9/26/24 5:20 PM CDT Update – Helene has become a Category 4 storm with 130 MPHsustained winds.
According to the National Hurricane Center (NHC), Helene is rapidly becoming one of the “largest hurricanes in decades.” Comparing Helene to previous hurricanes in the Gulf of Mexico, they say, “Helene is at the upper bound in terms of size.”
Widespread Impacts, “Immense Human Suffering”
Helene’s hurricane-force winds extend outward up to 60 miles from the center. And tropical-storm-force winds extend outward up to 345 miles.
“As a result , storm surge, wind, and rainfall impacts will extend far away from the center and well outside the forecast cone, particularly on the east side,” they say.
“In addition, the fast forward speed when Helene moves inland will result in a far inland penetration of strong winds. That includes strong gusts over higher terrain of the southern Appalachians.”
Jeff Lindner, Harris County’s meteorologist, characterized Helene as “extremely dangerous.” He said, “Widespread and significant impacts will produce immense human suffering by modern standards.”
Large parts of the SE US will have a greater than 50% chance of tropical-storm-force or higher winds from Helene.
Already High End of Category 2 at 10 AM
As of 10AM, maximum sustained winds had increased to near 105 MPH with higher gusts. That puts Helene just five miles per hour from becoming a major category three hurricane.
Helene was moving toward the Big Bend area of the Florida Panhandle at 14 MPH and will make landfall this evening. After landfall, Helene should turn northwestward and slow down over the Tennessee Valley on Friday and Saturday.
The minimum central pressure has plummeted to 947 mb.
Additionally, water level rise along the west coast of Florida has begun and will quickly worsen through the day. Catastrophic storm surge will reach up to 15-20 feet above normally dry ground.
Over portions of the Southeastern U.S. into the Southern Appalachians, Helene is expected to produce total rain accumulations of 6 to 12 inches, with isolated totals around 20 inches.
This rainfall will likely result in catastrophic and potentially life-threatening flash and urban flooding, along with significant river flooding. Numerous significant landslides are expected in steep terrain across the southern Appalachians.
Key Messages
A catastrophic and deadly storm surge is likely along portions of the Florida Big Bend coast, where inundation could reach as high as 20 feet above ground level, along with destructive waves. There is also a danger of life-threatening storm surge along the remainder of the west coast of the Florida Peninsula.
Potentially catastrophic hurricane-force winds are expected within the eyewall of Helene when it makes landfall in the Florida Big Bend region this evening. Damaging and life-threatening hurricane-force winds, especially in gusts, will penetrate well inland. Strong wind gusts are also likely farther north across portions of northern Georgia and the Carolinas, particularly over the higher terrain of the southern Appalachians.
Catastrophic and life-threatening flash and urban flooding, including numerous significant landslides, is expected across portions of the southern Appalachians through Friday. Widespread significant river flooding and isolated major river flooding are likely.
Helene in Historical Perspective
All indications at this point suggest Helene will have a huge impact on the southeastern US.
Helene at 10 AM Central Daylight TimeWider shot taken at 5:30 PM CDT slightly before landfall.
“This is likely to be the worst hurricane event for this area in over a generation. Conditions near the coast will not be survivable.”
Jeff Lindner, Harris County Meteorologist
Lindner continued, “Since 1851 there are no records of storms of this magnitude in Apalachee Bay. All coastal structures/infrastructure lower than 15 ft will be completely destroyed. Older slab built structures in this area will suffer catastrophic damage and likely be washed away. Water levels will almost certainly rise to the second floors of elevated structures and some of these will face total collapse. All available efforts should be utilized to evacuate these areas.”
Posted by Bob Rehak on 9/26/24 at 11 AMbased on information from NHC and Harris County
2585 Days since Hurricane Harvey
https://i0.wp.com/reduceflooding.com/wp-content/uploads/2024/09/1000x1000.jpg?fit=1000%2C1000&ssl=110001000adminadmin2024-09-26 11:41:132024-09-26 18:10:54Helene Will Be One of Largest Hurricanes in Decades
9/25/24 3PM CDT – Today, Helene intensified into a hurricane and it should become a major hurricane before making landfall tomorrow in the Big Bend area of the Florida Panhandle. Some forecasters are predicting a Category 3 storm, others a Cat 4.
Helene will accelerate to the north today and Thursday crossing the entire Gulf of Mexico in a 24-30 hour period and reach the Florida Gulf coast late Thursday, according to the National Hurricane Center (NHC).
