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Nicholas Largely Spares Lake Houston Area

Nicholas could have been much worse. In the days leading up to the storm, the National Hurricane Center and National Weather Service made a series of worst-case projections that included up to 20 inches of rain in isolated spots. In the end, the best-case projections were far closer to reality…at least in the Lake Houston Area. In fairness, the closer the storm got to Houston, the more forecasters focused on potential problems near the coast.

Still, with hurricanes, you prepare for the worst and hope for the best. And in the end, we got the best of Nicholas. Even the power outages happened in the middle of the night when most people were asleep.

Results of Scouting Trip This Morning

A scouting trip this morning showed the worst never materialized here. That’s not to say that we were damage free. I saw numerous downed trees, signs blown over, and water filling roadside ditches. But, thankfully, no flooded homes! There may have been some; I just didn’t see any.

*Kingwood Drive and Green Oak Drive in Kingwood.* *A sign of high winds during the night.* *See more images below.*

Modest Rainfall Spread Out over Time Kept Bayous in Banks

As of 11 AM on Tuesday 9/14/2021, all streams and bayous in Harris County were within their banks, winds were dying down, and the worst part of the storm had moved off to the east.

I had 3.7 inches of rain in my gage for the last two days, which is largely consistent with other gages in the area. The gage at US59 and the West Fork San Jacinto recorded 3.04 inches over a two-day period. The rain was gentle and spread out. The heaviest downpour occurred Monday afternoon between 1 and 2 PM when we received .64 inches in a few minutes. But that volume was well within the capacity of storm sewers which can generally handle 1-2 inches per hour.

*Mostly gentle rains were spread out enough to avoid flooding.*

*The stream gage at the same location showed the effects of lowering Lake Houston then the heavier parts of Nicholas’ rainfall.*

The rest of the City and County fared pretty much the same, with the exception of the far south and eastern portions.

*Two-day rainfall totals for Harris County during Nicholas*. *Note the sharp differences between north and south, and east and west.*

*Only Clear Creek came out of its banks as of 11 AM Tuesday morning.*

*The Kingwood Diversion Ditch was well within its banks. Photo taken at Kingwood Drive.*

The diversion ditch was typical of every ditch I checked in Kingwood. All were well within their banks.

Satellite Imagery Shows Worst of Nicholas Now Off to East

Visible satellite images show the distinctive “comma shape” of Nicholas.

*Visible satellite image as of 11 AM Houston time on 9/14/2021* *shows much of Houston area still covered in clouds.*..

*…But an infrared image taken minutes later shows the heaviest rains have moved east. Infrared images measure the cloud tops.*

*This water vapor image taken at the same time confirms that the storm is focused east of us now.*

Downed Trees, Debris, and Power Outages will be Biggest Problems for Most People

*Gus, the poodle, inspects a downed tree at Alligator Alley in East End Park. Note all the smaller debris scattered on the trail, too. That was typical of streets in the Kingwood area today.* *Photo courtesy of John Knoezer.*

It will take a while to recover from the storm, but nothing like Harvey, Imelda, or even May 7, 2019. As of this morning, there were power outages randomly affecting neighborhoods and commercial areas. Some places seemed to be operating normally; others still lacked power. About every third traffic light was blinking.

I personally lost power several times throughout the night for a total of about six hours.

What Next for Nicholas?

According to the National Hurricane Center at its 10 AM update this morning, doppler weather radar data from Houston and Lake Charles, along with surface observations, indicate that Nicholas has continued to weaken while moving farther inland.

The strongest winds recently reported near the Texas and Louisiana coasts have been 33-35 kt (40 mph) near Sabine Pass, Texas. The estimated central pressure of 1002 mb is based on surface observations in Houston. Further weakening is expected as Nicholas moves farther inland due to frictional effects, entrainment of very dry mid-level air from the southern Plains, and increasing southwesterly to westerly shear.

*As predicted, Nicholas is slowing to a crawl.*

Nicholas should become a tropical depression by tonight and degenerate into a remnant low by late Wednesday. Nicholas is now moving northeastward at only 5 kt. and should move even more slowly on Wednesday and Thursday. It is possible that Nicholas could stall over southwestern or central Louisiana. Although the winds associated with Nicholas will weaken, heavy rainfall and a significant flash flood risk will continue along the Gulf Coast during the next couple of days.

