Strong winds, heavy rain and floods in Uruguay

Strong winds, heavy rain and floods in Uruguay

9–19 June 2019, Various times

Strong winds, heavy rain and floods in Uruguay
Strong winds, heavy rain and floods in Uruguay

Torrential rain hit central Uruguay in June 2019, causing serious flooding.

Last Updated

20, November 2020

By Néstor Santayana (INUMET), Jose Prieto (EUMETSAT) and Sancha Lancaster (Pactum)

More than 8,000 people were displaced due to flooding caused by heavy rains and winds of up to 95 km/h, with peaks of up to 105 km/h in Punta del Este. The Meteosat-11 Coloured HRV (Figure 1) shows one of the systems which brought the heavy rain.

 Meteosat-11 Coloured HRV, 16 June 17:00 UTC
Figure 1: Meteosat-11 Coloured HRV, 16 June 17:00 UTC
 
 Precipitation anomaly in June 2019, reaching above 200 mm in central areas.
Figure 2: Precipitation anomaly in June 2019, reaching above 200 mm in central areas.

June 2019 was a very rainy month across Uruguay, particularly in central and eastern parts, where rainfall amounts between 200–430 mm were recorded.

Chamangá, in the Flores Department, recorded 430 mm (mainly in seven days — its highest rainfall amount in 100 years; while in the far north, in the city Artigas, only 30 mm was recorded. Figure 2 shows the distribution of the precipitation anomaly.

The main episode of precipitation occurred from 11–18 June. The right-hand panel on Figure 3 shows the amount of precipitable water, which reached 35–45mm above Uruguay, these amounts are considered high for winter.

The left-hand panel of Figure 3 shows a warm air mass advected from the northwest (low level jet) generating a pattern of surface temperature anomalies — high temperatures in what is usually the coldest month of winter.

 Surface temperature (left) and column water during the rainy period (11–18 June)
Figure 3: Surface temperature (left) and column water during the rainy period (11–18 June)
 

The animation in Figure 4 shows HRV images of the cloud distribution around 15:00–16:00 UTC (Noon local time), during the peak period of precipitation.

Under a weak, almost neutral El Niño–Southern Oscillation (ENSO) (3.4) and a positive Antarctic oscillation (which limits cold air at high latitudes), a low pressure system with a pronounced trough at medium levels on the surface of central Chile and Argentina sat over the Andes.

Figure 4: Meteosat-11 HRV animation, 10–18 June, at 17:00 and 18:00 UTC

The animation in Figure 5 shows Meteosat Dust RGB images during the peak period and the animation in Figure 6 shows the cloud tops from Meteosat channel 10.8 µm, with sliced colour, not producing very cold convection. Most of the precipitation was of a stratiform origin.

Figure 5: Meteosat-11 Dust animation, 9 June 00:00 UTC–18 June 23:00 UTC
Figure 6: Meteosat-11 coloured 10.8µm channel animation, 9 June 00:00 UTC–18 June 23:00 UTC

For comparison, Figure 7 shows the superior spectral and horizontal resolution by GOES-16 for that region. The temporal resolution is also better, 10 minutes for GOES and 15 minutes for Meteosat-11.

 GOES-11 (left) and Meteosat-11 (right) depiction of the Dust RGB on 12 June 02:00 UTC. Colours are enhanced and GOES uses four rather than three channels for the RGB composition.
Figure 7: GOES-11 (left) and Meteosat-11 (right) depiction of the Dust RGB on 12 June 02:00 UTC. Colours are enhanced and GOES uses four rather than three channels for the RGB composition.
 

The blocking configuration ultimately led to an extratropical cyclone south-east of Uruguay on 19/20 June, with a peculiar secondary vortex born inside the main one (see Figure 8).

 
 Meteosat-11 Airmass RGB with the location on 19 June for the humid air (cloudy part at the bottom) and the dry air intrusion (red hues in the centre), with a double circulation inside the vortex.
Figure 8: Meteosat-11 Airmass RGB with the location on 19 June for the humid air (cloudy part at the bottom) and the dry air intrusion (red hues in the centre), with a double circulation inside the vortex.
 

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