Tornado's in de VS #25 A new day

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8+ Very high probability of a tornado
6 - High probability of a tornado
4 - Moderate chance of a tornado nearby, but hail and/or high wind gusts possible
2 - Low chance of a tornado, but hail and/or high wind gusts possible
0 - Near-zero chance of a tornado or a severe thunderstorm

BIRTH OF INCREDIBLE EF-4 TORNADO!

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Op woensdag 27 april 2016 01:53 schreef MaryMouse het volgende:
Kan je tegenwoordig niet meer 'bij' chasers in de 'auto' springen? Al mijn linkjes geven wel de locatie van de auto's aan, maar geen live stream meer.

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Op woensdag 27 april 2016 09:48 schreef INViCTuS het volgende:
Beter voor de mensen daar

Nieuwe kansen zullen ongetwijfeld snel volgen

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Op donderdag 28 april 2016 02:57 schreef RipCity het volgende:
Goed artikel over gisteren en berichtgeving eromtrent: https://www.washingtonpos(...)&utm_campaign=buffer

twitter:

AMHQ twitterde op donderdag 28-04-2016 om 12:27:10 17 reports of #tornadoes yesterday in six states. This EF-1 in #Omaha was among them. No #injuries were reported. https://t.co/ZGOcGaEeWa reageer retweet

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Op donderdag 28 april 2016 19:57 schreef Houtenbeen het volgende:

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TVNweather twitterde op donderdag 28-04-2016 om 19:45:32 After careful thought and consideration, we have decided to discontinue the TVNweather Live Storm chasing service: https://t.co/Pn5bIVjopI reageer retweet

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Op dinsdag 10 mei 2016 18:10 schreef aloa het volgende:

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Violent Katie-Wynnewood, OK Tornado 5/9/2016

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Op woensdag 11 mei 2016 11:08 schreef mouzzer het volgende:
Foto van het schadepad van de 'stovepipe' tornado:

[ afbeelding ]

Zo te zien bovenstaande foto de plek welke vanaf minuut 10 in onderstaande video te zien is waar de tornado de weg over lijkt te steken maar dan stuk terug gaat om z'n pad weer te vervolgen. Op de foto is te zien dat hij op dat moment precies tussen de 2 witte gebouwen door is gegaan.

Violent Tornado East of Katie, OK (5/9/2016)

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Op woensdag 11 mei 2016 18:56 schreef i2Them2 het volgende:

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Ik begreep dat er een "satelite"-tornado rond dat systeem hing. En die zou dan tegen de gebruikelijke richting draaien. Maar vaak zijn die satelites veel zwakker en wordt er minder op gelet.
Hier onder een video die het proces kort en bondig uitlegt (rest van de video is ook ZEER interessant).

Storm Spotting Secrets

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An Oklahoma Tornado Rewrites the Rule Book

Overshadowed by the mighty EF4 and EF3 tornadoes that tore across south-central Oklahoma last Monday, May 9, another less damaging twister--from the same thunderstorm--has left seasoned scientists both astonished and fascinated. This tornado, which struck near Roff, OK, was rated an unexceptional EF1 on the Enhanced Fujita Tornado Damage Scale. However, the Roff tornado stands out in several other ways.

—It was an anticyclonic tornado, meaning that it rotated clockwise rather than counterclockwise. A few such twisters probably occur each year, but they account for only perhaps 1% of all U.S. tornadoes—and that’s a very rough estimate, according to tornado climatology expert Harold Brooks (NOAA National Severe Storms Laboratory). In fact, the Storm Data procedures maintained by NOAA include no specific requirement or methodology for reporting whether or not a tornado is anticyclonic.

—It developed in the “forward flank” part of the storm, enveloped in rain-cooled air. “This is the first time I’ve ever heard of a well-developed anticyclonic tornado buried inside the forward-flank core,” said Roger Edwards (NOAA Storm Prediction Center), who has predicted and observed tornadoes for more than 25 years.

