern and Southern Hemispheres have already claimed victims. Summer is in full bloom in the Southern Hemisphere, where two Category 4 storms formed last week: Tropical Cyclone Colin, which reached sustained winds of 135 mph midway between Madagascar and Australia on January 11, and Tropical Cyclone Ian, which intensified into a powerful Category 4 storm with 145 mph winds before roaring through the South Pacific islands of Tonga over the weekend. At least one death is being blamed on the storm in the northern Ha’apai Islands of Tonga, home to 8,000 people, and 70% of the buildings were damaged or destroyed, according to the Australia Network News. Tonga is an archipelago of 176 islands, with 100,000 people living on the 36 most populated islands. The economy relies on fish exports, tourism, and money from Tongans living overseas. About 40% of the population lives in poverty.
In the Philippines, heavy rains from tropical disturbance 91W have triggered flash floods and mudslides that are being blamed for six deaths on the southern island of Mindanao on Saturday, with eight other people missing. Twenty-four hour rainfall amounts in excess of 300 mm (11.81″) fell in northeast Mindanao, according to Project NOAH. The disturbance will move slowly north over the islands through Tuesday, and bring torrential rains in excess of 5″ to the islands of Leyte and Samar, ravaged by Super Typhoon Haiyan in November.
Figure 1. MODIS image of Tropical Cyclone Ian as its eye passed over Tonga at approximately 00 UTC on January 11, 2014. At the time, Ian was a Category 4 storm with winds of 145 mph. Image credit: NASA.
First U.S. Tornadoes of 2014 hit Virginia and Georgia
A modest severe weather outbreak over the Southeast U.S. on Saturday, January 11, brought the first tornadoes of 2014: three to Virginia, and one to Georgia:
1. EF-0 tornado near Waleska in Cherokee Co, GA, 3 mile path length, downed trees, damaged fence.
2. EF-0 in Isle of Wight Co., VA, 70-75 mph, 2 mile path, 50 yards wide, trees down, roof damage to homes, no injuries.
3. EF-0 near Smithfield, VA, EF-0, 75-80 mph, 1.4 mile path, 100 yards wide, trees down onto homes, no injuries.
4. EF-0 tornado in Hampton, VA, 80 mph, 1.25 mile path, 75 yards wide; trees snapped, shingles off homes, roof off City of Hampton school maintenance compound; Fox Hill Athletic Association building destroyed.
The strongest wind gust ever recorded at Raleigh-Durham International Airport, 86 mph, occurred at 1:57 PM Saturday, when a line of thunderstorms roared through central North Carolina.
t was a terrifying evening of tornado chaos and extreme atmospheric violence in the Oklahoma City area on Friday. Three tornadoes touched down near the city, killing nine, injuring at least 71, and causing widespread destruction. Huge hail up to baseball-sized battered portions the the metro area, accompanied by torrential flooding rains, widespread damaging straight-line winds, and lightning that flashed nearly continuously. The strongest tornado, which touched down west of Oklahoma City in El Reno, has been preliminarily rated an EF-3 with 136 – 165 mph winds. The tornado warning for the storm was issued 19 minutes before it touched down. Two other EF-3 tornadoes touched down near St. Louis, Missouri, and NOAA’s Storm Prediction Center (SPC) logged 20 preliminary tornado reports on Friday. Tinker Air Force Base on the east side of Oklahoma City reported sustained winds of 68 mph, gusting to 88 mph, at 8:09 pm CDT. The Oklahoma City airport had sustained winds of 53 mph, gusting to 71 mph at 7:26 pm. These winds were generated by the massive and powerful downdrafts from the supercell thunderstorm that spawned the El Reno tornado. Thankfully, Friday was likely the peak day for this week’s severe weather outbreak, as SPC is calling for only a “Slight Risk” of severe weather Saturday and Sunday.
Figure 1. TWC’s Mike Bettes crew caught this image of the El Reno, Oklahoma tornado of May 31, 2013 before the tornado caught them and rolled their vehicle.
Figure 2 and 3. Radar reflectivity (top) and Doppler velocity (bottom) images of the May 31, 2013 El Reno, Oklahoma tornado.
Figure 4. Preliminary tracks of the three tornadoes that touched done near Oklahoma City on May 31, 2013. Image credit: NWS Norman, OK.
Tornadoes and cars: a dangerous mix
A vehicle is about the worst place you can be in a tornado, as the tornado’s winds can easily roll a car. (The only place less safe is probably a mobile home, as a tornado’s winds can roll mobile homes almost as readily, and mobile homes don’t come with seat belts and air bags.) At least five of the deaths in Friday’s El Reno tornado occurred in vehicles attempting to flee. There was one local TV station that urged residents without underground shelters to get in their cars and “get south” in advance of the tornado that was approaching Oklahoma City, since chasers were reporting that the El Reno tornado may have been so strong that only an underground shelter would have provided adequate protection. This terrible piece of advice likely contributed to the incredible traffic jams that we saw on I-35, I-40, I-44, and other local roads Friday night. Thousands of cars were bumper-to-bumper on the roads as a dangerous tornado approached them. Had the El Reno tornado plowed directly down one of these car-choked interstates, the death toll could have easily exceeded 500. If you are located in a metro area and don’t have an underground shelter, the best thing to do it to take shelter in an interior windowless room or hallway, with protective furniture over your body. Getting in a car and attempting to flee the tornado is the worst thing you can do in an urban area. You may not be able to see the tornado if it is dark or the tornado is wrapped in rain. You are likely to encounter hazardous winds, rain, and hail, run into unexpected traffic, or flooded or debris-blocked roads that will put you directly in the path of the tornado. Even without an underground shelter, most people will be able to survive a dangerous EF-4 tornado. Case in point: during the Mannsford, Oklahoma EF- 4 tornado of 1984, a packed church received a direct hit, and everyone in the church survived. The only fatality was a man who drove to the church to get his wife. (Thanks to wunderground member AGWcreationists for this link.) It’s better to abandon your vehicle and take shelter in a ditch, if you are caught in a car during a tornado.
