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
Great Lakes Snow Event
Lake Effect Snow Event, Image: NOAA
The National Weather Service is predicting heavy snow from Upstate New York to Ohio as a cold artic airmass continues to descend across the country.
See my previous post on lake effect snow.
A quiet weather pattern will remain in place across portions of the Central Plains and Mid-Atlantic region until Saturday.
Expect heavy rain along the Gulf Coast this Friday into Saturday.
Along the West Coast, another storm system will be a rain event for the Bay Area and Los Angeles, a snow event for the Sierra.
-Dawn Brown
Winter Storms Blast West, Rockies
National Weather Warnings, Image: NOAA (Image is OLD!)
Click for the latest weather warnings across the US.
A large and potent storm begins its march across the US this week.
Parts of southeast Utah, southwest Colorado, Arizona and New Mexico are under blizzard warning this Monday as a large winter storm envelopes the Southwestern United States. This large and potent storm system could dump up to 3′ of snow in resort areas such as Crested Butte, Colorado.
National Satellite Map, Image: NOAA (Image is OLD!)
Click for the latest satellite image.
These warnings will continue through Tuesday until the storm system begins to move East, dumping heavy rain and snow in parts of Arkansas, Missouri and Tennessee before landing in the Northeast. By the time the storm system makes it to D.C., South Jersey, and New York it will most likely be a heavy rainmaker.
-Dawn Brown
Cold Air and Snow Dusts Southern States
Friday - Saturday Snow Forecast, Image: NOAA
- Friday – Saturday Snow Forecast, Image: NOAA
Dallas TV forecasters are reporting freezing conditions overnight after a snow storm left more than an inch of the white stuff on the ground in the Big-D.
The computer model image above shows where precipitation may fall Friday night into Saturday morning. I drew in the “snow line”, snow is forecast to fall in areas above the line. In this model, it is not forecast to snow as far south as New Orleans. However, these models update every few hours, and temperature changes in the storm itself Friday night may cause snow to fall and possibly accumulate. Watch the previous TV link for the latest forecast in Southeast Louisiana.
Snow is forecast across the Southern States in the next several days as a Gulf low develops. It’s very difficult to forecast snow, for several reasons. You need freezing temperatures in all levels of the atmosphere for snow to occur. (It can be above freezing at the surface, but the snow may not stick.) You also need ample moisture in all levels of the atmosphere. And, third, you need a lifting mechanism, in the form of low pressure, for air to rise and continually cool.
In New Orleans, where snowfall rarely sticks, there’s a slight chance for a rare early snow event. If it did snow in New Orleans, it would beat last years record event, which was the earliest snowfall in the city’s recorded history. Click here for the latest TV forecast in New Orleans.
Currently, winter storm watches are in effect North and West of Southeast Lousiana, where 1-3 inches of snow accummulations are expected, beginning late Friday evening.
This storm system will then track through the Mid-Atlantic region and then out to sea.
-Dawn Brown