National Weather Summary for September 2,2013,from weatherunderground.com

Weather Underground midday recap for Monday,September 2,2013.

Unsettled weather became focused over the East on Monday, while cooler and drier weather returned to the Midwest.

In the East, low pressure over the upper Great Lakes lifted northeastward into southeastern Canada on Monday, allowing an associated cold front with waves of low pressure to extend from the lower Great Lakes through the eastern Ohio Valley into the Southern Plains during the afternoon. Moist conditions ahead of this disturbance supported areas of scattered showers and chances of thunderstorms from the Northeast through the Deep South. Areas of the New York-Pennsylvania vicinity were at slight risk of severe thunderstorm development through the afternoon and evening with threats of damaging wind gusts and hail. Meanwhile, slow moving showers and thunderstorms coupled with periods of moderate to locally heavy rains became possible in the Northeast, especially northern Maine, as ample moisture pooled along a stationary front extending across the northern tier of the region. Flash flood watches were issued and remained in effect through Monday night.

As unsettled weather became more focused over the East and South, high pressure began to spread into the Midwest with drier and cooler weather conditions. Afternoon temperatures in the region ranged from the upper 50s and 60s in parts of the upper Great Lakes and upper Mississippi Valley to the 80s in the lower Ohio Valley.

Out West, showers and thunderstorms continued from areas of inland southern California through the desert Southwest into the Intermountain West. Flooding remained a concern for these areas, especially in the Intermountain West. Additional showers developed along the Pacific Northwest coast as a frontal disturbance from the Pacific reached the area.