Posted by Bob Rehak on 9/14/2021 at 12:30 PM based on personal observations and data from NHC and HCFCD

1477 Days since Hurricane Harvey and 1 since Nicholas

Nicholas, Now a Hurricane, Expected to Slow to a Crawl Near SW Louisiana

As of its 10 PM CDT update on 9/13/2021, the National Hurricane Center (NHC) upgraded Tropical Storm Nicholas to a hurricane.

Nicholas a Minimum Cat 1 Hurricane

A weather station at Matagorda Bay reported sustained winds of 66 kt (76 mph) with a gust to 83 kt. NHC expects no additional strengthening before the system makes landfall. Gradual weakening is expected during the next 2-3 days while Nicholas moves over southeastern Texas and southwestern Louisiana.

The minimum sustained winds for a Category 1 hurricane are 74 mph.

Light Steering Currents Will Slow Nicholas

According to NHC, “Nicholas is currently moving through a weakness in a mid-level subtropical ridge. Within 12 to 24 hours, after Nicholas has moved inland, the ridge should weaken and leave Nicholas in an area of light steering currents. As a result, during the next couple of days, the cyclone should turn eastward and slow to a crawl near southwestern Louisiana.”

*Nicholas should now reach the Houston Area with tropical-storm-force winds on Tuesday before slowing near the Louisiana border on Wednesday as a tropical depression..*

The current 10 PM official forecast shows Nicholas moving more slowly than the previous forecast.

Key Messages

Heavy rainfall will impact portions of southeastern Texas, Louisiana, and southern Mississippi through the middle of the week. Significant rainfall amounts are expected, potentially resulting in areas of life-threatening flash and urban flooding, along the eastern Texas coast into southwestern Louisiana. Minor to isolated major river flooding is also possible in smaller river basins and urban areas.
There is the danger of life-threatening storm surge inundation along the coast of Texas from Port Aransas to Sabine Pass. Residents in these areas should follow any advice given by local officials.

Wind Force Probabilities Increasing

*The probability of experiencing tropical-storm-force winds in the north Houston Area is very high.*

Rain Forecast Less Extreme in North Houston Area

*However, the Weather Prediction Center now shows major rain accumulations only near the coast and to the east of Houston.*

I already have 1.47 inches in my rain gage for today. The estimates above are for three days.

Flash Flooding Risk Now Mostly Along Coast

*The risk of flash flooding mirrors the rainfall map above. The Lake Houston Area now has only a slight chance of flooding.*

All in all, if the maps above are accurate, the Lake Houston Area could still see 2 to 6 inches of rain tomorrow, but that’s far better than previously predicted.

*This infrared image shows the areas of heaviest rainfall as of 11:26 PM CDT 9/13/2021*

Areas near the coast remain under a storm surge warning.

So far, none of the streams or bayous in Harris County have come out of their banks. To stay on top of potential local flooding on Tuesday, visit the Harris County Flood Warning System.

Posted by Bob Rehak at 11 PM Monday, 9/13/2021 based on information from NHC and HCFCD

1476 Days since Hurricane Harvey

Cone of Nicholas Shifts East, Now Includes Houston, Hurricane Watch Expanded

The 10 AM update from the National Hurricane Center shows that the eye of Nicholas is reforming yet again – further east from where it first reformed earlier today near Brownsville. This means that the cone of uncertainty for Nicholas has expanded. It now includes the entire Houston Area. And although chances of a hurricane are low, the hurricane watch has been extended northward to San Luis Pass.

Nicholas’ Cone Now Includes All of Houston

*Remember that every place within the cone has an equal change of having the storm pass over it.*

Main Threats from Tonight to Tomorrow Night

Bands of heavy rainfall and gusty winds continue to spread inland from the coast and will increase in frequency and intensity this afternoon into tonight. Core of Nicholas will move across southeast Texas….especially areas south of I-10 overnight into Tuesday with significant rainfall likely.

Harris County Meteorologist Jeff Lindner warns that while Nicholas is not forecasted to become a hurricane, it is possible that it could landfall as a minimal hurricane….but this does NOT change the impacts.

