As of this 11 a.m this morning, the National Hurricane Center (NHC) says that Invest 99L has turned into Tropical Depression 9 (TD9). Satellite imagery now shows circulation in the area of low pressure over the west-central Caribbean which I posted about yesterday. Cuba and the Caymans have already issued tropical-storm warnings. Extremely heavy rainfall is expected there. And the storm should strengthen into a hurricane by Sunday. Yet the effects on the Houston region will like be felt offshore and in coastal areas.
Center of circulation starting to form. NOAA Satellite image as of 9:50 a.m. CDT on August 26, 2021.
TD9 Current Intensity and Location
The initial intensity of TD9 as of 11 a.m. Houston time is approximately 35 mph with gusts to 40. An Air Force Reserve reconnaissance aircraft is scheduled to be in the system later this afternoon to provide more information on the system’s structure and intensity.
TD9, now located just south of Grand Cayman, is moving northwestward at 13 mph. The National Hurricane Center (NHC) indicates the system should move steadily northwestward. That would bring the center near or over western Cuba late Friday, over the southeastern Gulf of Mexico on Saturday, and approaching the US Central Gulf coast on Sunday.
Models are in relatively good agreement regarding the track forecast for TD9. However, error at Day 4 is around 175 miles, so don’t focus on details of the long-range track forecast. Some shifts in the track are likely until the system consolidates and becomes better defined, according to the NHC.
The cone of uncertainty for TD9 at this point stretches all the way from Houston to Mississippi. Every point within the cone has an equal chance of being hit.
TD9 will move over warm waters of the northwestern Caribbean during the next 24-36 hours. This, in combination with low vertical wind shear and a moist environment, should allow for steady strengthening.
Rapid Intensification Likely in Next 48 to 72 Hours
NHC forecasts TD9 to become a tropical storm later today or tonight. It could approach hurricane strength as it passes western Cuba.
Once the system moves into the Gulf of Mexico, conditions support additional strengthening. The NHC forecast explicitly shows rapid intensification between 48 and 72 hours for now.
The NHC intensity forecast brings the system near major hurricane strength when it approaches the northern Gulf coast on Sunday.
NATIONAL HURRICANE CENTER
Most global models show significant intensification of TD9 over the Gulf of Mexico. As a result, there is higher-than-normal confidence that a strengthening tropical cyclone will be moving over the Gulf this weekend.
Key Messages
1. Tropical storm conditions are likely in the Cayman Islands tonight and western Cuba Friday, with dangerous storm surge possible in western Cuba.
2. The system will likely produce life-threatening heavy rains, flash flooding and mudslides across Jamaica, the Cayman Islands, western Cuba, and portions of the Yucatan Peninsula.
3. This system should approach the northern Gulf Coast at or near major hurricane intensity on Sunday, although the forecast uncertainty is larger than usual since the system is just forming. There is a risk of life-threatening storm surge, damaging hurricane-force winds, and heavy rainfall Sunday and Monday along the northern Gulf Coast from the Florida Panhandle to the upper Texas coast, with the greatest risk along the coast of Louisiana. Interests in these areas should closely monitor the progress of this system and ensure they have their hurricane plan in place.
Most of the Houston area has a 30-40% chance of experiencing tropical-storm-force winds from this storm.Tropical-storm-force winds could arrive by early Sunday morning.
Likely Hazards in Islands and Mainland
The main hazards associated with TD9 as it passes Cuba and the Caymans will be:
STORM SURGE:
2 to 4 feet above normal tide levels in areas with onshore flow. Near the coast, the surge will be accompanied by large and destructive waves.
WIND:
Tropical storm conditions are expected in the Cayman Islands tonight and Cuba on Friday.
RAINFALL:
The depression is expected to produce total rainfall accumulations of 6 to 10 inches with maximum totals of 15 inches across Jamaica. Rainfall totals of 8 to 12 inches with isolated maximum amounts of 20 inches are expected across the Cayman Islands, western Cuba, and the northeast Yucatan Peninsula. These rainfall amounts may produce life-threatening flash floods and mudslides. Rainfall from this system is likely to begin impacting portions of the central U.S. Gulf Coast by early Sunday.
