Tonight, the Lake Houston area is under yet another flash flood watch. Residents of North Kingwood Forest and Elm Grove are wondering whether a new detention pond in Woodridge Village will be enough to protect them.
Another 1-4 Inches of Rain Possible
We may get another chance to test the engineering on the detention ponds in that new Woodridge Village under development in Montgomery County. Our area received 1-3″ of rain today and more is on the way tonight. The area remains under a flash flood watch until 7a.m. Monday morning.
Heavy rainfall and severe thunderstorms will be possible tonight into early Monday.
Jeff Lindner, Harris County Meteorologist warned at 8:30 p.m. Sunday night that, “Numerous thunderstorms are in progress over portions of Liberty, Harris, and Montgomery Counties. Heavy rainfall is the main threat with these cells with recent HCFCD gages in SE Montgomery County recording 2.60 inches in 1 hour. Additional rainfall amounts tonight of 1-2 inches with isolated totals of up to 4 inches are possible.”
The storms appear to be fast moving so the higher totals are less likely than in early May when approximately 200 homes flooded in Elm Grove and North Kingwood Forest just south and east of the area that Woodridge contractors had clearcut.
Role of Detention Pond in Reducing Flood Potential
Had the Woodridge Village S2 Detention Pond been excavated before May 7, it might have prevented much of the flooding. But despite the land being cleared for approximately six months, the pond had not yet been built. LJA Engineers designed the pond to hold 50 acre-feet of runoff. What does that mean?
How Much is An Acre Foot?
One acre foot would cover an entire acre to a depth of one foot. An acre is about the size of a football field. That means 50 acre feet would cover:
One football field to a depth of 50 feet
50 football fields to a depth of one foot
Or, in the case, of this pond, about 3.5 acres to a depth of about 15 feet.
The pictures below show what it looks like today. Very little of this area was excavated on May 7.
S2 has the shape of a hockey stick. Here’s the “face” of the stick. It took a 14mm super-wide-angle lens to get the width of this pond in the frame.This conveys its width but does not adequately convey its depth.This panoramic image was stitched together in Photoshop from seven still images taken with a normal focal length lens. It more accurately conveys the height of the sides. But there’s still nothing in the frame to communicate scale.Although the sides don’t look tall in the previous photo, this is what they look like when you turn and face them. This shot was taken while standing near the bottom. My eye level is more than six feet high and didn’t come halfway up the slope.This notch in the wall of the pond allows water from the ditch behind the grass to overflow into the pond instead of flooding North Kingwood Forest (behind the tree line. That’s the theory anyway … if the calculations are correct.The red circle shows the location of the notch between the pond and drainage ditch beyond it.
Hopefully, the amount of detention in place tonight is enough to handle the rain we get.
Posted by Bob Rehak on 6/16/2019
656 Days after Hurricane Harvey
Thoughts expressed in this post represent my opinions on matters of public policy and safety. They are protected by the First Amendment of the US Constitution and the Anti-SLAPP statute of the Great State of Texas.
https://i0.wp.com/reduceflooding.com/wp-content/uploads/2019/06/Woodridge6.17.19_01_01.jpg?fit=1500%2C1000&ssl=110001500adminadmin2019-06-16 22:40:432019-06-16 22:43:09Flash Flood Watch in Effect Until 7 a.m. Monday; Luckily, Woodridge Detention Pond Nearing Completion
Expect Heavy Rain Late Tonight but More Likely on Wednesday
Showers and thunderstorms are expected to develop tonight as a surge of tropical moisture approaches Southeast Texas and merges with a low coming from the west.
Rainfall rates could reach 2 to 3 inches per hour at times. Widespread rainfall totals of 2 to 4 inches are expected across Southeast Texas by Wednesday evening with isolated totals exceeding 6 inches. The heaviest rainfall is expected to fall along and east of the I-69/US 59 corridor.
Those totals are close to what we experienced in early May.