Video 1. The Weather Channel storm chasers weren’t the only ones who got themselves in an extremely dangerous situation on May 31. StormChasingVideo.com storm chaser Brandon Sullivan and his chase partner Brett Wright got caught in the tornado northwest of Union City, OK and slammed with debris as the tornado hit a barn that exploded in front of them.
Video 2. When the hunters became the hunted: Weather Channel storm chasers Mike Bettes and two photographers were in their Tornado Hunt vehicle when they were hit by a tornado in El Reno, Oklahoma on May 31, 2013. The tornado picked their car up off the ground and rolled it 6 – 8 times before depositing it in a field 200 yards away. All the occupants were wearing seat belts and the air bags deployed, likely saving their lives. Bettes sustained minor injuries, including stitches in his hand. It was the first injury sustained by a Weather Channel personality covering violent weather, according to company spokesperson Shirley Powell.
A storm chasers’ nightmare
Cars and tornadoes can prove a dangerous mix even for the world’s most experienced storm chasers. Driving at high speeds though heavy rain, large hail, and high winds is hazardous. If one is lucky enough to chase down a tornado, even the most experienced chasers can find themselves in a serious life-threatening situation when unpredictable events occur. Tornadoes by their nature are unpredictable, and can change course unexpectedly, or pop up suddenly. It’s particularly dangerous when a tornado is wrapped in rain, making it hard to see, or if a chaser is operating in a heavily populated area, where roads may suddenly become congested. All four of these conditions occurred Friday during the El Reno tornado, and it is very fortunate that multiple chasers were not killed. The El Reno tornado was wrapped in rain and difficult to see as it headed west towards Oklahoma City. The twister suddenly made a jog to the southeast as a Weather Channel team led by Mike Bettes was attempting to get in front of the storm, and the tornado lifted their vehicle off the ground, rolled it multiple times, and hurled it 200 yards into a nearby field. StormChasingVideo.com storm chaser Brandon Sullivan and his chase partner Brett Wright got caught in the tornado northwest of Union City, OK and slammed with debris as the tornado hit a barn that exploded in front of them. Meteorologist Emily Sutton and storm chaser Kevin Josefy of local Oklahoma City TV station KFOR also had a very close call with the El Reno tornado Friday afternoon. They got too close to the tornado, and were forced to floor the car in reverse to escape flying debris. With branches of trees crashing around them, Sutton began feeling debris hitting her back, and realized that the rear windshield of the car must have gotten destroyed. Both were uninjured. Reed Timmer’s armor-plated “Dominator” chase vehicle had its hood torn off by the tornado. Wunderground member Levi32 was out storm chasing during the El Reno Tornado, and got stuck in traffic on Highway 4 and couldn’t move. “We looked up above the car and saw the wall cloud over top of us, with very quick rotation and rising scud indicating the updraft. We were definitely too close. We made it home safely last night, but not until after an insanely wild day. One hour of chasing turned into six more of being chased by at least 2 tornadoes and a 3rd wall cloud, one of which was the one that went right through downtown Oklahoma City. At one point we were stuck in traffic underneath the El Rino wall cloud watching rotating, rising scud directly above the car. I am hoping and praying that the daylight does not reveal more fatalities.
Would I go again? Yes, but not today, or tomorrow, and I would take even greater care. We had no clue we would get caught the way we did. I thought we had done everything right. We were kind of freaking out for a while. That velocity signature you guys saw with radar folding and multiple vortices – we were under the southern edge of it. We never got a clear view of the tornado, but we could tell just how close it was to our north. It was unreal. The inflow got pretty strong.
We were almost ready to jump out and take cover right before we found a route south, which ended up being slow. It became a six-lane highway south as everyone panicked and drove on the wrong side of the road. Even we did so. We thought we were clear until we saw the training of tornadic supercells on radar, all connected somehow. I’ve never seen anything like that. My best pictures of the day were of the wall cloud that followed behind the El Reno storm. We didn’t see a funnel from that one either, but it chased us south for a long time, and we heard from radio that it spawned a confirmed tornado in Tuttle, when we realized that we were in Tuttle.
A third mesocyclone showed up behind that one as we continued slowly south, eventually reaching Blanchard. It looked weaker than the others but we weren’t going to escape it, so we took shelter in a storm room in the local grocery store for about an hour. It then took a long time to find a way around the huge hail cores to get back home. Lightning flashes were occurring 10 times per second as we drove home in the dark. It was almost calming to watch as we got over the semi-shock that we were all in. None of us in the car had seen a tornado before. We didn’t see one yesterday, but we were chased by two.”
Video 3. Birth of the El Reno wedge tornado. As the tornado touched down, it produced a rare display of suction vortices.
Video 4. Storm chasers Jeff Piotrowski and Kathryn Piotrowski captured impressive footage of a double vortex tornado near El Reno, Oklahoma on May 31, 2013.
Severe storms causing major flooding
The 5.64″ of rain that fell at the Oklahoma City Will Rogers Airport on Friday was their 6th wettest day in city history, and brought the total rainfall for the month of May to 14.52″, the wettest May in Oklahoma City’s history (Thanks to BaltimoreBrian for this link.) The North Canadian River in Oklahoma City rose sixteen feet in twelve hours, cresting at its 2nd highest flood on record this Saturday morning. The heavy rains have spread eastwards on Saturday, causing more flooding problems. Paducah, KY had its wettest June day and 3rd wettest day on record on June 1, with 5.73″ of rain (all-time record: 7.49″ on 9/5/1985.) Major flooding is occurring along a substantial stretch of the Mississippi River in Iowa, Illinois, and Missouri.
