Harris County Flood Control District (HCFCD) briefed the County’s Community Resilience Flood Task Force on how the extent of the May 2024 flood compared to Hurricane Harvey. In places, inundation matched Harvey. And in others it came close or fell short.
See the inundation map below. In my opinion, it dramatizes three things:
Serious flooding can happen any month of the year in the Houston region.
Flooding can happen anywhere that rain falls.
Flood-mitigation measures make a huge difference.
Inundation map from HCFCD comparing Harvey with May 2024 floods and evacuation zones.
Anytime
As the map above shows, major rain can fall outside of a hurricane season. In fact, May is usually the third wettest month of the year in Houston, exceeded only by June and October.
Of seven major storms to strike this area since 2016, four have happened outside of hurricane season.
Anywhere
The worst rainfall in the early May floods happened at the very top of the San Jacinto river basin in the upper portions of the East and West Forks. Parts of those watersheds received almost 20 inches of rain.
In Huntsville, Harvey dumped only 2 more inches of rain than a training band of thunderstorms in May 2024. The map above shows the results.
Cypress, Spring and Lake Creeks, which originate on the west side, received roughly a quarter to a third of the rain that fell to the north during early May.
However, during Harvey, the rainfall distribution was the opposite of the map above. Huntsville received about 17 inches while areas to the south received more than 40.
Flood-Mitigation Measures
The inundation map above shows the importance of another location-related variable: upstream stormwater detention. Note how much more blue you see on the West Fork than on the East Fork which is predominantly green. The West Fork has a dam at Lake Conroe which partially blocked the heaviest flows. The East Fork has no dams.
Development usually increases the speed and volume of runoff. Developers normally use detention basins to limit post-development runoff to pre-development rates, so that they don’t increase flooding.
But for the most part, that didn’t happen in Colony Ridge. And that contributed to flooding downstream.
The inundation map above should be a wakeup call. Of 16 major flood-mitigation projects identified in the San Jacinto River Basin Master Drainage Study, not one has even gotten to the drawing boards, much less off them – after four years.
Posted by Bob Rehak on 7/3/24
2500 Days since Hurricane Harvey
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.
https://i0.wp.com/reduceflooding.com/wp-content/uploads/2024/07/20240627-Harvey-Vs-May-24-Storm.jpg?fit=1100%2C712&ssl=17121100adminadmin2024-07-03 13:35:122024-07-03 13:41:21How May 2024 Flood Compared to Harvey
7/2/24 – Beryl has become an incredibly intense hurricane with maximum sustained winds of 165 MPH and a central pressure of 935mb. See this Infrared Satellite Loop at Tropical Tidbits. This is an unprecedented hurricane event for July.
According to Harris County Meteorologist Jeff Lindner, Beryl is the earliest Category 5 hurricane on record since 1851. It beats out hurricane Emily (2005), which became a Category 5 on July 17.
Beryl is now moving through the central Caribbean Sea toward Jamaica and the Cayman Islands.
Status Overview as of 8 AM 7/2/24
Based on NOAA aircraft data, hurricane force winds (75mph) extend outward 40 miles from the center. Tropical storm force winds (40mph) extend outward 125 miles from the center.
Beryl is moving toward the west-northwest near 22 mph.
On the forecast track, the center of Beryl will move quickly across the southeastern and central Caribbean Sea today. It should pass near Jamaica on Wednesday and the Cayman Islands on Thursday.
Weakening should begin later today, but Beryl is still expected to be near major hurricane intensity as it passes Jamaica and the Caymans.
Intensity Forecast Uncertain
The National Hurricane Center (NHC) cautions that Beryl’s intensity forecast is rather uncertain. Model guidance indicates that the hurricane will begin to weaken later today as Beryl encounters moderate-to-strong vertical wind shear. Later on, factors such as:
Possible interaction with the Jamaican elevated terrain
Dry air intrusions
Structure of the vertical wind shear
…will all play a role in the rate of weakening.
