Autumn-Like Chill Moving into the Great Lakes...Severe Storms for the Northeast and Ohio Valley

An unusually strong, highly amplified upper-level summer jet stream pattern will produce very cool temperatures tonight through Wednesday for the upper Midwest and the Great Lakes. Temperatures will be 15 to 20 degrees below normal today through Wednesday from eastern Montana to Wisconsin. High temperatures will rise into only the upper 50s with showers in northern Minnesota on Monday. Sunshine will return to northern Minnesota on Tuesday and Wednesday with highs only in the 60s to near 70. A strong upper-level low pressure system across Ontario combined with a strong ridge in the western United States will produce this unusual cool weather. The ridge in the west will produce unusual heat in the Northwest for the next few days with highs in the 90s to near 100 across interior portions of Oregon, Washington and Idaho. This highly amplified and intense upper-flow is not normally found this far south in summer, it normally does not occur across the northern United States until early fall. The combination of a strong jet steam flow, humid air from the south and cool air from the north will produce an extended period of heavy thunderstorms that will likely be severe in some locations beginning today and lasting until Tuesday across the Great Lakes, the northern Ohio Valley and into the Northeast and Mid-Atlantic by Monday and Tuesday. More than 4 inches of rain is expected in parts of the Northeast including New York City. With cool, Canadian high pressure in control, the weather will be sunny and pleasant Wednesday through Saturday across the Great Lakes and the Northeast.
George Wright is a Certified Consulting Meteorologist for Wright Weather Consulting, LLC. Visit our website at WrightWeather.com. Follow George Wright on Twitter @gwweather.