Warm Waters Will Fuel Rapid Intensification
Harris County Meteorologist Jeff Lindner says, “Helene will be passing over extremely warm waters that extend 100-200 feet deep. That supports great levels of intensity in developing hurricanes. Nearly all the hurricane intensity models bring Helene to Category 4 over the eastern Gulf of Mexico. The official forecast is for a 120mph category 3, but this may need to be adjusted upward given current trends and guidance.”
Regardless, all forecasters comment on the size of Helene. At 1PM, tropical storm force winds extended outward 275 miles from the center, according to NHC.
Hurricane Helene as of 1PM CDT on 9/25/24
As a result, they predict Helene’s impacts will extend well inland. Tropical storm force winds will likely reach Atlanta and even the southern Appalachian Mountains.
Life-Threatening Storm Surge
But the most certain threats to life and property have to do with storm surge. Today forecasters say it could reach up to 20 feet above land; yesterday it was 15.
Jeff Lindner, Harris County’s meteorologist says, “Structures lower than 10 ft will be completely destroyed along the entire Florida nature coast. This will potentially be a record storm surge event for the eastern side of the Florida Big Bend, likely surpassing previous records from the March 1993 ‘superstorm’ surge event.”
Torrential Rain and Flash-Flood Threats
Farther inland, the threat will be torrential rains. Atlanta, which usually doesn’t experience tropical threats, could receive 8-12 inches with higher isolated totals. Areas in the mountains north of Atlanta could receive 16-20 inches.
A potentially catastrophic inland flash flood event is becoming increasingly likely as Helene interacts with a stalled frontal boundary and the higher terrain of the southern Appalachian mountains from northern Georgia into western North Carolina and eastern Tennessee.
In the rainfall map above, note the red and brown colored areas along the North Carolina/Tennessee border. That is a mountainous region.
The excessive rainfall there is orographic in origin. Orographic means precipitation caused by hills or mountain ranges deflecting moisture-laden air masses upward, causing them to cool and precipitate their moisture.
All that precipitation will likely trigger flash flooding.
Widespread travel disruption is likely over the southeast from Thursday into Saturday. Recovery of essential services will be slow due to the widespread, significant impacts.
Key Messages
The NHC warns:
Due to the large size of Helene, there is a danger of life-threatening storm surge along the entire west coast of the Florida Peninsula and Florida Big Bend. Residents should follow the evacuation advice of local officials.
Devastating hurricane-force winds will reach from northern Florida into southern Georgia. Because of Helene’s expected fast forward speed, damaging and life-threatening wind gusts are expected to penetrate well inland to the southern Appalachians.
Helene will bring heavy rain and potentially life-threatening flash and urban flooding. Impacts will stretch across portions of northwestern and northern Florida, the Southeast, southern Appalachians, and the Upper Tennessee Valley Wednesday through Friday.
Widespread minor to moderate river flooding is likely, and isolated major river flooding is possible.
Types of Damage Associated with Category 4 Hurricanes
The National Weather Service lists types of damage typically associated with a Category 4 Hurricane. “Winds 130-156 mph. 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.”
https://i0.wp.com/reduceflooding.com/wp-content/uploads/2024/09/Hurricane-Helene.jpg?fit=1100%2C740&ssl=17401100adminadmin2024-09-25 15:00:272024-09-25 21:16:38Helene Now a Hurricane 550 Miles Across, Impacts Will Spread Far Inland
9/24/24 at 1 PM – This morning, Potential Tropical Cyclone 9 became Tropical Storm Helene when satellite images and Hurricane Hunter aircraft data noted a well-defined center of circulation and sustained winds of 45 MPH with higher gusts.
Helene is moving toward the northwest near 12 mph and will likely continue to do so through early Wednesday. The National Hurricane Center expects northward to north-northeastward motion at a faster forward speed on Wednesday and Thursday.
On the forecast track, the center of Helene will move across the far northwestern Caribbean Sea through tonight, and then move across the eastern Gulf of Mexico Wednesday and Thursday, potentially reaching the Gulf coast of Florida late Thursday.
Additional strengthening is forecast. Helene should become a hurricane on Wednesday and could become a major hurricane on Thursday.