Jeff Lindner, Harris County Meteorologist warned, “A low level convergence boundary may become established between the US 59 corridor and the coast and help to organize and focus thunderstorms and heavy rainfall. This pattern remains in place Wednesday and Wednesday night while 91L moves up the TX coast and likely either across SE TX or just offshore over our coastal waters.”
PRECAUTIONARY/PREPAREDNESS ACTIONS
A Flash Flood Watch means that conditions may develop that lead to flash flooding. Flash flooding is a very dangerous situation. You should monitor later forecasts and be prepared to take action should Flash Flood Warnings be issued.
Street Flooding Likely; Significant Rises on Bayous/Creeks Possible
Do not drive your vehicle into areas where the water covers the roadway. The water depth may be too great to allow your car to cross safely.
If water is deep enough to cover your tailpipe, your car will stall.
Vehicles caught in rising water should be abandoned quickly. If your vehicle stalls…abandon it and seek higher ground immediately. Rapidly rising water may engulf your vehicle and its occupants and sweep them away. Move to higher ground.
Check Drains and Creeks Near You; Park on High Ground
During storms last month, yard debris (leaves, twigs, small branches, grass clippings, etc.) washed into sewers and drainage ditches. Also, in places, large trees had fallen into creeks and ditches due to bank erosion. Flooding doesn’t always come from the river. It can come from blockages anywhere in the drainage system.
So while the weather is still nice today:
Make sure your drains are clear
Do not stack branches or garbage where they could back up water
If you live near a creek or drainage ditch, walk it. Look for downed trees. Focus on areas downstream from you that could back water up onto your property.
Report clogged street drains to City of Houston by calling 3-1-1. Have address ready when you call.
Move valuables and important papers to an upper floor or top shelf.
Make sure your cell phone and weather radio batteries are fully charged; have backup batteries in case of power outages.
Remember, streets are DESIGNED to be part of the floodwater retention system. They are meant to hold excess water until the ditches, creeks, streams and bayous can absorb it. So don’t park in the street if you can avoid it.
Attention Vacationers: Coastal Forecast is Rough
Winds will begin to increase this afternoon and evening over the coastal waters which will help to build seas on Wednesday. Tides are forecasted to reach near 3.5-4.0 ft on Wednesday which may cause minor coastal flooding on Bolivar and low lying coastal area on the west end of Galveston, Surfside, and in SE Harris County. A coastal flood advisory may be required on Wednesday.
Posted by Bob Rehak on 6/4/19
644 Days after Hurricane Harvey
https://i0.wp.com/reduceflooding.com/wp-content/uploads/2019/06/noaad2.gif.png?fit=887%2C640&ssl=1640887adminadmin2019-06-04 12:55:072019-06-04 12:55:16Flash Flood Watch In Effect from Midnight Tonight Through Thursday Morning: Simple Ways to Reduce Flood Risk
My friend, John Knoerzer, owner of Uniserve Air Conditioning, sent me this video from East End Park around sunset tonight. It shows the East Fork of the San Jacinto River has already come out of its banks. This was at about 6:22 p.m. Tuesday.
Even Gus the Poodle knows to stay away from the raging East Fork. Shown here: the North Loop Trail in East End Park.
I have no pictures from the West Fork, so this graph will have to do. It shows that the West Fork at US59 is already out of its banks and in the moderate flooding stage.
Flash Flood Watch Extended to 2AM Wednesday
Meanwhile, the National Weather Service has extended the Flash Flood Watch for Houston until 2 a.m. Wednesday. This means conditions are favorable for flooding to occur. A nearly stationary weak boundary is focusing training showers and thunderstorms across the watch area. Very heavy rainfall is occurring in a short time period, which can cause flooding of streets, creeks and bayous. With the loss of daytime heating, precipitation should begin to gradually weaken as we head into the overnight hours.
Said Jeff Lindner of Harris County Flood Control, “Rainfall amounts of 5-9 inches occurred this afternoon over NE Harris County in the Kingwood/Humble area resulting in significant street flooding. Water is taking time to go down due to the large volume of water that fell in such a short period of time.”
