Tropical Depression 18 Expected to Become Caribbean Hurricane Rafael » Yale Climate Relations

A hurricane warning flag has been hoisted in the Cayman Islands and a hurricane watch has been activated for western Cuba in response to Tropical Depression 18, which formed over the warm waters of the western Caribbean at 10 a.m. ET on Monday. TD 18 is expected to intensify into Tropical Storm Rafael on Monday night before impacting Cuba as a Category 1 hurricane on Wednesday morning.

TD 18 in organizational stage

At 10 a.m. ET on Monday, November 4, TD 18 was located 400 miles (645 kilometers) southeast of Grand Cayman Island, moving north at 6 mph (15 km/h), with maximum sustained Winds were 35 mph (55 km/h), with maximum sustained winds of 35 mph (55 km/h). Satellite imagery shows that TD 18 is not yet well organized, with a small number of severe thunderstorms, but is gradually becoming more organized. Conditions were very favorable for development, with wind shear speeds of 5-10 knots, a very humid atmosphere, very warm sea water, and temperatures of 30 degrees Celsius (86°F) – about 0.5 to 2 degrees Celsius (1-2°F) earlier than average in early November Temperatures are warm.

PTC 18 has been renamed TD18 after Air Force Hurricane Hunters confirmed clear circulation center @53rdWRS. This is a satellite loop from TD 18 showing the circulation tightening south of Jamaica. There is currently no change in trajectory/intensity. #FLKeys #FLwx #floridakey pic.twitter.com/q2Xxts8Blu

— NWS Key West (@NWSKeyWest) November 4, 2024

Western Caribbean TD 18 Forecast

A ridge of high pressure to the northeast of TD 18 will keep the storm moving mostly northwestward through Thursday, with the center of the storm about 50-80 miles (80-130 kilometers) west of Jamaica late Tuesday morning through Tuesday Heading to the Cayman Islands in the evening before entering western Cuba on Wednesday morning. Development conditions during this period are expected to be very favorable, with low wind shear, warm seawater, high heat content, and a very moist atmosphere. This could result in stable to rapid intensification (unless TD 18 flies close enough to Jamaica for significant land interactions to occur). The 6Z Monday run of the HWRF, HMON, and HAFS-A dynamic hurricane models predicts that TD 18 will become a borderline tropical storm/Category 1 hurricane by Wednesday morning and is expected to make landfall in western Cuba. The HAFS-B model is more aggressive, predicting a Category 3 hurricane to make landfall in Cuba. The 12Z Monday SHIPS model shows TD 18 will strengthen to Category 2 winds in the southeastern Gulf of Mexico with 110 mph winds by Thursday morning, with a 34% chance.

Impact of TD 18 on Cuba

TD 18 is expected to make landfall in Cuba at an inopportune time, as Cuba's largest power plant, the Antonio Guitras Power Plant, suffered a nationwide blackout from October 18 to 21 and the country's power grid continues to be unstable. The plant is located about 60 miles (95 kilometers) east of Havana and likely about 100 miles east of the TD 18 core, thus shielding it from the storm's significant impact. However, Cuba's power infrastructure is weak, and the possible widespread blackouts in western Cuba may last for a long time, and the national power grid may be at risk of collapse.

Conditions in the northern Gulf of Mexico are even harsher

Crossing western Cuba could disrupt TD 18, but once the storm enters the Gulf of Mexico, it is expected to move northwest over warm waters associated with 27-28 degrees Celsius (81-82°F). The circulation extends north from the western Caribbean into the Gulf of Mexico. middle part. By Thursday, all four high-resolution dynamic hurricane models had TD 18 becoming at least a Category 2 hurricane in the central Gulf. The intensity of TD 18 will help determine where the storm will go, and that uncertainty is why the track forecast for TD 18 in the Gulf region has higher uncertainty than usual, the National Hurricane Center commented during a discussion at 10 a.m. ET Part of the reason is sex. The GFS model and its ensemble members predict that TD 18 will continue to move northwest and make landfall near Louisiana later this week. The UKMET model and the European model and their ensemble suggest a westward turn in the Gulf of Mexico south of the northern Gulf Coast (see tweet below).

The further north Rafael pushed in the Gulf of Mexico, the less favorable conditions became for development. In recent weeks, recurring fall cold fronts have spread cold air over the bay, causing the water to cool significantly. Water temperatures within about 200 miles (320 kilometers) of the northern Gulf Coast have dropped below 26 degrees Celsius (79°F). What's more, the jet stream has shifted more southward in recent weeks, so the TD 18 will encounter high wind shear of 20-30 knots as it approaches the U.S. coast. In addition, very dry air is expected to develop in the North Gulf later this week, with a relative humidity of 40-45%.

The combination of high wind shear, dry air, and cooler ocean temperatures may cause steady to rapid weakening, and none of the highest intensity models show TD 18 hitting the United States as a hurricane. The main concern is that, assuming TD 18 moves into the central Gulf Coast, heavy rainfall could occur across the southeastern United States: the storm is expected to bring unusually large amounts of atmospheric moisture in early November. By later this week, there will be more clarity on where and how much rain will fall.

Another riot could hit Bahamas and South Florida next weekend

The tail of the northwest Atlantic cold front may try to organize into a tropical disturbance later this week that will move west-northwest toward the Bahamas and South Florida. Some members of the European and Global Flight Services model ensembles show modest development of this disturbance as it moves south of the unusually strong upper high pressure over the southeastern United States and northwest Atlantic Ocean, which will also guide Rafael. Confidence in the steering pattern is relatively high, and sea surface temperatures remain unusually warm—enough to support tropical cyclones. However, wind shear and upper-level wind structure will be less than ideal, and ensemble models strongly suggest that there is likely to be only modest development, perhaps an extended period of gusty winds and poor sea conditions that will plague the western edge of the region as TD 18 passes of the Gulf of Mexico.

In the Tropical Weather Outlook issued at 7 a.m. ET on Monday, the National Hurricane Center projected that the future system would have a 20% chance of developing into at least a tropical depression within seven days, and an almost zero chance within two days.

Patty transitioned from subtropical storm to tropical storm to residual depression in less than a day

Far from the tropics, a large area of ​​low pressure behind a cold front in the Northeast Atlantic gathered enough showers and thunderstorms to become Subtropical Storm Patty early Saturday. Early Sunday, Patty's top winds reached 65 mph as it moved through the Azores without significant impact, then briefly gained enough deep circulation, symmetry, and concentrated convection to clear the path early Sunday at 1:00 pm EDT. It became Tropical Storm Patty at 10 p.m. But colder waters and increasing wind shear soon took their toll, and at 10 a.m. ET Monday, the National Hurricane Center reclassified Patty as a remnant depression.

The aftermath of Patti will move poleward near the western Iberian Peninsula on Tuesday, potentially bringing one to three inches of rain along and near the coasts of northwestern Portugal and Spain. Fortunately, rain is still expected to stay away from flood-ravaged areas of Valencia in eastern Spain.