South America Forecast Discussion

Ciclogenesis e imagenes satelitales

By: sasastorm, 6:35 PM GMT on October 31, 2012

When thinking of cyclones, often the first images that come to mind are those from satellite imagery. However, we typically use numerical models, not satellite imagery, to look for cyclogenesis (the initial development and strengthening of a surface cyclone) and then look at surface variables for indications that it has occurred. Why don't we just look for cyclogenesis on satellite imagery since that is what we tend to think of when it comes to cyclones? To help in this regard, we will explore satellite patterns associated with extratropical cyclogenesis.

Having a basic understanding of extratropical cyclone development is helpful before moving to a satellite perspective. Cyclones tend to form along pre-existing fronts (baroclinic zones), with the approach of an upstream mid- to upper-tropospheric perturbation. The surface baroclinic zone kinks, creating a cyclonic circulation and a cyclone is born. me/2012305/crefl2_143.A2012305092500-2012305093000 .2km.jpg

Below, we will examine primary cyclogenetic features as viewed on satellite imagery.

Cyclogenesis can have different intensity and different depths. Summarizing is easy to understand words; cyclogenesis can form in two ways:

1 - If the advance of a mass of cold, dry air over the continent meets another warm characteristics, their interaction begin to cause a rapid decrease in pressure.
This decrease is due to the warm air mass is forced to ascend and positioned parallel to the cold face. The air ahead of the cold front begins to push and create a cyclonic rotor ends sometime for independence of the low pressure system associated with the advancing cold air.

2 - The second and more likely to occur, is due to a disturbance of mid-level cold air begins to generate promotions as air sinks. This rise is maintained with the addition of warm, moist air north and cold, dry air south.

Cyclogenesis in Uruguay 2012-10-19

In a satellite image is very distinct pattern of cold, dry air due to the formation of clouds fragmented type, while in front of the low observed a thick layer of clouds.
The surface winds associated with the rotating hands of a clock and always tangential one. That is why the greatest intensities are located ahead and behind.

for more severe weather forecast see Link



South America Forecast Discussion

By: sasastorm, 9:53 PM GMT on October 24, 2012

During the 2012-2013 summer in Soth America the main concerns in Argentina and around the world are linked to two parameters, temperature and precipitation.
As we know exists in the atmosphere a pattern of movement that is not isolated from what is happening in the ocean or land. These interactions are known as teleconnections and is nothing more than a mathematical representation of atmospheric and oceanic systems.
One such teleconnections directly affects the forecast long-term weather in South America and is known as ENSO (El Niño South Oscillation) forecasts predict a weak Niño phase or neutral phase for December-January-February

The Southern Oscillation Index (SOI) is one measure of the large-scale fluctuations in air pressure occurring between the western and eastern tropical Pacific (i.e., the state of the Southern Oscillation) during El Niño and La Niña episodes. Traditionally, this index has been calculated based on the differences in air pressure anomaly between Tahiti and Darwin, Australia. In general, smoothed time series of the SOI correspond very well with changes in ocean temperatures across the eastern tropical Pacific. The negative phase of the SOI represents below-normal air pressure at Tahiti and above-normal air pressure at Darwin. Prolonged periods of negative SOI values coincide with abnormally warm ocean waters across the eastern tropical Pacific typical of El Niño episodes. Prolonged periods of positive SOI values coincide with abnormally cold ocean waters across the eastern tropical Pacific typical of La Niña episodes.

and SST

But this is not the only one to take into account that affects South America, the other is known as Maiden MDJ or Julian Oscillation. This last, very little known by the general public is a pattern in the atmosphere, which originates in the Indian Ocean and begins a long journey and throughout the South Pacific to lead. is a pattern that repeats every 45-60 days and causes rainfall contribution from the Pacific

so is we see the last map, we can forecast a very rainy end of January on Argentina coast. Finally wwe can make a Summer map to Argentina according to

Anomaly Temperature Maps Forecast

you can found more information and the summer maps on Link

Climate Change Blizzard


About sasastorm

Bachelor on science Atmosphere and Ocean. The EwsSat is a system to prevent people about the most several weather; specially on USA an Argentina.

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