Impact Predictions Remain Unchanged Since Last Update

Rainfall, wind, and storm surge impacts remain unchanged from my post earlier this morning.

Significant rains will begin early this evening and likely continue into Tuesday morning.

Rainfall rates of 2-4 inches per hour will be possible yielding rapid street flooding and significant rises on bayous and creeks.

Lindner’s main concern is watersheds south of I-10 (Clear Creek, Armand Bayou, Vince and Little Vince Bayous, Keegans Bayou, and possibly Brays Bayou). However, Lindner still sees risk north I-10.

Some bayous and creeks may overflow their banks. Structure flooding is possible tonight. The majority of the rainfall is going to be tonight into Tuesday morning.

Residents should stay where they are after 6:00 PM this evening and remain there through the duration of Nicholas.
Jeff Lindner, Harris County Meteorologist

Best Ways to Monitor Nicholas

Closely monitor bayou and creek conditions and rainfall trends. The best way to do that is through the Harris County Flood Warning System.

Also, closely monitor the National Hurricane Center website. This page contains their latest satellite image updates. During storms like this, they update them hourly. Here’s one from 11:46 AM Houston time.

*Nicholas as of 11:46 AM on Monday, 9/13/2021.*

Posted by Bob Rehak on 9/13/2021 at 10:30 AM and again at Noon

1476 Days since Hurricane Harvey

Eye of Nicholas Reforms, Timetable Moved Up

8am CDT, 9/13/2021

According to Harris County meteorologist Jeff Lindner, “The center of Nicholas has reformed overnight about 150 miles to the northwest of the previous center or just off the tip of the northeast Mexican coast. With the center reformation, the track timing has been moved up by about 12 hours.”

*NOAA Satellite image taken at 7:06 am Houston time this morning.*

*Infrared image taken at 8:16 am Houston time this morning. Infrared imagery is useful for determining thunderstorm intensity. Strong to severe thunderstorms will normally have very cold tops.*

Nicholas will now make landfall along the middle Texas coast later this afternoon or this evening.
National Hurricane Center

Said Lindner, “The center is now clearly defined on Brownsville radar and has been sampled by a USAF mission. The latest mission has found that the central pressure is starting to fall and is down to 1001 mb. Maximum sustained winds now reach 60mph. A large mass of very deep convection now extends several hundred miles into the Gulf of Mexico. Nicholas is moving toward the NNW around 14mph and will pass just offshore of Brownsville this morning. This will be a significant rainfall event for southeast Texas.”

Watches and Warnings Now in Effect

A Tropical Storm Warning is in effect for…
- Mouth of the Rio Grande to High Island Texas
- Barra el Mezquital to the U.S./Mexico border

A Tropical Storm Watch is in effect for…
- East of High Island Texas to Sabine Pass

A Hurricane Watch is in effect for…
- Port Aransas to Freeport Texas

Flash Flood Watch is in effect for:
- Areas along and SE of US 59

A Storm Surge Warning is in effect for…
- Port Aransas to San Luis Pass Texas
- Aransas Bay, San Antonio Bay, and Matagorda Bay

Storm Surge Watch is in effect for…
- Mouth of the Rio Grande to Port Aransas Texas
- San Luis Pass Texas to Rutherford Beach Louisiana, including Galveston Bay
- Baffin Bay and Corpus Christi Bay

Track

Forecasters predict a general northward motion toward the Matagorda Bay area followed by a gradual turn toward the NNE and NE. The forward motion of Nicholas will slow after moving inland over the TX coast.

Intensity

Radar shows the Nicholas is attempting to form an inner core. However, moderate wind shear and dry air reaching into the center have slowed this process. With that said, Nicholas is now moving over very warm waters. Lindner predicts the shear may weaken over the next 8-10 hours. That may let Nicholas intensify close to hurricane strength at landfall. Nicholas should make landfall as a strong tropical storm or minimal hurricane.

Tropical storm force winds currently extend outward 115 miles…mainly to the east of the center.

*NHC gives most of the Houston area a 30-60% chance of experiencing tropical-storm-force winds.*

Impacts

Rainfall:

Significant rainfall is expected along and east of the track of Nicholas. This rainfall may produce areas of considerable flash and urban flooding, especially in highly urbanized metropolitan areas. Additionally, there is the potential for isolated minor to moderate river flooding.