SURF:
Swells generated by this system will begin affecting Jamaica, the Cayman Islands and Cuba tonight and Friday. These swells are likely to cause life-threatening surf and rip current conditions.
Lindner Cautiously Optimistic At This Point
Jeff Lindner, Harris County meteorologist believes, “Impacts along the upper TX coast will likely be increasing swells and minor coastal flooding at high tide late this weekend into early next week.”
Monitor forecasts closely in case things change and be prepared for anything. We still won’t reach the peak of hurricane season until mid-September.
Statistical peak of Hurricane Season is September 10.
Posted by Bob Rehak at noon on 8/26/2021 based on information from NHC and HCFCD
1458 Days after Hurricane Harvey
https://i0.wp.com/reduceflooding.com/wp-content/uploads/2021/08/144701_5day_cone_no_line_and_wind.png?fit=897%2C736&ssl=1736897adminadmin2021-08-26 12:23:532021-08-26 12:38:11TD9 Dumping Up to 20 Inches on Caymans, Hurricane Likely in Gulf by Sunday
Jeff Lindner, Harris County’s meteorologist, forecasts a potential hurricane threat for the western and northwestern Gulf of Mexico early next week. And it’s following the same track as Harvey – almost four years later to the day.
Current Location of 99L in South-Central Caribbean
A tropical wave currently designated 99L and moving westward in the Caribbean off the coast of Columbia still has no center of circulation. However, global models indicate that it will continue to develop over the western Caribbean Sea either Friday or Saturday and move into the south-central Gulf of Mexico over the weekend.
Area of Investigation 99L is that large blob between the eastern tip of Cuba and the northern coast of Colombia.99L on left should reach the southern Gulf by this weekend.
Still a Wide Range of Potential Tracks for 99L
There has been a significant shift during the last 24 hours to the right (east). The majority of the models now show 99L heading in the direction of the northwest Gulf of Mexico. However, models also show a wide range of potential tracks from northern Mexico to the Mississippi coast.
The black line is the most likely track but uncertainty remains high.
So, a fair amount of uncertainty exists in the forecast, especially since there is such spread in the ensemble guidance. The lack of a defined surface center at the moment increases that uncertainty.
Hurricane Harvey’s track in 2017. Note the similarity in area of origin and projected paths. Also note where Harvey intensified.
This weekend will be the fourth anniversary of Harvey. It’s eerie to note the similarities between that storm and this one.
Intensification Very Likely
Conditions over the Gulf of Mexico appear to be favorable for intensification.
Nearly all global models see 99L turning into a hurricane. Some see it turning into an intense hurricane in the Gulf by early next week.
Lindner warns that It is too early to start discussing impacts because of the uncertainty on the track. However, he does see increasing tides and 10-15 foot waves from Sunday into Monday. Rain chances will increase starting today and remain high into the weekend.
“Obviously,” says Lindner, “the forecast and potential impacts will have significant changes as the track become more clear in the coming days.”
Residents and interest along the TX and LA coast should review hurricane plans and make sure hurricane supplies are fully stocked. Monitor forecasts closely and frequently.
Posted by Bob Rehak on 8/25/2021 based on information from HCFCD, NOAA, NHC and Tropical Tidbits
1457 Days since Hurricane Harvey
https://i0.wp.com/reduceflooding.com/wp-content/uploads/2021/08/two_atl_5d0-3.png?fit=900%2C665&ssl=1665900adminadmin2021-08-25 11:39:052021-08-25 11:54:07So Far, 99L Headed Toward Gulf Along Same Track as Harvey
For more than a year, HCFCD has excavated Ben’s Branch in four different phases. However, significant sediment remained under the Kingwood Drive Bridge. That’s property owned and maintained by the City of Houston. And now they are excavating that to eliminate a bottleneck. Such bottlenecks can back water up, damaging homes and businesses.
Photographs by Stan Sarman on 8/24/2021. Taken along Ben’s Branch looking north toward Kingwood Drive.The excavation also affected the area between the two halves of Kingwood Drive.Sediment will drain and dry before being removed from the banks.