Figure 5. The North Canadian River in Oklahoma City rose sixteen feet in twelve hours, reaching its 2nd highest flood on record this Saturday morning.
Figure 6. Radar-estimated rainfall in the Oklahoma City area reached 8+” over some areas from Friday’s storm.
Remains of Hurricane Barbara may bring heavy rains to Mexico, Florida, and Cuba
Today, June 1, is the official first day of the Atlantic Hurricane season, and we already have our first Atlantic tropical disturbance to talk about. Hurricane Barbara, which died on Thursday as it attempted to cross Mexico’s Isthmus of Tehuantepec into the southernmost Gulf of Mexico, has left behind an area of disturbed weather over the southernmost Gulf of Mexico. There is very little heavy thunderstorm activity associated with Barbara’s remnants apparent on satellite loops this Saturday afternoon. 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. NHC is giving the disturbance a 10% chance of developing into a tropical cyclone by Monday. Moisture from the remnants of Barbara may combine with moisture from an area of heavy thunderstorms expected to build over the Western Caribbean this weekend, and begin bringing heavy rains to Mexico’s Yucatan Peninsula and Western Cuba on Sunday and Monday. These heavy rains may spread to Southwest Florida as early as Monday night. The computer models predict that this disturbance should be large and poorly organized, making development into a Gulf of Mexico tropical cyclone unlikely.
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.
In 2011, a series of violent severe storms swept across the Plains and Southeast U.S., bringing an astonishing six billion-dollar disasters in a three-month period. The epic tornado onslaught killed 552 people, caused $25 billion in damage, and brought three of the five largest tornado outbreaks since record keeping began in 1950. In May 2011, the Joplin, Missouri tornado did $3 billion in damage–the most expensive tornado in world history–and killed 158 people, the largest death toll from a U.S. tornado since 1947. An astounding 1050 EF-1 and stronger tornadoes ripped though the U.S. for the one-year period ending that month. This was the greatest 12-month total for these stronger tornadoes in the historical record, and an event so rare that we might expect it to occur only once every 62,500 years. Fast forward now to May 2012 – April 2013. Top-ten coldest temperatures on record across the Midwest during March and April of 2013, coming after a summer of near-record heat and drought in 2012, brought about a remarkable reversal in our tornado tally–the lowest 12-month total of EF-1 and stronger tornadoes on record–just 197. This was an event so rare we might expect it to occur only once every 3,000 – 4,000 years. And now, in May 2013, after another shattering EF-5 tornado in Moore, Oklahoma, residents of the Midwest must be wondering, are we back to the 2011 pattern? Which of these extremes is climate change most likely to bring about? Is climate change already affecting these storms? These are hugely important questions, but ones we don’t have good answers for. Climate change is significantly impacting the environment that storms form in, giving them more moisture and energy to draw upon, and altering large-scale jet stream patterns. We should expect that this will potentially cause major changes in tornadoes and severe thunderstorms. Unfortunately, tornadoes and severe thunderstorms are the extreme weather phenomena we have the least understanding on with respect to climate change. We don’t have a good enough database to determine how tornadoes may have changed in recent decades, and our computer models are currently not able to tell us if tornadoes are more likely to increase or decrease in a future warmer climate.
Video 1. Remarkable video of the tornado that hit Tuscaloosa, Alabama on April 27, 2011, part of the largest and most expensive tornado outbreak in U.S. history–the $10.2 billion dollar Southeast U.S. Super Outbreak of April 25 – 28, 2011. With damage estimated at $2.2 billion, the Tuscaloosa tornado was the 2nd most expensive tornado in world history, behind the 2011 Joplin, Missouri tornado. Fast forward to minute four to see the worst of the storm.
Figure 1. Will climate change increase the incidence of these sorts of frightening radar images? Multiple hook echoes from at least ten supercell thunderstorms cover Mississippi, Alabama, and Tennessee in this radar image taken during the height of the April 27, 2011 Super Outbreak, the largest and most expensive tornado outbreak in U.S. history. A multi-hour animation is available here.
Changes in past tornado activity difficult to assess due to a poor database
It’s tough to tell if tornadoes may have changed due to a changing climate, since the tornado database is of poor quality for climate research. We cannot measure the wind speeds of a tornado directly, except in very rare cases when researchers happen to be present with sophisticated research equipment. A tornado has to run over a building and cause damage before an intensity rating can be assigned. The National Weather Service did not begin doing systematic tornado damage surveys until 1976, so all tornadoes from 1950 – 1975 were assigned a rating on the Fujita Scale (F-scale) based on old newspaper accounts and photos. An improved Enhanced Fujita (EF) scale to rate tornadoes was adopted in 2007. The transition to the new EF scale still allows valid comparisons of tornadoes rated, for example, EF-5 on the new scale and F5 on the old scale, but does create some problems for tornado researchers studying long-term changes in tornado activity. More problematic is the major changes in the Fujita-scale rating process that occurred in the mid-1970s (when damage surveys began), and again in 2001, when scientists began rating tornadoes lower because of engineering concerns and unintended consequences of National Weather Service policy changes. According to Brooks (2013), “Tornadoes in the early part of the official National Weather Service record (1950 – approximately 1975) are rated with higher ratings than the 1975 – 2000 period, which, in turn, had higher ratings than 2001 – 2007.” All of these factors cause considerable uncertainty when attempting to assess if tornadoes are changing over time. At a first glance, it appears that tornado frequency has increased in recent decades (Figure 2). However, this increase may be entirely caused by factors unrelated to climate change:
1) Population growth has resulted in more tornadoes being reported. Heightened awareness of tornadoes has also helped; the 1996 Hollywood blockbuster movie Twister “played no small part” in a boom in reported tornadoes, according to tornado scientist Dr. Nikolai Dotzek.
