Torrential downpours from Alberto to drench Chicago, midwestern US at midweek
As Alberto moves northward, downpours, isolated flash flooding and locally severe thunderstorms will affect parts of the Midwest, including the Chicago area, at midweek.
Showers and thunderstorms from Alberto will spread from the lower Ohio Valley to the lower Great Lakes Wednesday night and then part of southern Canada on Thursday.
The air will be noticeably more humid as the storm moves across the region. This high level of moisture in the air will fuel locally torrential downpours.
The storm still contains enough of a circulation to cause a stiff breeze for a time and locally gusty thunderstorms.
Motorists should be prepared for sudden downpours that may flood streets and low-lying portions of highways.
Where downopurs and thunderstorms approach major metro areas, such as Chicago, Milwaukee, Indianapolis and Cincinnati, the potential for airline delays will increase significantly.
Alberto may spawn severe thunderstorms
One area that may experience locally severe thunderstorms is forecast to extend from southern Michigan through much of Ohio to central West Virginia, eastern Kentucky and southwestern Pennsylvania.
"Although Alberto did not produce any tornadoes through Tuesday evening, there is a chance of a couple of tornadoes being spawned over parts of the Midwest during Wednesday evening," according to AccuWeather Senior Storm Warning Meteorologist Rich Putnam.
The greatest threats from the storms will be from flash flooding and damaging wind gusts.
Indirect effects from Alberto, by way of tropical downpours, will extend into the northeastern United States as well.
Cooler, less humid air to slowly advance in Alberto's wake
During the latter part of the week, Alberto will travel northeastward across Canada, and its direct impact will diminish. However, non-tropical impacts from non-tropical weather systems will remain and increase.
Humid air will linger in the wake of Alberto over the Ohio Valley and eastern Great Lakes on Thursday. This humid air may continue to allow showers and thunderstorms to pop up.
Dry and cooler air is forecast to build southward from central Canada and across the Great Lakes and upper Mississippi Valley for a time late this week and this weekend.
Much of the area from the Mississippi River to the Ohio Valley, Great Lakes and New England may be free of rain on Saturday.
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