According to Sarman, who talked with the construction manager, after the crew completes work here, it will remove sediment from the bottleneck at the Kingwood Diversion Ditch next to the fire station on Kingwood Drive.
These are little things that make a big difference to people who previously flooded. And there were plenty of them along Ben’s Branch, especially in the Town Center Area. Some businesses still haven’t recovered. The shopping center north of these photos is still largely vacant thanks to catastrophic flooding during Harvey and a ditch whose conveyance was severely reduced, in part, by bottlenecks like this one.
Thanks go to Mayor Pro Tem Dave Martin and his staff at the District E council office.
Posted by Bob Rehak on 8/24/2021 with photos from Stan Sarman
1456 Days since Hurricane Harvey
https://i0.wp.com/reduceflooding.com/wp-content/uploads/2021/08/20210824-IMG_6790.jpg?fit=1200%2C900&ssl=19001200adminadmin2021-08-24 18:15:242021-08-24 18:15:28City Starting to Excavate Bottlenecks Under Kingwood Drive
TD9 Dumping Up to 20 Inches on Caymans, Hurricane Likely in Gulf by Sunday
As of this 11 a.m this morning, the National Hurricane Center (NHC) says that Invest 99L has turned into Tropical Depression 9 (TD9). Satellite imagery now shows circulation in the area of low pressure over the west-central Caribbean which I posted about yesterday. Cuba and the Caymans have already issued tropical-storm warnings. Extremely heavy rainfall is expected there. And the storm should strengthen into a hurricane by Sunday. Yet the effects on the Houston region will like be felt offshore and in coastal areas.
TD9 Current Intensity and Location
The initial intensity of TD9 as of 11 a.m. Houston time is approximately 35 mph with gusts to 40. An Air Force Reserve reconnaissance aircraft is scheduled to be in the system later this afternoon to provide more information on the system’s structure and intensity.
TD9, now located just south of Grand Cayman, is moving northwestward at 13 mph. The National Hurricane Center (NHC) indicates the system should move steadily northwestward. That would bring the center near or over western Cuba late Friday, over the southeastern Gulf of Mexico on Saturday, and approaching the US Central Gulf coast on Sunday.
Models are in relatively good agreement regarding the track forecast for TD9. However, error at Day 4 is around 175 miles, so don’t focus on details of the long-range track forecast. Some shifts in the track are likely until the system consolidates and becomes better defined, according to the NHC.
TD9 will move over warm waters of the northwestern Caribbean during the next 24-36 hours. This, in combination with low vertical wind shear and a moist environment, should allow for steady strengthening.
Rapid Intensification Likely in Next 48 to 72 Hours
NHC forecasts TD9 to become a tropical storm later today or tonight. It could approach hurricane strength as it passes western Cuba.
Once the system moves into the Gulf of Mexico, conditions support additional strengthening. The NHC forecast explicitly shows rapid intensification between 48 and 72 hours for now.
Most global models show significant intensification of TD9 over the Gulf of Mexico. As a result, there is higher-than-normal confidence that a strengthening tropical cyclone will be moving over the Gulf this weekend.
Key Messages
1. Tropical storm conditions are likely in the Cayman Islands tonight and western Cuba Friday, with dangerous storm surge possible in western Cuba.
2. The system will likely produce life-threatening heavy rains, flash flooding and mudslides across Jamaica, the Cayman Islands, western Cuba, and portions of the Yucatan Peninsula.
3. This system should approach the northern Gulf Coast at or near major hurricane intensity on Sunday, although the forecast uncertainty is larger than usual since the system is just forming. There is a risk of life-threatening storm surge, damaging hurricane-force winds, and heavy rainfall Sunday and Monday along the northern Gulf Coast from the Florida Panhandle to the upper Texas coast, with the greatest risk along the coast of Louisiana. Interests in these areas should closely monitor the progress of this system and ensure they have their hurricane plan in place.
Likely Hazards in Islands and Mainland
The main hazards associated with TD9 as it passes Cuba and the Caymans will be:
STORM SURGE:
2 to 4 feet above normal tide levels in areas with onshore flow. Near the coast, the surge will be accompanied by large and destructive waves.