—Its damage path was initially estimated to be as much as 13 miles long, as documented in a preliminary storm survey conducted by the National Weather Service in Norman, OK. If confirmed, this path length will likely be a record; I have been unable to find evidence of any other anticyclonic tornado with a path this long. The estimated duration of 35 minutes might also end up as a record-setter for anticyclonic tornadoes. However, reanalysis of the damage could reduce the estimated path length and duration, as the radar signature of the tornado was shorter-lived, according to Gabriel Garfield (University of Oklahoma/CIMMS/NWS), who participated in the storm survey.

he scarcity of anticyclonic tornadoes is not a direct result of the Coriolis effect, which makes tropical cyclones spin cyclonically. The Coriolis force actually has little direct influence on circulations as small as tornadoes (not to mention toilets or other drains that happen to cross the equator). What appears to be the main driver is the wind shear that produces rotating supercell thunderstorms. In the Northern Hemisphere, a blossoming supercell will often split in two, with one cell angling to the right of the mean upper-level wind, spinning cyclonically, and the other angling leftward and rotating anticyclonically. Rightward-moving, cyclonically-spinning cells are the ones better positioned to ingest warm, moist air and grow more vigorously. Thus, most tornadoes are cyclonic, spawned by mesocyclones within cyclonically rotating supercells. (This Wikipedia page includes a nice conceptual diagram of a supercell thunderstorm.) Toward the outer edge of a storm's rear-flank gust front, there can be anticyclonically rotating features; very rarely, one of these will spin up an anticyclonic twister.

What happened in Oklahoma last week doesn't quite fit the classic picture: the anticyclonic Roff tornado developed right in the rain-cooled heart of the storm rather than on its periphery. The Roff tornado was embedded in rain for most or all of its lifespan. "We saw no evidence of it in the gray murk of heavy rain to our [west], nor any suspicious wind shifts," reported Edwards, who was on the same storm photographing the nearby Sulphur tornado. As for what caused the anticyclonic Roff tornado, "we can offer only speculation and conjecture at this point," said Edwards in a blog post. The smoking gun could end up being a stray left-moving storm, evident on radar, that zipped northward and became embedded in the larger, stronger supercell that produced the Roff and Sulphur tornadoes. It's conceivable that this left-moving cell injected some anticyclonic spin into the forward flank of the storm.

Deducing what happened will take some doing, as this storm was more than 50 miles from the Oklahoma City NEXRAD radar. Data from mobile radar, including the RaXPol unit operated by Howard Bluestein and colleagues (University of Oklahoma), may shed some light on the oddly positioned Roff twister. "Having a tornado in that location is worrisome for my team," said Doppler on Wheels chief scientist Joshua Wurman in an email, "because we count on being able to transect cores safely. That's not where we expect to find danger."

Edwards mused: "The odds are extraordinarily tiny of ever seeing another anticyclonic tornado entombed in the forward-flank core of even a violently tornadic supercell. Yet now we know it's possible, and we must be vigilant of that."

Some clockwise pioneers
There are extremely rare cases where a left-moving, anticyclonically rotating thunderstorm generates an "anti-mesocyclone" that spawns an anticyclonic twister, as occurred near Sunnyvale, CA, on May 4, 1998. However, the best-known examples of anticyclonic twisters occur in conjunction with more powerful cyclonic twisters as part of a single supercell thunderstorm, as was the case in Oklahoma last week. Sometimes these are weak, short-lived satellite twisters very close to the companion cyclonic tornado; others are stronger and more separated. Wurman unraveled DOW data for several of these in a 2013 Weather Analysis and Forecasting paper. "Our paper does not include any observations of [forward-flank] anticyclonic tornadoes, so this current one is certainly an outlier," Wurman told me.

One classic case--probably the first anticyclonic tornado ever filmed--unfolded just west of Ames, IA, on June 13, 1976. In this storm, a powerful F3 anticyclonic tornado (the strongest anticyclonic tornado documented to date) closely paralleled the path of an F5 that ripped through the town of Jordan and the nearby countryside. The twisters were only about a mile apart as they moved largely in sync (see Figure 3). The YouTube clip at bottom shows both tornadoes.

A few years later, Ted Fujita and Roger Wakimoto examined the mammoth, nearly stationary supercell that tormented Grand Island, NE, for nearly three hours on June 3, 1980. (This is the storm that inspired the book and movie "Night of the Twisters"). Of the seven tornadoes that emerged that night, three were found to be anticyclonic. "This storm produced the most complex damage patterns imaginable," wrote James McDonald (Texas Tech University) in the Bulletin of the American Meteorological Society. "No one but Ted Fujita could have sorted them out."

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Storm, flood and tornadoes across Alabama and Mississippi
Tens of thousands of people have lost power as severe weather rolled through the southern United States and turned deadly on Monday, January 2, 2017. As of early January 3 (UTC), at least 5 people have lost their lives. Authorities fear the death toll will rise and urge people to pay attention to the warnings and act accordingly.

A low pressure system brought severe thunderstorms to parts of the South on Monday, spinning off several tornadoes, flooding widespread areas and leaving more than 100 000 people without power.

