Joe Lundberg

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A Sagging Front to Focus Stormy Weather

June 18, 2014; 11:27 AM ET

Wednesday, noon

A ribbon of hot, humid air has been fueling some nasty thunderstorms in recent days, and that continues today. Look at just the severe weather reports for the past 24 hours, ending at 8 a.m. EDT:

One disturbance pulled some of the heat and humidity toward the mid-Atlantic and New England, triggering potent thunderstorms with a lot of wind damage, mainly across upstate New York. Much farther west, some thunderstorms spawned tornadoes in Nebraska and northwestern Iowa. Part of that was tied to the upper-level low over Idaho, while the rest in the Midwest was more triggered by a relatively weak upper-level disturbance moving across the region.

This afternoon that same disturbance will spark nasty thunderstorms with damaging winds, hail, flooding downpours and even an isolated tornado, from southeastern Wisconsin and northern Illinois into southern Michigan and across the Ohio Valley.

Most of these thunderstorms will run along the boundary that separates the truly hot and humid air from an air mass that's not as hot and clearly not as humid. The thunderstorms coming out of the Midwest and across the Great Lakes and Ohio Valley will essentially be tied to a cold front that will easily pass off the southern New England coast tomorrow morning but run into more and more resistance trying to get through the mid-Atlantic. In the latter area, the unsettled weather will linger deep into tomorrow, and, in some cases, even tomorrow night.

The front will finally stall by Friday morning from the lower Chesapeake Bay back to near Chicago, and it will remain the focal point for showers and thunderstorms. South and west of that boundary, the air mass will remain very toasty and humid with dew point temperatures close to, if not a little above, 70. And that boundary isn't apt to move an awful lot going into the weekend. If you examine the upper-level pattern, the anchor point will be the intense upper-level low over Labrador, seen here Saturday evening:

With weak upper-level ridging over the Rockies, the upper-level flow will be oriented east-southeastward toward the mid-Atlantic coast, keeping that boundary largely in place. And as a result, it will mean little ripples or upper-level disturbances moving along this boundary, trying to pull it or push it one direction or another. And this will continue through the weekend.

In the end by early next week, this boundary will be a little farther south, and the air will be rather stable and dry in the Northeast, at least for a time. In contrast, there may not be a dry day in the next week across the Midwest and middle Mississippi Valley into the Ohio Valley! Farther south, it will be seasonably hot and humid with scattered afternoon and evening thunderstorms, but nothing very well organized.

The tropics remain quiet 18 days into the Atlantic season, and there's a very good chance we escape June with no tropical development in the Atlantic Basin.

The views expressed are those of the author and not necessarily those of AccuWeather, Inc. or AccuWeather.com

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About This Blog

Joe Lundberg
Joe Lundberg, a veteran AccuWeather.com forecaster and meteorologist, covers both short and long-term U.S. weather on this blog.