WIND:
Tropical storm conditions are expected in the Cayman Islands tonight and Cuba on Friday.
RAINFALL:
The depression is expected to produce total rainfall accumulations of 6 to 10 inches with maximum totals of 15 inches across Jamaica. Rainfall totals of 8 to 12 inches with isolated maximum amounts of 20 inches are expected across the Cayman Islands, western Cuba, and the northeast Yucatan Peninsula. These rainfall amounts may produce life-threatening flash floods and mudslides. Rainfall from this system is likely to begin impacting portions of the central U.S. Gulf Coast by early Sunday.
SURF:
Swells generated by this system will begin affecting Jamaica, the Cayman Islands and Cuba tonight and Friday. These swells are likely to cause life-threatening surf and rip current conditions.
Lindner Cautiously Optimistic At This Point
Jeff Lindner, Harris County meteorologist believes, “Impacts along the upper TX coast will likely be increasing swells and minor coastal flooding at high tide late this weekend into early next week.”
Monitor forecasts closely in case things change and be prepared for anything. We still won’t reach the peak of hurricane season until mid-September.
Posted by Bob Rehak at noon on 8/26/2021 based on information from NHC and HCFCD
1458 Days after Hurricane Harvey
So Far, 99L Headed Toward Gulf Along Same Track as Harvey
Jeff Lindner, Harris County’s meteorologist, forecasts a potential hurricane threat for the western and northwestern Gulf of Mexico early next week. And it’s following the same track as Harvey – almost four years later to the day.
Current Location of 99L in South-Central Caribbean
A tropical wave currently designated 99L and moving westward in the Caribbean off the coast of Columbia still has no center of circulation. However, global models indicate that it will continue to develop over the western Caribbean Sea either Friday or Saturday and move into the south-central Gulf of Mexico over the weekend.
Still a Wide Range of Potential Tracks for 99L
There has been a significant shift during the last 24 hours to the right (east). The majority of the models now show 99L heading in the direction of the northwest Gulf of Mexico. However, models also show a wide range of potential tracks from northern Mexico to the Mississippi coast.
So, a fair amount of uncertainty exists in the forecast, especially since there is such spread in the ensemble guidance. The lack of a defined surface center at the moment increases that uncertainty.
This weekend will be the fourth anniversary of Harvey. It’s eerie to note the similarities between that storm and this one.
Intensification Very Likely
Conditions over the Gulf of Mexico appear to be favorable for intensification.
Lindner warns that It is too early to start discussing impacts because of the uncertainty on the track. However, he does see increasing tides and 10-15 foot waves from Sunday into Monday. Rain chances will increase starting today and remain high into the weekend.
“Obviously,” says Lindner, “the forecast and potential impacts will have significant changes as the track become more clear in the coming days.”
Residents and interest along the TX and LA coast should review hurricane plans and make sure hurricane supplies are fully stocked. Monitor forecasts closely and frequently.
Posted by Bob Rehak on 8/25/2021 based on information from HCFCD, NOAA, NHC and Tropical Tidbits
1457 Days since Hurricane Harvey
City Starting to Excavate Bottlenecks Under Kingwood Drive
For more than a year, HCFCD has excavated Ben’s Branch in four different phases. However, significant sediment remained under the Kingwood Drive Bridge. That’s property owned and maintained by the City of Houston. And now they are excavating that to eliminate a bottleneck. Such bottlenecks can back water up, damaging homes and businesses.
According to Sarman, who talked with the construction manager, after the crew completes work here, it will remove sediment from the bottleneck at the Kingwood Diversion Ditch next to the fire station on Kingwood Drive.
These are little things that make a big difference to people who previously flooded. And there were plenty of them along Ben’s Branch, especially in the Town Center Area. Some businesses still haven’t recovered. The shopping center north of these photos is still largely vacant thanks to catastrophic flooding during Harvey and a ditch whose conveyance was severely reduced, in part, by bottlenecks like this one.
Thanks go to Mayor Pro Tem Dave Martin and his staff at the District E council office.
Posted by Bob Rehak on 8/24/2021 with photos from Stan Sarman
1456 Days since Hurricane Harvey