This animated JET STREAM FORECAST shows how the northern and southern streams are to combine or "phase" to generate the vertical motions in the atmosphere which will drop Central U.S. barometric pressures precipitously---generating wind and significant precip in the process. The color scheme highlight wind velocities. Note how a powerful phased "wind max" develops aloft over the Central U.S. in this animated forecast. It's that wind max that is to drive rapid intensification of the winter storm

Watch this 16-day National Weather Service GFS model upper air (jet stream) forecast animation at the 500 mb. level (roughly 18,000 ft.) and the troughs which begin digging into the central and eastern U.S. in the 1-2 week range. While none is YET forecast to generate a storm system likely to DIRECTLY impact Chicago, this IS A PATTERN SHIFT which suggests deeper penetration of cold air surges into the eastern and central U.S. and a more favorable pattern for storm development. The morning GFS en

What exactly is a jet stream and how does it affect the weather? Learn this and more in the latest lesson from SciJinks, brought to you by NOAA's GOES-R series of satellites! Full lesson: go.usa.gov/xpJFj | NOAA Satellite and Information Service

Whilst it won't be as strong as last week, the jet stream will bring another rather unsettled week of weather | Met Office