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Inmet issued an orange danger alert for storms on the May 1st holiday in 534 cities in Santa Catarina and Rio Grande do Sul. The warning starts at 3 AM this Friday and continues until 12 PM on Saturday (2). Up to 100 mm of precipitation per day, intense winds of up to 100 km/h, and hail are expected. An extratropical cyclone in the Atlantic Ocean drives the cold front that causes instability and puts five states on alert.
An extratropical cyclone is advancing over Brazil and will turn the Labor Day long holiday into a test of endurance for 534 cities in Santa Catarina and Rio Grande do Sul. Inmet (National Institute of Meteorology) issued an orange danger alert for storms with up to 100 mm of precipitation per day, intense winds of up to 100 km/h, and hail. The warning starts at 3 AM this Friday (1st) and continues until 12 PM on Saturday (2nd), a period when millions of Brazilians will be traveling or engaged in outdoor activities.
The risks are concrete: power outages, crop damage, falling trees, and floods. The extratropical cyclone forms in the Atlantic Ocean and drives a cold front that advances through Southern Brazil, creating conditions for severe storms that can affect 10 regions of both states simultaneously. Inmet advises the population not to shelter under trees during wind gusts, avoid parking near transmission towers, and turn off electrical appliances and the main power panel if possible.
The 534 cities on alert and the 10 affected regions
The Inmet alert covers 534 municipalities distributed across 10 regions of Santa Catarina and Rio Grande do Sul. In the Gaúcho territory, the most exposed areas include the Northwest, West Central, Southwest, Metropolitan Porto Alegre, Southeast, Northeast, and East Central Rio Grande do Sul. In Santa Catarina, the West, Serra, and Southern Santa Catarina are under the same danger warning.
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The scope of the alert indicates that practically the entire southern half of Brazil will be affected to some degree by the storms. Cities such as Porto Alegre, Chapecó, Lages, Passo Fundo, and dozens of smaller municipalities enter the risk period, and the coincidence with the long holiday weekend increases concern because many people are away from home, on roads, or in leisure areas where exposure to bad weather is greater.
Winds of 100 km/h and what they can cause
Wind gusts of up to 100 km/h represent enough force to knock down large trees, rip off roof tiles, topple advertising signs, and damage light structures such as sheds, tents, and temporary coverings. In rural areas, winds of this intensity can destroy entire crops, especially crops that are in the harvesting phase or that are tall, such as corn and tobacco. The impact on agriculture can generate losses that add to urban damage.
For those on the road during the long holiday weekend, 100 km/h winds combined with intense rain drastically reduce visibility and increase the risk of hydroplaning. Tall vehicles such as trucks, motorhomes, and trailers are particularly vulnerable to side gusts that can destabilize the vehicle and cause accidents. The advice is to reduce speed, maintain a safe distance, and, if possible, stop in a safe place until conditions improve.
Up to 100 mm of rain in a single day
The 100 mm of precipitation predicted by Inmet is equivalent to 100 liters of water per square meter in 24 hours, a volume that exceeds the drainage capacity of many cities and causes flooding in urban areas with precarious infrastructure. Rivers and streams can overflow rapidly, especially in mountainous regions where the slope accelerates runoff and concentrates large volumes of water in a short period of time.
Intense rain combined with strong winds and hail creates a scenario of severe storm that requires heightened attention from Civil Defense and residents of the 534 cities on alert. Areas historically vulnerable to floods in Rio Grande do Sul and Santa Catarina should be monitored from the early hours of Friday morning, when the Inmet warning comes into effect and conditions begin to deteriorate.
The extratropical cyclone driving the cold front
The extratropical cyclone causing the storms forms in the Atlantic Ocean and pushes a cold front over Southern Brazil. The system is intense enough to alter meteorological conditions in five states, including not only Rio Grande do Sul and Santa Catarina, but also Paraná, São Paulo, and Rio de Janeiro in the following days. The combination of an oceanic cyclone with a continental cold front creates atmospheric instability that fuels the storms and sustains the rain for prolonged periods.
Unlike isolated storms that pass in a few hours, the frontal system associated with the cyclone can maintain adverse conditions for more than 24 hours in the same region. Inmet has set the alert period between 3 AM on Friday and 12 PM on Saturday, totaling 33 hours of potentially dangerous conditions. For those planning outdoor activities during the long holiday weekend, the recommendation is to reschedule or have covered alternatives available.
How to protect yourself during the holiday weekend storms
Inmet’s guidance is clear for the population of the 534 cities on alert. During wind gusts, do not take shelter under trees due to the risk of falling branches and lightning strikes. Avoid parking vehicles near transmission towers and advertising signs that can be knocked down by the wind. Unplug electrical appliances and the main power panel to prevent damage caused by grid fluctuations.
In case of emergency, Civil Defense can be called at 199. For residents of areas at risk of landslides or floods, the guidance is to leave home preventively and seek shelter in safe locations indicated by the city hall. The Labor Day holiday weekend coincides with one of the most widespread storms of the year, and early preparation can be the difference between a scare and a tragedy.
Is your city among the 534 on storm alert this holiday weekend, or did you manage to escape the cyclone? Tell us in the comments what the weather is like in your region and if you changed your plans because of Inmet’s warning.
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