Monday, June 13, 2016

Storm Threat Increases Midweek

Return to summer-like heat again for Monday as a warm front lifts across northern Illinois and southern Wisconsin bringing temperatures into the upper 80's. Dew points will also increase through the afternoon,making it feel a bit more humid late in the day. There is an isolated rain chance late in the day but more so this evening as a wave of energy swings through northern Illinois and southern Wisconsin. It will be harder to see any rain at first, as we still have relatively dry air in place, and the wave will be weakening.

A higher threat for showers and storms arrives later Tuesday afternoon with a ridge in place through much of Tuesday. A dip in the jet stream, or trough, will be moving out of the northern plains and will bring more of the instability west of the Stateline, as well as allowing an area of low pressure to develop there. There is an enhanced risk for strong to severe thunderstorms Tuesday afternoon extending through eastern Nebraska and Kansas, and into southwest Iowa and northwest Missouri near the stalled boundary and low pressure. The Stateline's storm threat increases late Tuesday and into Wednesday.

A warm front will be to the northeast of northern Illinois and southern Wisconsin. This allows the area to be in the 'warm sector' of the system that will keep temperatures in the mid and upper 80's as well as allowing for a increase in moisture. This will also bring elevated CAPE (Convection Available Potential Energy) which increases the threat for stronger storms in the area. Because wind shear in minimal, the threats we will watch for in any strong to severe storms that develop will be large hail and strong winds.Upward vertical motion in place in the upper portions of the atmosphere as well as closer to the surface will also add to the storm threat. Right now northern Illinois and southern Wisconsin is under a slight risk for strong to severe storms. This means that we could see a few scattered stronger to severe storms Tuesday night into Wednesday. With the low passing north of us, and the cold front east into Wednesday afternoon the threat for rain will end mid to late day.

Temperatures cool closer to 80° Thursday behind the front with northeasterly winds. Heights rise in the upper levels allowing for a ridge to build across the Midwest, this will bring warmth and minimal threat for rain Thursday through Sunday.


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