A major factor in the forecast of hazards is the size of the storm. Currently, tropical-storm-force winds extend outward up to 140 miles to the east of the center. Helene’s forecast radii are at the 90th percentile of hurricane size at similar latitudes. If accurate, that means only 10% of hurricanes will exceed its size.
Due to the forecast large size of this system, storm surge, wind, and rainfall impacts will extend well away from the center, particularly on the east side.
Hazards Affecting Land
Rainfall
Heads up if you have friends, family or travel plans in the southeast this week. Helene should produce total rain accumulations of 4 to 8 inches with isolated totals around 12 inches. This rainfall will likely result in areas of considerable flash and urban flooding, with minor to moderate river flooding likely, and isolated major river flooding possible.
The combination of a dangerous storm surge and high tide will cause normally dry areas near the coast to flood. The water could reach 10-15 feet above ground between Ochlockonee River, FL and Chassahowitzka. For other areas see the map below.
Hurricane conditions are possible within the U.S. watch areas Wednesday night and early Thursday.
Tropical storm conditions should hit the Lower Florida Keys beginning Wednesday, and are possible in the watch area in the Middle Florida Keys beginning late Wednesday.
Helene should make landfall in the Panhandle Thursday morning and reach Atlanta by Thursday evening or Friday morning.
Compared to yesterday’s forecast, the chance of damaging winds now extends much farther north, well into Georgia.
The fast forward speed of the storm when it crosses the coast will likely result in inland penetration of strong winds over parts of the southeastern United States well after landfall.
Surf
Swells will spread northward toward the west coast of Florida and the northeastern Gulf Coast on Wednesday and Thursday. These swells are likely to cause life-threatening surf and rip current conditions.
Intensification
Several factors suggest rapid intensification of Helene:
Shear over the system will decrease. Model guidance continues to show relatively low to moderate shear for the next 48 hours or so.
Oceanic heat content values are very high.
The system will move through an environment of upper-level divergence.
Therefore, NHC anticipates significant strengthening. NHC’s intensity forecast shows the system reaching a peak intensity around 100 kt (116 MPH) in 48 hours while over the eastern Gulf of Mexico.
Given the system’s large size, it might only weaken slowly even if it encounters sheer near the Panhandle. As a result, there is still a risk that the system could reach the coast as a major hurricane.
Key Messages
1. Helene will be near hurricane strength early Wednesday when it shoots the gap between the Yucatan and Cuba.
2. Helene should rapidly intensify over the eastern Gulf and become a major Category 3 hurricane as it approaches the coast on Thursday. The risk of life-threatening storm surge and damaging hurricane-force winds continues to increase along the coast of the Florida Panhandle and Florida’s west coast. Hurricane and Storm Surge Watches are in effect for much of that area. Residents should follow advice given by local officials.
3. Helene will bring heavy rain which will likely result in locally considerable flash and urban flooding across portions of Florida, with isolated flash and urban flooding possible across the Southeast, Southern Appalachians, and the Tennessee Valley Wednesday through Friday. Minor to isolated moderate river flooding will also be possible.
Here’s what Helene looked like this morning from space.
Helene as of 10AM 9/24/24 CDT circled in red.
Posted by Bob Rehak at 1 PM on 9/24/24
2584 Days since Harvey
https://i0.wp.com/reduceflooding.com/wp-content/uploads/2024/09/TS-Helene.jpg?fit=1100%2C723&ssl=17231100adminadmin2024-09-24 13:03:342024-09-24 13:15:22TS Helene Pushing North, Intensifying, Expanding
Helene Will Be One of Largest Hurricanes in Decades
9/26/24 5:20 PM CDT Update – Helene has become a Category 4 storm with 130 MPH sustained winds.
According to the National Hurricane Center (NHC), Helene is rapidly becoming one of the “largest hurricanes in decades.” Comparing Helene to previous hurricanes in the Gulf of Mexico, they say, “Helene is at the upper bound in terms of size.”
Widespread Impacts, “Immense Human Suffering”
Helene’s hurricane-force winds extend outward up to 60 miles from the center. And tropical-storm-force winds extend outward up to 345 miles.
“As a result , storm surge, wind, and rainfall impacts will extend far away from the center and well outside the forecast cone, particularly on the east side,” they say.
“In addition, the fast forward speed when Helene moves inland will result in a far inland penetration of strong winds. That includes strong gusts over higher terrain of the southern Appalachians.”