As Beryl approaches the Yucatan, models show quite a wide range of solutions – from a strong tropical storm to a major hurricane. However, the NHC forecast shows Beryl reaching the Yucatan as a hurricane in about 72 hours and emerging as a tropical storm into the Gulf of Mexico on Saturday.
Track Shifted North
Beryl has tracked slightly north of predictions during the last 12 hours. This is likely due to the much stronger intensity of the hurricane.
Overall the direction has been trending north over the last 24 hours. Beryl is being steered by a strong high pressure ridge to the north. A W to WNW motion through the next 72 hours is likely. That will likely bring core of the hurricane to the eastern Yucatan early Friday morning.
Beryl will cross into the southern Gulf of Mexico by early this weekend. At that time, the current ridge of high pressure over the southern plains will be breaking down and moving east. Low pressure should replace it, pulling Beryl a little more to north, compared to the current track.
However, there is also uncertainty with the track in the Gulf of Mexico. It is difficult to tell how organized Beryl will be when it emerges from the Yucatan. It is also difficult to predict how quickly the southern plains high will break down.
Such factors also will affect the forward speed of the hurricane.
Due to Beryl’s high forward speed, it could drop a foot of rain on Jamaica. But as it slows in the Gulf…
Lindner urges people along the Texas and Louisiana coast to monitor Beryl’s progress closely. NHC is now updating information on Beryl every few hours on this page.
For those who need a refresher course in hurricane preparation, ReduceFlooding’s Links page contains advice from 19 authoritative sources.
7/1/24. – Last night, Tropical Storm Chris became the third named storm of the 2024 hurricane season. According to the National Hurricane Center (NHC), the third named storm usually doesn’t happen until August. That puts the current hurricane season well ahead of the 30-year average for the Atlantic Basin.
Climatology Data from NHC
Data from 1991 through 2020 indicates we usually have one named storm in June and one in July before the Atlantic season heats up in August, September and October. Then we’re back to one in November.
However, the NHC and a variety of academic and commercial forecasters predicted an extremely active 2024 hurricane season because of high sea surface temperatures and low wind shear associated with the developing La Niña.
Tropical Storm Alberto has already come and gone. It dissipated into the Bay of Campeche last month. But we are now into July.
3 Areas of Interest Currently in Atlantic
At the moment, we have three areas of interest in the Atlantic.
Tropical Storm Chris Dissipating
The remnants of Chris are currently moving inland over Mexico.
Hurricane Beryl Nearing High End of Cat 4
The eye of Beryl began crossing the Windward Islands this morning. A hurricane hunter aircraft measured 150 MPH sustained winds at 11:10 AM as Beryl made landfall on Carriacou Island.
150 MPH puts Beryl near the top of Cat 4 on the Saffir-Simpson scale that predicts wind damage. Category 4 goes from 130 MPH to 156 MPH.
NHC advises that in a Cat 4 storm “Catastrophic damage will occur: Well-built framed homes can sustain severe damage with loss of most of the roof structure and/or some exterior walls. Most trees will be snapped or uprooted and power poles downed. Fallen trees and power poles will isolate residential areas. Power outages will last weeks to possibly months. Most of the area will be uninhabitable for weeks or months.”
However, Beryl is likely to encounter some wind shear in the Caribbean that will slow it down. The latest advisory from NHC predicts Beryl will weaken into a tropical storm before crossing the Yucatan and entering the Gulf on Saturday. See below.
Meanwhile NHC has urged island residents to shelter in place and not venture out during what it describes as “life-threatening conditions.”
Central Atlantic Still Disturbed
A third disturbance is still out in the central, tropical Atlantic more than 1000 miles east-southeast of the Windward Islands. According to NHC, a tropical depression could form by the middle part of this week. Formation chance through 2 days is low – only 20%. However, the chance through 7 days is medium – 50%.
Satellite images show training storms moving off the coast of Africa. This probably won’t be the last disturbance we see originating in these latitudes in coming weeks.
Note Beryl spinning on the far left of the image above!