2) Advances in weather radar, particularly the deployment of about 100 Doppler radars across the U.S. in the mid-1990s, has resulted in a much higher tornado detection rate.
3) Tornado damage surveys have grown more sophisticated over the years. For example, we now commonly classify multiple tornadoes along a damage path that might have been attributed to just one twister in the past.
Figure 2. The total number of U.S. tornadoes since 1950 has shown a substantial increase. Image credit: NOAA/NCDC.
Figure 3. The number of EF-0 (blue line) and EF-1 and stronger tornadoes (maroon squares) reported in the U.S. since 1950. The rise in number of tornadoes in recent decades is seen to be primarily in the weakest EF-0 twisters. As far as we can tell (which isn’t very well, since the historical database of tornadoes is of poor quality), there is not a decades-long increasing trend in the numbers of tornadoes stronger than EF-0. Since these stronger tornadoes are the ones most likely to be detected, this implies that climate change, as yet, is not having a noticeable impact on U.S. tornadoes. Image credit: Kunkel, Kenneth E., et al., 2013, “Monitoring and Understanding Trends in Extreme Storms: State of Knowledge,” Bull. Amer. Meteor. Soc., 94, 499–514, doi: http://dx.doi.org/10.1175/BAMS-D-11-00262.1
Figure 4. Insured damage losses in the U.S. due to thunderstorms and tornadoes, as compiled by Munich Re. Damages have increased sharply in the past decade, but not enough to say that an increase in tornadoes and severe thunderstorms may be to blame.
Stronger tornadoes do not appear to be increasing
Tornadoes stronger than EF-0 on the Enhanced Fujita Scale (or F0 on the pre-2007 Fujita Scale) are more likely to get counted, since they tend to cause significant damage along a long track. Thus, the climatology of these tornadoes may offer a clue as to how climate change may be affecting severe weather. If the number of strong tornadoes has actually remained constant over the years, we should expect to see some increase in these twisters over the decades, since more buildings have been erected in the paths of tornadoes. However, if we look at the statistics of U.S. tornadoes stronger than EF-0 or F-0 since 1950, there does not appear to be any increase in their number (Figure 3.) Damages from thunderstorms and tornadoes have shown a significant increase in recent decades (Figure 4), but looking at damages is a poor way to determine if climate change is affecting severe weather, since there are so many human factors involved. A study in Environmental Hazards (Simmons et al., 2012) found no increase in tornado damages from 1950 – 2011, after normalizing the data for increases in wealth and property. Also, Bouwer (BAMS, 2010) reviewed 22 disaster loss studies world-wide, published 2001 – 2010; in all 22 studies, increases in wealth and population were the “most important drivers for growing disaster losses.” His conclusion: human-caused climate change “so far has not had a significant impact on losses from natural disasters.” Studies that normalize disaster data are prone to error, as revealed by a 2012 study looking at storm surge heights and damages. Given the high amount of uncertainty in the tornado and tornado damage databases, the conclusion of the “official word” on climate science, the 2007 United Nations IPCC report, pretty much sums things up: “There is insufficient evidence to determine whether trends exist in small scale phenomena such as tornadoes, hail, lighting, and dust storms.” Until a technology is developed that can reliably detect all tornadoes, there is no hope of determining how tornadoes might be changing in response to a changing climate. According to Doswell (2007): “I see no near-term solution to the problem of detecting detailed spatial and temporal trends in the occurrence of tornadoes by using the observed data in its current form or in any form likely to evolve in the near future.”
Figure 6. Six-hourly periods per year with environments supportive of significant severe thunderstorms in the U.S. east of the Rocky Mountains. The line is a local least-squares regression fit to the series, and shows no significant change in environments supportive of significant severe thunderstorms in recent decades. Image credit: Brooks, H.E., and N. Dotek, 2008, “The spatial distribution of severe convective storms and an analysis of their secular changes”, Climate Extremes and Society
How are the background conditions that spawn tornadoes changing?
An alternate technique to study how climate change may be affecting tornadoes is look at how the large-scale environmental conditions favorable for tornado formation have changed through time. Moisture, instability, lift, and wind shear are needed for tornadic thunderstorms to form. The exact mix required varies considerably depending upon the situation, and is not well understood. However, Brooks (2003) attempted to develop a climatology of weather conditions conducive for tornado formation by looking at atmospheric instability (as measured by the Convective Available Potential Energy, or CAPE), and the amount of wind shear between the surface and 6 km altitude. High values of CAPE and surface to 6 km wind shear are conducive to formation of tornadic thunderstorms. The regions they analyzed with high CAPE and high shear for the period 1997-1999 did correspond pretty well with regions where significant (F2 and stronger) tornadoes occurred. Riemann-Campe et al. (2009) found that globally, CAPE increased significantly between 1958 – 2001. However, little change in CAPE was found over the Central and Eastern U.S. during spring and summer during the most recent period they studied, 1979 – 2001. Brooks (2013) found no significant trends in wind shear over the U.S. from 1950 – 2010 (Figure 5.) A preliminary report issued by NOAA’s Climate Attribution Rapid Response Team in July 2011 found no trends in CAPE or wind shear over the lower Mississippi Valley over the past 30 years.
Figure 7. Change in the number of days per year with a high severe thunderstorm potential as predicted by the climate model (A2 scenario) of Trapp et al. 2007, due to predicted changes in wind shear and Convective Available Potential Energy (CAPE). Most of the U.S. east of the Rocky Mountains is expected to see 1 – 2 additional days per year with the potential for severe thunderstorms. The greatest increase in potential severe thunderstorm days (three) is expected along the North and South Carolina coast. Image credit: NASA.
How will tornadoes and severe thunderstorms change in the future?
