Meterology Professor Joe Schneider describes the forces at play:
By: BRI HEANEY NEWS EDITOR
The only city in the U.S. that received more snow than St. Louis the weekend of January 11-13 was Juneau, Alaska. Professor of Meteorology, Joseph Schneider described the storm as a showdown in the skies of St. Louis and surrounding midwestern areas, which would result in snow. Schneider described what kind of atmospheric conditions generated the snowy skies that St. Louis experienced by explaining where it all started – the clouds. “Precipitation is formed in the troposphere which is the lowest level of the atmosphere,” Schneider said. “In the winter, the temperature of the entire cloud is going to be below freezing. Then if the temperatures, when it falls out of the cloud three miles above the surface, give or take, are all below freezing all the way down to the surface. Then you have all these ice crystals that combine together and coalesce, and that makes the frozen snowflake.” This is the typical way in which snow is produced. With the two components of snow being cold air and moisture, Schneider said that for both to exist in one place (in this case, the skies of St. Louis), the two major streams must converge paths. “We have two jet streams, the northern and the southern. To get winter precipitation, you must combine the two jet streams, the northern which brings the cold air and the southern that brings in the moisture,” said Schneider. He said the more exceptional circumstances that brought about this particular storm and contributed to its massive nature was a fragmented polar vortex and a Modoki El Nino effect. “This particular winter is being run by a Modoki El Nino pattern. Modoki is Japanese for ‘ the same, but different,” says Schneider. The usually warm El Nino winds bring in moisture from the Pacific Ocean, said Schneider. “This is Modoki El Nino – the different part is, we’re getting the cold to wrap into this pattern,” said Schneider. Much of the snow that blanketed St. Louis that weekend was the product of water from both the Gulf of Mexico and the Pacific Ocean. “There was moisture being pulled off of the Pacific Ocean, coming across the desert region of the southwest and being hauled all the way into the midwest,” said Schneider. “During El Niño years, this subtropical jet is stronger and allows the pulling of moisture from the Pacific”. The jet stream moved across the country and began picking up water from the Gulf of Mexico, too. “That’s why we were able to get so much snow in this area. Because you were combining two sources of moisture, Pacific Coast moisture and Gulf of Mexico moisture. Usually it’s just Gulf of Mexico moisture,” said Schneider. Once this wet front reached the midwest, it began to mix with the second component, the Polar Front Jet Stream, and that’s what provided St. Louis with its wintery weather, he said. “Combining that with the northern jet stream, it is providing a nice winter storm,” said Schneider.
