The likelihood of another October Atlantic storm is fading rapidly » Yale Climate Connection

The tropical Atlantic has calmed down after a period of intense activity in early October, and we are observing two tropical disturbances with a low probability of developing into named storms. Hurricane Milton will likely end up being the last named storm in October. However, it’s not too early to close the books on the 2024 Atlantic hurricane season now as a pulse of the Madden-Julian Oscillation (MJO) is due to arrive in the Atlantic in early November, increasing the likelihood of rising air and tropical cyclone formation. morning.

94L near the Leeward Islands

On Thursday, a Cape Verdean disturbance in the mid-Atlantic known as “Invest 94L” was approaching the northern Leeward Islands westward at about 20 mph. Although this disturbance had mild wind shear and record warm ocean temperatures of 30 degrees Celsius (86°F), conducive to development, 94L was embedded in a very dry air mass, which kept severe thunderstorm activity limited, as the satellite shown in the loop. Its development was also hampered by its rapid advance, which made it difficult for the 94L to align the center of its upper deck with the center of its surface. Additionally, 94L is fighting an unfavorable configuration of the Madden-Julian Oscillation (MJO), which favors sinking air over the Atlantic Ocean.

By Saturday, 94L's development will face two major obstacles: increased wind shear, and potential interaction with Hispaniola's mountainous terrain. Models were less than enthusiastic about developing the 94L, with widespread predictions of its demise on Sunday. The disturbance could bring 1-2 inches (25-50 mm) of heavy rain to the Leeward Islands, Virgin Islands, Puerto Rico and the Dominican Republic Friday into Saturday.

In its Tropical Weather Outlook issued at 8 a.m. ET Thursday, the National Hurricane Center projected a 20 percent chance of 94L developing within two days and a 30 percent chance of developing within seven days. The next name on Atlantic’s list is Nadine.

Heavy rains hit parts of Belize and southeastern Mexico

There's a slim chance that a disturbance swirling around the Central American Gyre will develop into a tropical cyclone before making landfall this weekend, but it could bring dangerously large amounts of rainfall regardless. The disturbance, centered about 50 miles off the northeastern coast of Honduras, drifted northwest with a central pressure of 1,007 millibars and was surrounded by a disorganized series of showers and thunderstorms Thursday morning. Ensemble models agree that the disturbance will gradually move west or west-northwest and make landfall along the coast of Belize or the Mexican state of Quintana Roo around Saturday.

The system is in the relatively humid mid-atmosphere and its sea surface temperatures will reach around 29-30 degrees Celsius (84-86°F), but strong upper-level winds from the northwest will threaten high wind shear before the disturbance moves inland. Only limited time to develop. Only a few GFS cluster members, and even fewer European cluster members, develop the system into a tropical depression, or at best a weak tropical storm.

As of 8 a.m. ET Thursday, the National Hurricane System projected a 20% chance of the disturbance developing during the 2-day and 7-day periods, with these chances primarily in effect on Saturday before the system moves inland. Regardless of its conditions, the unrest could bring torrential downpours from southern and eastern Mexico to parts of Belize, Guatemala and Honduras, with rainfall amounts exceeding 15 to 20 inches in some locations, increasing the risk of mudslides and flash floods. threaten.

It's cyclone season in the northern Indian Ocean

There are two tropical cyclone seasons in the northern Indian Ocean – one concentrated in May, before the onset of the monsoon, and the other in October/November, after the monsoon has weakened. During the peak monsoon period from June to September, tropical cyclones are less common due to disturbances in the monsoon circulation. As the monsoon gradually weakens, the region's autumn cyclone season is likely to kick into full gear next week, helped by a favorable phase of the Madden-Julian Oscillation (MJO) for the region. Multiple models predict a tropical cyclone will form in the eastern Bay of Bengal on Monday and then move northwest or north over unusually warm waters: about 1 degree Celsius (1.8°F) above average. The MJO will also be favorable for typhoon development in the western Pacific next week (see tweet below).

According to the Joint Typhoon Warning Center, the most recent Category 3 or stronger cyclone to make landfall on the Bay of Bengal coast was Cyclone Moka, which struck Myanmar on May 14, 2023 as a Category 4 storm with winds of 155 mph. At 0 UTC on May 14, 8 hours before landfall, the Joint Typhoon Warning Center rated Mocha as a Category 5 storm with wind speeds of 175 mph, tying it with Cyclone Fani in May 2019 as the strongest ever recorded in the northern Indian Ocean. of tropical cyclones. Mocha killed 151 people and caused $2.3 billion in damage. Unfortunately, Myanmar has been engaged in a catastrophic civil war that has killed tens of thousands and displaced more than 1 million people after a 2021 military coup ousted the democratically elected government. Because of the war, Mocha's death toll should be considered unreliable.