While rainfall totals are indicated over the 5 -7 day period, much of the rainfall is expected to fall over a 2-3 day period starting later tonight.

Coastal counties: widespread 10-15 inches (isolated totals up to 20 inches)
South/East of US 59: widespread 8-12 inches (isolated totals up to 15 inches)
North of I-10: widespread 4-6 inches (isolated totals up to 8 inches)

After landfall, models do not aon how quickly the tropical cyclone will move northeastward out of Texas. The forward speed is important to the heavy rainfall forecast, and this trend will be one to watch.

The usually conservative Space City Weather team warns that the flood threat in this event may compare to Tropical Storm Imelda and the 2016 Memorial Day weekend.

*Rainfall will generally be heaviest near the coast with diminishing amounts as you move inland. However, training bands could create much higher than predicted totals in northern areas.*

*Water vapor satellite image captured at 8:21 Houston time this morning.*

*The National Weather Service’s Weather Prediction Center gives most of the Houston area a moderate risk of flash flooding, but some areas near the coast will have a high risk.*

Winds:

Tropical storm force winds are likely along the coast from Matagorda to Galveston Bay and inland to the US 59 corridor. Sustained winds in the 65-75mph range will be possible over the Matagorda Bay region northward into Jackson and possibly southern Wharton Counties with sustained tropical storm force winds spreading inland into portions of Harris, Fort Bend, and Colorado Counties.

Maximum sustained winds are currently near 60 mph (95 km/h) with higher gusts. Strengthening is forecast today, and Nicholas could reach the northwest Gulf coast as a hurricane. Weakening is anticipated on Tuesday and Wednesday while Nicholas moves over land.

Tropical-storm-force winds extend outward up to 115 miles (185 km) from the center. South Padre Island recently reported a wind gust to 45 mph.

Tropical storm conditions are expected to first reach southern Texas this morning, making outside preparations difficult or dangerous. These conditions will spread northward within the warning area through tonight. Hurricane conditions are possible in the Hurricane Watch area as early as this afternoon. Tropical storm conditions are possible within the watch area by tonight or early Tuesday.

Tides:

Expect storm surge of 3-5 feet from Port O Connor to Sargent and 2-4 feet from Sargent to High Island above normal dry ground. Some significant inundation is possible around Matagorda Bay. Additionally, waves on top of the surge will result in significant beach erosion and wave run-up.

*Areas NE of Galveston Bay could experience 2-4 feet of storm surge, while areas SW could experience 3-5.*

Gradual Weakening Predicted

Nicholas should weaken after landfall, diminish into a tropical depression within a couple of days, and degenerate into a remnant low in about 3 days.

Key Messages

Heavy rainfall will impact portions of the Texas and Louisiana coasts through the middle of the week. Significant rainfall amounts are possible, potentially resulting in areas of considerable flash and urban flooding, especially in highly urbanized metropolitan areas. Isolated minor to moderate river flooding is also expected.
There is the danger of life-threatening storm surge inundation along the coast of Texas from Port Aransas to San Luis Pass. Residents in these areas should follow any advice given by local officials.
Nicholas is forecast to approach the middle Texas coast as a strong tropical storm today, and could be near hurricane intensity at landfall. Tropical storm conditions are expected along portions of the middle Texas coast beginning by this afternoon, with hurricane conditions possible from Port Aransas to Freeport this afternoon and tonight.
Tropical storm conditions are expected along portions of the northeastern coast of Mexico and the coast of south Texas beginning during the next few hours.

Posted by Bob Rehak on 9/13/2021 at 8AM based on information from HCFCD and NHC

1476 Days since Hurricane Harvey

Tropical Storm Nicholas Forms in Gulf

A USAF mission this morning found low-level circulation and a large area of 40-50mph winds over the western Gulf. Additionally, satellite images show an expansion of the scattered deep convection associated with the system. Based on this, the system has been upgraded to Tropical Storm Nicholas. The storm is moving NNW at 13mph and this motion is expected to continue today.

