The National Hurricane Center (NHC) is actively monitoring several significant weather events as tropical systems develop across the Atlantic and Pacific Oceans.
On Thursday morning, a tropical wave a few hundred miles west-southwest of the Cabo Verde Islands was designated as Invest 91L due to its increasing organization.
This wave is currently moving west-northwest at a speed of approximately 5-10 mph, showcasing a small area of heavy thunderstorms that exhibit a moderate degree of spin according to satellite imagery.
The system’s location, which is well south of the Saharan Air Layer’s dry air, is conducive for development.
With sea surface temperatures around 28 degrees Celsius (82°F) and light wind shear between 5-10 knots, conditions are favorable for further strengthening.
Major weather models support the system’s potential for development, indicating a likely formation of a tropical depression or tropical storm by the weekend.
The wave is expected to take a west to west-northwest trajectory, potentially impacting the Lesser Antilles Islands between September 10-12.
However, the potential threat it poses to the mainland U.S. will remain uncertain for several days.
This uncertainty largely hinges on the upcoming position and strength of a trough of low pressure expected to settle near the U.S. East Coast late next week.
If 91L strengthens into a hurricane early on, it may curve north and east, reducing the likelihood of landfall on the U.S. mainland.
Conversely, if it remains a weaker storm, it could present a greater long-term threat to the U.S. coastal areas.
In its 8 a.m. EDT Tropical Weather Outlook on Wednesday, the NHC assigned development odds of 50% over the next two days and 80% over the next week for Invest 91L.
The next name on the Atlantic storm list is Gabrielle.
Meanwhile, Tropical Storm Lorena, which was downgraded from hurricane status on Thursday morning, is anticipated to stall before making landfall.
Although weakened, the storm is expected to impact northwest Mexico and the western regions of the U.S. Sun Belt with heavy rainfall and flooding.
Having reached Category 1 hurricane status with winds of 85 mph on Wednesday night, Lorena has since faced high wind shear of 20-25 knots and cooler ocean waters, reducing its strength.
As of 11 a.m. EDT Thursday, the storm had weakened to 70 mph and was located about 125 miles (200 km) west-southwest of Cabo San Lazaro, Mexico, moving northwest at 8 mph (13 km/h).
Lorena is likely to weaken further into a remnant low by Friday night, positioning itself just off the sparsely populated coastline of Mexico’s middle Baja Peninsula.
The primary risk from Lorena and its remnants involves localized flash flooding and mudslides.
Ample moisture streaming inland is expected to generate widespread rainfall of 1 to 4 inches, with isolated areas potentially receiving up to 12 inches from central Baja California into coastal regions of Sinaloa and Sonora states.
While showers and thunderstorms will be less frequent across the far southwestern United States, heavy rain is still possible, especially in southeast California, southern Arizona on Thursday, and southern New Mexico on Friday.
Flood watches are currently in effect for various areas, urging motorists and hikers to remain cautious of rapidly filling dry washes due to hazardous runoff.
Despite the flooding concerns, the moisture from Lorena is welcomed since much of the region is under severe to extreme drought conditions, as highlighted by the latest U.S. Drought Monitor released on Thursday.
Additionally, in the Pacific, Major Hurricane Kiko continues to remain a significant storm, having peaked at Category 4 strength initially before undergoing an eyewall replacement cycle that decreased its top sustained winds to 130 mph.
As of the latest reports, Kiko was located far from land, nearly 1500 miles (2400 km) east-southeast of Hilo, Hawaii, and is progressing westward at 9 mph (15 km/h).
Kiko is gradually transforming into an annular storm characterized by a large core of intense showers and thunderstorms, coupled with minimal spiral banding.
This structural change is beneficial for Kiko’s longevity, as annular storms generally exhibit greater durability.
Forecasts indicate a decline in wind shear from 15 knots to around 5-10 knots from Friday into Sunday, with sea surface temperatures remaining stable at around 27 degrees Celsius (81 degrees Fahrenheit).
These conditions suggest that Kiko may retain its strength for several more days, potentially reaching another intensity peak on Thursday night before gradually weakening through the weekend as it shifts west-northwest.
As the week progresses, there is a rising chance that Hawaii may experience some impacts from Kiko.
Although higher wind shear and drier mid-level air are expected to invade the storm by Sunday and Monday, leading to significant weakening, the National Hurricane Center predicts that Kiko will still remain a tropical storm by Tuesday.
At that time, Kiko is anticipated to be approaching the Hawaiian Islands, but there exists a higher-than-usual uncertainty regarding the storm’s trajectory, meaning it could either miss the islands or move over or near them.
Residents and travelers in Hawaii are urged to monitor Kiko’s progress closely over the coming days.
image source from：yaleclimateconnections
