The Central American tour could cause dangerous floods. Could it also cause tropical growth? | The Weather Channel – Articles from The Weather Channel

  • A large low-pressure vortex is expected to form over Central America.
  • These “rounds” often cause dangerous, life-threatening floods there.
  • Sometimes, these high speeds can also cause tropical depression and thunderstorms.
  • The probability of this happening in the Caribbean seems very low, for a number of reasons.

Weeks before the official start of the Atlantic hurricane season 2022, a low-pressure system could bring flooding to Central America, but its chances of causing the first tropical depression or storm in the Caribbean are very low – at present.

We understand if this can get you a little trouble-free. It’s just May. But there is a regulated scenario that can sometimes lead to tropical growth.

First, a large, wide area of ​​low pressure is expected to form over Central America in the coming days, something meteorologists refer to as the Central American Round, or CAG.

These CAGs are formed more often than May to June and again from October to Novemberbut it can happen at any time in the next six months.

Why CAGs are important for growth

These CAGs can generate or affect tropical storms in the Caribbean, the Gulf of Mexico, or the eastern Pacific.

Two years ago, such a CAG was also created in late May.

It pushed tropical storm Amanda of the eastern Pacific inland into Guatemala, and then drove its remnant into Campeche Bay, where tropical storm Cristobal soon formed. The CAG forced Cristobal to make a strange noose over southeastern Mexico before Cristobal finally turned north toward the Gulf Coast on June 7, 2020.

About 50 percent of CAGs have a tropical cyclone associated with them, Philippe Papin, a hurricane specialist at the National Hurricane Center and a CAG expert, told

“When a tropical cyclone occurs, it tends to form on its east side [gyre] “and it rotates counterclockwise around the largest traffic,” Papin said.

This suggests a prominent computer forecasting model – the Global Prediction System (GFS) – that could happen in its various updates from the end of last week.

Although this sounds a bit daunting, there are potential issues with predicting this model.

First, while the GFS model can detect tropical storm formations in the western Caribbean, also has a high rate of false alarms. This means that this particular model will often predict tropical growth that does not end up happening.

Other forecasting models, such as one from the European Center for Medium-Term Weather Forecasting (ECMWF), suggest that the CAG could focus further west over Central America or the Eastern Pacific, making growth prospects higher in the eastern Pacific and the Pacific. sea.

Even at the slightest chance of a tropical depression forming in the Caribbean, he faces two other obstacles.

First, wind shear in the Gulf of Mexico and the northwestern Caribbean is strong, as one would expect in May. This variable wind speed and direction with height usually dissolves the tropical disturbances they are trying to organize.


Current wind shear

Areas with clouds appear white. Areas with strong wind shear, the difference in wind speed and direction with altitude, appear in purple. Wind shear is hostile to mature tropical cyclones and those trying to develop.)

Second, there is an air boost coming from the Sahara Desert heading across the Caribbean Sea in the coming days.

Known as the Sahara Air Layer (SAL), these dry, steady, dust-laden western waves suppress storms, the building blocks needed to form a tropical depression. Part of this air may be in place over the western Caribbean by the weekend.


Water vapor satellite image

(Areas with drier air appear as darker orange and red. Areas with deeper humidity appear with white to purple to green shading. In this case, drier air is pushed into the Caribbean by a layer of Saharan air.)

The bottom line is that at the moment, we are not worried in this case about a tropical depression or storm forming in the Caribbean Sea in this setting.

Dangerous flood threat regardless

As the high low is above or near Central America, it could wrap deep moisture in areas from southeastern Mexico to Panama next week.

Some areas could find more than 6 inches of rain, especially on windy mountainous terrain.

This could lead to life-threatening floods and mud landslides.


Possibility of rainfall

(This should be interpreted as a broad perspective on where the heaviest rain may fall. Larger amounts may occur when the rain zones stop for a period of a few hours, especially near higher ground.)

CAGs were notorious producers of flash floods, often with fatal consequences.

The combination of Amanda, Cristobal and CAG for nine days rained down to 34 inches of rain in southeastern Mexico, 42 inches in El Salvador and 26 inches in Guatemala. Forty-three deaths were attributed to floods or landslides in Central America.

In early October 2017, a CAG gave birth to Hurricane Nate, which landed in Category 1 land along the Mississippi Gulf Coast.

But Nate’s early stage as a tropical depression and hurricane, combined with the CAG, soaked Central America. In some parts of Costa Rica, 10 to 19 inches of rain fell.

Floods and mudslides have killed 44 people and destroyed thousands of homes, especially in Costa Rica and Nicaragua, according to a final report by the National Hurricane Center.

Floods are observed in San Jose, Costa Rica, on Thursday, October 5, 2017, as Tropical Storm Nate brings dangerous torrential rains to the area.  (Twitter / @ JorgeAlfaroCR)

Floods are observed in San Jose, Costa Rica, on Thursday, October 5, 2017, as Tropical Storm Nate brings dangerous torrential rains to the area.

(Twitter / @ JorgeAlfaroCR)

In 2005, Hurricane Stan disappeared over the mountains of central Mexico, but its remaining rotation became part of a larger wheel that caused heavy rainfall in Central America.

While the immediate release of Stan resulted in about 80 deaths, severe flooding and mud landslides on the tire cost about 1,000 to 2,000 lives across Central America, according to the National Hurricane Center.

The Weather Company’s primary journalistic mission is to report breaking weather, the environment and the importance of science in our lives. This story does not necessarily represent the position of our parent company, IBM.

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