A widespread severe weather event developed across Southeast Texas on Thursday October 23, 1997 in which numerous tornadoes, funnel clouds, gusty winds and large hail were reported. There were a number of interesting meteorological parameters that came together to produce this severe weather episode.
On the large scale, a cold front had pushed through Southeast Texas on Tuesday evening (October 21st) and became stationary across deep south Texas between Corpus Christi and Brownsville. In the upper levels of the atmosphere, the polar jet was nearly zonal for the western two thirds of the nation with a deepening trough developing over the eastern third. A slow moving upper level low pressure system and associated low pressure trough dominated the western half of the sub-tropical jetstream. A confluent zone developed over the eastern third of the nation as the polar and sub-tropical jetstream merged. The cold front over deep south Texas began to return north as a warm front Wednesday night. The upper level low in the sub-tropical jetstream was ejected eastward Wednesday night and Thursday. As this feature moved east, the polar jetstream curved to the northeast while the subtropical jetstream became zonal. This created a large area of diffluence aloft over southeast Texas and southwest Louisiana.
By Thursday morning, the warm front had entered Southeast Texas. Surface dewpoints were rising into the lower and middle 60s and surface winds were becoming southeast while just off the surface, a southerly low level jet of 30 to 40 knots had developed. By mid-Thursday morning, a 110 to 120 knot wind speed maximum at 200 mb embedded in the subtropical jetstream approached south Texas putting southeast Texas in the favorable left front quadrant. An intrusion of dry air at 500 mb further destabilized the atmosphere producing incredibly unstable lapse rates. Data from LCH and CRP soundings and the KHGX VWP indicated tremendous turning in the atmosphere as southeast surface winds became south at 1000 feet, southwest between 2000 and 3000 feet and west at 5000 feet. Model helicity values were progged to exceed 400 m2/s2 between 12z Thursday and 00z Friday. As the upper level wind speed maximum approached south Texas, showers and thunderstorms developed rapidly with some of the storms becoming severe.
Eleven separate tornadoes touched down during this event. Many of these tornadoes were spawned from the same supercell. Every tornado that formed had a tornado warning in effect before the damage was produced. Average lead time was 24 minutes between tornado warning issuance and tornado touchdown, ranging from 4 minutes to 58 minutes. No deaths occurred and only one injury was reported.
The first tornado touched down at 2:00 PM in Sugar Land. The tornado was mostly F0 with some F1 damage. The tornado path length was 3 miles long and 1/4 mile wide at its strongest stage. Over 1 million dollars in damage to homes.
At 3:22 PM a tornado touched down in northern Walker County near Hwy 75. This tornado destroyed one home and heavily damaged a second. This was an F1 tornado with a path length of 2 miles and 50 yards wide.
At 3:32 PM the same supercell that produced the tornado at Sugar Land spawned a second tornado near Crosby. The tornado first touched down on the east shore of Lake Houston and moved northeast into extreme western Liberty County. This tornado was mostly F0 and F1 with some F2 damage at Foley Rd and Dallas Rd where a boat house was severely damaged. An 18 wheeler in the same area was turned over and moved 50 feet by the tornado. This tornado was on the ground for 12 miles and the damage path was 1/4 mile wide at its strongest stage. This storm lifted around 3:56 PM in western Liberty County.
At 3:43 PM, a new supercell spawned a short lived tornado south of Bellville in Austin County. Only trees were damaged by this tornado.
At 4:07 PM the Crosby tornadic thunderstorm spawned a short lived tornado near Kenefick. This tornado was on the ground for less than 2 miles. Damage was mostly to trees and some minor roof damage. This was an F0 tornado.
At 4:25 PM another tornado was spawned by this same supercell. This F0 tornado was short and narrow and damage was confined to trees.
At 5:00 PM an F2 tornado touched down southwest of Midway in Montgomery County. This was probably the most significant in strength and length that occurred this day. The tornado was on the ground for 25 miles and the width of the damage was 1/4 mile at its strongest point. Several homes and mobile homes received major damage. A young boy was injured in a mobile home when the tornado picked up the home and wrapped it around a tree completely destroying it. Damage to trees was extensive with many trees being snapped off above the ground. This storm was surveyed from the air and had continuous tree damage from Midway to south of Shepherd in southern San Jacinto County. This tornado lifted back into the parent thunderstorm around 5:25 PM southeast of Shepherd.
At 5:15 PM an F0 tornado touched down in the Bear Creek Community in San Jacinto County. This tornado was the result of the Midway tornadic thunderstorm splitting and the left moving storm moving over Bear Creek. Damage was mostly to trees but a volunteer fire department building was also heavily damaged. Path length was less than 2 miles long.
A new supercell spawned a short lived tornado over Conroe with flag poles at the Conroe High School Football Stadium bent over. As the storm passed just south of Conroe Airport the ASOS recorded 57 mph winds from the south. This was an F0 tornado and touched down at 5:22 PM.
The supercell that spawned the tornado at Conroe spawned a second tornado along Hwy 105 near Cut-N-Shoot at 5:30 PM. This tornado moved along Hwy 105 with a path length of 4 miles. This was an F1 tornado with damage to homes, businesses and a school. This supercell continued moving east and followed much the same path as the earlier tornado that started near Midway. It is possible this supercell produced another tornado across eastern Montgomery County into southern San Jacinto County but it would be difficult to distinguish between the two storms. This storm lifted at 5:40 PM.
The above supercell did eventually produce one more tornado in Polk County. An F0 tornado touched down near Segno and moved northeast to near Dallardsville and continued northeast to near the Polk/Tyler County line. This tornado touched down at 6:35 PM and stayed on the ground for 15 minutes.