Detailed video below I recommend you watch..
Here is the quick summary for those who are not interested in the finer details..
1. Polar Vortex crashes into our area Tuesday causing the lowest temps in 20 years over the country.
2. We have a shot at light snow Friday
3. This is followed by a mild weather pattern for about 7 days.
4. After January 15th all indications (explained in the video) are for winter to make a sharp return
5. I am looking at the threat for a storm between the 16-19th and then again on the 22-24th
6. This progressive pattern should continue into Feb.
One major factor in this forecast are temperatures rising in the stratosphere (highest levels in the atmosphere). When the stratosphere warms, it causes the polar vortex to split and creates cold conditions for the USA 1-3 weeks later. Below you can see the stratosphere is starting to warm as indicated by red and yellow colors.
That stretched area of low pressure is the polar vortex under attack in the image above. Normally the vortex should be circular over the pole. The end result 1-3 weeks later very cold conditions over the lower latitudes (US and Europe) due to the vortex being displaced south like we will see on Tuesday.
More in the coming days...