Beta Archives - Reduce Flooding

Final HCFCD Report on Tropical Storm Beta Finds Only 25-30 Homes Flooded

The Harris County Flood Control District (HCFCD) issued its first and final report on Tropical Storm Beta today. The 24-page report found that only 25-30 homes in Harris County flooded from the storm, none in the Lake Houston Area. In most places, streams and bayous remained well within their banks. The report also says that HCFCD flood-reduction projects along Braes and Sims Bayous prevented the flooding of 930 structures. The combination of low rainfall intensities, frequent breaks in heavy rainfall, and dry grounds going into the event likely helped reduce the number of homes flooded, according to the report.

Understanding the Uniqueness of Storms

As with all such HCFCD reports, this one presents a treasure trove of statistics, graphs, charts and illustrations. Taken together, they help you understand the uniqueness of individual storms and how to compare them to each other.

Frequent Breaks in Storm Prevented More Severe Flooding

Tropical Storm Beta could have been much worse. The report says, “While Beta did produce heavy rainfall over the county, there were frequent breaks in the training rain bands.”

Overall rainfall intensities were generally in the 1.0-2.0 inch per hour range.
HCFCD final report on tropical storm beta

Most storm drains in the City of Houston are designed to handle 2″ per hour. The report continued, “The lower rainfall rates along with breaks in heavy rainfall allowed most creeks and bayous and internal drainage systems to effectively carry storm water capacities with limited flooding.”

2- to 10-Year Rains in Most Harder-Hit Areas

In most of the harder-hit areas, the storm dropped between 2- and 10-year rains. Those included Clear Creek, Brays Bayou, Keegans Bayou, Willow Waterhole, Buffalo Bayou, White Oak Bayou and Cypress Creek. One place along Sims Bayou recorded a 50-year rain. All other Harris County watersheds had generally less than a 50% (2-yr) rainfall exceedance probability, says the report. Those rainfall exceedance probabilities correspond to new Atlas-14 rates adopted after Harvey.

Intense Short-Duration Rains Cause Most Street Flooding

House flooding in Harris County correlates strongly to the intensity of short duration rainfall rates. In Tropical Storm Beta, short duration rainfall rates generally fell below intensities that lead to widespread and significant house flooding from:

Overwhelming capacity of primary drainage systems or…
Exceeding capacities of bayous and creeks.

The following chart compares the maximum rainfall amounts recorded in Harris County from Tropical Storm Imelda, Hurricane Harvey, Tropical Storm Allison, and Tropical Storm Beta for various time periods.

*From page 3 of HCFCD’s Final Report on Tropical Storm Beta*.

The chart above compares the maximum rainfall amounts recorded in Harris County from Tropical Storm Imelda, Hurricane Harvey, Tropical Storm Allison, and Tropical Storm Beta for various time periods.

For the 1-hr rainfall rate, Beta was nearly 50% lower than Imelda, Allison, and Harvey and nearly 8-10 inches lower for the 3-hr rainfall rates.
HCFCD Final Report on Beta

Beta Rates Lower than Other Recent Major Storms

As the chart above shows, rainfall rates associated with Tropical Storm Beta fell significantly below other recent tropical storms that impacted Harris County. The lower rainfall rates were likely a function of a dry air mass wrapping into the circulation, and a general lack of organized and persistent thunderstorm activity.

Beta’s short duration rainfall rates remained slow enough that drainage systems could remain effective. Additionally, dry grounds leading into the event allowed the first few inches of rainfall to be absorbed, helping to reduce run-off.
Jeff Lindner, Harris County Meteorologist

Dramatic NW to SE Rainfall Gradient

The maximum rainfall over 48 hours shows a dramatic gradient aligning from northwest to southeast. As you can see from the iso-map below, people in the Lake Houston Area received less than a third of the rainfall that people received on the southwest side of Houston.

To see the entire 24-page report, click here. For easy future reference, this report can also be found under the Major Storms Tab on the Reports page.

Posted by Bob Rehak on 10/5/2020 based on information from Harris County Flood Control

1133 Days after Hurricane Harvey and 382 after Imelda

Woodridge Village Detention Ponds Pass Another Test

Back on June 25, 2020, the Woodridge Village detention ponds passed their first modest test when they retained a 2.32-inch rain that fell in a little more than an hour. The mostly excavated, but not-quite-finished ponds eroded badly, but no one in Elm Grove or North Kingwood Forest flooded. Then came Beta.

Design Capacity of Detention Ponds

LJA Engineering designed the Woodridge Village detention ponds to hold only a 12-inch rain in 24 hours. And the night before the storm, forecasters predicted Beta could drop 12 inches in the Lake Houston Area. Beta had already dumped 15-inches just a few miles south. All this created high anxiety. But in the end, the Lake Houston Area received less rain.