The first line of storms storm hit parts of Texas around 05:00 local time, downing power lines, dropping small hail and sparking at least one house fire. At least 18 000 were without power. The second line of storms rolled in with the sunrise causing flash flooding.

The storms then headed east, causing significant damage to Louisiana, Mississippi, Alabama, and Florida. Much of the damage was caused by flash flooding after a series of storms soaked the region over the past week. Some regions received up to 180 - 230 mm (7 to 9 inches) of rain in just a couple of days.

In Louisiana, a possible tornado reportedly damaged several homes in LeCompte. Severe damage was also reported throughout Avoyaleles Parish, including houses that trees fell through and a building that lost its roof. More than 16 000 customers in the state were without power at one point.

In Alabama, four people were killed in a single home when a tornado hit the town of Rehobeth in the state's south and crashed a tree onto their mobile home.

In Florida, the body of a 70-year-old man was found floating outside his travel-trailer, the Walton County Sheriff's Office said. The death was ruled an accidental drowning.

Downed trees and damaged buildings were reported in at least 28 counties in Mississippi, 15 parishes in Louisiana and 15 counties in Texas, The Weather Channel meteorologist Danielle Banks said.

In Mississippi, a confirmed tornado touched down Monday afternoon near Mendenhall, southeast of Jackson. A second, radar confirmed tornado hit near Mt. Olive, about 13 km (8 miles) northeast of Collins.

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The frequency of large tornado outbreaks in the US is increasing
The frequency of large-scale tornado outbreaks is increasing in the United States, particularly when it comes to the most extreme events, according to research recently published in Science.

The study by researchers including Joel E. Cohen, a visiting scholar at the University of Chicago, finds the increase in tornado outbreaks does not appear to be the result of a warming climate as earlier models suggested. Instead, their findings tie the growth in frequency to trends in the vertical wind shear found in certain supercells—a change not so far associated with a warmer climate.
"What's pushing this rise in extreme outbreaks, during which the vast majority of tornado-related fatalities occur, is far from obvious in the present state of climate science," said Cohen, the Abby Rockefeller Mauzé Professor at Rockefeller University and Professor of Earth and Environmental Sciences at Columbia University, who conducted the research while a visiting scholar in UChicago's Department of Statistics.

Tornado outbreaks are large-scale weather events that last one to three days, featuring several thunderstorms and six or more tornadoes in close succession. In the study, published in the Dec. 16 issue of Science, the researchers used new statistical tools, including extreme value analysis—a branch of statistics dealing with deviations—to analyze observation-based meteorological estimates associated with tornado outbreaks together with National Oceanic and Atmospheric Administration datasets.

The researchers estimated that the number of tornadoes in the most extreme outbreak in a five-year interval doubled over the last half-century. This means that in 1965 the worst outbreak expected over five years would have had about 40 tornadoes, while in 2015 the worst outbreak expected over five years would have had about 80 tornadoes.

"Viewing the data on thousands of tornadoes that have been reliably recorded in the United States over the past half-century as a population has permitted us to ask new questions and discover new, important changes in outbreaks of these tornadoes," Cohen said.

To understand the increased frequency in tornado outbreaks, the researchers looked at two factors: convective available potential energy, or CAPE, and storm relative helicity, which is a measure of vertical wind shear.

Earlier studies had projected a warming climate would increase CAPE, creating conditions favorable to a rise in severe thunderstorms—and potentially tornado outbreaks. But Cohen and his colleagues found the increases in outbreaks were driven instead by storm relative helicity, which has not been projected to increase under a warming climate.

"Our study raises new questions about what climate change will do to severe thunderstorms and what is responsible for recent trends," said co-author Michael K. Tippett, an associate professor at Columbia University's Fu Foundation School of Engineering and Applied Science. "The fact that we didn't see the presently understood meteorological signature of global warming in changing outbreak statistics for tornadoes leaves two possibilities: Either the recent increases are not due to a warming climate, or a warming climate has implications for tornado activity that we don't understand."

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Op vrijdag 20 januari 2017 14:36 schreef Nattekat het volgende:

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Dat is vroeg

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High-risk declarations for severe weather are rare. The last such issuance was June 3, 2014, according to Weather.com and hasn’t occurred in winter since 2008 . Since 1984, 42 percent of tornado fatalities have coincided with such high-risk days, according to the Weather Channel’s Kathryn Prociv.

The region under high risk hasn’t seen such a designation in a decade, the website for U.S. Tornadoes reported.