Jeff Lindner, Harris County’s meteorologist, characterized Helene as “extremely dangerous.” He said, “Widespread and significant impacts will produce immense human suffering by modern standards.”
Already High End of Category 2 at 10 AM
As of 10AM, maximum sustained winds had increased to near 105 MPH with higher gusts. That puts Helene just five miles per hour from becoming a major category three hurricane.
Helene was moving toward the Big Bend area of the Florida Panhandle at 14 MPH and will make landfall this evening. After landfall, Helene should turn northwestward and slow down over the Tennessee Valley on Friday and Saturday.
The minimum central pressure has plummeted to 947 mb.
Additionally, water level rise along the west coast of Florida has begun and will quickly worsen through the day. Catastrophic storm surge will reach up to 15-20 feet above normally dry ground.
Over portions of the Southeastern U.S. into the Southern Appalachians, Helene is expected to produce total rain accumulations of 6 to 12 inches, with isolated totals around 20 inches.
This rainfall will likely result in catastrophic and potentially life-threatening flash and urban flooding, along with significant river flooding. Numerous significant landslides are expected in steep terrain across the southern Appalachians.
Key Messages
Helene in Historical Perspective
All indications at this point suggest Helene will have a huge impact on the southeastern US.
Lindner continued, “Since 1851 there are no records of storms of this magnitude in Apalachee Bay. All coastal structures/infrastructure lower than 15 ft will be completely destroyed. Older slab built structures in this area will suffer catastrophic damage and likely be washed away. Water levels will almost certainly rise to the second floors of elevated structures and some of these will face total collapse. All available efforts should be utilized to evacuate these areas.”
Posted by Bob Rehak on 9/26/24 at 11 AM based on information from NHC and Harris County
2585 Days since Hurricane Harvey
Helene Now a Hurricane 550 Miles Across, Impacts Will Spread Far Inland
9/25/24 3PM CDT – Today, Helene intensified into a hurricane and it should become a major hurricane before making landfall tomorrow in the Big Bend area of the Florida Panhandle. Some forecasters are predicting a Category 3 storm, others a Cat 4.
Helene will accelerate to the north today and Thursday crossing the entire Gulf of Mexico in a 24-30 hour period and reach the Florida Gulf coast late Thursday, according to the National Hurricane Center (NHC).
Warm Waters Will Fuel Rapid Intensification
Harris County Meteorologist Jeff Lindner says, “Helene will be passing over extremely warm waters that extend 100-200 feet deep. That supports great levels of intensity in developing hurricanes. Nearly all the hurricane intensity models bring Helene to Category 4 over the eastern Gulf of Mexico. The official forecast is for a 120mph category 3, but this may need to be adjusted upward given current trends and guidance.”
The wind speed break point between Categories 3 and 4 is 130 MPH.
Impacts Will Be Felt Far Inland
Regardless, all forecasters comment on the size of Helene. At 1PM, tropical storm force winds extended outward 275 miles from the center, according to NHC.
As a result, they predict Helene’s impacts will extend well inland. Tropical storm force winds will likely reach Atlanta and even the southern Appalachian Mountains.
Life-Threatening Storm Surge
But the most certain threats to life and property have to do with storm surge. Today forecasters say it could reach up to 20 feet above land; yesterday it was 15.
Jeff Lindner, Harris County’s meteorologist says, “Structures lower than 10 ft will be completely destroyed along the entire Florida nature coast. This will potentially be a record storm surge event for the eastern side of the Florida Big Bend, likely surpassing previous records from the March 1993 ‘superstorm’ surge event.”
Torrential Rain and Flash-Flood Threats
Farther inland, the threat will be torrential rains. Atlanta, which usually doesn’t experience tropical threats, could receive 8-12 inches with higher isolated totals. Areas in the mountains north of Atlanta could receive 16-20 inches.
A potentially catastrophic inland flash flood event is becoming increasingly likely as Helene interacts with a stalled frontal boundary and the higher terrain of the southern Appalachian mountains from northern Georgia into western North Carolina and eastern Tennessee.
In the rainfall map above, note the red and brown colored areas along the North Carolina/Tennessee border. That is a mountainous region.
The excessive rainfall there is orographic in origin. Orographic means precipitation caused by hills or mountain ranges deflecting moisture-laden air masses upward, causing them to cool and precipitate their moisture.
All that precipitation will likely trigger flash flooding.
Widespread travel disruption is likely over the southeast from Thursday into Saturday. Recovery of essential services will be slow due to the widespread, significant impacts.