Areas under flash flood watch as of 8:30PM Tuesday night.
Romerica Land Going Under for 7th Time in 14 Months
Be Prepared. People should bring their pets inside and delay travel or outdoor activities during periods of heavy rainfall. If travel is unavoidable, reduce your speed to avoid hydroplaning. If a Flash Flood Warning is issued for your area, DO NOT travel.
Turn Around, Don’t Drown®: Do not drive through flooded areas. If you see water covering the road, do not attempt to cross it. Only a few inches of water can float a vehicle . If you find yourself in a dangerous situation where your vehicle is taking on water, get out of the vehicle, get to a higher position, and call 911.
Monitor Official Sources for Current Information: Harris County Flood Warning System (harriscountyfws.org), Houston TranStar (houstontranstar.org), and the National Weather Service Houston/Galveston Forecast Office (weather.gov/hgx).
Monitor Stream, Bayou, and Creek Conditions: Rain may move repeatedly across the same area, causing creeks and bayous to rise and possibly exceed their banks. Stay informed of current conditions and avoid traveling near creeks and bayous.
Avoid Traveling during Periods of Heavy Rain: Rain can reduce visibility and prevent you from seeing the road ahead, which could lead to accidents.
Posted by Bob Rehak on 5/7/19 at 8:30 PM
616 Days since Hurricane Harvey
https://i0.wp.com/reduceflooding.com/wp-content/uploads/2019/05/East-Fork-Out-of-Banks.jpg?fit=1500%2C1003&ssl=110031500adminadmin2019-05-07 20:35:202019-05-07 20:56:46East and West Forks Out of Banks Already, Flash Flood Watch Extended to 2 a.m. Wednesday
Flash flooding and flooding will be possible Wednesday into Thursday. A band of heavy rainfall may form Wednesday morning from College Station to Crockett and heavy rainfall may continue to occur through the day. Gulf moisture will also move into the area and cause additional rainfall mainly east of I-45.
Southeast Texas has already had rainfall the last seven days which will cause any additional rainfall to runoff. Isolated thunderstorms may cause brief heavy rainfall of 1 inch an hour. Overall areas in the watch may get 2 to 3 inches of rainfall with isolated bands of 4 inches.
Potential Flood Impacts
In urban areas, street flooding and flooding of underpasses and typical low lying areas can be be expected. Bayous and creeks may have rapid rises and could reach out of banks. Rural low lying areas, low water crossings and poor drainage areas may flood. Rises on area rivers can be expected and this could extend river flooding that is on going.
PRECAUTIONARY/PREPAREDNESS ACTIONS
A Flash Flood Watch means that conditions may develop that lead to flash flooding. Flash flooding is a very dangerous situation. You should monitor later forecasts and be prepared to take action should Flash Flood Warnings be issued.
Additional Guidance from Harris County Flood Control
Jeff Lindner, Harris County Flood Control’s meteorologist added this:
Widespread rainfall…some heavy…will lead to rises on area watersheds and potentially some flooding of creeks and rivers.
Upper level storm system is digging into the SW US and will impact the state for the next 24-36 hours.
As moisture increases from the SSW this evening, light rain and showers will develop and spread NNE into the area. A secondary front from roughly Lake Livingston to Columbus will likely remain stationary and be the focus for rainfall production tonight into early Wednesday in that region. Expect numerous showers and thunderstorms to develop by midday along the coast and inland south of the stalled inland front…this rainfall will likely become heavier in nature and slightly more convective with potentially higher rainfall rates. Upper level system will move across the area early Thursday with rains continuing before dry WNW winds sweep across the area in the afternoon ending rainfall.