Using a high-resolution regional climate model (25 km grid size) zoomed in on the U.S., Trapp et al. (2007) and Trapp et al. (2009) found that the decrease in 0-6 km wind shear in the late 21st century would more than be made up for by an increase in instability (CAPE). Their model predicted an increase in the number of days with high severe storm potential for most of the U.S. by the end of the 21st century, particularly for locations east of the Rocky Mountains (Figure 7.) Brooks (2013) also found that severe thunderstorms would likely increase over the U.S. by the end of the century, but theorized that the severe thunderstorms of the future might have a higher proportion causing straight-line wind damage, and slightly lower proportion spawning tornadoes and large hail. For example, a plausible typical future severe thunderstorm day many decades from now might have wind shear lower by 1 m/s, but a 2 m/s increase in maximum thunderstorm updraft speed. This might cause a 5% reduction in the fraction of severe thunderstorms spawning tornadoes, but a 5% increase in the fraction of severe thunderstorms with damaging straight-line winds. He comments: “However, if the number of overall favorable environments increases, there may be little change, if any, in the number of tornadoes or hailstorms in the US, even if the relative fraction decreases. The signals in the climate models and our physical understanding of the details of storm-scale processes are sufficiently limited to make it extremely hazardous to make predictions of large changes or to focus on small regions. Projected changes would be well within error estimates.”
Figure 8. From 1995 (the first year we have wind death data) through 2012, deaths from high winds associated with severe thunderstorms accounted for 8% of all U.S. weather fatalities, while tornadoes accounted for 13%. Data from NOAA.
Severe thunderstorms are capable of killing more people than tornadoes
If the future climate does cause fewer tornadoes but more severe thunderstorms, this may not end up reducing the overall deaths and damages from these dangerous weather phenomena. In 2012, the warmest year in U.S. history, the death toll from severe thunderstorms hit 104–higher than the 70 people killed by tornadoes that year. Severe thunderstorms occur preferentially during the hottest months of the year, June July and August, and are energized by record heat. For example, wunderground weather historian Christopher C. Burt called the number of all-time heat records set on June 29, 2012 “especially extraordinary,” and on that day, an organized thunderstorm complex called a derecho swept across a 700-mile swath of the Ohio Valley and Mid-Atlantic, killing thirteen people and causing more than $1 billion in damage. The amount of energy available to the derecho was extreme, due to the record heat. The derecho knocked out power to 4 million people for up to a week, in areas where the record heat wave was causing high heat stress. Heat claimed 34 lives in areas without power in the week following the derecho. Excessive heat has been the number one cause of weather-related deaths in the U.S since 1995, killing more than twice as many people as tornadoes have. Climate models are not detailed enough to predict how organized severe thunderstorm events such as derechos might change in a future warmer climate. But a warmer atmosphere certainly contributed to the intensity of the 2012 derecho, and we will be seeing a lot more summers like 2012 in coming decades. A future with sharply increased damages and deaths due to more intense severe thunderstorms and derechos is one nasty climate change surprise that may lurk ahead.
Figure 9. Lightning over Tucson, Arizona on August 14, 2012. A modeling study by Del Genio et al.(2007) predicts that lighting will increase by 6% by the end of the century, potentially leading to an increase in lightning-triggered wildfires. Image credit: wunderphotographer ChandlerMike.
Lightning may increase in a warmer climate
Del Genio et al.(2007) used a climate model with doubled CO2 to show that a warming climate would make the atmosphere more unstable (higher CAPE) and thus prone to more severe weather. However, decreases in wind shear offset this effect, resulting in little change in the amount of severe weather in the Central and Eastern U.S. late this century. However, they found that there would likely be an increase in the very strongest thunderstorms. The speed of updrafts in thunderstorms over land increased by about 1 m/s in their simulation, since upward moving air needed to travel 50 – 70 mb higher to reach the freezing level, resulting in stronger thunderstorms. In the Western U.S., the simulation showed that drying led lead to fewer thunderstorms overall, but the strongest thunderstorms increased in number by 26%, leading to a 6% increase in the total amount of lighting hitting the ground each year. If these results are correct, we might expect more lightning-caused fires in the Western U.S. late this century, due to increased drying and more lightning. Only 12% of U.S. wildfires are ignited by natural causes, but these account for 52% of the acres burned (U.S. Fire Administration, 2000). So, even a small change in lightning flash rate has important consequences. Lightning is also a major killer, as an average of 52 people per year were killed by lightning strikes over the 30-year period ending in 2012, accounting for 6% of all U.S. weather-related fatalities.
We currently do not know how tornadoes and severe thunderstorms may be changing due to climate change, nor is there hope that we will be able to do so in the foreseeable future. It does not appear that there has been an increase in U.S. tornadoes stronger than EF-0 in recent decades, but climate change appears to be causing more extreme years–both high and low–of late. Tornado researcher Dr. Harold Brooks of the National Severe Storms Laboratory in Norman, Oklahoma said in a 2013 interview on Andrew Revkin’s New York Times dotearth blog: “there’s evidence to suggest that we have seen an increase in the variability of tornado occurrence in the U.S.” Preliminary research using climate models suggests that we may see an increase in the number of severe thunderstorms capable of producing tornadoes over the U.S. late this century, but these thunderstorms will be more likely to produce damaging straight-line winds, and less likely to produce tornadoes and large hail. This will not necessarily result in a reduction in deaths and damages, though, since severe thunderstorms can be just as dangerous and deadly as tornadoes–especially when they knock out power to areas suffering high-stress heat waves. Research into climate change impacts on severe weather is just beginning, and much more study is needed.
