Houston-Pasadena Tornado

The 2018 Northwest Houston-Pasadena Tornado was a particularly intense EF5 that touched down to the NE of Brenham in Washington County, TX and was on the ground for over 2 Hours as it tore a path of destruction from Benham to Seabrook, killing 2,478, injuring more than 200,000, and doing $17.89 Billion in damages. The first EF5 since 2013, it remains as the costliest and deadliest tornado in history. This is one of 24 EF5s confirmed during the May 1st-12th, 2018 Outbreak Sequence.

Meteorological Synopsis
On the morning of May 2nd, 11:51 UTC, extremely favorable conditions were developing over SE TX as a deep positive trough had settled just west of the Houston Metro, the eastern half screaming EVE from Texas to North Carolina. Speeds of the jet ranged from 100 to 200 Mile per hour, the strongest winds situated over SE Texas.

At only 7:00 AM, CAPE values had already reached 5500 J/kg to 6000 J/kg, and were expected to increase throughout the day. Dewpoints were already up to 80°F with a predicted high of 102°F for the greater Houston Area, with Pasadena potentially seeing a high of 105°F. Deep layer wind shear speeds of 55–70 kn (63–80 mph) would greatly enhance storm organization and intensity. These factors, along with CAPE values in excess of 4000 J/kg and an embedded speed maxima rotating around the southern periphery of the low, made the threat of significant severe thunderstorms increasingly probable. These ingredients were present in front of a strong cold front and Dryline extending deep into Mexico. This set up was unusual for this time of year, as such a system so far south is more common in early April rather than early May. As such for the ever increasing probability of Significant sever weather, the SPC issued a PDS High Risk for much of SE Texas and into Louisiana, and a Moderate Risk that Extended into Arkansa. Most of the Marginal to Enhanced Severe Risk was along the boundary created by the ENE Jet that stretched from SE TX, to SWC NC.

Storm Track and Development
At 19:15 UTC, a quasi-linear storm complex exploded to the East of Austin, TX where CAPE had exceeded 8000 J/kg, generating extreme intability in the atmosphere. Within half an hour, the storms had quickly reached severe status, quickly being warned for Grape-Fruit sized hail and damaging downbursts. This storm system was made up of several embedded supercells, each producing large, violent tornadoes along an ESE track. By 19:45, elven tornado warnings had been issued for the system, including a particularly broad and powerful circulation in the largest and southern-most storm. Despite not being a very tight circulation, Dopplar radar indicated windspeeds of 100+ mph, with some spots reaching speeds of 140 mph. At 20:27 UTC, a Tornado Emergency was issued for Brenham in Washington County as the circulation had begun to tighten as it approached the small populace. At 20:40 UTC, Storm spotters reported seeing several large, brief funnels dancing around under a massive, low base, with violent motion in the wall cloud somtimes reaching the ground itself. Despite the HP state of the storm, the rain-free base was relatively dry, prompting great visibility and hordes of chasers to come see the behemoth that was about to form before them. At 20:43 UTC, the entire base had dropped to the ground just NE of Brenham; chasers scurrying for a safe viewing angle as the sudden development had caught them off guard. As it dropped, it had done so right on top of a large, well builted house that was found to have been properly secured with Anchor Bolts. Immediately the House exploded in the splinters, killing all 5 inside. The Concrete slab of the house was picked up and moved several feet from its original position. In only minutes the storm reached EF5 intensity, tearing ESE at 50 MPH. At 20:58, it completely leveled 90% of the town of Chapple Hill, killing 23. At this point, DOW had recorded Windspeeds in excess of 295 mph, and they were increasing. Houses in Chapple Hill were found to be completely splintered and scattered from the intensity of the storm, with most of the houses remaining as bare slabs with scouring on the surfaces. Cars in Chapple hill were found to have been hurled over a mile and obliterated.

As the storm continued to parrallel US-Route 290, it suddenly arched SE towards Hempstead. The storm then arched back to ESE, clipping the northern edge of Hempstead, obliterating several structures and destroying many others. During this erratic movement, the tornado's forward speed had increased to over 70 mph, giving little warning to the city of Hempstead. 52 people were killed. As it jumped across Route 290, 13 people were killed as cars, vans, trucks, and semis were hurled for several hundred yards and up to a mile away, obliterating the vehicles in the process. As it righted its track, the storm cut straight through the heart of Prairie View, leveling the entire town and destroying Prairie View A&M University, killing 110. After which the foreward speed slowed to 30 mph, generating extreme ground scouring up to 30 inches deep. Houses in this area were completely decimated, their slabs being lifted off the ground and tossed several yards. 4 people were killed. At 21:23 UTC, DOW measured windspeeds of 314 mph. At this point, the tornado was 2.5 Miles wide, as wide as the Hallam, NE F4, and still growing. At 21:27 UTC the tornado accelerated ESE parrallel to Route-290. Houses along this path were all destroyed, killing 18. At 21:44 UTC, The town of Hockey was completely decimated, killing 27. The storm continued ESE, beginning to turn SE as it approached Northwest Houston. A Tornado Emergency was issued for the entire city as the tornado arrived at 22:01. Houses in the suburb were completely destroyed. Well built houses were ripped from their foundations and exploded in midair. For nearly an hour the tornado ripped through the city, obliterating houses and destroying several buildings. Cars were smashed against skyscrapers, with one collapsing during the storm as a result of a loss of structural integrity. 579 people died in that tower. The storm continued on a SE track. At 22:37 the tornado began to tear through the heart of Pasadena. 1,134 people were killed here alone due to a lack of basements and several poorly built houses. The tornado continued SE until it reach Seabrook, where upon reaching the bay, the tornado quickly weakened, taking a sharp right turn over the water before finally lifting. After several weeks of searches and clean up, the death toll rose to 2,560, 82 of those being non-tornadic.

At its most intense the storm reach speeds of 321 MPH and a width of 2.9 miles. These are both the fastest windspeeds ever recorded on Earth and the widest Tornado ever recorded. It was found that a majority of deaths were a result of the poor construction of houses and lack of sufficient shelter, prompting the President to pass a law that made it required that all houses feature a Tornado Shelter and be well constructed with anchor bolts in hopes to prevent such a disaster again.