Elm Grove resident Jeff Miller measured just 5.5 inches in his rain gage – well within the theoretical design capacity of the detention ponds. But that was almost exactly the amount that flooded Elm Grove on May 7, 2019.

Ponds 40% Short of Atlas-14 Requirements

On top of that coincidence, other factors contributed to the anxiety felt by residents. LJA did not design the ponds to meet new Atlas-14 rainfall requirements; they’re 40% short. Nor did LJA acknowledge floodplains or wetlands on the property when they calculated detention requirements. All of these factors contributed to flooding Elm Grove last year and called LJA’s ethics into question.

So it was a welcome relief when the people of Elm Grove rolled out of bed Wednesday morning to find they didn’t flood.

How Well Did Ponds Perform?

Here’s what the ponds looked like after about five to six inches of rain. All photos were taken shortly after Beta’s rain stopped on Wednesday, 9/23/2020.

Looking north at N3 Detention Pond along eastern border of Woodridge Village where it joins the east-west portion of Taylor Gully. Note pond is a little less than half full, not surprising for a rain that was a little less than 50% of the design capacity.

*Likewise, the massive N2 detention pond on the western border was less than half full.*

*Looking SE across the empty N1 pond on the western border. It had already drained into N2.*

Two Failures in N3 Pond

However, there were two failures, both in the N3 pond. Neither was mission critical.

*Water could not get into N3 without overflowing the edge of the pond, causing erosion. Stormwater seems to want to collect here. This same area eroded badly in a previous storm.*

*In a second place along N3, erosion blew out the entire western wall.*

Overflow Spillway Apparently Not Used

The overflow spillway at the county line between the concrete lined channel and the S2 detention pond was apparently not needed during Beta. There were no signs of erosion (see below) that were present afte r previous floods.

Rain was spread out enough that it appears water from Taylor Gully and N3 stayed in the concrete-lined channel rather than using the emergency overflow spillway that leads back into the S2 detention pond (right) and the twin culverts.

Nevertheless, despite recently planting grass along the banks of the ponds, Perry Homes still has a significant erosion problem. Note the color of the water in Taylor Gully at the top of the image above. The company is redepositing silt in the ditch, which HCFCD just cleaned out.

Living Under the Threat of Bad Planning

A big test of these ponds will be a 12-inch rain. If the ponds can successfully detain that much rain without flooding Elm Grove, we will know they at least function as planned…despite their 40% shortfall in capacity.

But the ultimate test will be when we get a larger rain. LJA Engineering and Perry Homes did NOT design them for that.

Unless Harris County and the City can piece together a deal to buy this property and build more detention, residents could flood again. The real disaster scenario here could be the purchase deal falling through. If Perry or some other builder develops this property, downstream residents will forever live under the threat of that 40% shortfall.

Posted by Bob Rehak on 9/24/2020 with thanks to Jeff Miller

1122 Days since Hurricane Harvey and 371 since Imelda

The thoughts expressed in this post represent opinions on matters of public concern and safety. They are protected by the First Amendment of the US Constitution and the Anti-SLAPP Statute of the Great State of Texas.

Lake Houston Area Lucked Out With Beta

Beta is now off to the east. As of 10:30 am on 9/23/2020, the East and West Forks are well within their banks. So are the lesser tributaries with the exception of Cypress Creek. Lake Conroe is still below 200 feet. And Lake Houston, thanks to a pre-release, is only about a tenth of an inch above normal so far, though it is rising this morning.

4-Day Rainfall Total for Storm

The radar image below shows the total rainfall accumulations across the Houston Area for the duration of the storm, starting at 2:37p.m. on 9/19/2020. This was a story of selective drenching. The south and southwest sides of the city received four times as much rain as Kingwood, Crosby and Atascocita. And more than twice as much rain as Humble. They got caught under a training feeder band; we missed it.

Here are the totals associated with the different colors above:

Light green = 2 inches
Dark green = 3 inches
Light purple = 4 inches
Dark purple = 5 inches
Light blue = 6 inches
Dark blue = 7 inches
Yellow = 8 inches
Orange = 10 inches
Red = 12 inches
Brown = 15 inches

Harris County Flood Warning System Shows Slightly Higher Totals

The radar image may understate the totals. The four-day-rain totals from Harris County Flood Control District gages mirror the pattern above, but show slightly higher numbers. For instance, the radar image shows 3-4″ for Kingwood, but the gages show 4-5″. I live in Kingwood and my personal weather station recorded 4.92 inches for the same four-day period.

Regardless, those caught under training feeder bands on the south and southwest sides got drenched. The Lake Houston Area escaped the worst of the rains.

Source: Harris County Flood Warning System

Sheer, Dry Air Result in Low-Side of Predictions

While these totals are within the ranges predicted at the start of the storm, they definitely fall on the low side. Why?