Posted by Bob Rehak on 7/1/24 based on information from NOAA and NHC
2498 Days since Hurricane Harvey
https://i0.wp.com/reduceflooding.com/wp-content/uploads/2024/07/Hurricane-Climatology.png?fit=2218%2C1366&ssl=113662218adminadmin2024-07-01 14:15:552024-07-02 18:49:17Third Named Storm Puts 2024 Hurricane Season a Month Ahead
How May 2024 Flood Compared to Harvey
Harris County Flood Control District (HCFCD) briefed the County’s Community Resilience Flood Task Force on how the extent of the May 2024 flood compared to Hurricane Harvey. In places, inundation matched Harvey. And in others it came close or fell short.
See the inundation map below. In my opinion, it dramatizes three things:
Anytime
As the map above shows, major rain can fall outside of a hurricane season. In fact, May is usually the third wettest month of the year in Houston, exceeded only by June and October.
Of seven major storms to strike this area since 2016, four have happened outside of hurricane season.
Anywhere
The worst rainfall in the early May floods happened at the very top of the San Jacinto river basin in the upper portions of the East and West Forks. Parts of those watersheds received almost 20 inches of rain.
In Huntsville, Harvey dumped only 2 more inches of rain than a training band of thunderstorms in May 2024. The map above shows the results.
Cypress, Spring and Lake Creeks, which originate on the west side, received roughly a quarter to a third of the rain that fell to the north during early May.
However, during Harvey, the rainfall distribution was the opposite of the map above. Huntsville received about 17 inches while areas to the south received more than 40.
Flood-Mitigation Measures
The inundation map above shows the importance of another location-related variable: upstream stormwater detention. Note how much more blue you see on the West Fork than on the East Fork which is predominantly green. The West Fork has a dam at Lake Conroe which partially blocked the heaviest flows. The East Fork has no dams.
But the East Fork and Luce Bayou do have the sprawling Colony Ridge Development. And Colony Ridge, especially the first 12,000 acres, has only a minuscule amount of stormwater detention. The development is now 50% larger than Manhattan.
Development usually increases the speed and volume of runoff. Developers normally use detention basins to limit post-development runoff to pre-development rates, so that they don’t increase flooding.
But for the most part, that didn’t happen in Colony Ridge. And that contributed to flooding downstream.
The inundation map above should be a wakeup call. Of 16 major flood-mitigation projects identified in the San Jacinto River Basin Master Drainage Study, not one has even gotten to the drawing boards, much less off them – after four years.
Posted by Bob Rehak on 7/3/24
2500 Days since Hurricane Harvey
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.
Beryl Becomes Earliest Cat 5 Hurricane Ever
7/2/24 – Beryl has become an incredibly intense hurricane with maximum sustained winds of 165 MPH and a central pressure of 935mb. See this Infrared Satellite Loop at Tropical Tidbits. This is an unprecedented hurricane event for July.
According to Harris County Meteorologist Jeff Lindner, Beryl is the earliest Category 5 hurricane on record since 1851. It beats out hurricane Emily (2005), which became a Category 5 on July 17.
Beryl is now moving through the central Caribbean Sea toward Jamaica and the Cayman Islands.
Status Overview as of 8 AM 7/2/24
Based on NOAA aircraft data, hurricane force winds (75mph) extend outward 40 miles from the center. Tropical storm force winds (40mph) extend outward 125 miles from the center.
Beryl is moving toward the west-northwest near 22 mph.
On the forecast track, the center of Beryl will move quickly across the southeastern and central Caribbean Sea today. It should pass near Jamaica on Wednesday and the Cayman Islands on Thursday.
Weakening should begin later today, but Beryl is still expected to be near major hurricane intensity as it passes Jamaica and the Caymans.
Intensity Forecast Uncertain
The National Hurricane Center (NHC) cautions that Beryl’s intensity forecast is rather uncertain. Model guidance indicates that the hurricane will begin to weaken later today as Beryl encounters moderate-to-strong vertical wind shear. Later on, factors such as:
…will all play a role in the rate of weakening.
As Beryl approaches the Yucatan, models show quite a wide range of solutions – from a strong tropical storm to a major hurricane. However, the NHC forecast shows Beryl reaching the Yucatan as a hurricane in about 72 hours and emerging as a tropical storm into the Gulf of Mexico on Saturday.