The Midwest U.S. is under the gun again today, as a potent storm system that spawned a preliminary count of 24 tornadoes in five states on Sunday reloads and prepares to dish out another afternoon and evening of atmospheric mayhem. Sunday’s tornadoes swept through Oklahoma, Kansas, Iowa, Missouri, and Illinois, with Oklahoma bearing the brunt of the assault. The outbreak’s only deadly tornado hit Shawnee, Oklahoma, a town of 30,000 located 35 miles southeast of Oklahoma City. The twister leveled a trailer park, killing one person, and blew a semi-trailer off of an expressway overpass on I-40. At least 21 people were injured and 300 homes destroyed over the five-state area by the tornadoes. The 24 tornadoes from May 19 make it the biggest day for tornadoes in the U.S. this spring, and the highest number reported in one day since January 30, when 44 tornadoes touched down from Georgia to Indiana.
Figure 1. The Shawnee, Oklahoma tornado at 6:44 pm CDT May 19, 2013, as it passed just NW of Shawnee. The tornado killed one person in a mobile home park in Shawnee. Viewer submitted photo. #okwx pic.twitter.com/UCH9e8o9G8 Matt Mahler@themahler
Figure 2. The Shawnee tornado hurled a semi-trailer off of an expressway overpass at Highway 117 and I-40 in Oklahoma, and toppled another semi. Four people who sheltered under this overpass were injured, one seriously, and taken to the hospital. Highway overpasses can act to amplify a tornado’s winds, and are very dangerous places to be during a tornado. According to the NWS in Norman Oklahoma, during the tornado outbreak of May 3, 1999, tornadoes crossed three highway overpasses, and at all three locations, there was a fatality. One of the fatalities occurred from an EF-2 tornado in a rural area, which suggests that a tornado need not be a large, violent tornado with a considerable debris cloud to cause fatal injuries to people seeking shelter from storms under overpasses. In addition to the fatal injuries to three people, there were also many severe, potentially life-threatening and gruesome injuries inflicted upon people underneath the overpasses, that in some cases, has left these people with permanent disabilities. Don’t take shelter under a highway overpass from a tornado! Image credit: KFOR.com.
Figure 3. Radar reflectivity image taken at 6:08 pm CDT May 19, 2013 of the supercell thunderstorm that spawned the Shawnee, Oklahoma tornado.
Figure 4. Doppler velocity image taken at 6:08 pm CDT May 19, 2013 of the supercell thunderstorm that spawned the Shawnee, Oklahoma tornado. Note the couplet of dark red colors right next to light blues near the center of the image, showing that the air was moving both towards the radar and away from it within a short distance, indicating a tight rotation of the tornado’s parent mesocyclone.
Iowa’s record tornado-free streak ends at 359 days
A tornado touched down near Slater, Iowa at 6:10 pm CDT on Sunday, May 19, one of six tornadoes reported in the state that day. Remarkably, it was the first tornado recorded in the state since May 24, 2012 (Fayette County.) The 359-day streak without a tornado was the longest tornado-free period in state history. The previous record was 355 days, set between May 5, 1955, and April 26, 1956. The new streak is far more impressive because digital technology and spotter networks today are so comprehensive, resulting in far fewer missed tornadoes. There was a much higher likelihood back in the 1950s for tornadoes to be missed. The exceptional tornado-free period was due to the combination of the state’s dry summer of 2012 (3rd driest on record) and cold spring of 2013 (8th coldest March – April on record). Thunderstorms like heat and moisture to form, and its tough to get a tornado if you’re experiencing a top-ten driest or coldest spring or summer.
Figure 5. Radar reflectivity image of the tornado-spawning supercell thunderstorm that dropped an EF-1 tornado just to the southwest of Wichita, Kansas, on May 19, 2013.
Wichita gets lucky
At 3:30 pm Sunday, Kansas’ largest city, Wichita, got a major scare when a large supercell thunderstorm spawned a half-mile wide tornado to the southwest of the city. The tornado headed directly for the airport and downtown Wichita, prompting the issuance of “Tornado Emergency” for the city. In the wake of the deadly EF-5 tornado that leveled Joplin, Missouri in 2011, the NWS decided to give local NWS offices the option to issue special, strongly worded tornado warnings to let the population know when a particularly dangerous tornado–one that has been confirmed by spotters to be on the ground–is approaching. The NWS issued one of these very strongly-worded tornado warnings on Sunday for Wichita:
Statement as of 3:47 PM CDT on May 19, 2013
… A Tornado Warning remains in effect for southern Sedgwick County until 415 PM CDT…
… Tornado emergency for Wichita…
At 345 PM CDT… a confirmed large… violent and extremely dangerous tornado was located on the southwest side of Wichita… and moving northeast at 30 mph.
This is a particularly dangerous situation.
Hazard… deadly tornado.
Source… weather spotters confirmed tornado.
Impact… you could be killed if not underground or in a tornado shelter. Complete destruction of neighborhoods… businesses and vehicles will occur. Flying debris will be deadly to people and animals.
Locations impacted include…Maize… downtown Wichita… Wichita… Bel Aire… McConnell Air Force Base…east Wichita and Oaklawn.
This is an extremely dangerous tornado with complete devastation likely. You could be killed if not underground or in a tornado shelter. Do not delay… seek shelter now! If no underground shelter is available seek shelter in an interior room of the lowest level of a structure… or if time allows… consider moving to an underground shelter elsewhere. Mobile homes and outbuildings will offer no shelter from this tornado.
Wichita TV station KSNW did an excellent job covering the tornado, but were forced to abandon the studio during the height of the storm, as seen on this video clip. You can hear hail pounding the roof as the news crew scrambles for shelter. Station meteorologist J.D. Rudd has this to say: “We are okay. I’ll tell you though, it got intense. That thing passed right over our studio. Luckily, it had lifted. But I truly thought the roof of our studio was about to peel off. And the sound of the hail was deafening. What a day. Three hours of coverage with the largest city in the state under a TOR warning for a long time. Weather service called it a Tornado Emergency…’Large, violent tornado on the ground’. Words that gave me chills when I read them.” Preliminary damage surveys from the NWS indicate that the Wichita tornado was an EF-1 with a path length 4.6 miles that lifted two miles south of the Wichita airport.