Space City Weather offered this. “We had two big allies over the last week; moderate wind shear to prevent Beta from strengthening, and dry air over the state from a weak front that disrupted its circulation and prevented the formation of several, thick bands of rainfall. Instead, if you watched the radar closely, there was only ever really one strong band that was perhaps 10 to 15 miles across. This just happened to set up over Houston on Monday and Monday night…”

The Lessons of Beta

Even the heaviest rains we received were about one fourth of what Harvey dropped (40-60 inches). Beta was not unusual. As Space City Weather offered, “A tropical storm that brings a range of 5 to 15 inches rain across Houston, with rainfall rates below 2 inches per hour, is a fairly common event.”

Yet some areas still flooded. In my opinion, this underscores the need for:

HCFCD to continue and accelerate (if possible) its work.
All governments in the region to adopt higher regulations for new developments that reflect Atlas-14 rainfall tables.
People at all levels of government (Federal, State, Counties, Cities) to work together and make flood mitigation a top priority.
Leaders throughout the region to realize that we are all in this together. Slowing floodwater down in one area while speeding it up in another is a losing battle that undermines the economic heart of the region.

Posted by Bob Rehak on 9/23/2020

1121 Days after Hurricane Harvey and 370 after Imelda

Lake Houston Area Could Be in Beta’s Crosshairs Tonight

The center of Beta is currently near Bay City and moving ENE. For the next 24 hours, the National Hurricane Center (NHC) forecasts maximum winds at 30 mph.

If any readers in the Lake Houston Area felt left out by Beta, tonight could be your night. According to the NHC, Harris County Meteorologist Jeff Lindner and Space City Weather, models continue to show that a heavy band of rainfall will begin to develop over the next few hours across the northern portions of Harris County.

Beta Tuesday Evening — Beta Tuesday evening at 5PM, courtesy of RadarScope. The bands are moving from SE to NW. But the forward motion of the storm is perpendicular, from SW to NE. That could push new feeder bands into the Lake Houston Area later tonight.

Current Radar Trends Show Storm Moving Toward Northeast Harris County

“Current radar trends show what may be the start of this banding feature from Downtown Houston to Jersey Village to Waller where a broken band of heavy to excessive rainfall is forming,” said Lindner at 4pm today.

He continued, “Models show this band continuing well into the evening and overnight hours across much of northern and northeastern Harris County into Liberty County. Training of heavy rainfall is likely with this banding along with flash flooding.”

Additional rainfall of 4-7 inches will be possible over the northern portions of Harris County into Liberty County and possibly southern Montgomery County with isolated totals of 10-12 inches possible.
JEFF LINDNER, HARRIS COUNTY METEOROLOGIST

(Update At 9:10 PM) The radar image above looked like this and heavy rain had started in Kingwood.

However, in the upper San Jacinto Watershed, the expected rainfall amounts will likely produce flooding only on Cypress and Little Cypress Creeks.

In other parts of Houston, the following streams could flood:

Greens Bayou
Halls Bayou
Hunting Bayou
White Oak Bayou tributaries
Cedar Bayou
Gum Gully
Langham Creek
Horsepen Creek
South Mayde Creek
Bear Creek

The largest threat at this point is street flooding. So move your cars out of the street tonight.

West Fork Still At Normal Level

At 4PM CDT Tuesday, the West Fork San Jacinto at US59 is still nearly seven feet from coming out of its banks.

Source: Harris County Flood Warning System. *The normal level of Lake Houston at this gage is 42.4 feet.*

Flood Warning System Shows Effects of Heavy Training

The high rainfall gradient across Harris County should the effects of heavy training by Beta’s feeder bands during the last 48 hours. Places under the bands received 12 to 14 inches of rains. Meanwhile, the Lake Houston Area received only around an inch so far.

*Beta’s heaviest rainfall until now focused on SW Harris County. Figures shown represent last 48 hours.* *Source: Harris County Flood Warning System.* *Note 13.44 inches on HW288!*

Worst Likely Over for SW Harris County

Some heavy rainfall is still possible in already hard-hit southern and southwestern Harris County. However, where and potentially how much may fall in that area is uncertain.

Beta Continuing to Weaken

High-resolution visible satellite imagery, surface observations, and NOAA Doppler weather radar data from San Antonio and Houston, Texas, indicate that Beta has continued to weaken.

Cloud tops only extend up to 25,000- 30,000 ft, mainly near and northeast of the center. However, they are quite prodigious rain-producers. Rainfall totals of 13-14 inches having been measured across portions of the Houston metropolitan area thus far.

The Future of Beta

Since Beta should remain inland throughout the forecast period, the cyclone is not expected to regain tropical storm status. Beta should degenerate into a remnant low within 36 hours and dissipate over Mississippi or Alabama in 96 hours, if not sooner.

