Weather Patterns Collide
Texas Snowfall Totals, Image: NOAA
It’s snowing again in Texas! Snow showers have been falling all day in the Lone Star State. Dallas, Texas has very few accumulations (snow on the ground), but hill country areas such as Waco have 3 inches of snow on the ground.
The National Weather Service has issued Winter Storm Warnings for Texas, California, New York and other parts of the Northeast.
US Watches and Warnings, Image: NOAA
Two weather patterns are colliding over the United States this winter to produce storm after storm for the southern Gulf Coast and the Northeast. The El Nino Southern Oscillation is a weather pattern that causes a warming of the Pacific Ocean off the coast of Central America. This winter, El Nino is being credited with the surge of moisture and added rainfall/snow events in California, Arizona, New Mexico, Texas, and the Gulf Coast. At the same time El Nino is occurring, scientists are also examining the effects of a Negative Arctic Oscillation. The NAO is associated with cold winters across the Northern Hemisphere, as more cold air descends from the Arctic to the nearby continents of North America, Europe and Asia.
Arctic Oscillation, Image: NOAA
The above graphic is data taken from the entire month of December 2009. What this graphic shows is average temperatures across Asia, Europe and North America have been substantially cooler than normal, whereas temperatures in the Arctic, Africa and parts of the Mid-East have been warmer.
Forecasted Lows, Image: NOAA
Take a look at the large dip of cold air across Minnesota, Iowa and the Dakotas. Once again, folks in Minneapolis will be waking up to below freezing temperatures. Look at the forecast lows across Louisiana… below freezing. If you add the extra moisture coming in from the Pacific due to El Nino and the cold air due to the Arctic Oscillation, you have the perfect recipe for snow.
TV forecasters in Shreveport and New Orleans, Louisiana are reporting once again on the unusual snowfall events. In the Northeast, where snow has caused massive transportation problems, another round this week is expected.
-Dawn Brown