Figure 6. Severe weather outlook for Monday, May 20, calls for a “Moderate Risk” of severe weather over much of Oklahoma, and portions of surrounding states. You can follow today’s severe weather outbreak from our Severe Weather page.
Another big severe weather day today in the Midwest
The latest forecasts from NOAA’s Storm Prediction Center call for an active severe weather day again on Monday, with a “Moderate Risk” of severe weather over much of Oklahoma, plus portions of Southwest Missouri, Northwest Arkansas, and extreme North Texas. The highest threat for tornadoes will be in Southern Oklahoma and into North Texas. The severe weather outbreak will continue on Tuesday and Wednesday, progressing eastwards into the Ohio Valley and Great Lakes. Only a “Slight Risk” of severe weather is expected those days.
Video 1. Impressive footage (peaking at 4:30 of the video) of the huge tornado that devastated Carney, Oklahoma on May 19, 2013.
Video 2. The “Dominator 3” armored tornado intercept vehicle saw plenty of action on Sunday, as seen in this video, taken just northeast of Edmond, Oklahoma. From the http://tvnweather.com/ description of the video: “This tornado was one of the strongest ever intercepted, and we needed all 10,000k pounds of the new Dominator because I have never felt vibration like that before as we were slammed by suction vortices wrapping all around the vehicle. Jim Cantore was on board and he’s hooked. All part of #TornadoChasers, Season 2013 coming up this fall on http://tvnweather.com/ondemand”
Wunderblogger Lee Grenci has an interesting post discussing how last Wednesday’s Granbury, Texas tornado was able to form in an atmosphere that seemingly had too little wind shear to get a supercell thunderstorm spinning. The Granbury tornado was an EF-4 with 166 – 200 mph winds that killed six people, and was part of a weather system separate from the one that is generating the current Midwest U.S. tornado outbreak.
news9.com out of Oklahoma City had some excellent live helicopter coverage of Sunday’s storms, and will likely be out there again today.
After going twelve months with a record-low tornado death toll of just seven people, last night we received a jolting reminder that tornadoes typically kill a lot more people than that in the U.S. A deadly tornado swept through Granbury, Texas near 8 pm CDT, killing six and injuring up to 100. The weather system that spawned the Granby tornado also unleashed a mile-wide twister that hit Cleburne, about 25 miles southeast of Granbury. Damage was heavy in Cleburne and a state of emergency declared, but only seven minor injuries were reported. A third tornado hit the small town of Millsap, about 40 miles west of Fort Worth, causing roof damage a destroying a barn, but caused no injuries. Preliminary figures indicate that a total ten tornadoes touched down in Texas last night, and NWS damage survey teams are out today to determine the exact total and how strong they were. The National Weather Service out of Fort Worth has issued a preliminary rating of EF-4 to the Granbury tornado, making it the first tornado stronger than EF-0 reported in May 2013. The storms also dumped softball-sized hail up to 4″ in diameter in Mineral Wells, TX.
Video 1. The Granbury, Texas tornado of May 15, 2013.
Thursday’s tornado was the deadliest U.S. tornado in over a year. The last time six people died in a U.S. tornado was on April 14, 2012, during an EF-3 tornado that hit Woodward, Oklahoma. The last Texas tornado that was deadlier occurred on April 24, 2007 in Maverick County, when an EF-3 tornado hit Eagle Pass, Texas, killing seven. Texas has had one other tornado death in 2013, from a twister that hit on February 21, 2013, in Sabine County. The region of Texas hit by last night’s tornadoes has few basements, which may have contributed to the death toll. According to underground member Seattleite, “In this part of Texas basements are very uncommon. The reason is due to the soil, it is basically clay. It contracts and expands with temperature and moisture levels on the order of a foot or more in a typical year. The pressure from this can cause basement walls to cave. They can be built, but it costs at least an extra $20,000+, as they surround the basement with a sand-like barrier to handle the changes in the ground.”
Figure 1. Softball, anyone? One of the 4″ hailstones that fell near Mineral Wells, Texas on May 15, 2013. Image from Patrick Vondra via Twitter.
Is the 2012 – 2013 tornado drought over?
Thanks to the cold spring in the Midwest during 2013, and the 2012 Midwest drought, the 197 EF-1 and stronger tornadoes that occurred during May 2012 – April 2012 was an all-time minimum for any twelve-month period since at least 1954, wrote tornado researcher Harold Brooks at the U.S. Severe Weather Blog (previous minimum: 247 tornadoes from June 1991-May 1992.) The death toll of just seven was also a record low for any twelve-month period since 1950. Amazingly, this tornado drought occurred less than two years after the record maximum: 1050 EF-1 and stronger tornadoes from June 2010 – May 2011. The extraordinary contrast underscores the crazy fluctuations we’ve seen in Northern Hemisphere jet stream patterns during the past three years. Call it “Weather Whiplash” of the tornado variety. A blog post by meteorologist Patrick Marsh of NOAA’s Storm Prediction Center argues that the record 12-month tornado maximum of 1050 EF-1 and stronger tornadoes from June 2010 – May 2011 was a 1-in-62,500 year event. The record 12-month minimum of 197 EF-1 and stronger tornadoes that occurred from May 2012 – April 2013 was a 1-in-3000 to 1-in-4000 year event. In Marsh’s words: “Anyway you look at it, the recent tornado “surplus” and the current tornado “drought” is extremely rare. The fact that we had both of them in the span of a few years is even more so!”