Rainfall Amounts
Widespread rainfall of 2-3 inches looks likely over much of the area with isolated totals of 4-5 inches. Some fairly decent agreement in the models today with respect to two rainfall maximums over the area…the first over our NW/N counties tonight in Wednesday and then a second Wednesday afternoon into Thursday morning from Houston ENE toward Liberty and then NE toward Lake Livingston. WPC has expended the slight risk of excessive rainfall exceeding flash flood guidance to include a larger part of SE TX. Think maximum hourly rainfall rates will be on the order of .5 to 1.25 inches which most urban areas will be able to handle. Overall fairly long duration of rainfall over a fairly large area will lead to significant amounts of run-off especially into area river systems as well as the creeks in northern Harris County.
Flash Flood Guidance
Flash Flood Guidance for the area is between 3.0-4.4 inches for 6-hrs which seems high and a review of soil saturation levels via the NASA SPORT webpage shows saturation levels of 65-70% over much of the area…or you can walk in the yard and quickly tell that the ground is still very wet from the rainfall on Sunday. Think much of what falls is going to run-off given how wet the ground is and widespread amounts of dormant vegetation.
Several watersheds are still high from the rainfall last Thursday and rainfall of this magnitude will likely result in renewed rises on nearly all watersheds. Main concern will be the Trinity and San Jacinto basins, along with the Navasota and Brazos. In Harris County, significant rises on Spring, Cypress, Little Cypress, Willow, Cedar, and the creeks that feed into Addicks and Barker Reservoirs are likely. Will also include lower Greens (east of US 59) and Halls, Hunting. Some of these watersheds may rise to levels that would impact low lying areas and roadways near the creek or bayou.
Flooding Probable on East and West Forks
Flooding on both the East and West Forks of the San Jacinto River (low lands and streets) certainly looks probable. At this time the threat for significant creek and bayou flooding as well as any flooding of structures is low.
Current thinking is that watersheds will see similar responses to last Thursday morning…although a few may see higher levels since they will be starting at higher current flows versus last Thursday.
Think hourly rainfall rates will be low enough to prevent widespread street flooding, but street flooding in areas of poor drainage and in rural areas where roadside ditches or small creeks spill onto the roadway will be possible.
Posted by Bob Rehak on 1/1/2019
480 Days Since Hurricane Harvey
https://i0.wp.com/reduceflooding.com/wp-content/uploads/2019/01/Balcom_25.jpg?fit=1500%2C1000&ssl=110001500adminadmin2019-01-01 18:30:232019-01-01 18:30:29Flash Flood Watch Issued from 6 a.m. Wednesday to Noon Thursday
Now would be a good time to make sure nothing is blocking the storm drains on your street. The National Weather Service has issued a Flash Flood Watch for Houston from Friday afternoon through Saturday morning. This means conditions are favorable for flooding to occur. Heavy rain is expected to impact Houston beginning 6 p.m. Friday, December 7, and periods of intense and/or prolonged rainfall may cause flash flooding.
National Weather Service Flash Flood Prediction as of Dec 6 @ 5:40 a.m.
Protective Actions
Be Prepared. Bring pets inside. Delay travel or outdoor activities during periods of heavy rainfall. If travel is unavoidable, reduce your speed to avoid hydroplaning. Make sure storm drains on your street are clear.
If a Flash Flood Warning is issued for your area:
DO NOT travel. Do not drive through flooded areas. If you see water covering the road, do not attempt to cross it. Only a few inches of water can float a vehicle . If you find yourself in a dangerous situation where your vehicle is taking on water, get out of the vehicle, get to a higher position, and call 911.
National Weather Service Houston/Galveston Forecast Office (weather.gov/hgx).
Monitor Stream, Bayou, and Creek Conditions: Rain may move repeatedly across the same area, causing creeks and bayous to rise and possibly exceed their banks. Stay informed of current conditions and avoid traveling near creeks and bayous.
Avoid Traveling during Periods of Heavy Rain: Rain can reduce visibility and prevent you from seeing the road ahead, which could lead to accidents.
Lake Houston Lowered in Anticipation of Storm
Council Member Dave Martin’s office says that the City of Houston has been lowering Lake Houston water levels since late last night.
