New forecasts that show higher than previously predicted rainfall amounts for the next three days have caused the City to begin lowering Lake Houston.
Widespread 3-6 Inches Expect, Higher Isolated Totals
All week long, meteorologists have predicted heavy rains starting on Wednesday, 4/5/23, through Friday, 4/7/23. This morning, guidance from Harris County Meteorologist Jeff Lindner indicated that the rainfall could be even heavier than previously predicted. Instead of widespread 2-4 inches, Lindner now predicts widespread 3-6 inches. Last night, ABC13 predicted up to a foot of rain in isolated places, especially north and west of US59, i.e., the San Jacinto Watershed.
Lake Lowering Began at Noon
As a result, the City of Houston began lowering Lake Houston today at noon.
According to Mayor Pro Tem Dave Martin, Houston Public Works, Coastal Water Authority, and San Jacinto River Authority have worked together closely over the last 24 hours to monitor local forecasts. Based on this morning’s forecast within the San Jacinto Watershed, the City decided to open the floodgates on the Lake Houston Spillway Dam.
Houston Public Works will keep the flashboard and tainter gates open throughout the inclement weather and Coastal Water Authority will continue storm operations allowing the inflow to pass through Lake Houston until the weather threat concludes.
SJRA NOT Lowering Lake Conroe Level
SJRA has confirmed they will NOT lower Lake Conroe. This will maximize the City of Houston’s lake-lowering efforts.
An approaching low-pressure system from the northwest will stall when it encounters a high-pressure system over the Gulf.
The two fronts will funnel moisture from both the Pacific and Gulf between them. That’s because in the Northern Hemisphere, high-pressure systems rotate clockwise and low-pressure systems rotate counterclockwise. So atmospheric moisture will be squeezed between them along a steady line for days. Think of meshed gears.
Because of dry grounds, moisture that falls during the first day will likely soak in. But after that, runoff rates will increase.
The areas receiving the most rainfall will likely be north and west of Houston, because that’s where the frontal boundary will likely linger longest.
Street flooding will be a concern through Friday.
Says Lindner, “Smaller creeks, rural watersheds, and San Jacinto River system will be the most vulnerable to higher run-off flows. While widespread creek and bayou flooding is currently not expected, some watersheds may experience significant rises and a few locations potentially to flood levels. Any sustained training of heavy rainfall over any certain watershed for an extended period of time could result in flooding. It will be important to monitor rainfall amounts and locations through the period for any significant watershed responses.
Watch the following watersheds closely: Willow Creek, Little Cypress Creek, Cypress Creek (and Waller County tributaries), Spring Creek (and Montgomery/Waller County tributaries), Bear Creek, South Mayde Creek, Cedar Bayou, East/West Forks of the San Jacinto River, Keegans Bayou, Clear Creek, Halls Bayou.
For Current Information 24/7
Bookmark these links to monitor weather and lake conditions, especially if you live in low-lying areas with a history of flooding:
- For weather, visit the National Weather Service’s Houston page: http://www.weather.gov/hgx/
- Harris County Flood Control District’s Flood Warning System tracks rainfall and monitors water levels in bayous and major streams on a real-time basis: https://www.harriscountyfws.org/
- Coastal Water Authority reports water levels in Lake Houston: https://www.coastalwaterauthority.org/
- San Jacinto River Authority reports Lake Conroe releases and water levels: https://www.sjra.net/
- For real-time alerts, please visit https://houstonemergency.org/alerts/
Posted by Bob Rehak on 4/5/2023 at Noon
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