Tropical Storm Imelda

Imelda originated from a mid-to-upper level trough located over the Eastern United States. Between September 10–12, the low moved to the southwest towards the eastern Gulf of Mexico. Once over the Gulf, associated convection began to increase, as a weak surface trough formed within the upper—level low on September 14, traversing to the west—northwest.^[5] That same day, the National Hurricane Center began to monitor the low for possible tropical cyclogenesis.^[6] Although, the NHC only gave the disturbance a low chance of formation. By September 17, the system had reached the east coast of Texas.^[7] Soon afterward, organization in the system rapidly increased, and at 17:00 UTC that day, the system organized into Tropical Depression Eleven, just off the coast of Texas.^[8] At 17:45 UTC, an observation deck at Freeport, Texas recorded sustained winds of 40 mph (65 km/h) with gusts of 47 mph (76 km/h), indicating that the depression had strengthened to Tropical Storm Imelda.^[9]

Shortly thereafter, at 18:30 UTC, Imelda made landfall near Freeport, Texas at peak intensity, with maximum 1-minute sustained winds of 45 mph (75km/h) and a minimum central pressure of 1,003 millibars (29.6 inHg).^[10] Imelda weakened after landfall, becoming a tropical depression at 03:00 UTC on the next day. At that time, the NHC passed on the responsibility for issuing advisories to the Weather Prediction Center (WPC).^[11] Imelda retained status as a tropical depression over land for the next 2 days, gradually weakening and slowing its motion, before degenerating into a trough on September 19, as it began passing over Louisiana; Imelda's remnants continued producing heavy rain and a few isolated tornadoes.^[12] Imelda's remnants persisted for another couple of days, before dissipating early on September 21.^[13][14]

Imelda's slow movement over Southeast Texas and a continuous influx of tropical moisture led to copious amounts of rainfall over the region.^[5] This moisture supported the formation of rainbands that repeatedly moved across the same areas of Southeast Texas between September 17–19.^[19] Several counties spanning parts of the Greater Houston metropolitan area and Beaumont, Texas, recorded over 30 in (760 mm) of rain. A maximum rainfall total of 44.29 in (1,125 mm) was documented at a station 2 mi (3.2 km) south-southwest of Fannett, Texas; this made Imelda the seventh-wettest tropical cyclone in U.S. history, fifth-wettest in the contiguous U.S., and fourth-wettest in Texas history.^[5] The same station recorded 31 in (790 mm) of rain in 12 hours.^[20] Rain fell at over 5 in (130 mm) per hour in several places.^[21] Flood depths in some locations exceeded those recorded in Hurricane Harvey due to the high rainfall rates.^[22] Where rainfall was heaviest, the rainfall total represented a 1-in-1000-year rainfall event.^[20] Destructive flooding occurred along Interstate 10 between Winnie and Orange, Texas, where over 42 in (1,100 mm) of rain fell. Over one thousand vehicles were caught in flood waters. Many homes and businesses were also flooded, resulting in numerous high-water rescues. Approximately 8,200 homes were flooded in Harris, Jefferson, Liberty, and Montgomery counties in Texas.^[5] Five deaths were directly attributed to the floods, of which three occurred in Jefferson, while two occurred in Harris County.^{[5][23][24][25]} The National Centers for Environmental Information estimated Imelda inflicted $5 billion in damage.^[5]

Jefferson County, Texas, was the county most heavily impacted by Imelda.^[5] An estimated 5,100 homes were flooded in the county, suffering $14 million in damage.^[5][20] Major street flooding occurred in Beaumont where the Jefferson County flooding first began.^[22] Over 38 inches (97 cm) of rain fell in the city.^[26] Encroaching floodwaters prompted the evacuation of Riceland Medical Center in Chambers County, Texas.^[5][27] Stream flooding persisted for days in Hardin County, Texas, where 10–40 in (250–1,020 mm) of rain was measured. Many buildings and roads were rendered impassable.^[28][5] Sixty homes were flooded in the county, resulting in $2.3 million in damage. In Orange County, Texas, Imelda flooded 2,679 homes, resulting in $12 million in damage. Near Mauriceville, Cow Bayou reached its second-highest crest on record. In Jasper and Newton counties in Texas, an estimated $2.4 million in damage was incurred following the flooding of 15 homes.^[20]