Property owners should expect a lowering of up to 18 inches. Should additional lowering be necessary, Council Member Martin will work with Houston Public Works to make sure that everything possible is done to secure life and property in the Lake Houston area.
As of 1:30 a.m. Thursday afternoon, the Coastal Water Authority reported the level of Lake Houston at 41.54 ft. That’s about 12 inches below normal. Pre-releasing water from the Lake creates extra capacity for incoming floodwater to reduce the risk of flooding.
Harris County Meteorologist Discusses Local Impacts
Jeff Lindner, the Harris County meteorologist, also issued a special report this morning warning that, “Flash Flooding of streets along with significant rises on area bayous, creeks, and rivers to flood levels is possible.
Says Lindner, “Powerful upper level storm system moving into S CA and NW MX this morning will track generally eastward and into TX over the next 48 hours. Activity will increase today from the coastal bend northward along the I-35 corridor. Some of this activity will likely affect our far western and southwestern counties later this morning into the afternoon hours.”
Friday-Saturday
Lindner warns, “An excessive rainfall event is likely Friday afternoon-Saturday morning, resulting in flooding.”
“Models continue to suggest near record/record moisture levels will be in place by Friday afternoon. Forecast soundings show little instability, but loaded with plentiful moisture form the surface into the upper levels indicating convection will be very effective at heavy rainfall production. Unfortunately it appears the slow moving surface front will be nearing the US 59 corridor around the time that maximum parameters for heavy rainfall focus over SE TX. This includes a very strong 45-55kt low level jet which will transport copious moisture into the frontals slope. Add in a slow moving surface boundary and a nearly “tropical air mass” and you pretty much have everything needed for excessive rainfall rates.”
Widespread Rainfall of 3-6″, 8-10″ in Places
According to Lindner, widespread rainfall amounts of 3-6 inches appear likely over nearly all of the area with isolated totals of 8-10 inches. It is still somewhat uncertain where those higher isolated totals may occur, but areas along and NW of US 59 may have a slightly greater risk than areas S of US 59. Much of the higher totals will tend to focus closely with the surface front and where it slows at times as it crosses the region. In addition to the overall totals, high hourly rainfall rates of 2-3 inches per hour will be possible which will lead to rapid urban flooding of street systems.”
River Forecast
The National Weather Service predicts significant rises in area watersheds. They say most basins can handle 6 hour totals of 3-4 inches, but anything greater than about 4 inches in 6 hours is going to likely be cause for concern. For Harris County, all of the creeks and bayous will likely see significant rises and exceeding of flood stage levels is possible. Greatest concern at the moment is for the watersheds over the northern half of Harris County. Some structure flooding will be possible if watersheds exceed their banks or intense rainfall rates overwhelm street systems.
They made the following predictions at 12:46 p.m., Thursday.
San Jacinto: minor to moderate flooding expected on the West Fork. Minor flooding on the East Fork
Cypress Creek: minor flooding forecast from Katy Hockley to West Fork of the San Jacinto River
Trinity: minor to moderate flooding expected along the entire river below Riverside
Brazos: Minor flooding expected at Hempstead and Bryan and will likely see at least minor at Richmond and Rosharon
Summary
Timing: Friday morning College Station area, mid to late afternoon Houston area through Saturday morning
Amounts: 3-6 inches widespread isolated 8-10 inches. US59 corridor may get the worst.
Watersheds: flooding of creeks, bayous, and rivers probable
Street Flooding: high threat for street flooding
Severe: a few storms late Friday night may become severe near the coast with a tornado threat.
Forecast Rainfall Amounts
Excessive rainfall amounts for Day 2
Posted by Bob Rehak on 12/6/2018
464 Days since Hurricane Harvey
https://i0.wp.com/reduceflooding.com/wp-content/uploads/2018/12/image001.gif?fit=750%2C562&ssl=1562750adminadmin2018-12-06 11:33:392018-12-06 17:44:42Flash Flood Watch Issued from Friday Noon to Saturday Noon For All SE Texas