At 4 p.m. Tuesday, September 22, 2020, the National Hurricane Center (NHC) issued its last update on Beta.

Said Space City Weather, “The good news is that this mess will begin to clear our of here by Wednesday morning, if not sooner for some areas. The bad news is that we’ve got to get through later today and tonight.”

Posted by Bob Rehak on 9/22/2020 based on data from HCFCD, NHC and Space City Weather

1120 Days after Hurricane Harvey and 369 since Imelda

Beta Downgraded to Tropical Depression

At 10 a.m. CDT, the National Hurricane Center (NHC) downgraded Tropical Storm Beta to a tropical depression. The NHC also cancelled the tropical storm and storm surge warnings that were in effect. However, flash flood warnings remain in effect for large parts of the seven-county Houston region, especially the southern part. A flash flood watch remains in effect for the entire region.

RadarScope split image. Left half shows track of active storms as of 9:06AM CDT. Right half shows total rainfall accumulation for Beta. Note band of extreme rainfall near Sugar Land and sharp drop-off near Kingwood.

Flash Flood Warnings and Watches

A flash flood warning means that flooding is in progress. A Flash Flood Watch means that conditions may develop that lead to Flash Flooding.

*Source: National Weather Service. Updated at 10:29 a.m. 9/22/2020. Reddish area = Flash flood warning. Green = Flash flood watch.*

Lake Conroe/Lake Houston Within Banks

Neither Lake Conroe, nor Lake Houston have yet been adversely affected by Beta.

The level of Lake Conroe stands at 199.63 feet. Normal conservation pool equals 201.

According to the Coastal Water Authority, Lake Houston is at:

Lake Level	41.41 ft.
Normal Pool	42.4 ft.

Source: Coastal Water Authority

USGS shows that even though the lake has received about 1.75 inches of rainfall to date…

…the lake level has been dropping, no doubt due to a preemptive release.

Posted by Bob Rehak at 10:50 on 9/22/2020 based on NHC, NWS, and RadarScope data

1120 Days since Hurricane Harvey and 369 since Imelda

Beta Stalling Onshore Around Victoria; Will Start Moving Toward Houston Tonight

Tropical Storm Beta moved inland last night around 10 p.m. The center is now near Victoria and moving toward the northwest near 3 mph. The National Hurricane Center predicts Beta will weaken and stall today, but will then begin to move slowly toward the Houston Area tonight. They expect forward speed to increase Wednesday through Friday.

At the moment, maximum sustained winds are near 40 mph with higher gusts. Tropical-storm-force winds extend outward up to 105 miles from the center. A sustained wind of 39 mph and a gust to 47 mph were recently reported at Victoria, Texas. But at the moment, my wind gage is reading ZERO here in Kingwood.

Yesterday’s Heaviest Rains Narrowly Missed Lake Houston Area

Yesterday’s heaviest rainfall narrowly missed us. While the Lake Houston Area received around an inch of rain, the southwest corner of Loop 610 received 11.64 inches due to a training feeder band.

The main threat today to the Lake Houston Area is having a similar feeder band train over us.

Below are the two-day storm totals so far for Beta in Harris County.

Source: Harris County Flood Warning System as of 6:30 am 9/22/2020.

Rainfall Predictions

For the middle and upper Texas coast, additional rainfall of 6 to 12 inches with isolated storm totals up to 20 inches is expected.

Significant flash and urban flooding is occurring south and west of the Lake Houston Area and will continue today.

*RadarScope image as of 6:30 a.m. CDT on 9/22/2020. Center of storm located over Victoria in lower left.*

Minor river flooding is likely. Rainfall totals of 3 to 5 inches are expected northward into the ArkLaTex region and east into the Lower Mississippi Valley through the end of the week.

Track

Steering currents around the storm are now collapsing, and Beta is expected to meander during the next 12-24 hours. By this time tomorrow, however, a mid-level trough over west Texas should begin moving eastward and scoop Beta up. That will cause the storm to move toward the east-northeast near or just inland of the upper Texas coast through 36 hours.

After that time, Beta will likely turn northeastward, moving farther inland across Louisiana and Mississippi before dissipating in about 4 days. Beta should weaken to a tropical depression in about 24 hours before it reaches the Lake Houston Area. It will become a remnant low in 2-3 days.

Tornadoes

A tornado or two could occur today near the upper Texas and southwestern Louisiana coasts.

Surf

Swells generated by a combination of Beta and a cold front over the northern Gulf of Mexico will continue along the coasts of Louisiana and Texas during the next couple of days. These swells are likely to cause life-threatening surf and rip current conditions.

Winds

It is unlikely we will see tropical storm strength winds in the Lake Houston Area.

