Philippe Expected to Strengthen to a Hurricane as Tropical Storm Rina Weakens

The experts at the National Hurricane Center expected that Tropical Storm Rina would continue moving to the northwest through Sunday night. Then, they expect it to move more to the north on Monday. Winds from Tropical Storm Rina are moving out about 140 miles from the storm's center.

Tropical Storm Rina has stayed disorganized with deep convection sheared off well southeast of the center. The storm is not getting enough heat and moisture at elevations about four miles above the water to get organized.

Maximum center pressure is 29.39 inches.

Tropical Storm Rina Following Tropical Storm Philippe

Tropical Storm Rina is following along the same path as Tropical Storm Philippe. Tropical Storm Rina is about 550 miles east of Tropical Storm Philippe, making forecasting both storms more challenging. This sets up the conditions for the Fujiwhara effect.

While forecasters expect Tropical Storm Rina to fall apart, Tropical Storm Philippe could become more robust, impacting the northern Leeward Islands, the Virgin Islands and Puerto Rico during the first part of next week. As of Saturday morning, this storm is moving slightly southwest at about five miles per hour.

Fujiwhara Effect

The Fujiwhara effect is why forecasters expect Tropical Storm Rina to weaken. It should become a tropical depression by Sunday night and disappear a few days later without doing any damage to land. Meanwhile, Tropical Storm Philippe should become more vigorous and forming into a hurricane in the Central Atlantic Ocean.

As of Saturday morning, Tropical Storm Philippe was about 455 miles east of the Northern Leeward Islands. It had maximum sustained winds of 50 miles per hour, with some stronger wind gusts. Tropical storm-force winds extend out about 140 miles from the storm's center. The estimated minimum central pressure was 29.50 inches.

Image provided by NOAA

The proximity of the two tropical storms has caused the two storms to rotate around a common core. This has pushed Tropical Storm Rina more northwest than would typically be predicted.

Some forecasters argue that Tropical Storm Rina and Philippe do not exhibit a complete Fujiwhara Effect because the storms are very mismatched in size, with Tropical Storm Rina being much smaller than Tropical Storm Philippe.

Effect of Full Moon on Tropical Storm Rina

Tropical Storm Rina, except for the full moon effect, may not have formed. When a full moon occurs, the sun, Earth and moon are arrayed in a straight line, causing a stronger gravitational pull on the Earth. This effect causes a bulge in the ocean, making it easier for tropical storms to form as waves become taller and more robust. The last supermoon of 2023 occurred on Thursday night.

Busy Season in the Atlantic Ocean

Tropical Storm Rina is the 17th storm of 2023, which runs from June 1 to November 30. This is two more than average, despite a strong El Nino. The Madden-Julian Oscillation may be the cause behind the increase, which has already caused more tropical storms than in a complete average season. The Madden-Julian Oscillation is a wave that travels around the globe.

There is a disturbance at the top of the atmosphere, causing water to move upward more easily. These disturbances are more likely to form in August and September when wind sheer and atmospheric conditions are more favorable for tropical storm development.

When the wave arrived in the Atlantic Ocean, it encountered extremely dry conditions, causing storms to develop more easily by allowing air to rise more rapidly. Despite these conditions, wind shear also played a role by stopping storms from intensifying.

Therefore, Tropical Storm Rina has not had the chance to get well organized because wind sheer is spreading the storm in the upper atmosphere instead of letting it get better organized.

Tropical Storm Rina should dissipate over the next few days without impacting any land because of its location in the Atlantic Ocean. Forecasters expect it to become a tropical depression on Monday or Tuesday.

This storm has been affected by Tropical Storm Philippe, which may intensify and become a hurricane early next week. Tropical Storm Rina may have formed because of Madden-Julian Oscillation, but wind shear has stopped it from becoming well organized. Tropical Storm Rina is the 17th named storm of the 2023 hurricane season, which lasts until November 30. This is three more than occurs typically throughout the entire season.