New Atlas-14 data from the National Oceanographic and Atmospheric Administration (NOAA) sheds some light on the intensity of storms in the last week. How unusual were they?
May 3rd was a 200-year storm. May 7 was a 100-year storm. And we can expect a week that wet about once every 5-10 years. Here’s how to find the probability for any storm, location or interval.
Step One: Find Gage Nearest You
Large variations in rainfall totals exist even within small geographic areas. So finding the gage nearest you is the first step. For instance, in this week’s storms, official gages in New Caney and Humble registered differences of more than 25% for the same event. Harris County Flood Control has a Flood Warning System that shows all gages in Harris County and many in surrounding counties. You can also use your own data if you have a rain gage.
Step Two: Determine Time and Volume
When you’re obtaining the official gage data, try to narrow down the duration as close as possible. That’s because you’re estimating rainfall INTENSITY – a function of both time and volume. A two-inch rain spread out over a day is NOT the same as a two-inch rain in ten minutes.
Step Three: Find Average Recurrence Interval
Once you know how much rain fell in your area in a given amount of time, the next step is to determine the “average recurrence interval (ARI).” That tells you how often you’re likely to experience a storm of that intensity. Here’s where and how to find it.
Once you’re at the NOAA site, click your location on the map. Here, I clicked on the approximate location of Elm Grove in Kingwood.
A chart showing the average recurrence intervals for Kingwood will appear below the map.
From NOAA Atlas-14. NOAA offers both tabular and graphical formats, but the tables seem easier to interpret. Atlas 14 includes the latest data, including Hurricane Harvey.
On Tuesday, May 7, the Porter/New Caney area received about 8-10 inches of rain in less than six hours. That was an estimated 100-year rain.
For the seven days starting May 3, gages in the Lake Houston area averaged 10-12 inches. We can expect a week that wet about every 5-10 years.
Probabilities Can Be Mind-Benders
But wait! How can that be? How can you get a 200-year rain and 100-year rain four days apart? And how can we get weeks this wet in 2015, 2016, 2017 and 2019 if it’s supposedly a 5-year event? Simple. You’re dealing in probabilities of independent events. If you toss a coin ten times and it comes up heads each time, the chances of it coming up heads on the 11th toss are still 50%.
It’s the same way with weather. Just because you won the lottery last week doesn’t mean you can’t win it again this week. With that happy thought, I’ll wish you pleasant skies today.
Posted by Bob Rehak on 5/11/2019with help from Diane Cooper
620 Days since Hurricane Harvey
https://i0.wp.com/reduceflooding.com/wp-content/uploads/2019/05/image-3.png?fit=976%2C828&ssl=1828976adminadmin2019-05-11 06:05:472019-05-11 06:23:35How Unusual Were Recent Storms? New NOAA Data Sheds Light
“Few of the victims had flood insurance,” said Crenshaw. “Let’s come together as a community to help our neighbors, just as we did after Hurricane Harvey. Please drop off gift cards that can help people recover. In the parking lot of Building B at Second Baptist on US59 this Saturday from 10 to 12.”
Always appreciated at times like these: gift cards for restaurants, hardware stores, and clothes. No amount is too large or small. Think about what you needed after Harvey. Thank you for helping.
Posted by Bob Rehak on 5/10/19
619 Days after Hurricane Harvey
https://i0.wp.com/reduceflooding.com/wp-content/uploads/2019/05/IMG_1513.jpg?fit=1016%2C1167&ssl=111671016adminadmin2019-05-10 17:27:012019-05-10 17:28:33Crenshaw Coordinating Gift Card Drive for Flood Victims, May 11, 10-Noon, at Second Baptist Church
From the date on the USFWS letter, February 28, it appears that USFWS arrived at its recommendation even before the close of the public comment period on March 1.
The applicant understated the likely impact on waters and wetlands resulting from fill material, raised buildings, infrastructure development and construction activities. They called the applicant’s proposal “misleading.”
USFWS expressed concerns about:
Bird strikes and mortalities associated with the high-rise buildings
The loss of highly functioning forested wetlands
Significant reduction in biological functions, particularly those related to fish and wildlife habitat
Water quality issues
A marina district built entirely within the floodway
The absence of appropriate stormwater management
Failure to fully disclose impacts on wetlands and surrounding properties
Inconsistencies in access road descriptions
Failure to fully disclose the project’s footprint impacts
Failure to provide an analysis of practicable alternatives to the proposed wetland and stream fill
Failure to demonstrate that the project meets the requirements of the EPA’s CWA 404(b)(1) guidelines
An incomplete compensatory mitigation plan
Improper assessment of the high level of functions of the onsite aquatic resources and surrounding upland habitats
An inadequate bald eagle survey
Disturbance and loss of bald eagle habitat.
Conclusion and Recommendation of USFWS
The USFWS recommended “permit denial due to the application’s deficiencies.”
Reaction
I’m happy that a government agency validated the concerns of residents, especially the numerous deficiencies that became so glaringly obvious during the public comment period. Example: when I asked one of the engineers at the March 18th public meeting where all the fill would be put, he couldn’t tell me. It seemed like a simple, but important question. Turns out it was.
Jill Boullion, Executive Director of the Bayou Land Conservancy said, “The Bayou Land Conservancy is gratified that US Fish & Wildlife service has confirmed our opinion that the Romerica project site is ecologically rich and diverse. It is, in its natural state, already providing the community immeasurable services. We believe the highest good for the community is to preserve this valuable resource, not develop it.”
Romerica’s spokesperson, Leah Howard Manlove, contacted me earlier this week to say that the Romerica team would meet next week to discuss their options and a plan of action. At this point, Romerica has two options: answer all the questions and concerns raised during the public comment period or quietly let the project die.