Winds will increase today as Beta moves in our direction. But Beta is barely at tropical storm strength now and is weakening. The most likely arrival time for the heaviest winds: tonight at 8 p.m.

Flash-Flooding Potential

A flash flooding event is in progress over Harris County. “Numerous roadways are flooded. Avoid travel.
Jeff Lindner, Harris County Meteorologist

At this time (8am Tuesday, 9/22/2020), the main problem areas are south and west of Houston near the coast. However, that could change as the storm moves toward us.

*Channel Status in Harris County. Green means “within banks.” Yellow means “flooding possible.” Red means “flooding likely.”*

See data on the problem areas below.

Harris County Flood Control District – Hydrologic Operations Division
Rain and Channel Status Report at 09/22/2020 07:30 AM
============================================

Maximum Rainfall the last 1hr
1.56 inches – Gage 435 @ 435 Willow Water Hole @ Willowbend Boulevard
1.4 inches – Gage 440 @ 440 Brays Bayou @ Rice Avenue
1.24 inches – Gage 370 @ 370 Sims Bayou @ SH 288
1.16 inches – Gage 190 @ 190 Clear Creek @ SH 288
1.04 inches – Gage 430 @ 430 Brays Bayou @ Stella Link Road

Maximum Rainfall the last 6hrs
5.72 inches – Gage 430 @ 430 Brays Bayou @ Stella Link Road
5.0 inches – Gage 2265 @ 2265 Buffalo Bayou @ Piney Point Rd
4.56 inches – Gage 440 @ 440 Brays Bayou @ Rice Avenue
4.6 inches – Gage 2260 @ 2260 Buffalo Bayou @ San Felipe Drive
4.48 inches – Gage 435 @ 435 Willow Water Hole @ Willowbend Boulevard
4.4 inches – Gage 2270 @ 2270 Buffalo Bayou @ West Beltway 8
4.44 inches – Gage 2255 @ 2255 Briar Branch @ Campbell Road
4.52 inches – Gage 420 @ 420 Brays Bayou @ South Main Street

Maximum Rainfall the last 12hrs
8.4 inches – Gage 430 @ 430 Brays Bayou @ Stella Link Road
8.28 inches – Gage 435 @ 435 Willow Water Hole @ Willowbend Boulevard
8.0 inches – Gage 370 @ 370 Sims Bayou @ SH 288
7.76 inches – Gage 440 @ 440 Brays Bayou @ Rice Avenue
7.4 inches – Gage 445 @ 445 Willow Water Hole @ Landsdowne Drive
7.28 inches – Gage 180 @ 180 Clear Creek @ Mykawa Road
7.2 inches – Gage 360 @ 360 Sims Bayou @ Martin Luther King Road
6.96 inches – Gage 460 @ 460 Brays Bayou @ Gessner Road
6.56 inches – Gage 175 @ 175 Clear Creek @ Pearland Parkway
6.48 inches – Gage 380 @ 380 Sims Bayou @ Hiram Clark Rd
6.44 inches – Gage 465 @ 465 Brays Bayou @ Beltway 8
6.32 inches – Gage 2265 @ 2265 Buffalo Bayou @ Piney Point Rd
6.04 inches – Gage 470 @ 470 Brays Bayou @ Belle Park Drive
6.2 inches – Gage 420 @ 420 Brays Bayou @ South Main Street

Maximum Rainfall the last 24hrs
11.04 inches – Gage 180 @ 180 Clear Creek @ Mykawa Road
11.0 inches – Gage 370 @ 370 Sims Bayou @ SH 288
10.88 inches – Gage 435 @ 435 Willow Water Hole @ Willowbend Boulevard
10.56 inches – Gage 445 @ 445 Willow Water Hole @ Landsdowne Drive
10.36 inches – Gage 430 @ 430 Brays Bayou @ Stella Link Road
10.12 inches – Gage 175 @ 175 Clear Creek @ Pearland Parkway
10.12 inches – Gage 380 @ 380 Sims Bayou @ Hiram Clark Rd
9.96 inches – Gage 440 @ 440 Brays Bayou @ Rice Avenue
9.92 inches – Gage 150 @ 150 Clear Creek @ Country Club Drive
9.84 inches – Gage 145 @ 145 Clear Creek @ Dixie Farm Road
9.8 inches – Gage 190 @ 190 Clear Creek @ SH 288
9.6 inches – Gage 460 @ 460 Brays Bayou @ Gessner Road
9.4 inches – Gage 105 @ 105 Marys Creek @ Winding Road
9.44 inches – Gage 360 @ 360 Sims Bayou @ Martin Luther King Road
8.68 inches – Gage 135 @ 135 Clear Creek @ FM 2351
8.56 inches – Gage 465 @ 465 Brays Bayou @ Beltway 8
8.36 inches – Gage 115 @ 115 Cowart Creek @ Baker Road
8.28 inches – Gage 140 @ 140 Turkey Creek @ FM 1959

