Autumnal Stirrings
September 14, 2012; 9:22 AM
Friday 10:30 a.m.
The pace of change will pick up next week as the upper-air flow becomes stronger. The greater the horizontal temperature difference, the faster the winds will increase as you go up. Temperatures tend to change the most near frontal boundaries. Low pressure areas will usually form along fronts. Since the winds increase aloft the fastest over these areas, the jet stream position is related to fronts and the movement of low pressure areas.
A series of cold fronts will advance from Canada through the northern states next week. The first will probably interact with moisture streaming northward from the Gulf of Mexico and the South Atlantic states to cause significant rain in the Northeast between Monday and Wednesday. It will turn quite a bit chillier behind the front, with the greatest cooling affecting the area from the northern Plains to the Great Lakes. After a brief recovery, the second front will usher in even chillier air, and the first snow showers of the season may occur downwind from the upper Great Lakes. We''ll have more details about this next week.
The cold front approaching the East today is marked by a band of clouds and showers. Since a lot of cooling will be taking place aloft, some thunderstorms can form along the front this afternoon and tonight. This picture shows the frontal system at mid-morning Friday:
The views expressed are those of the author and not necessarily those of AccuWeather, Inc. or AccuWeather.com