 Credit: College of DuPage GOES 16 DISCUSSION: While the summer heat takes hold across portions of the Northern Hemisphere, the Southern Hemisphere is dealing with winter and in some locations snow. The longest continental mountain range in the world runs across the western coast of South America. With the length over 4500 mi, and the highest peak over 22,800 ft, the Andes mountains are impressive. While the Southern Hemisphere receives much less snow than North America, the next several days will feature snowy conditions across portions of the Andes, mainly in Chile and Argentina. Image Set 1 Description: The first two images are model representations for the afternoon/evening hours South America local time on Tuesday, or 18Z. Circled in the bottom left of both images is the disturbance that produces the first significant shot of snow and moisture. The 500 mb map, first image, shows a short-wave trough (inverted because of the Southern Hemisphere) while the second image shows the induced deep mid latitude cyclone just downstream of the 500 mb trough. The surface pressure pattern and simulated precipitation rate are depicted in the second imagery showing rain along the coast and snow across the higher elevations. Image Set 2 Description: These next two images represent overnight Thursday. By this time a much deeper trough dove south and is now paralleling the coast. The 500 mb pattern shows not only the intense energy associated with this system via the vorticity, but also the strong winds with 50+ knots across the region. The surface pattern in the following image shows the precipitation once again with intense snows continuing along a narrow band with other areas of snow across the general area. Let’s look at the atmospheric setup that will produce these snows. A disturbance with an associated cold front moved through on Monday, June 24th and set the stage advecting in a cold air mass and producing snow. The next short-wave trough is currently diving into the region Tuesday, June 25th and develops an intense mid latitude cyclone. This system tracks across far southern South America inducing rain and snows across Chile and Argentina as a moisture surge pushes into central and southern portions of the Andes. Snow has fallen with more heavy snow being modeled on the way. The next system is a large, slow-moving upper level system with a reinforcing shot of cold air. Impressive energy aloft (500 mb vorticity and strong winds), a strong jet streak (upward motion), along with the terrain (the mountains provide a source of low to mid-level upward motion), create the perfect scenario on the large scale for heavy precipitation. All levels of the atmosphere come together to produce a long lasting rather heavy snow event for regions of the Andes. The slideshows above show the progression of the upper levels/surface. Image Set 3 Description: A comparison of the ECMWF (first image) and GFS (second image) is shown above, credit to Windy.com. Both models over the next 5 days show several feet of snow across the border of Chile and Argentina. Whether these amounts are a bit elevated or not remains to be seen, however the relatively good agreement in the models gives confidence in the result of a robust snow event. The third image represents the snow depth anomaly through the weekend. When all is said and done, feet of snow are being modeled to fall across Chile and Argentina (comparison of GFS and ECMWF shown above). To put this event in perspective, the graphic above from Pivotal Weather shows the GFS forecasted snow depth anomaly (also above in the slide show). By late this week, positive anomalies are off the charts! It will be interesting to see this event unfold, GOES 16 on the College of DuPage site is a great area to view this storm. Click here to watch this event or South American weather in general via satellite imagery! To learn more about South American weather click here! ©2019 Meteorologist Joe DeLizio
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