Stream Water Surface Elevation Data

Out of Banks:
Gage 110 @    Clear Creek @ I-45
Gage 120 @    Clear Creek @ FM 528
Gage 130 @    Clear Creek @ Bay Area Boulevard
Gage 135 @    Clear Creek @ FM 2351
Gage 145 @    Clear Creek @ Dixie Farm Road
Gage 175 @    Clear Creek @ Pearland Parkway
Gage 180 @    Clear Creek @ Mykawa Road
Gage 610 @    Taylors Bayou @ Shoreacres Boulevard
Gage 2150 @    South Mayde @ Greenhouse Road

Near Bankfull:
Gage 100 @    Clear Lake 2nd Outlet @ SH 146
Gage 140 @    Turkey Creek @ FM 1959
Gage 150 @    Clear Creek @ Country Club Drive
Gage 160 @    Beamer Ditch @ Hughes Road
Gage 170 @    Clear Creek @ Nassau Bay
Gage 190 @    Clear Creek @ SH 288
Gage 200 @    Taylor Lake @ Nasa Road 1
Gage 410 @    Brays Bayou @ Lawndale Street
Gage 420 @    Brays Bayou @ South Main Street
Gage 430 @    Brays Bayou @ Stella Link Road
Gage 440 @    Brays Bayou @ Rice Avenue
Gage 460 @    Brays Bayou @ Gessner Road
Gage 480 @    Keegans Bayou @ Roark Road
Gage 710 @    San Jacinto River @ Rio Villa
Gage 720 @    San Jacinto River @ US 90
Gage 740 @    Lake Houston @ FM 1960
Gage 1610 @    Greens Bayou @ Normandy Street
Gage 1720 @    Cedar Bayou @ SH 146
Gage 2115 @    Langham Creek @ Clay Rd
Gage 2210 @    Buffalo Bayou @ Turning Basin
Gage 2253 @    Buttermilk Creek @ Moorberry Lane
Gage 2255 @    Briar Branch @ Campbell Road
Gage 2265 @    Buffalo Bayou @ Piney Point Rd

Key Messages

Posted by Bob Rehak on 9/22/2020 at 8am based on data from Jeff Lindner, Harris County Meteorologist, the National Hurricane Center, Harris County Flood Warning System and RadarScope

1120 Days After Hurricane Harvey and 369 since Imelda

Beta Feeder Band Could Dump 1-2″ Per Hour; Street Flooding Possible

Feeder Band Approaching from South

Jeff Lindner, Harris County Meteorologist noted at 1:35 PM that a feeder band of heavy rainfall from Tropical Storm Beta is moving from northern Brazoria and northern Galveston Counties into southern Harris and Fort Bend Counties.

Lindner says that “rainfall amounts of 1-2 inches per hour will be possible under this band for the next 1-2 hours. This may lead to street flooding in typical areas of poor drainage.” Rates above 2 inches per hour will generally flood streets.

According to Space City Weather, currently, it looks like these storms may produce 2 to 3 inches of rain total as they slowly progress northward, so they could impact the afternoon and evening commute home.

Beta Weakening As It Approaches Landfall

The center of Beta is nearing landfall on the TX coast near Matagorda Island with 45mph winds.

At its 1 p.m. update, the National Hurricane Center said the storm weakened this morning. Sustained winds dropped from 50 to 45 mph. The storm’s central pressure also rose from 996 to 999 mb, another sign of weakening. Welcome signs!

Heavy Rainfall From Training Feeder Bands Will Continue

Heavy rainfall threat in bands to the east and northeast of the center will continue into tonight and Tuesday. “This threat will not subside until the center of the circulation is east of the area on Wednesday,” says Lindner.

Lindner further expects “No significant changes to the rainfall totals. Amounts of 4-8 inches are most likely with isolated higher amounts. But these higher totals will likely be strongly correlated to training feeder bands.”

Posted by Bob Rehak on 1/21/2020 based on data from the National Hurricane Center, Space City Weather and Jeff Lindner, Harris County Meteorologist.

1119 Days after Hurricane Harvey and 368 after Imelda

Excessive Rainfall Threat from Beta Spreads Inland

As of mid-day Sunday, all of East Texas now faces some level of excessive rainfall and flash flood risk from Tropical Storm Beta.

The projected path of the storm has shifted inland, so rainfall will reach father north. The latest track now takes the storm on a path right up US59 from Sugar Land to Humble and Kingwood. However, Beta likely be a tropical depression by the time it reaches the north side.

