Storms lashed sections of the Chicago area again Monday after a weekend hiatus----and it's a virtual certainty more are on the way over the next two days. Wind gusts hit nearly 60 mph late Monday evening at O'Hare and Waukegan and reached 50 mph at Wadsworth. Doppler radar indicated a tornadic circulation over McHenry County around 10:20 pm Monday followed by a spotter funnel cloud sighting. That prompted a tornado warning over sections of McHenry and Lake Counties. Power lines were reported down in other storms which slammed sections of southwest suburban Grundy County.
Radar-detected tornadic circulations weren't limited to northern Illinois. Others occurred in sections of southern Wisconsin -- including the Madison and Milwaukee areas, prompting additional tornado warnings. Three National Weather Service damage survey teams out of the Sullivan, Wis., forecast office will investigate tornado and wind damage reports Tuesday near Eagle in southwestern Waukesha County and in other sections of the Milwaukee area. Reports that homes had been flattened and that roads were impassable due to a covering of debris in the Eagle area suggest the storms there were particularly violent -- possibly tornadic. An estimated 40,000 residents were without power in the wake of those storms.
Another tornado is reported to have touched down Monday afternoon at 4:56 pm nearly 100 miles south of Chicago in Ford County near Melvin. And damaging storms also swept extreme southeast Iowa and sections of west-central Illinois Monday afternoon. Thunderstorm gusts took out power lines and downed trees and tree limbs there and were followe by flooding late evening downpours.
The atmospheric situation is to grow explosive at times
The atmosphere in the current pattern, while capable of extended storm-free periods spanning hours or even the better part of a day, can easily erupt into storms. While the passage of storms is able to stabilize the air for a time, it's not a situation which lasts when the air is dripping with moisture close by and vigorous daytime heating is able to occur. These can initiate the churning of the air which leads to thunderstorm-genesis.
Model forecasts are insistent in keeping the atmosphere in and around Chicago in an "explosively unstable" state through midweek -- one in which heated air is to become buoyoant at times, propelling cottony cumulus clouds high into the atmosphere. It's the perfect set up for building towering cumulonimbus clouds ("thunderheads") from which thunderstorms originate.
Thunderstorms, because of their vertical build, are uniquely capable of sweeping moisture in from the surrounding environment and channeling it into intense downpours -- so the potential for huge rain tallies occurring quickly is real the next two days, and flooding may become a problem under the heaviest storms.
It's a 'ring of fire' pattern
Meteorologists refer to the current atmospheric set-up as the "ring of fire". It's a configuration which typically comes together later in the summer season -- but has arrived early in recent weeks. Months of lengthening days and strengthening sunlight contribute to the development of huge domes of hot air in many summers, around which jet stream and hot, moist low-level winds help organize vigorous thunderstorm clusters.
Wilting downstate heat accompanied by Amazon River Valley type-humidities
Heat advisories continue Tuesday in downstate Illinois and Indiana. Blazing heat, including mid 90-degree daytime highs, are likely to be accompanied by tropical-rain-forest-level low 80-degree dew points in some areas -- enough to produce dangerous 105 to 110-degree heat indexes.
Break in storms due Thursday and Friday -- but new storms likely this weekend
High pressure cuts the supply of Gulf moisture and lowers temperatures later this week. Thunderstorms exit Thursday and Friday but threaten to return as temperatures rise and humidities resurge this weekend.
Radar-detected tornadic circulations weren't limited to northern Illinois. Others occurred in sections of southern Wisconsin -- including the Madison and Milwaukee areas, prompting additional tornado warnings. Three National Weather Service damage survey teams out of the Sullivan, Wis., forecast office will investigate tornado and wind damage reports Tuesday near Eagle in southwestern Waukesha County and in other sections of the Milwaukee area. Reports that homes had been flattened and that roads were impassable due to a covering of debris in the Eagle area suggest the storms there were particularly violent -- possibly tornadic. An estimated 40,000 residents were without power in the wake of those storms.
Another tornado is reported to have touched down Monday afternoon at 4:56 pm nearly 100 miles south of Chicago in Ford County near Melvin. And damaging storms also swept extreme southeast Iowa and sections of west-central Illinois Monday afternoon. Thunderstorm gusts took out power lines and downed trees and tree limbs there and were followe by flooding late evening downpours.
The atmospheric situation is to grow explosive at times
The atmosphere in the current pattern, while capable of extended storm-free periods spanning hours or even the better part of a day, can easily erupt into storms. While the passage of storms is able to stabilize the air for a time, it's not a situation which lasts when the air is dripping with moisture close by and vigorous daytime heating is able to occur. These can initiate the churning of the air which leads to thunderstorm-genesis.
Model forecasts are insistent in keeping the atmosphere in and around Chicago in an "explosively unstable" state through midweek -- one in which heated air is to become buoyoant at times, propelling cottony cumulus clouds high into the atmosphere. It's the perfect set up for building towering cumulonimbus clouds ("thunderheads") from which thunderstorms originate.
Thunderstorms, because of their vertical build, are uniquely capable of sweeping moisture in from the surrounding environment and channeling it into intense downpours -- so the potential for huge rain tallies occurring quickly is real the next two days, and flooding may become a problem under the heaviest storms.
It's a 'ring of fire' pattern
Meteorologists refer to the current atmospheric set-up as the "ring of fire". It's a configuration which typically comes together later in the summer season -- but has arrived early in recent weeks. Months of lengthening days and strengthening sunlight contribute to the development of huge domes of hot air in many summers, around which jet stream and hot, moist low-level winds help organize vigorous thunderstorm clusters.
Wilting downstate heat accompanied by Amazon River Valley type-humidities
Heat advisories continue Tuesday in downstate Illinois and Indiana. Blazing heat, including mid 90-degree daytime highs, are likely to be accompanied by tropical-rain-forest-level low 80-degree dew points in some areas -- enough to produce dangerous 105 to 110-degree heat indexes.
Break in storms due Thursday and Friday -- but new storms likely this weekend
High pressure cuts the supply of Gulf moisture and lowers temperatures later this week. Thunderstorms exit Thursday and Friday but threaten to return as temperatures rise and humidities resurge this weekend.
Northern Illinois is progged as a moderate risk area for severe weather, does this look like a straight-line wind event or might rotation be a possibility?