Tropical Storm Warnings have been issued from the Mouth of the Rio Grande to Port Aransas TX
Tropical Storm Watches have been issued from Port Aransas TX to High Island TX including Matagorda and Galveston Bays.
Storm surge watch has been issued from the mouth of the Rio Grande to High Island TX
Flash Flood Watch from 7PM tonight through Tuesday night for most of Houston region

*NOAA satellite image of Nicholas as of 10AM CDT Houston time.*

*Nicholas’ track should bring the storm onshore near Matagorda Bay.*

Jeff Lindner, Harris County Meteorologist, predicts, “Nicholas will be moving over warm waters of the western Gulf of Mexico in fairly favorable upper level conditions and steady intensification is likely up to landfall. Most models predict the system to become a mid-range tropical storm. The National Hurricane Center forecasts a 65mph tropical storm at landfall. A reasonable worst case potential is a category 1 hurricane, but at this time that looks unlikely.

Nicholas’ track places southeast Texas on the “dirty” side of the system with onshore winds and bands of heavy rainfall,” says Lindner.

Rainfall Starting Later Today

By late today, heavy rain is expected to reach portions of the Texas and Louisiana coasts, with a heavy rain threat continuing across coastal areas through the middle of the week. Localized significant rainfall could produce areas of flash, urban, and isolated river flooding.

Hourly rainfall rates could be high during this time with 2-3 inches possible, which would lead to some flooding in more urban areas.

How far this storm moves inland will determine how far heavy rains advance on Monday. Says Lindner, “Certainly the coastal counties (Chambers, Galveston, Brazoria, Matagorda, and Jackson) will see heavy rainfall, but this could extend inland into southern Liberty, southern Harris, Fort Bend, and Wharton counties also.” He predicts:

Coastal Counties: widespread 5-8 inches (isolated areas 10-15 inches)
South of I-10: widespread 3-6 inches (isolated areas 8-12 inches)
North of I-10: widespread 2-4 inches (isolated areas 6 inches)

*The NWS Weather Prediction Center shows heavy rain and flash flooding are possible for most of the upper Texas coast through mid-week.*

Flood Potential

Lindner says, “Given the tropical moisture in place hourly rainfall rates of 2-4 inches will be possible under the stronger cells which will lead to quick accumulations. While grounds are dry initially, waves of rainfall will gradually saturate the soils leading the increasing run-off. Flooding will be possible, especially across the coastal counties and areas south of I-10 where the greatest rainfall is most likely at the moment.”

*Most of the Houston area will have a slight (10%) chance of flash flooding for the next three days.*

Tropical-Storm-Force Winds Should Arrive in Houston Tuesday Morning

*Tropical storm force winds should hit the Houston area Tuesday morning.*

2-4 Feet of Storm Surge Likely in Galveston Bay

*Nicholas should bring 2-4 feet of storm surge to the upper Texas coast.*

Posted on 9/12/2021 by Bob Rehak based on Information from NHC and HCFCD

1475 Days since Hurricane Harvey

Tropical Cyclone Formation Likely over Gulf

According to the National Hurricane Center, a large area of disorganized showers and thunderstorms centered around the Yucatan has a 70% chance of turning into a tropical cyclone in the next two days. NHC gives it an 80% chance of formation within five days.

NOAA satellite image as of 8am CDT Houston time.

Environment Becoming Conducive for Development

Although upper-level winds are not currently conducive for tropical cyclone development. However, they should become more favorable during the next day or so. A tropical depression is likely to form on Sunday or Monday while the disturbance moves northwestward and then northward near the coast of northeastern Mexico. Further development will be possible through the middle of next week if it remains over water. However, because the storm has no organized center at this time, where it will make landfall is hard to predict.

*As of 7am CDT Saturday, September 11, 2021*

“Global forecast models agree that a surface low will form, but where exactly remains in question,” says Jeff Lindner, Harris County Meteorologist.

The majority of the models predict the storm will focus on the western Gulf coastline. However, some models bring the storm closer to the Houston area.

Regardless, counter-clockwise rotation around any tropical cyclone should put Houston on the dirty side.

Heavy Rains Could Produce Flash and Urban Flooding

People along the western and northwestern Gulf coast should monitor the progress of this system. This disturbance should produce heavy rain across portions of Central America and the Yucatan Peninsula through today which may lead to flash flooding and mudslides.

