Cyclogenesis off Uruguay and southern Brazil

Filter by


EUMETSAT Users Twitter

RSS Feed

RSS Icon Image Library

Explosive cyclogenesis off the Uruguay coast and near southern Brazil in early April could be seen in satellite imagery.

Date & Time
2 April 2020 15:50 UTC and 29 April 13:20 UTC
Airmass RGB, Solar RGB

By Néstor Santayana (INUMET) and José Prieto (EUMETSAT)

On 2 and 3 April, a cyclogenesis with explosive characteristics developed near the coast of Uruguay and southern Brazil. It deepened intensely, reaching 19 mb in 24 hours with a centre of less than 985 hPa.

Image comparison
GOES-16 Solar RGB GOES-16 Airmass RGB
Figure 1: GOES-16 composites for ABI channels around 1.6 µm,0.8 µm,0.5 µm (left) and Airmass RGB (right), 2 April 15:50 UTC.

This is the first extratropical cyclone with storm characteristics in 2020, near the coasts of Uruguay. Wind gusts reached 100 km/h on the coasts of the Departments of Canelones and Maldonado, and a even higher in the Department of Rocha (104 km/h). Cyclones are more common during the austral winter (from June to August) and the transition to spring.

The cyclone shown on the GOES-16 imagery on 2 April, caused an increase in the size of waves due to the persistent fetch wind from the southwesterly direction for at least 24 hours. Some houses in the coastal town of Aguas Dulces (Rocha) were badly damaged. Trees and electricity posts were also pulled down, the latter affecting more than 10,000 customers.

Well into the winter, on 30 June, prefrontal instability following a line pattern, with winds of 90-130 km/h, created a 400 km swath of damage in the southern states of Brazil and killed 12 people. The event can be characterised as a 'derecho' (explanation in Spanish), with downbursts, induced by, but separate from, the explosive cyclogenesis on the synoptic scale. The explosive cyclogenesis is rather a sudden drop of the surface pressure.

Figure 2 shows the GOES-16 airmass and phase depictions of the phenomenon. The most northern cloudy area over the south of Brazil gave birth to the derecho.

Image comparison
GOES-16 Airmass RGB GOES-16 phase-solar RGB
Figure 2: GOES-16 ABI airmass RGB (left) and phase-solar RGB (right) for 30 June at 17:10 UTC. The phase-solar RGB is based on R=0.86 µm-1.6 µm, G=0.8 µm, B=0.64 µm-0.86 µm.

Between April and June that area recorded at least 11 cyclogenesis events, most of them following the same pattern. As did another instance on 29 April, as shown on Figure 3.

Figure 3
Figure 3: Clockwise from upper left: Cloud phase composite, natural, colour-enhancement of 10.3 µm and Airmass at 13:20 UTC on 29 April.

Related content

We use essential cookies to ensure that we give you the best experience on our website. To analyse website traffic we also use third-party performance cookies. If you are ok with the use of essential as well as non-essential cookies, please select Accept & Continue. Instructions on how to prevent the use of non-essential cookies are available under our Terms Of Use, or simply select Decline Cookies.