*Kingwood is the blue dot next to Spring.*

Six to 15 Inches of Rain Now Predicted

According to the local National Weather Service office and the National Hurricane Center, most of the Houston region can expect 6 to 15 inches with the highest totals closer to the coast.

Harris, Montgomery and Liberty Counties (and the whole Houston region) face a high to moderate threat of flooding rains. The first rainbands from Beta have already started to move onshore today, but the heaviest rain will not occur until Monday into Tuesday.

North Houston Under Moderate Flooding Rain Threat

Flash Flood Watch in Effect

The entire region is under a flash flood watch. Coastal areas also face storm surge and tropical storm warnings.

Slow Moving Storm Will Produce Prolonged Rains

Beta is meandering slowly at about 3 mph northwest toward the coastline west of Houston and will then curl back over Houston. It should move inland sometime Monday or Monday night and turn from a storm into a depression by the time it reaches Houston.

However, Beta could dump rain on us from later today all the way through Wednesday.

40-50% Chance of Tropical Storm Force Winds Reaching North Houston

The North Houston Area has a 40-50% chance of seeing tropical storm force winds from Beta.

If the high winds reach this far inland, they would likely arrive Monday evening. Winds extend outward from the center for 195 miles as of Sunday morning.

Feeder Bands Extend Outward 190 Miles

In fact, at 11 a.m. Sunday morning, the first feeder band was approaching the eastern side of Houston, as you can see in the radar image below.

This image shows how the wind and rain from Beta could remain with us for days as the storm’s center wanders around the Gulf.

These feeder bands reach out 190 miles. That is roughly the distance from Houston to San Antonio. So Beta will produce long-duration rainfall from the middle Texas coast to southern Louisiana.

Flash, Urban, and River Flooding Likely

The National Weather Service warns that coastal flooding will remain a threat through midweek with the worst of the storm surge anticipated on Monday and Tuesday.

Elsewhere impacts from the excessive rain include:

Rainfall flooding may prompt evacuations and rescues.
Rivers and tributaries may rapidly overflow their banks.
Small streams, creeks, canals, and ditches may become dangerous rivers.
Flood control systems and barriers may become stressed.
Flood waters may cover escape routes.
Streets and parking lots may become rivers of moving water with underpasses submerged.
Driving conditions may become dangerous.
Many roads and bridges may close with some weakened or washed out.

Lake-Level Situation

According to the SJRA, Beta has the potential to dump up to 8 inches of rain in Montgomery County.

SJRA is operating under standard protocols for a severe weather event and will be onsite at Lake Conroe throughout the duration of Tropical Storm Beta.

Lake Conroe remains 18 inches low, and based on the current forecast, no reservoir releases are expected.
SJRA

Real-time information on lake level can be found on the SJRA homepage at the “Lake Operations and Rainfall Dashboard” link.

At of this writing, Lake Houston is down a foot compared to its normal pool level (41.38 vs 42.4). You can monitor Lake Houston levels via the Coastal Water Authority website.

Monitor Downstream River Levels

You can monitor stream and river levels in near-real time at Harris County Flood Warning System. Make sure you check out the inundation mapping feature.

Posted by Bob Rehak on 9/20/2020 based on information from the National Weather Service and National Hurricane Center

1118 Days after Hurricane Harvey

Beta Rainfall Estimates Increasing; 6-10 Inches Now Predicted for Lake Houston Area

Beta has turned toward the Texas coast. Adverse conditions will likely begin Sunday along coast and spread inland. The main forecast change since this morning? An increase in rainfall amounts, which could be significant. See rainfall section below.

A Flash Flood Watch will likely be issued on Sunday for the area.
Jeff Lindner, Harris County Meteorologist

Discussion

There has been little change in the overall organization of Beta today. Forecasters expect slow intensification as Beta approaches the TX coast.

Track:

There have been no significant changes in the track reasoning today and the official forecast remains similar from earlier this morning. With that said, there is some uncertainty on when Beta will turn toward the N and NE near the mid Tx coast early next week, but generally impacts will be the same for much of SE TX.

Intensity:

Given the lack of organization of the system and the lurking dry air to the west, it is now unlikely that Beta will attain hurricane intensity. The National Hurricane Center now keeps the system as a strong tropical storm as it approaches the TX coast. It should slowly as it moves NE or ENE up the coast.

Impacts

Storm Surge:

Water levels will rise along the upper TX coast beginning Saturday and worsen Sunday into Monday due to the expansion of the tropical storm force wind field. Expect swells reaching 15-25 feet over the NW Gulf. Four- to eight-foot waves could break on beaches. These large swells will lead to wave run up on top of the elevated tides.

