Severe Storms Possible From the Upper Midwest to the Northeast Through the Weekend

July 21,2016
Stormy weather will impact parts of the Midwest and Northeast through this weekend.
NOAA's Storm Prediction Center has issued the following severe weather watches:

• A severe thunderstorm watch valid until 9 p.m. CDT for portions of south-central and southeast Wisconsin. This includes Milwaukee and Madison, Wisconsin.
• A severe thunderstorm watch valid until midnight CDT for portions of northeast Illinois and northwest Indiana. This watch area includes Chicago and Peoria, Illinois and Gary, Indiana.  

The storms could turn severe at times with damaging wind gusts and large hail. In addition, torrential downpours may cause flash flooding in some areas.

Current Radar, Watches and Warnings

Early Thursday morning, severe storms moved through Duluth, Minnesota, where trees and power lines were knocked down. In northern Wisconsin, winds gusted to 75 mph in Ashland.
Later Thursday, the severe threat shifted south and east into southern Wisconsin and northern Illinois. Construction damage was reported on the University of Wisconsin-Madison campus due to 60 mph wind gusts from the storms.
(MORE: Storm Damage in the Midwest)
The severe weather is being triggered by disturbances sometimes called "ridge riders" by meteorologists since they are moving along the northern periphery of a hot ridge of high pressure aloft. That high-pressure system is the same one responsible for bringing dangerous heat to the central and eastern U.S. through this weekend.
(MORE: Dangerous Heat Ahead This Week)
Below are more details on the forecast into this weekend.

Thunderstorm Forecast

Thursday Evening

• Forecast: Scattered severe thunderstorms are likely around the Great Lakes
• Impacts: Large hail and damaging wind gusts are the main threats. Locally heavy rain is also possible.
• Cities: Marquette, Michigan | Muskegon, Michigan | Detroit

Thursday Evening's Thunderstorm Forecast

Friday

• Forecast: Scattered severe storms are possible from the Northeast westward into the southern Great Lakes region. Severe weather may approach the I-95 corridor of the Northeast by Friday evening.
• Impacts: Damaging wind gusts and large hail are the main threats. 
• Cities: Buffalo, New York | Albany, New York | Burlington,Vermont | Boston

Friday's Thunderstorm Forecast

Friday Evening's Thunderstorm Forecast

Saturday

• Forecast: The next disturbance will produce another round of severe weather across the Upper Midwest.
• Impacts: A few storms may turn severe, with large hail damaging wind gusts being the main threats.
• Cities: Fargo, North Dakota | Duluth, Minnesota | Minneapolis | La Crosse, Wisconsin

Saturday's Thunderstorm Forecast

Ridge Rider Pattern Triggers Storms

Disturbances in the middle portion of the atmosphere ride along the northern periphery of the hot high-pressure system.

A massive ridge of high pressure aloft (bulge in the jet stream) is anchored across a large portion of the nation. Locations underneath this ridge will have a low chance for thunderstorms.
A couple of strong disturbances often called "ridge riders" by meteorologists will move across the top of this ridge, however, and they will produce thunderstorms and some will turn severe.
An upper-level disturbance will progress eastward into the Northeast by Friday.
A second disturbance will produce another round of scattered severe thunderstorms by Friday night and Saturday across the Upper Midwest.
MORE: Lightning Strikes on Iconic Places