In Houston, Imelda's rainfall caused many of the local bayous to overtop their banks and flood residential areas. More than 1,000 people were rescued from floodwaters. All bus and rail services were temporarily shut down in the city. A roof of a United States Postal Service building collapsed, leaving three people with minor injuries. George Bush Intercontinental Airport closed for about 90 minutes due to flooding on the runways, canceling 655 flights.^[29] Throughout Houston, hundreds of homes were affected by flooding and more than 1,600 vehicles were towed. In Harris County alone, 422 people required high-water rescue; the Texas National Guard rescued 130 people.^[30] During the flood, nine barges escaped a shipyard, and at least two struck the Interstate 10 bridge over the San Jacinto River, causing visible damage to some of the columns supporting the highway.^[31][32] The bridge was subsequently closed to traffic in both directions.^[33] Significant flooding occurred in Splendora, inundating parts of FM 2090 and U.S. 59, as well as gas pumps at a filling station.^[34]

Within the weeks following Imelda, aid from FEMA was not received. This left some residents uncertain if any would come.^[35]

Flooding from Imelda in southwestern Louisiana was relatively minor. Freshwater flooding in Johnson Bayou inundated most secondary roads and was augmented by the elevated tide levels caused by the tropical storm.^[5][36] The remnants of Imelda produced up to 7.6 in (190 mm) of rain in southeastern Oklahoma between September 6–7.^[5] Heavy rainfall also occurred in portions of Arkansas.^[37]

In addition to the rain, weather stations reported winds between 37 and 44 mph (59–70 km/h) as Imelda made landfall. At Baton Rouge Metropolitan Airport, an embedded thunderstorm within one of Imelda's rainbands produced a microburst that flipped four airplanes and damaged hangar doors on September 17; the airport registered a peak gust of 66 mph (106 km/h).^[5][38] Storm surge also resulted in minor coastal flooding along the upper Texas and Louisiana coasts, inundating areas with 1–2 ft (0.30–0.61 m) of water. A National Ocean Service gauge at Eagle Point, Texas, measured a peak surge height of 2.35 ft (0.72 m) above normal tide levels. After September 17, freshwater runoff originating from inland flooding reached the coast and exacerbated the initial storm surge flooding. A gauge on Buffalo Bayou documented water levels 4.32 ft (1.32 m) above normal tide levels once runoff reached the coast. Imelda also produced two confirmed tornadoes: an EF1 tornado unroofed a home and downed large tree limbs on in Harris County, Texas on September 18 and an EF0 tornado flipped a recreational vehicle and knocked down several trees near Hackberry, Louisiana, in Cameron Parish on September 19.^[5]

• Tropical cyclones in 2019
• List of Texas hurricanes (1980–present)
• List of wettest tropical cyclones in the United States
• Tropical Storm Allison (1989) – A tropical storm that had similar intensity, stalled over Eastern Texas/Western Louisiana, causing $560 million with severe flooding.
• Tropical Storm Allison (2001) – Another system of a similar intensity that stalled over Texas and caused severe flooding.
• Hurricane Harvey (2017) – A Category 4 hurricane that also caused catastrophic flooding in the same region when it stalled as a tropical storm.

Wikimedia Commons has media related to Tropical Storm Imelda (2019).

• The NHC's Advisory Archive on Tropical Storm Imelda
• The WPC's Advisory Archive on Tropical Storm Imelda
• The Weather Prediction Center's storm summaries on Tropical Storm Imelda