Track Shifted North
Beryl has tracked slightly north of predictions during the last 12 hours. This is likely due to the much stronger intensity of the hurricane.
Overall the direction has been trending north over the last 24 hours. Beryl is being steered by a strong high pressure ridge to the north. A W to WNW motion through the next 72 hours is likely. That will likely bring core of the hurricane to the eastern Yucatan early Friday morning.
Beryl will cross into the southern Gulf of Mexico by early this weekend. At that time, the current ridge of high pressure over the southern plains will be breaking down and moving east. Low pressure should replace it, pulling Beryl a little more to north, compared to the current track.
However, there is also uncertainty with the track in the Gulf of Mexico. It is difficult to tell how organized Beryl will be when it emerges from the Yucatan. It is also difficult to predict how quickly the southern plains high will break down.
Such factors also will affect the forward speed of the hurricane.
Due to Beryl’s high forward speed, it could drop a foot of rain on Jamaica. But as it slows in the Gulf…
Lindner urges people along the Texas and Louisiana coast to monitor Beryl’s progress closely. NHC is now updating information on Beryl every few hours on this page.
For those who need a refresher course in hurricane preparation, ReduceFlooding’s Links page contains advice from 19 authoritative sources.
Posted by Bob Rehak on 7/2/24
2499 Days since Hurricane Harvey
Third Named Storm Puts 2024 Hurricane Season a Month Ahead
7/1/24. – Last night, Tropical Storm Chris became the third named storm of the 2024 hurricane season. According to the National Hurricane Center (NHC), the third named storm usually doesn’t happen until August. That puts the current hurricane season well ahead of the 30-year average for the Atlantic Basin.
Climatology Data from NHC
Data from 1991 through 2020 indicates we usually have one named storm in June and one in July before the Atlantic season heats up in August, September and October. Then we’re back to one in November.
However, the NHC and a variety of academic and commercial forecasters predicted an extremely active 2024 hurricane season because of high sea surface temperatures and low wind shear associated with the developing La Niña.
Tropical Storm Alberto has already come and gone. It dissipated into the Bay of Campeche last month. But we are now into July.
3 Areas of Interest Currently in Atlantic
At the moment, we have three areas of interest in the Atlantic.
Tropical Storm Chris Dissipating
The remnants of Chris are currently moving inland over Mexico.
Hurricane Beryl Nearing High End of Cat 4
The eye of Beryl began crossing the Windward Islands this morning. A hurricane hunter aircraft measured 150 MPH sustained winds at 11:10 AM as Beryl made landfall on Carriacou Island.
150 MPH puts Beryl near the top of Cat 4 on the Saffir-Simpson scale that predicts wind damage. Category 4 goes from 130 MPH to 156 MPH.
NHC advises that in a Cat 4 storm “Catastrophic damage will occur: Well-built framed homes can sustain severe damage with loss of most of the roof structure and/or some exterior walls. Most trees will be snapped or uprooted and power poles downed. Fallen trees and power poles will isolate residential areas. Power outages will last weeks to possibly months. Most of the area will be uninhabitable for weeks or months.”
However, Beryl is likely to encounter some wind shear in the Caribbean that will slow it down. The latest advisory from NHC predicts Beryl will weaken into a tropical storm before crossing the Yucatan and entering the Gulf on Saturday. See below.
Meanwhile NHC has urged island residents to shelter in place and not venture out during what it describes as “life-threatening conditions.”
Central Atlantic Still Disturbed
A third disturbance is still out in the central, tropical Atlantic more than 1000 miles east-southeast of the Windward Islands. According to NHC, a tropical depression could form by the middle part of this week. Formation chance through 2 days is low – only 20%. However, the chance through 7 days is medium – 50%.
Satellite images show training storms moving off the coast of Africa. This probably won’t be the last disturbance we see originating in these latitudes in coming weeks.
Note Beryl spinning on the far left of the image above!
Posted by Bob Rehak on 7/1/24 based on information from NOAA and NHC
2498 Days since Hurricane Harvey