Key Messages
The NHC warns:
Types of Damage Associated with Category 4 Hurricanes
The National Weather Service lists types of damage typically associated with a Category 4 Hurricane. “Winds 130-156 mph. 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.”
Sounds a lot like Beryl.
Posted by Bob Rehak on 9/25/24
2584 Days since Hurricane Harvey
TS Helene Pushing North, Intensifying, Expanding
9/24/24 at 1 PM – This morning, Potential Tropical Cyclone 9 became Tropical Storm Helene when satellite images and Hurricane Hunter aircraft data noted a well-defined center of circulation and sustained winds of 45 MPH with higher gusts.
Helene is moving toward the northwest near 12 mph and will likely continue to do so through early Wednesday. The National Hurricane Center expects northward to north-northeastward motion at a faster forward speed on Wednesday and Thursday.
On the forecast track, the center of Helene will move across the far northwestern Caribbean Sea through tonight, and then move across the eastern Gulf of Mexico Wednesday and Thursday, potentially reaching the Gulf coast of Florida late Thursday.
Additional strengthening is forecast. Helene should become a hurricane on Wednesday and could become a major hurricane on Thursday.
A major factor in the forecast of hazards is the size of the storm. Currently, tropical-storm-force winds extend outward up to 140 miles to the east of the center. Helene’s forecast radii are at the 90th percentile of hurricane size at similar latitudes. If accurate, that means only 10% of hurricanes will exceed its size.
Due to the forecast large size of this system, storm surge, wind, and rainfall impacts will extend well away from the center, particularly on the east side.
Hazards Affecting Land
Rainfall
Heads up if you have friends, family or travel plans in the southeast this week. Helene should produce total rain accumulations of 4 to 8 inches with isolated totals around 12 inches. This rainfall will likely result in areas of considerable flash and urban flooding, with minor to moderate river flooding likely, and isolated major river flooding possible.
Flash-Flood Risk
Most of the Florida Panhandle and Georgia have a moderate (40-70%) chance of flash flooding.
Storm Surge
The combination of a dangerous storm surge and high tide will cause normally dry areas near the coast to flood. The water could reach 10-15 feet above ground between Ochlockonee River, FL and Chassahowitzka. For other areas see the map below.
Wind
Hurricane conditions are possible within the U.S. watch areas Wednesday night and early Thursday.
Tropical storm conditions should hit the Lower Florida Keys beginning Wednesday, and are possible in the watch area in the Middle Florida Keys beginning late Wednesday.
Helene should make landfall in the Panhandle Thursday morning and reach Atlanta by Thursday evening or Friday morning.
Compared to yesterday’s forecast, the chance of damaging winds now extends much farther north, well into Georgia.
The fast forward speed of the storm when it crosses the coast will likely result in inland penetration of strong winds over parts of the southeastern United States well after landfall.
Surf
Swells will spread northward toward the west coast of Florida and the northeastern Gulf Coast on Wednesday and Thursday. These swells are likely to cause life-threatening surf and rip current conditions.
Intensification
Several factors suggest rapid intensification of Helene:
Therefore, NHC anticipates significant strengthening. NHC’s intensity forecast shows the system reaching a peak intensity around 100 kt (116 MPH) in 48 hours while over the eastern Gulf of Mexico.
Given the system’s large size, it might only weaken slowly even if it encounters sheer near the Panhandle. As a result, there is still a risk that the system could reach the coast as a major hurricane.
Key Messages
1. Helene will be near hurricane strength early Wednesday when it shoots the gap between the Yucatan and Cuba.
2. Helene should rapidly intensify over the eastern Gulf and become a major Category 3 hurricane as it approaches the coast on Thursday. The risk of life-threatening storm surge and damaging hurricane-force winds continues to increase along the coast of the Florida Panhandle and Florida’s west coast. Hurricane and Storm Surge Watches are in effect for much of that area. Residents should follow advice given by local officials.
3. Helene will bring heavy rain which will likely result in locally considerable flash and urban flooding across portions of Florida, with isolated flash and urban flooding possible across the Southeast, Southern Appalachians, and the Tennessee Valley Wednesday through Friday. Minor to isolated moderate river flooding will also be possible.
Here’s what Helene looked like this morning from space.
Posted by Bob Rehak at 1 PM on 9/24/24
2584 Days since Harvey