Posted by Bob Rehak on May 10, 2019
619 Days since Hurricane Harvey
The thoughts expressed in this post represent my opinions on matters of public policy and are protected under the First Amendment of the US Constitution and the Anti-SLAPP statute of the Great State of Texas.
https://i0.wp.com/reduceflooding.com/wp-content/uploads/2019/04/DSC06408.jpg?fit=2031%2C1648&ssl=116482031adminadmin2019-05-10 16:07:302019-05-10 19:51:28U.S. Fish & Wildlife Service Urged Corps to Deny Romerica Permit
How Unusual Were Recent Storms? New NOAA Data Sheds Light
New Atlas-14 data from the National Oceanographic and Atmospheric Administration (NOAA) sheds some light on the intensity of storms in the last week. How unusual were they?
Step One: Find Gage Nearest You
Large variations in rainfall totals exist even within small geographic areas. So finding the gage nearest you is the first step. For instance, in this week’s storms, official gages in New Caney and Humble registered differences of more than 25% for the same event. Harris County Flood Control has a Flood Warning System that shows all gages in Harris County and many in surrounding counties. You can also use your own data if you have a rain gage.
Step Two: Determine Time and Volume
When you’re obtaining the official gage data, try to narrow down the duration as close as possible. That’s because you’re estimating rainfall INTENSITY – a function of both time and volume. A two-inch rain spread out over a day is NOT the same as a two-inch rain in ten minutes.
Step Three: Find Average Recurrence Interval
Once you know how much rain fell in your area in a given amount of time, the next step is to determine the “average recurrence interval (ARI).” That tells you how often you’re likely to experience a storm of that intensity. Here’s where and how to find it.
To determine the ARI for any location, go to this page on the NOAA site.
Example
Once you’re at the NOAA site, click your location on the map. Here, I clicked on the approximate location of Elm Grove in Kingwood.
A chart showing the average recurrence intervals for Kingwood will appear below the map.
On Friday, May 3, Kingwood received 5-6 inches in less than an hour. Scrolling down to the 60-minute line and over to the column that shows 5.49 inches, we can see that that was an estimated 200-year rainfall.
On Tuesday, May 7, the Porter/New Caney area received about 8-10 inches of rain in less than six hours. That was an estimated 100-year rain.
For the seven days starting May 3, gages in the Lake Houston area averaged 10-12 inches. We can expect a week that wet about every 5-10 years.
Probabilities Can Be Mind-Benders
But wait! How can that be? How can you get a 200-year rain and 100-year rain four days apart? And how can we get weeks this wet in 2015, 2016, 2017 and 2019 if it’s supposedly a 5-year event? Simple. You’re dealing in probabilities of independent events. If you toss a coin ten times and it comes up heads each time, the chances of it coming up heads on the 11th toss are still 50%.
It’s the same way with weather. Just because you won the lottery last week doesn’t mean you can’t win it again this week. With that happy thought, I’ll wish you pleasant skies today.
Posted by Bob Rehak on 5/11/2019 with help from Diane Cooper
620 Days since Hurricane Harvey
Crenshaw Coordinating Gift Card Drive for Flood Victims, May 11, 10-Noon, at Second Baptist Church
U.S. Congressman Dan Crenshaw is in a new fight now – to help provide flood relief.
Elm Grove had hundreds of flash flood victims this week; other villages had smaller numbers.
Gift Cards Needed
“Few of the victims had flood insurance,” said Crenshaw. “Let’s come together as a community to help our neighbors, just as we did after Hurricane Harvey. Please drop off gift cards that can help people recover. In the parking lot of Building B at Second Baptist on US59 this Saturday from 10 to 12.”
Always appreciated at times like these: gift cards for restaurants, hardware stores, and clothes. No amount is too large or small. Think about what you needed after Harvey. Thank you for helping.
Posted by Bob Rehak on 5/10/19
619 Days after Hurricane Harvey
U.S. Fish & Wildlife Service Urged Corps to Deny Romerica Permit
The U.S. Fish & Wildlife Serivice (USFWS) has urged the Army Corps of Engineers to deny outright Romerica’s application to build high rises and a marina in the floodplain and floodway of the San Jacinto.
From the date on the USFWS letter, February 28, it appears that USFWS arrived at its recommendation even before the close of the public comment period on March 1.
Read the full text of the five-page letter here or the summary below.
Summary of USFWS Concerns
The letter states that:
Conclusion and Recommendation of USFWS
The USFWS recommended “permit denial due to the application’s deficiencies.”
Reaction
I’m happy that a government agency validated the concerns of residents, especially the numerous deficiencies that became so glaringly obvious during the public comment period. Example: when I asked one of the engineers at the March 18th public meeting where all the fill would be put, he couldn’t tell me. It seemed like a simple, but important question. Turns out it was.
Jill Boullion, Executive Director of the Bayou Land Conservancy said, “The Bayou Land Conservancy is gratified that US Fish & Wildlife service has confirmed our opinion that the Romerica project site is ecologically rich and diverse. It is, in its natural state, already providing the community immeasurable services. We believe the highest good for the community is to preserve this valuable resource, not develop it.”
Romerica’s spokesperson, Leah Howard Manlove, contacted me earlier this week to say that the Romerica team would meet next week to discuss their options and a plan of action. At this point, Romerica has two options: answer all the questions and concerns raised during the public comment period or quietly let the project die.
Posted by Bob Rehak on May 10, 2019
619 Days since Hurricane Harvey
The thoughts expressed in this post represent my opinions on matters of public policy and are protected under the First Amendment of the US Constitution and the Anti-SLAPP statute of the Great State of Texas.