According to Lindner, “By late this weekend, heavy rain will likely reach portions of the western Gulf coast. Expect rain over most of coastal Texas and Louisiana through the middle of next week. Localized significant rainfall amounts will be possible, potentially resulting in areas of flash and urban flooding.”

“Significant rainfall will be possible from Monday through Wednesday with excessive short-term rainfall rates of 2-4 inches per hour under any banding, training, or clustering of stronger cells.”
Jeff Lindner, Harris County Meteorologist

Expect very wet days early next week, especially near the coast. How far inland the heavy rains extend will depend on the degree of tropical cyclone development and the track of the storm. At this time, with high uncertainty, forecasters expect the heaviest rains near the coast with lower amounts inland.

Widespread rainfall amounts of 2-4 inches will be common over much of the area with much higher totals of 5-10 inches near the coast. Isolated totals in certain areas could exceed 10 inches.

*Rainfall accumulations expected in next 7 days by the NWS Weather Prediction Center.*

While grounds are generally dry over the area, the magnitude of the rainfall in a short period of time could result in significant run-off generation especially over urban areas. Flooding concerns will increase as grounds become saturated early next week.

Winds/Seas/Tides

The high degree of uncertainty on where where any tropical cyclone will strike also affects winds, seas, and tides. But at the present, Lindner predicts easterly and southeasterly winds today into Sunday. He sees them increasing into the 20-30 mph range with seas building 6-10ft offshore by late Sunday into Monday.

Larger swells moving onto the coast will likely lead to some wave run-up and minor coastal flooding during high tides from late Sunday into early next week.

Posted by Bob Rehak on 9/11/2021 based on information from NHC and HCFCD

1474 Days since Hurricane Harvey

Elm Grove Lawsuits Settled!

Jason Webster, lead attorney for hundreds of Elm Grove, North Kingwood Forest and Porter plaintiffs in lawsuits arising from two floods in 2019, confirmed for ReduceFlooding.com that the defendants have reached a settlement agreement with plaintiffs. Defendants in the Elm Grove lawsuits included Perry Homes; Figure Four Partners LTD.; PSWA, Inc; LJA Engineering; Double Oak Construction, Inc.; Rebel Contractors, Inc.; Texasite, LLC; and Concourse Development, LLC.

Settlement Comes Two Years After Second Flood

Confirmation of the settlement comes almost two years to the day after sheet flow from Woodridge Village flooded Elm Grove and North Kingwood Forest for the second time in five months.

*Elm Grove debris pile from Imelda, two days after sheet flow from Woodridge Village flooded the area.*

Webster says the settlement agreement prohibits disclosure of the terms, but he did say that it was “…resolved to our satisfaction.” Webster says he and co-counsel Kimberley Spurlock, who also represented plaintiffs in the lawsuits, “…still have to communicate with the clients on this and we have not done so yet as far as amounts. That has to be determined by a special master which has been appointed to administer the settlement.”

However, Webster added, “All plaintiffs who participated in the lawsuit will receive a settlement offer.”

Hints of Movement Toward an Agreement in Early August

I first caught wind of a potential settlement from updates to the Harris County District Clerks’ website when Webster and Spurlock moved to establish an Elm Grove Settlement Fund and appoint a Master-in-Chancery in early August. Then, on August 16, Judge Lauren Reeder approved both the Fund and the Chancery motions. However, two defendants, LJA and Rebel, still objected. Interestingly, the Rebel objection contained a reference that it was not a party to a global settlement with the other defendants.

Then yesterday, an unsigned trial preparation order showed up on the District Clerk’s website. I emailed Webster and later that day, he confirmed the settlement.

*Motion to set trial was to be heard on 9/20/2021.* *That should no longer be necessary.*

Facing a trial on the merits of the case often brings defendants to the settlement table when they realize delays are no longer possible. I have been on jury panels for several cases over the years. Interestingly, in every single instance, the defendants chose to settle when the jury panel walked into the room to begin the selection process.

The settlement should come as a welcome relief for many plaintiffs who were devastated financially by the repeat floods.

