HCFCD Issues Reports on Late January Flooding, Tornados
Jeff Lindner, Harris County Meteorologist, has issued a report on January flooding, heavy rainfall and a significant tornado on January 24, 2023. He also released intensity tables for 24th to the 31st. They help us understand the cumulative impact of back-to-back heavy rainfalls on the 24th and 29th.
Says Lindner, “Early on the 24th, surface low pressure developed over south-central Texas. It helped draw a warm front northward. It eventually formed a line from near Sealy to Downtown Houston to Chambers County. This warm front when combined with strong lift, impressive low level wind shear, and winds changing direction, resulted in the formation of supercell thunderstorms along a line from near Victoria to Sealy to Conroe.
They trained across northwest Harris County. Rainfall amounts southeast of US59 ranged from 1-2 inches, but 2-6 inches northwest of 59.
One of the storms along the front produced a tornado over southern Fort Bend County. Another formed over northern Brazoria county near Pearland. Rotation increased as it tracked through SE Houston, Pasadena, Deer Park and Baytown.
Duration and Rates
The heaviest rainfall occurred over portions of west, northwest, and northern Harris County in a 3 to 6 hr period. Several locations in northwest Harris County recorded 1.0-3.0 inches of rainfall in an hour during the late morning hours. Additionally, as the line of storms moved eastward, numerous locations recorded 1.0-2.0 inches of rainfall in 15-45 minutes. That resulted in rapid street flooding over many portions of Harris County during the early to mid afternoon hours.
Total 6-hr rainfall amounts ranged from 3.0-6.0 inches from north of Katy along west/north of FM 1960 into the Humble and Kingwood areas. The highest amount was at John Paul Landing Park in northwest Harris County where 5.48 inches was recorded in 3 hours. Unfortunately, most of this rain fell on grounds that were still wet from heavy rainfalls on January 8 and 9. This maximized runoff into area creeks.
Lindner points out that, “Heavy rainfall and flooding can occur every month of the year in Harris County and there have been other recent heavy rainfall events in January. Compare rainfall duration and intensity in the table below.”
Interestingly, all of the January flooding events listed above had identical contributing factors: a surface warm front, high moisture levels, and training movement over the same area.
Rainfall amounts for the 1- and 3-hour time periods ranged from 2- to 10-year rains on the Atlas 14 scale. For the most part, channels could accommodate the rainfall. No widespread house flooding occurred although streams came out of their banks at numerous locations and came dangerously close to homes. See below.
The tornados were a different story, though. As they swept across the southern part of the county at 40 to 60 mph, they produced significant damage.
Lindner said, “Video obtained from the City of Deer Park indicated a tornado heavily shrouded in heavy rainfall with very little if any visibility of a condensation funnel or lofted debris. Unlike tornadoes in the Great Plains, many of the tornados along the US Gulf coast are hidden within heavy rainfall and very difficult to observe.”
For a complete listing of rainfall intensities and damage assessments at different locations through the county, see Lindner’s report here. It contains an interesting history of tornados in Harris County.
The pictures below were taken by a retired Kingwood resident, John Knoerzer, who owned a business in one of the hardest hit areas. They illustrate damage in Pasadena at one of his former employee’s home and shop.
Never Bet Against Mother Nature
Lindner’s report and these images provide powerful reminders of why we should never take flood or wind risk for granted. And why we need to see flood-mitigation projects through to completion.
These were only 5-year storms. But remember. Those exceedance probabilities are like odds on a Las Vegas roulette wheel. I once saw the same number come up six consecutive times!
Don’t bet against Mother Nature. Insurance gives you much better odds.
To explore historical rainfall in your area, consult the Harris County Flood Warning System.
Posted by Bob Rehak on 2/8/23 with thanks to John Knoerzer for his images and Jeff Lindner for his reporting
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