Results:

Significant beach erosion
Damage to fragile dune systems.
Damage to coastal infrastructure
Inundation of low lying roads near the coast.
Once the water begins to rise on Saturday evening, some low lying areas may remain flooded into the middle of next week.
Overwash is likely on Hwy 87.
Ferry operations at both the Galveston-Bolivar and the Lynchburg sites may be impacted.

Rainfall:

While there is still some uncertainty, the storm could produce very heavy rainfall rates and amounts.
Jeff Lindner, Harris County Meteorologist

The rainfall forecasts have been adjusted upward, even though some models suggest only meager amounts of rainfall with Beta. Jeff Lindner, Harris County Meteorologist, currently predicts:

Coast: 12-18 inches
Coastal counties: 10-15 inches
South of I-10: 10-15 inches
South of Hwy 105: 6-10 inches
North of Hwy 105: 4-6 inches

*Note that the rainfall amounts above are for a five-day total.*

Given the forecast rainfall amounts…flooding of creeks and bayous across Harris County may flood depending on how the rain falls and how much falls at one time.

*By Tuesday, when the ground is saturated, NOAA gives the Lake Houston Area a **slight** chance of flash flooding.*

Six inches could fill smaller creeks; 7-8 inches could fill larger streams and bayous such as Buffalo.

Addicks and Barker Reservoirs are currently empty.

Winds:

Tropical storm force winds will be possible starting Sunday evening around Matagorda Bay with sustained 40mph winds likely spreading northward along the upper TX coast on Monday including Galveston Bay. Sustained winds of 55-65mph will spread up the TX coast Tuesday into Wednesday. Across Harris County wind will increase into the 25-35mph range on Monday and possibly 40-45mph range on Tuesday into Wednesday with higher gusts, especially near Galveston Bay.

Note: Tropical storm force winds will begin to reach the coast on Monday…well ahead of any landfall of the center…due to the expanding wind field. Tropical storm force winds now extend 175 miles outward from the center of the storm.

Summary of Watches/Warnings In Effect

As of 4PM Saturday, 9/19/20:

A STORM SURGE WARNING IS IN EFFECT FOR

PORT ARANSAS TEXAS TO HIGH ISLAND TEXAS INCLUDING:
- COPANO BAY
- ARANSAS BAY
- SAN ANTONIO BAY
- MATAGORDA BAY
- GALVESTON BAY

A STORM SURGE WATCH IS IN EFFECT FOR:

* BAFFIN BAY TEXAS TO PORT ARANSAS TEXAS INCLUDING BAFFIN BAY AND CORPUS CHRISTI BAY
* HIGH ISLAND TEXAS TO CAMERON LOUISIANA INCLUDING SABINE LAKE AND LAKE CALCASIEU

A HURRICANE WATCH IS IN EFFECT FOR:

* PORT ARANSAS TEXAS TO HIGH ISLAND TEXAS

A TROPICAL STORM WARNING IS IN EFFECT FOR:

PORT ARANSAS TEXAS TO INTRACOASTAL CITY LOUISIANA

A TROPICAL STORM WATCH IS IN EFFECT FOR:

SOUTH OF PORT ARANSAS TEXAS TO THE MOUTH OF THE RIO GRANDE
EAST OF INTRACOASTAL CITY LOUISIANA TO MORGAN CITY LOUISIANA

Protective Actions

Bookmark and monitor Harris County Flood Warning System throughout the storm. Familiarize yourself with the real-time inundation mapping feature.
Bookmark and monitor the National Hurricane Center for the most current updates on Beta.
Prepare now for a long period of coastal flooding and periods of heavy rainfall.
Voluntary evacuations have been recommended for:
- Western end of Galveston Island, west of the seawall
- Bolivar Peninsula
- Low-lying areas of Chamber, Brazoria and Matagorda Counties (outside levee protection)
- Low-lying areas of Seabrook.

AlertHouston Recommends Taking These Steps Now

Ensure your family has 5-7 days of food, water, and necessary supplies.
- This includes enough prescription medication for at least this duration, in case pharmacies and doctor’s offices are closed.
- Consider the unique needs of small children, seniors, family members with access and functional needs, and pets.
Decide what you and your family will do if the storm impacts your area. Most City of Houston residents are not vulnerable to storm surge and do not need to evacuate before a hurricane or tropical storm. Vulnerable residents who require electricity may also consider evacuation in advance of a major storm. For a map of hurricane evacuation zones and mandatory evacuation areas, visit: houstonoem.org/hurricanes
Develop a family communication plan, so that you know who to check in with after a storm. Visit readyhoustontx.gov for more information on developing a plan.
Know how to turn off your utilities. This includes electricity, water, and gas. Only turn off gas if instructed by local officials or by CenterPoint Energy.

Posted by Bob Rehak on 9/19/2020 with data from the NHC, HCFCD, and City of Houston

1117 Days since Hurricane Harvey and 1 Year since Imelda