Elm Grove activist Jeff Miller had this to say about the settlement. “I am thrilled for those that suffered greatly and hope that this settlement will discourage future negligence by bad actors.”

Posted by Bob Rehak on 9/10/2021

1473 Days since Hurricane Harvey and 722 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.

Excessive Rainfall Likely Next Week

Tomorrow, September 10th, is the statistical peak of hurricane season.

And the National Hurricane Center (NHC) is actively monitoring four areas in the Atlantic Basin.

Currently, a 40% Chance of Tropical Cyclone Formation

That orange area is currently where Ida and Mindy both formed in the last two weeks. In the last couple days, the NHC has steadily upgraded its chances of tropical formation. As of tonight, they give it a 40% chance sometime within the next five days.

*Currently, NHC describes Area #1 as a tropical wave.*

The northern portion of the wave is producing disorganized showers and thunderstorms over northeastern Honduras and the western Caribbean Sea.

This system should move into the Bay of Campeche and merge with a pre-existing heavy weather in the southwestern Gulf of Mexico this weekend. Environmental conditions support gradual development. A tropical depression could form by early next week before the system moves inland over mainland Mexico. According to NHC:

Formation chance through 48 hours…low…20 percent.
Formation chance through 5 days…medium…40 percent.

Increasing Chances of Excessive Rainfall, Likely Starting Sunday

Dry air currently over the region will yield hot days and “coolish” nights into Saturday with no chance of rainfall. However, the tropical wave will change that. A pool of deep tropical moisture will increase rain chances along the TX coast from Sunday through Wednesday of next week. It could arrive as early as Saturday evening, but more likely will arrive on Sunday.

Shower and thunderstorm activity over the western Gulf will become widespread during the weekend and into early next week. Global models are largely in agreement on a surge of moisture along the TX coast from Sunday through Wednesday. Copious rainfall is likely.

The National Weather Service extended 7-day forecast has been increasing the forecast amounts for the north Houston area throughout the day.

*Between this morning and this evening, that bright orange area has crept farther inland.*

Widespread 5-7 Inches, 10-12 Possible

Jeff Lindner, Harris County Meteorologist, warns that a weak tropical cyclone could form from this. “Several models have been bouncing around with this over the last several days. They show weak closed surface lows along the Mexican or Texas coastline next week,” says Lindner. “While any sort of surface low that may form next week would help to focus rainfall in that particular area, it is unclear where any low may form if at all and generally does not change the overall wet pattern that is incoming.”

The NWS Weather Prediction Center currently shows rainfall accumulations for next week could total 5-7 inches near the coast with slightly less inland. Lindner, however, predicts that isolated areas could see as much as 10-12 inches by the middle of next week.

No predictions have been made yet regarding potential flooding issues.

Posted by Bob Rehak on 9/9/2021 based on information from NHC, NWS, and HCFCD

1472 Days since Hurricane Harvey and 721 since Imelda

Save the Date: National Public Lands Day Volunteer Event on September 25

Established in 1994 and held annually on the fourth Saturday in September, National Public Lands Day is traditionally the nation’s largest single-day volunteer effort. It provides all lovers of the environment an opportunity to show appreciation for precious natural resources through volunteer opportunities.

Join the Bayou Land Conservancy and REI in Conserving Public Land

This year, National Public Lands Day falls on Saturday September 25. The theme is “More Ways to Connect to Nature,” and there are many ways to connect in this area. I highly recommend joining the Bayou Land Conservancy (BLC) – a local, environmental non-profit – at the Lake Houston Wilderness Park. BLC specializes in preserving land along streams for flood control, clean water, and wildlife.

The BLC and volunteers will partner with REI for the day to help spruce up the park and get a guided tour from park naturalists. Refreshments will be provided, but they recommend bringing your own water in a reusable container and a snack. If you’ve never been to Lake Houston Wilderness Park, it’s a big, tranquil place filled with wetlands and dense forests. In fact, it’s the largest urban nature park in America – almost 5,000 acres – and like stepping back in time.

To see some of this gorgeous park, and the difference it makes in the San Jacinto East Fork Watershed (compared to the West Fork), see this post I developed in 2018 about the importance of riparian vegetation in reducing erosion.

