Slow Moving Upper Low Pressure System Generated Amazing Clouds and Showers Across the Northeast this Weekend...

An upper-level low or vortex generated dramatic clouds, scattered showers and thunderstorms across the Northeast including the New York City metropolitan area this weekend.  The dominate cloud types were stratocumulus, cumulus and cumulus humilis, cumulunimbus and nimbostratus. The vortex is formed by cold air and lower pressure in the upper-levels of the atmosphere that generates instability especially during the afternoon in response to solar heating.  These upper lows are most common in the Northeast during the spring and fall.  Doppler radar indicated scattered showers in central and southern New Jersey and even a few isolated thunderstorms during Sunday afternoon (Sept. 30, 2012) in northwest New Jersey, central New Jersey and eastern Pennsylvania.  Rotating atmospheric disturbances or spokes of vorticity are advected by the jet stream wind around these vortices's leading to enhanced convection that this weekend produced the amazing cloud formations and scattered showers during the morning and afternoon on Saturday and Sunday.  An examination of the 300 mb forecast maps indicated that a relatively strong jet stream or "jet streak" was forecast to track across central and southern NJ during Sunday afternoon that enhanced vertical uplift that produced the showers.  The upper-level low will lift northeastward into New England Sunday night and into the Canadain Maritimes on Monday. 

George Wright is a Certified Consulting Meteorologist for Wright Weather Consulting, LLC. Our website is WrightWeather.com. George is also a meteorologist with ABC News and Cablevision News 12. Follow George Wright on Twitter.