Heavy rain to douse southern US as tropical development risk persists
By
Alex Sosnowski, AccuWeather senior meteorologist
Updated Sep 9, 2021 9:09 PM EST
An area of disturbed weather forecast to drift northward over the Gulf of Mexico has the potential to develop into an organized tropical system and produce torrential downpours to part of the storm-ravaged Gulf Coast region this week.
The good news for Gulf Coast residents recovering from Hurricane Ida is that another powerful hurricane does not appear likely to develop. Unfortunately, flooding downpours are expected for some of the hardest-hit regions whether or not a new tropical depression or storm takes shape.
Flash flood watches were in effect Monday for parts of Louisiana including around New Orleans and Houma. More than 495,000 customers remained without power in the state eight days after Ida's landfall, according to PowerOutage.US.
A broad area of disorganized clouds, showers and thunderstorms, dubbed Invest 91L by the National Hurricane Center, has been bubbling up and dissipating through Sunday near southeastern Mexico and the southern Gulf of Mexico. More grouping of the shower and thunderstorm activity was apparent on satellite imagery on Monday.
This image, taken at midday on Tuesday, Sept. 7, 2021, shows a gathering area of showers and thunderstorms over the central Gulf of Mexico. (CIRA at Colorado State/GOES-East)
Thus far, pockets of dry air and wind shear have been impeding further organization of this feature and may continue to do so through the middle of the week. However, there continues to be some indication that a weak area of low pressure will form in the Gulf. That low-pressure area is forecast to approach the area from Louisiana to the Florida Panhandle spanning Wednesday and Thursday.
Wind shear is likely to relax somewhat as the area of low pressure approaches the northeastern Gulf Coast and a small window for organization may open up at midweek, according to AccuWeather Meteorologist Randy Adkins said.
This low chance of development may continue through Thursday along the northeastern Gulf coast, even if the center of the low-pressure area drifts over marshy coastal land for a time.
AccuWeather meteorologists say that the same system will have an opportunity to organize and gain strength upon reaching waters along the coasts of northeastern Florida to the Carolinas late this week.
"As the low pressure drifts off the coasts of northeastern Florida and Georgia and moves over the Atlantic between the U.S. and Bermuda from Friday through this weekend, the chance of development is likely to increase to between 40 and 60%," Adkins explained.
Anticipated steering breezes should keep the low pressure from pushing very far to the north along the Atlantic coast this weekend. Downpours could expand northward along the Carolina coast for a time into Friday and perhaps early Saturday, just ahead of a new dip in the jet stream.
If a dip in the jet stream is slow to advance, then there might there be more room for the disturbance to crawl northward to the mid-Atlantic coast with heavy rain and gusty winds.
Regardless of how far to the north rain advances this week along the Atlantic coast, seas and surf are forecast to remain rough as swells propagate outward from powerful Hurricane Larry.
With the amount of moisture forecast to increase in proximity to the low pressure while it's over the Gulf of Mexico, downpours may become intense enough to lead to incidents of flash flooding from southeastern Louisiana, southern Mississippi and southern Alabama to southern Georgia and northern Florida from the middle to the latter part of this week.
A general 1-3 inches of rain is forecast to fall along the southeastern U.S. coast with local amounts to 5 inches possible. Heavier rain could unfold should the system ramp up to a tropical depression or possibly a tropical storm prior to pushing eastward across northern Florida.
If the system does develop into a tropical storm, it would take the name Mindy.
Travel along the Interstate 10 corridor in the Southeast states can be difficult at times due to showers and thunderstorms into Friday. Farther to the north, an old frontal zone will continue to lead to sporadic showers and thunderstorms from central Louisiana to the southern Appalachians into the middle of this week.
Additional threats, whether the system develops or not, include locally gusty thunderstorms and the risk of a few waterspouts as the feature travels eastward from the northeastern Gulf coast into Thursday to areas in northeastern Florida and coastal Georgia from Thursday night to Friday and perhaps part of Saturday.
Elsewhere in the Gulf of Mexico, enough of an area of disturbed weather may remain behind to raise a second concern for tropical development.
"Should wind shear decrease, there is the risk of tropical development centered over the southwestern Gulf of Mexico this weekend to early next week," Adkins said.
Elsewhere in the Atlantic, Larry will remain the most formidable tropical system in the basin into this weekend. The powerful hurricane is forecast to pass close enough to Bermuda to bring some rain and wind to the islands on Thursday and could track close enough to unleash significant rain and wind to Atlantic Canada, and and could make landfall on the islands of Newfoundland, early this weekend.
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There is another area on AccuWeather meteorologists' radar over the Atlantic in the long term.
"As disturbances continue to roll westward from the coast of Africa, there may be an opportunity for a robust tropical wave to organize this weekend near the Cabo Verde Islands," Adkins said.
Dry air was suppressing the upheaval of showers and thunderstorms to start this week, but there are some signs that the environment near the Cabo Verde Islands may have more moisture by Friday.
Tropical waves that emerge from Africa represent the backbone of the Atlantic hurricane season, and this wave train is at its peak during the month of September.
For the latest weather news check back on AccuWeather.com. Watch AccuWeather Network on DIRECTV, DIRECTVstream, Frontier, Spectrum, fuboTV, Philo, and Verizon Fios. AccuWeatherNOW is streaming on Roku and XUMO.
