Wind direction does make a difference

What a difference a week makes.  This time last Monday temperatures were well on their way to the middle 90s and today we'll be a good 20° cooler.  So, just what exactly happened?  Last week a very strong ridge of high pressure built across much of the Midwest, Great Lakes and East coast.  The gusty southwest wind allowed the heat, built up from the very dry conditions across Texas, to extend all the way up into Canada.  A lot of times you can get this kind of heat when the wind direction is from the south/southwest throughout the atmosphere.  This allowed temperatures to reach near record levels across the Stateline Monday through Wednesday.  The pattern was finally able to break when a fairly significant cold front pushed through not only dropping our temperatures but also bringing severe weather across southern Wisconsin and northern Illinois.  Now we haven't seen that ridge build back north as it has remained settled across the southern states for some time. 

Bringing it back to the present and cool, Canadian high pressure has changed our winds at the surface more so from the east and northeast.  Not only does the high help pull down cooler air but it's also modified some because of the cooler Lake Michigan water temperatures.  Temperatures across Lake Michigan remain in the middle 40s and only the low 50s along the shores.  That's still cool.  So as that air moves over the cooler lake surface it does become modified some.  That's why typically you'll see places along the lake shore cooler than locations further west.  Temperatures today will remain in the 60s along the lake but be able to rise into the middle 70s here.  Even though we will have that easterly breeze, mid-June sunshine is able to help warm us.