Major changes in the atmosphere are setting up a busy stretch of weather across the United States, with a tropical system drawing closer attention near Hawaii, another disturbance developing in the Atlantic, and a shifting thunderstorm pattern expected to keep parts of the Lower 48 unsettled through the end of the week.
Meteorologist Jonathan Kegges, host of the YouTube channel JustWeather, said the evolving setup includes a large area of high pressure building across the southern United States, repeated thunderstorm clusters riding around its northern edge, and growing tropical concerns in both the Pacific and Atlantic basins.
“There’s also a changing thunderstorm pattern in the Lower 48,” Kegges said, while describing a broader pattern that will separate very hot, relatively dry conditions in the South from stormier weather farther north.
Hawaii Could See Direct Tropical Impacts
Kegges said the Pacific system known as Invest 93C deserves particularly close attention because there is a growing chance that it could affect Hawaii directly, although he stressed that the forecast remains uncertain until a well-defined low-level center develops.
The disturbance was still spread across a broad, disorganized area of low pressure, which makes its eventual track difficult to determine because the center could consolidate in different locations within the larger circulation.
“If you’ve never watched any of my videos before, until we get a low-level center, it is going to be pretty much impossible to figure out where this thing is going to go exactly,” Kegges said.
He explained that if the center forms farther north, the system could track farther north, while a center that develops farther south could shift the eventual path in that direction.
One consensus model shown by Kegges brought the system across the Big Island and into other parts of Hawaii, while the Google DeepMind ensemble also showed several members passing near or directly over the Big Island and Maui.
Kegges cautioned against treating any one model solution as a final forecast, but said the clustering of possibilities was enough to raise concern.
“There is a growing chance that we do have direct impacts of a tropical system in Hawaii,” he said, adding that it remains too early to know exactly where the strongest effects would occur or how severe they might become.
Large Waves Could Reach The Islands This Weekend
Even if the system does not move directly over Hawaii, Kegges said rough surf could become a significant issue because model guidance was showing unusually large waves around the islands.
The European model solution he displayed took the system north of Hawaii, but still produced wave heights above 20 feet in some areas around the Big Island and Maui during the weekend.
If the eventual track shifts south instead, the highest surf would likely focus more heavily on southern-facing shores.
Kegges said the modeled waves looked considerably larger than those produced by the previous two tropical systems that only brushed the islands.
That means Hawaii could see meaningful ocean impacts even without a direct landfall, and the uncertainty in the storm’s exact organization makes the next several days especially important for people near the coast.
Atlantic Invest 92L Has A High Chance To Develop
Kegges also highlighted Invest 92L in the Atlantic, a tropical wave that emerged from Africa and is moving generally westward toward the Caribbean.
He said the European ensemble showed a very high probability of tropical development, with the model indicating better than a 90% chance that a tropical depression could form.
The system may approach the northeastern Caribbean around Monday, August 17, although Kegges said wind shear could help keep it relatively weak.
He noted that rainfall from a weaker tropical system could be beneficial in some locations, while emphasizing that stronger development would obviously bring greater concerns.
Another disturbance, Invest 93L, was also becoming better organized farther north in the Atlantic, but Kegges said that system appeared much less likely to affect land.
His focus was clearly on 92L as the Atlantic feature with the more meaningful potential over the coming days.
Thunderstorms Will Ride Around A Growing Heat Dome
Across the Lower 48, Kegges said the weather pattern is reorganizing around a large area of high pressure building over the southern Plains and Deep South.
Rather than thunderstorms developing beneath the center of the ridge, where sinking air tends to suppress storm formation, they are expected to form along its outer edge and then move around it.
Kegges referred to these systems as “ridge riders.”
The resulting storm track is expected to stretch from parts of the Southwest and central Plains through the Midwest and toward the Ohio River Valley.
Wednesday is expected to bring another cluster of thunderstorms from the Dakotas into Minnesota before the activity rides southeast around the ridge.
By Thursday morning, Kegges said another round could reach Illinois and continue into the Ohio Valley, an area that has already dealt with repeated episodes of severe weather this year.
“Illinois can’t catch a break this year in terms of severe weather,” he said.
The pattern is expected to remain in place for several days, meaning individual rounds may come and go while the broader setup changes very little.
Flash Flooding Remains A Concern In The West
Farther west, Kegges said the monsoon pattern remains active across Arizona and New Mexico, where scattered thunderstorms could produce very heavy rainfall in localized areas.
That keeps the threat of flash flooding in place, particularly where storms repeatedly develop over the same terrain or dump intense rain over normally dry washes and low-lying areas.
The heaviest seven-day rainfall pattern shown by Kegges extended from the Southwest northeastward toward the Ohio Valley, reflecting the way storms are expected to travel around the developing ridge.
This is a good example of how one large-scale atmospheric feature can produce very different weather depending on location. Areas beneath the high pressure remain hot and comparatively dry, while locations along its edge repeatedly encounter thunderstorms and heavy rain.
Heat Builds Across The South Into The Weekend
Underneath the ridge, temperatures are expected to climb substantially across the Gulf Coast, southern Plains and Southeast as the week progresses.
Kegges pointed to forecast highs around 97 degrees in Houston, 101 in Oklahoma City and 96 in Atlanta, while locations farther north remained noticeably cooler.
The heat is expected to strengthen through Friday and into the weekend as the high-pressure system expands.
That temperature contrast between the very warm South and relatively cooler air farther north also helps maintain the boundary where thunderstorms can repeatedly form.
By Thursday, the high-pressure cell is expected to become more established along the Gulf Coast, with storms continuing to fire around its outer edge while much of the region underneath stays dry.
Kegges said that pattern should become even more pronounced heading into Friday and the weekend.
A More Active Pattern Is Taking Shape
Taken together, Kegges’ forecast shows several parts of the weather map becoming more active at the same time, although for very different reasons.
Hawaii is watching a still-developing Pacific disturbance that could bring direct impacts or at least very large surf, while the Atlantic has another tropical wave with a strong chance of organization as it moves west.
Across the continental United States, the growing southern heat dome is expected to lock thunderstorms into a repeated track from the northern Plains and Midwest toward the Ohio Valley, while monsoon moisture keeps flash-flood concerns alive in parts of the Southwest.
The common thread is that the atmosphere is settling into a more organized and persistent pattern rather than a brief one-day event, which means some regions may see the same type of weather repeated several times before conditions meaningfully shift.
For the next several days, Kegges’ message is largely one of continued monitoring, especially in Hawaii and along the storm corridor wrapping around the heat ridge, where relatively small changes in position could determine which communities see the strongest impacts.
Mark grew up in the heart of Texas, where tornadoes and extreme weather were a part of life. His early experiences sparked a fascination with emergency preparedness and homesteading. A father of three, Mark is dedicated to teaching families how to be self-sufficient, with a focus on food storage, DIY projects, and energy independence. His writing empowers everyday people to take small steps toward greater self-reliance without feeling overwhelmed.
