This is the blog for the United States' national forecast. These summaries are by Weather Underground forecasters and are updated twice each day.
By: nationalsummary , 10:12 PM GMT on August 12, 2014
Weather Underground Forecast for Wednesday, August 13, 2014
A cold front will extend from the western Gulf Coast the the northern Mid-Atlantic on Wednesday, while a separate cold front will move across the Northwest.
A low pressure system will move slowly across the northern Mid-Atlantic on Wednesday. This system will carry heavy rain and thunderstorms across the Northeast, which could lead to flash flooding over Connecticut, Massachusetts, Vermont, New Hampshire and southwest Maine. Isolated showers and thunderstorms will also develop over the northern Mid-Atlantic. Additionally, a cold front associated with this low pressure will extend across the Eastern Seaboard and the Gulf Coast. As this cold front interacts with a warm, muggy air mass, thunderstorms will develop across the southern Mid-Atlantic, the Southeast and the Gulf Coast. High pressure will keep conditions clear across the Mississippi Valley, the Tennessee Valley and the western tier of the Ohio Valley.
A separate cold front will stretch from the northern Plains to the western Great Lakes. Rain and thunderstorms are forecast to develop over the northern and central Plains on Wednesday. Just to the southwest, monsoonal moisture will continue to initiate scattered thunderstorms across the Four Corners and parts of the Desert Southwest. These thunderstorms will bring a threat of flash flooding to northwest New Mexico and southwest Colorado.
A strong low pressure system will move eastward over the Pacific Northwest. A cold front associated with this system will extend across Washington, Oregon and northern California. Severe thunderstorms are forecast to develop ahead of this frontal boundary over southeast Washington, northeast Oregon, Idaho and western Montana. These thunderstorms will be capable of producing large hail, dangerous straight line winds and heavy rain.
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