Draft:2007 Greensburg, Kansas tornado

2007 Greensburg, Kansas tornado

The tornado (illuminated by a lightning flash) as it was approaching Greensburg
Meteorological history
Date	May 4, 2007
Formed	9:00 PM CDT (0200 UTC)
Dissipated	10:05 PM CDT (0305 UTC)
Duration	one hour, five minutes
EF5 tornado
on the Enhanced Fujita scale
Highest winds	205 mph (330 km/h)
Overall effects
Fatalities	11
Injuries	63
Damage	$250 million
Areas affected	Greensburg
Part of the Tornado outbreak of May 4–6, 2007 and Tornadoes of 2007

On the night of May 4, 2007, a very large, violent, and destructive EF5 tornado touched down in rural south central Kansas, directly impacting the town of Greensburg, heavily damaging or destroying 95% of the town. It was the first tornado to be rated EF5 since the implementation of the Enhanced Fujita scale in February, and the first overall to achieve the highest rating since 1999. It was part of a larger outbreak sequence that produced dozens of tornadoes throughout the evening of May 4 and into the early morning hours of May 5.

The tornado began in northwest Comanche County, 8.3 miles (13.4 km) northeast of Lexington at 9:00 PM CDT (0200 UTC). It crossed into Kiowa County and rapidly expanded in width, reaching 1.7 miles (2.7 km) wide nearly 6 miles (9.7 km) south-southwest of Greensburg. A tornado emergency was issued for the city at 9:41 PM CDT, before the tornado entered the southern side of town at 9:45 PM CDT. Widespread devastation occurred in Greensburg, before it executed a counterclockwise loop and dissipating at 10:05 PM CDT (0305 UTC).

The tornado resulted in 11 fatalities, with 63 additional injuries also being confirmed. The damage to 1,484 structures amounted to $250 million.

Meteorlogical synopsis

Some sentences and paragraphs were taken from the synopsis section of the outbreak page

The Day 1 convective outlook of May 4, showing a moderate risk in Kansas as well as portions of Oklahoma, Nebraska, and Colorado.

It is the combination of warm humid air from the Gulf and dry air from the deserts of the Southwest that produce deadly storms. These conditions cause instability that allows severe storms to develop. Although tornadoes occur on every continent except Antarctica, they are most common in North America, especially the United States.

The tornado, as well as the severe weather event itself, can be traced back to a powerful, slow-moving low pressure area with a warm front to the north over Nebraska and Missouri. On May 4, the low stalled over the High Plains and additional moisture coming from the Gulf of Mexico moved in behind the warm front and increased amounts of instability across much of the region, with CAPE values as high as 5,500 J/kg. In addition, the dry line, which marks a divided line between the dry and humid air mass, was positioned over the southern High Plains. This allowed for the initiation of scattered supercells on May 4. High wind shear also allowed for intense rotation in the atmosphere. All of the ingredients were present in the atmosphere for the developing of supercell thunderstorms producing damaging wind, large hail and tornadoes.

A moderate risk was issued for the western half of Kansas, with a 15% hatched tornado risk, and a 10% hatched risk of tornadoes of EF2-EF5 strength within 25 miles of a point. Additionally, a 30% damaging wind risk, and a 45% hail risk was issued throughout the moderate risk area. The Storm Prediction Center (SPC) predicted that a majority of the activity would occur throughout the evening hours.

The storm that would eventually produce the EF5 Greensburg tornado formed in the northeastern corner of the Texas Panhandle after 5:00 PM CDT. A few isolated tornadoes touched down across the Oklahoma Panhandle as the storm began to organize itself. By 8:35 PM CDT, the first tornado warning associated with the cell was issued for Clark County, Kansas.

Tornado track & damage

Several tornadoes preceded the main Greensburg tornado between 8:32 to 8:50 PM CDT (0132-0150 UTC). The main tornado touched down around 9:00 PM CDT (0200 UTC) in northwest Comanche County, tracking in a northeasterly trajectory. By the time it crossed into Kiowa County, it had already grew to nearly 3⁄4 of a mile (1.2 of a km). Continuing to the northeast, the tornado continued to expand in width, eventually reaching a peak width of 1.7 miles (2.7 km) south-southwest of Greensburg. Whilst the tornado was widening, a tornado warning was already in effect, giving residents 26 minutes to take shelter before the tornado hit. At 9:41 PM CDT (0241 UTC), the National Weather Service in Dodge City, Kansas issued a tornado emergency for the town, urging residents to take cover as the violent tornado made its approach toward the town.

4 minutes after the alert was issued, around 9:45 PM CDT (0245 UTC), the massive tornado entered the south side of Greensburg. A row of houses along S. Main Street were swept cleanly away, with debris being scattered a long distance in a nearby field. Out of the seven houses that were swept away, three were well-bolted to their foundations. In addition, ground scouring occurred in a field nearby. Damage in the area was rated EF5 as a result. Entering the main parts of town, the tornado slightly weakened, but remained violent as more structures were destroyed, including Delmar Day Elementary School, which was destroyed at high-end EF4 intensity. A small area of EF5 damage was observed just across the street of the school, where four well-anchored houses were swept away among the hundreds in the area. Trees also suffered debarking, a few of which had objects lodged into them, most notably, one with a fork, and another with a license plate. According to YouTuber and storm chaser Chris Riske, the amount of kinetic energy within both of them were 405 and 243 joules, more energy than a .22 caliber bullet, and more than double of that of a Major League Baseball pitch.

EF4 damage continued throughout downtown Greensburg, as hundreds of buildings in the path were levelled or swept away. The Big Well was destroyed, the nearby water tower was crumpled, and a 1,000 lb (450 kg) meteorite was feared to have been blown away, but was later found underneath a collapsed wall. EF4 damage continued as the tornado moved north-northwest, where more homes were flattened, trees were debarked and denuded, and cars were heavily damaged or destroyed. The town's grain elevator, despite being hit, remained mostly intact.

The tornado left the town, then fully occluded into the storm; executing a counterclockwise look northwest of town before dissipating at 10:05 PM CDT, after being on the ground for 65 minutes (1 hour, 5 minutes) and tracking for 28.8 miles (46.3 km). As the main Greensburg tornado dissipated, the same supercell produced three very large tornadoes, all of EF3 intensity, near the Trousdale and Macksville areas.