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
9/23/24 at 12 PM – The National Hurricane Center has designated a disturbance in the northwestern Caribbean as Potential Tropical Cyclone 9. Currently, NHC gives the storm a 90% chance of development in the next two days.
According to Harris County Meteorologist Jeff Lindner, models indicate it will likely escalate into a Category 4 hurricane as it heads north over the warm waters of the Gulf.
However, it will likely make landfall along the Florida Panhandle. Current forecasts indicate no threat to Texas. Overnight, the projected track of the storm shifted farther east.
Projections as of Noon Monday
I’m posting this because Houston residents may have friends, relatives or travel plans in affected areas. See below.
Center of storm has equal change of tracking anywhere within cone. Cone does not indicate width of storm.
Tropical storm force winds associated with Potential Tropical Cyclone 9 should arrive in the big bend area of the Florida panhandle sometime between Wednesday night and Thursday morning.
NHC predicts a 50:50 chance for tropical storm force winds extending north into Georgia.
The National Weather Service has this to say for people in the Panhandle and southern Georgia, “There is a potential for significant storm surge; heavy rainfall and flooding; and strong winds across the north and eastern Gulf Coast.”
“Impacts could begin as early as Wednesday night and last into Friday,” says NWS. “More detailed and specific impacts will be highly dependent on future track/intensity and we’ll be including those in future updates in the next day or two.”
Winds have a 95 percent chance of a 75 MPH increase during the next 72 hours.
National Hurricane Center
Frequency of Major Hurricanes
When/if the Potential Tropical Cyclone 9 reaches 39 MPH, NHC will dub it Helene.
We’ve already had one major hurricane in the Gulf this year – Beryl. The second major hurricane usually develops in the Atlantic Basin by September 19. So, even though this season has fewer than normal named storms, it will have an average number of major hurricanes for this part of the season if Helene becomes a Category 3 or higher.
At present, NHC says the area of concern in the northwestern Caribbean between Honduras and Cuba continues to produce disorganized showers and thunderstorms. Some mid-level rotation is evident in visible satellite images.
A gradual turn toward the northwest is expected during the next day or so. Models agree that the center of the system should reach the northeast Gulf on Thursday.
Since the disturbance currently lacks a well-defined center, future track adjustments may be required. Given the large size of the tropical-storm-force wind field and fast forward speed that is forecast, storm surge, wind, and rainfall impacts will likely extend well away from the center, particularly to the east of the system.
While the system is currently broad and not well organized, the models suggest a more well-defined center should develop during the next day or so.
Once the system becomes better organized and develops an inner core, the environmental and oceanic conditions appear favorable for significant strengthening. The sea surface temperature anomaly chart below shows that temperatures in the Caribbean and Gulf are up to 8 degrees Fahrenheit warmer than average for this time of year.
An Air Force Reserve reconnaissance aircraft will investigate the system this afternoon.
Tropical Storm Warnings and Hurricane Watches have already been issued for portions of western Cuba and the Yucatan Peninsula of Mexico.
Key Messages
The disturbance will strengthen and be near hurricane strength when it reaches the far northwestern Caribbean Sea Tuesday night.
The system will intensify and could become a major hurricane when it reaches the northeastern Gulf Coast on Thursday.
There is an increasing risk of life-threatening storm surge and damaging hurricane-force winds along portions of the northern and northeastern Gulf Coast, including the Florida Panhandle and portions of the Florida west coast. But it is too soon to specify the exact location and magnitude of impacts.
Potential Tropical Cyclone Nine will bring heavy rain to portions of the western Caribbean. That may lead to flooding and possible mudslides in western Cuba.
Potential Tropical Cyclone Nine will likely produce total rain accumulations of 4 to 8 inches over western Cuba and the Cayman Islands with isolated totals around 12 inches.
Heavy rainfall will spread into the Southeast U.S. starting on Wednesday and continuing through Friday, bringing a risk of flash and river flooding.
For the latest rainfall forecasts associated with Potential Tropical Cyclone Nine, see the National Weather Service Storm Total Rainfall Graphics.
Posted by Bob Rehak on 9/23/24
2582 Days since Hurricane Harvey
https://i0.wp.com/reduceflooding.com/wp-content/uploads/2024/09/153941_5day_cone_no_line_and_wind.png?fit=897%2C736&ssl=1736897adminadmin2024-09-23 12:40:592024-09-23 16:50:08NHC Issues Advisory on Potential Tropical Cyclone 9
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
NHC Issues Advisory on Potential Tropical Cyclone 9
9/23/24 at 12 PM – The National Hurricane Center has designated a disturbance in the northwestern Caribbean as Potential Tropical Cyclone 9. Currently, NHC gives the storm a 90% chance of development in the next two days.
According to Harris County Meteorologist Jeff Lindner, models indicate it will likely escalate into a Category 4 hurricane as it heads north over the warm waters of the Gulf.
However, it will likely make landfall along the Florida Panhandle. Current forecasts indicate no threat to Texas. Overnight, the projected track of the storm shifted farther east.
Projections as of Noon Monday
I’m posting this because Houston residents may have friends, relatives or travel plans in affected areas. See below.
Tropical storm force winds associated with Potential Tropical Cyclone 9 should arrive in the big bend area of the Florida panhandle sometime between Wednesday night and Thursday morning.
NHC predicts a 50:50 chance for tropical storm force winds extending north into Georgia.
The National Weather Service has this to say for people in the Panhandle and southern Georgia, “There is a potential for significant storm surge; heavy rainfall and flooding; and strong winds across the north and eastern Gulf Coast.”
“Impacts could begin as early as Wednesday night and last into Friday,” says NWS. “More detailed and specific impacts will be highly dependent on future track/intensity and we’ll be including those in future updates in the next day or two.”
Frequency of Major Hurricanes
When/if the Potential Tropical Cyclone 9 reaches 39 MPH, NHC will dub it Helene.
We’ve already had one major hurricane in the Gulf this year – Beryl. The second major hurricane usually develops in the Atlantic Basin by September 19. So, even though this season has fewer than normal named storms, it will have an average number of major hurricanes for this part of the season if Helene becomes a Category 3 or higher.
Current Status
At present, NHC says the area of concern in the northwestern Caribbean between Honduras and Cuba continues to produce disorganized showers and thunderstorms. Some mid-level rotation is evident in visible satellite images.
A gradual turn toward the northwest is expected during the next day or so. Models agree that the center of the system should reach the northeast Gulf on Thursday.
Since the disturbance currently lacks a well-defined center, future track adjustments may be required. Given the large size of the tropical-storm-force wind field and fast forward speed that is forecast, storm surge, wind, and rainfall impacts will likely extend well away from the center, particularly to the east of the system.
While the system is currently broad and not well organized, the models suggest a more well-defined center should develop during the next day or so.
Once the system becomes better organized and develops an inner core, the environmental and oceanic conditions appear favorable for significant strengthening. The sea surface temperature anomaly chart below shows that temperatures in the Caribbean and Gulf are up to 8 degrees Fahrenheit warmer than average for this time of year.
An Air Force Reserve reconnaissance aircraft will investigate the system this afternoon.
Tropical Storm Warnings and Hurricane Watches have already been issued for portions of western Cuba and the Yucatan Peninsula of Mexico.
Key Messages
Posted by Bob Rehak on 9/23/24
2582 Days since Hurricane Harvey