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News / Hurricane
Heavy rain to douse southern US as tropical development risk persists
By Alex Sosnowski, AccuWeather senior meteorologist
Updated Sep 9, 2021 9:09 PM EST
An area of disturbed weather forecast to drift northward over the Gulf of Mexico has the potential to develop into an organized tropical system and produce torrential downpours to part of the storm-ravaged Gulf Coast region this week.
The good news for Gulf Coast residents recovering from Hurricane Ida is that another powerful hurricane does not appear likely to develop. Unfortunately, flooding downpours are expected for some of the hardest-hit regions whether or not a new tropical depression or storm takes shape.
Flash flood watches were in effect Monday for parts of Louisiana including around New Orleans and Houma. More than 495,000 customers remained without power in the state eight days after Ida's landfall, according to PowerOutage.US.
A broad area of disorganized clouds, showers and thunderstorms, dubbed Invest 91L by the National Hurricane Center, has been bubbling up and dissipating through Sunday near southeastern Mexico and the southern Gulf of Mexico. More grouping of the shower and thunderstorm activity was apparent on satellite imagery on Monday.
This image, taken at midday on Tuesday, Sept. 7, 2021, shows a gathering area of showers and thunderstorms over the central Gulf of Mexico. (CIRA at Colorado State/GOES-East)
Thus far, pockets of dry air and wind shear have been impeding further organization of this feature and may continue to do so through the middle of the week. However, there continues to be some indication that a weak area of low pressure will form in the Gulf. That low-pressure area is forecast to approach the area from Louisiana to the Florida Panhandle spanning Wednesday and Thursday.
Wind shear is likely to relax somewhat as the area of low pressure approaches the northeastern Gulf Coast and a small window for organization may open up at midweek, according to AccuWeather Meteorologist Randy Adkins said.
This low chance of development may continue through Thursday along the northeastern Gulf coast, even if the center of the low-pressure area drifts over marshy coastal land for a time.
AccuWeather meteorologists say that the same system will have an opportunity to organize and gain strength upon reaching waters along the coasts of northeastern Florida to the Carolinas late this week.
"As the low pressure drifts off the coasts of northeastern Florida and Georgia and moves over the Atlantic between the U.S. and Bermuda from Friday through this weekend, the chance of development is likely to increase to between 40 and 60%," Adkins explained.
Anticipated steering breezes should keep the low pressure from pushing very far to the north along the Atlantic coast this weekend. Downpours could expand northward along the Carolina coast for a time into Friday and perhaps early Saturday, just ahead of a new dip in the jet stream.
If a dip in the jet stream is slow to advance, then there might there be more room for the disturbance to crawl northward to the mid-Atlantic coast with heavy rain and gusty winds.
Regardless of how far to the north rain advances this week along the Atlantic coast, seas and surf are forecast to remain rough as swells propagate outward from powerful Hurricane Larry.
With the amount of moisture forecast to increase in proximity to the low pressure while it's over the Gulf of Mexico, downpours may become intense enough to lead to incidents of flash flooding from southeastern Louisiana, southern Mississippi and southern Alabama to southern Georgia and northern Florida from the middle to the latter part of this week.
A general 1-3 inches of rain is forecast to fall along the southeastern U.S. coast with local amounts to 5 inches possible. Heavier rain could unfold should the system ramp up to a tropical depression or possibly a tropical storm prior to pushing eastward across northern Florida.
If the system does develop into a tropical storm, it would take the name Mindy.
Travel along the Interstate 10 corridor in the Southeast states can be difficult at times due to showers and thunderstorms into Friday. Farther to the north, an old frontal zone will continue to lead to sporadic showers and thunderstorms from central Louisiana to the southern Appalachians into the middle of this week.
Additional threats, whether the system develops or not, include locally gusty thunderstorms and the risk of a few waterspouts as the feature travels eastward from the northeastern Gulf coast into Thursday to areas in northeastern Florida and coastal Georgia from Thursday night to Friday and perhaps part of Saturday.
Elsewhere in the Gulf of Mexico, enough of an area of disturbed weather may remain behind to raise a second concern for tropical development.
"Should wind shear decrease, there is the risk of tropical development centered over the southwestern Gulf of Mexico this weekend to early next week," Adkins said.
Elsewhere in the Atlantic, Larry will remain the most formidable tropical system in the basin into this weekend. The powerful hurricane is forecast to pass close enough to Bermuda to bring some rain and wind to the islands on Thursday and could track close enough to unleash significant rain and wind to Atlantic Canada, and and could make landfall on the islands of Newfoundland, early this weekend.
CLICK HERE FOR THE FREE ACCUWEATHER APP
There is another area on AccuWeather meteorologists' radar over the Atlantic in the long term.
"As disturbances continue to roll westward from the coast of Africa, there may be an opportunity for a robust tropical wave to organize this weekend near the Cabo Verde Islands," Adkins said.
Dry air was suppressing the upheaval of showers and thunderstorms to start this week, but there are some signs that the environment near the Cabo Verde Islands may have more moisture by Friday.
Tropical waves that emerge from Africa represent the backbone of the Atlantic hurricane season, and this wave train is at its peak during the month of September.
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For the latest weather news check back on AccuWeather.com. Watch AccuWeather Network on DIRECTV, DIRECTVstream, Frontier, Spectrum, fuboTV, Philo, and Verizon Fios. AccuWeatherNOW is streaming on Roku and XUMO.
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