Our tornado drought may be at its end, as the latest forecasts from NOAA’s Storm Prediction Center call for an active severe weather pattern Saturday – Monday. The current forecast calls for just a “Slight Risk” on Saturday over the Northern Plains, but the threat will grow on Sunday and Monday as a powerful spring weather system gathers strength over the center of the country.
Saturday’s main threat areas: SD to NE, and northern KS
Sunday : IA, parts of MO/KS, to central/eastern OK
Monday : IL/MO to OK/TX border
Figure 2. MODIS image of Tropical Cyclone Mahasen taken at 06:50 UTC Thursday May 16, 2013. Mahasen made landfall about two hour prior to this image as a tropical storm with 50 mph winds. Image credit: NASA.
Tropical Storm Mahasen hits Bangladesh Tropical Storm Mahasen hit the Bangladesh coast near 08 UTC Thursday, May 16 near a place called Feni north of Chittagong. Mahasen was a tropical storm with top winds of 50 mph at landfall. Satellite observations suggest that the storm was becoming much more organized just before landfall, and it is fortunate that the storm ran out of time to intensify when it did. Mahasen likely brought a storm surge of up to a meter (3.3 feet) to the coast of Bangladesh, but it is the storm’s rains that are causing the main problems. Satellite rainfall forecasts made at landfall show that Mahasen could dump up to 20 inches of rain along a swath through Bangladesh and into Northeastern India. These rains will be capable of causing destructive flooding, and ten deaths have already been reported in Bangladesh from the storm. At least eight people have been killed in Sri Lanka due to landslides triggered by Mahasen’s heavy rains, and a boat carrying refugees capsized on Monday, killing eight and leaving 50 missing.
First tropical storm of the year, Alvin, forms in the Eastern Pacific
The official start of hurricane season in the Eastern Pacific is Wednesday, May 15, and Mother Nature emphatically agreed, bringing us the first named storm of the year, Tropical Storm Alvin. With wind shear a moderate 10 – 20 knots and the storm currently struggling to hold itself together, it currently appears unlikely that we will see a Hurricane Alvin. The storm is moving west-northwest into the Central Pacific, and is not a threat to any land areas.
February 2013 was the globe’s 9th warmest February since records began in 1880, said National Oceanic and Atmospheric Administration’s National Climatic Data Center (NCDC) on Thursday. February 2013 global land temperatures were the 11th warmest on record, and global ocean temperatures were the 8th warmest on record. February 2013 was the 336th consecutive month with global temperatures warmer than the 20th century average and the 37th straight warmer-than-average February. The last time Earth had a below-average February global temperature was in 1976, and the last below-average month of any kind was December 1984. Global satellite-measured temperatures in February 2013 for the lowest 8 km of the atmosphere were 10th or 8th warmest in the 35-year record, according to Remote Sensing Systems and the University of Alabama Huntsville (UAH), respectively. The Northern Hemisphere snow cover extent during February 2013 was the 16th largest in the 47-year period of record. Wunderground’s weather historian, Christopher C. Burt, has a comprehensive post on the notable weather events of February 2013 in his February 2013 Global Weather Extremes Summary. Costly weather disasters were relatively rare in February, according to AON Benfield. The most expensive weather-related disasters in February 2013 were:
1) Drought in Central and Eastern China, 1/1 – 2/28, $541 million
2) Winter storm in Eastern China, 2/18 – 2/21, $124 million
3) Winter Storm Nemo, Northeast U.S., 2/8 – 2/9. $100+ million
4) Hattiesburg, MS tornado and associated storm damage, 2/9 – 2/11, $100+ million
The deadliest February weather disaster was Tropical Cyclone Haruna, which hit Madagascar at 00 UTC Friday, February 22, as a Category 2 storm with 105 mph winds, killing 26.
Figure 1. Departure of temperature from average for February 2013, the 9th warmest February for the globe since record keeping began in 1880. Colder than average conditions occurred in the Western U.S., western Europe, and northern Russia. No land areas in the Southern Hemisphere were cooler than average, and record warm conditions were experienced in parts of Indonesia and northern Australia. Image credit: National Climatic Data Center (NCDC) .
Figure 2. The deadliest weather disaster of February 2013 was Tropical Cyclone Haruna, which hit Madagascar at 00 UTC Friday, February 22, as a Category 2 storm with 105 mph winds, killing 26. In this image, Haruna is over Madagascar at 11:05 UTC February 22, 2013, and was a Category 1 storm with 90 mph winds. Image credit: NASA.
Figure 3. The most expensive weather disaster of February 2013 was the on-going drought in Central and Eastern China, which has cost $541 million since the beginning of 2013. Image credit: Beijing Climate Center.
Neutral El Niño conditions continue in the equatorial Pacific
For the 11th month in row, neutral El Niño conditions existed in the equatorial Pacific during February 2013. NOAA’s Climate Prediction Center (CPC) expects neutral El Niño conditions to last through spring. Temperatures in the equatorial Eastern Pacific need to be 0.5°C below average or cooler for three consecutive for a La Niña episode to be declared; sea surface temperatures were 0.1°C below average as of March 11, and have ranged from 0.1 – 0.6°C below average during 2013.
Arctic sea ice falls to 7th lowest February extent on record
Arctic sea ice extent during February reached its seventh lowest extent in the 35-year satellite record, according to the National Snow and Ice Data Center (NSIDC). This was the 11th consecutive February and 141st consecutive month with below-average Arctic sea ice extent. The last ten years (2004 to 2013) have seen the ten lowest February extents in the satellite record. Arctic sea ice is nearing its winter maximum and will soon begin to melt.
I am including a link below to a curious video from the Unsealed Case Files series concerning recent weather anomalies, animal mutations and deaths, whale migratory patters, etc., etc., etc. It is here for your information. As always, do your research: