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In this Weather Underground forecast for Sunday, Sept. 23, 2012, a cold front pulls offshore into the Atlantic Ocean, allowing for high pressure to build in and dry out the East Coast. Meanwhile, a low pressure system in the West brings scattered showers and thunderstorms to the Intermountain West and Great Basin. (AP Photo/Weather Underground)

Wet weather will diminish across the East Coast on Sunday as a low pressure system in eastern Canada lifts northeastward and away from the region. Flow around the system will continue producing lake effect rain showers across the southeastern shores of the Great Lakes, but shower activity will be light and widespread.

A cold front associated with the system will lift northeastward by mid-day, allowing for a few more showers and thunderstorms to develop over the far Northeast early in the day.As the system moves further away, it will continue pushing cool air in from central Canada. This will allow for chilly Fall weather to spread from the Upper Midwest and into the Ohio River Valley and Northeast.

High temperatures will remain in the 60s for these areas, while overnight lows will dip into the upper 20s for some of the Northern Tier states. Frost and freeze advisories will remain in effect for parts of the Upper Midwest and Great Lakes regions.

In the South, showers and thunderstorms will continue across southern Florida as a cold front lingers over the region. This obtains moisture from the eastern Gulf of Mexico, spreading more heavy rains and strong thunderstorms over southern Florida throughout the day.

Out West, a low pressure system moves eastward from the Pacific Northwest and into the Intermountain West on Sunday. This will push moisture in from the Pacific Ocean, triggering widespread showers and thunderstorms across the Intermountain West, Great Basin, and moving into the Northern Rockies. Breezy winds and cooler temperatures will accompany this system. Temperatures ranged Saturday in the lower 48 states from a morning low of 15 degrees at Hazen, N.D., to a high of 102 degrees at Imperial, Calif.



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