*Riparian vegetation in Lake Houston Park helps prevent erosion, sustain wildlife, and reduce flooding.*

*Shoreline of Lake Houston Park.* *Fall colors light up the landscape as well as people’s faces.*

*Looking NW across the vastness of unspoiled Lake Houston Park. Photo taken Jan. 1, 2021*

Directly Benefitting the Lake Houston Headwaters and Reducing Flooding

The focus of work at the Lake Houston Wilderness Park on the 25^th will directly benefit the Gully Branch-Peach Creek watershed, right in Kingwood’s backyard plus, Porter’s, New Caney’s and Huffman’s!

With 2.5 months left in hurricane season, take time to help preserve nature and reduce flooding in a natural ,cost-free way. More conserved lands mean more safe places for water to go without endangering our communities.

How to Register, Learn More

Please join BLC in conserving land on National Public Lands Day on the 25^th of September! With 5,000 acres, there’s plenty of room for social distancing in a healthy environment.

For more information on the day’s events and how to register, visit BLC’s website at Bayouland.org/national-public-lands-day.

Posted by Bob Rehak on 9/8/2021

1471 Days after Hurricane Harvey

‘Wind Fingerprints’: Scientists Dissect What Accounts for the Destructiveness of Different Storms

Last week, a story about ‘wind fingerprints’ in The Washington Post caught my eye. It purported to show the difference between Ida and Katrina. The story by Bonnie Berkowitz and Laris Karklis starts with this teaser: “Ida hit Louisiana with faster winds than Katrina, but a hurricane’s category number is just part of what makes each storm unique — and uniquely destructive.” I was hooked.

Factors in Fingerprinting Storms

“Ida struck Louisiana on Aug. 29 as a strong Category 4 on the Saffir-Simpson scale, with maximum winds of about 150 mph — much higher than the maximum winds of 125 mph from Katrina, a Category 3,” say the authors.

However, the wind speed is just part of the picture. To get the big picture, one must also consider:

Breadth of the wind field
Wind direction
Total energy contained in the storm
Forward motion
Angle at which it struck the coastline
Track
Proximity to population centers
And more.

The story quotes Michael Kozar, a meteorologist who models storms for risk-analysis company RMS. Says Kozar, each wind field is like a fingerprint.

“Each wind fingerprint is unique to the storm, and it is why each storm produces a unique amount of loss and has unique impacts.”
Michael Kozar, RMS

Examples of Wind Fingerprint Differences

“A very large storm with moderate winds may contain more integrated kinetic energy than an intense but small storm, and it may create havoc for people on land in a different way,” says the story.

The story goes into great detail comparing Ida to Katrina. Ida packed higher winds (150 vs. 125 mph peaks). But Katrina packed more energy – 116 terajoules vs. 47 for Ida. By comparison, Superstorm Sandy in 2012 had an estimated 330 terajoules of energy.

A terajoule is so large, it’s hard to find an analogy that puts it in perspective for most people. But scientists estimate that the atomic bomb over Hiroshima released about 63 terajoules of energy – slightly more than Ida, but a little less than half of Katrina.

RMS estimates the smaller punch of Ida was due in part to the shorter time it was able to gather steam, so to speak, over open water. Ida gained full strength just hours before landfall. But Katrina churned over the open Gulf for three days before slamming into Louisiana. It grew much larger, in fact, about twice as large.

*Relative size of wind fields estimated by risk-analysis firm RMS. Katrina more than doubled Ida’s diameter.*

RMS also explained how Katrina came in east of Lake Pontchartrain, while Ida came in to the west. With the counter-clockwise rotation of low pressure systems in the northern hemisphere, that meant Katrina pushed water toward New Orleans and Ida pushed water away.

The forward speed of a storm can make a huge difference in the types of damage it causes compared to its rotational speed. Category 4 Harvey, for instance, stalled over Houston for days, dropping torrential rains. But Category 5 Hurricane Andrew ripped through south Florida in hours. Harvey flooded homes. Andrew tore them apart.

This article gives you both insights and food for thought that can help you prepare better for the next storm. It’s highly recommended reading.

Posted by Bob Rehak on 9/7/2021 based on a story by Bonnie Berkowitz and Laris Karklis in The Washington Post and data from RMS

1470 Days since Hurricane Harvey