Explaining the 108 new lows ought to prove interesting...
Each time some one post this question or something related to it I'm going to post this.

This heat wave is Caused by a death ridge over the midwest at 500 millibars.The cooler then normal air--- on each side of a ridge there is normally a "trough" a trough is a dip within the jet stream with the cooler air to the north of the jet stream...So imagine the midwest is within a intense ridge with record hot and dry weather, but the west coast is within the cold and rainy crap. One of the coldest for Portland in the past 70 years so far.

Lets think about the ridge as divergence at the surface, which pretty much means the air is moving inwards at the upper levels 200-300 millibars, but moving outwards as it moves to 500 to 1013 millibars. What this does is increase the pressure of the column of air and that rises the pressure. This also does the opposite of the air within a area of low pressure. Air within the northern side of the jet stream normally favors low pressure area's and is cooler as said above. Low pressure moves inward and warm moist air raises into the Atmosphere and cools towards its dew point--->this is what we call condensation once it cools to that. Clouds and rainy weather. The air raising from the surface to the 25-40 thousand feet is why a low pressure is called a low pressure, and is why it lowers the pressure as the column of air is now pressing down less pressure onto the surface.
A low pressure of 992 millibars is causing 9,920 bars of pressure on the surface, but a high could cause 1020 millibars or 10,200 bars onto that surface.

In yes that is a difference of air pressure pressing onto the surface.
Not really so much climate when you think about the day to day, but imagine for a second that the
above avg area's are above normal, but cover a larger area of the earth and of course your going to get below normal area's at the same time---the earth is not uniform my friends...It really is how you avg it out is how you get a idea of what changes a change climate may of had. Europe and the east coast last winter was very cold, but the arctic was 10-15c warmer then normal at the same time. Much of northern russia to was warmer if I remember...
Lets look at this in another way...
You have 10,526,000 sq miles of .5c above normal
You have 6,546,456 sq miles at -.5c above normal
Yes this is very simple, but lets say for a second that those two made up the surface area of the earth...You would have a above normal global avg!
Portland can be colder, but a larger percentage of the United states has been above normal so far this summer season---In I agree it is one of the coldest summers I've seen.
...
When you increase the "heat" you also increase the cold anomalies, but the heat or above avg is larger in scale then the cold anomalies. Weather being that the jet stream and weather systems will still spin around our globe, but the droughts and rainfalls will increase.
That might go over your heads being that you might think, wow shit, if you have more rainfall shouldn't there be NO droughts? But remember the patterns of the jet stream and ridges and troughs will remain(weather) and occur. You will get ridges of high pressure that sit for months on end with that hotter drier air. Doing what you see in Texas and of course you will have on the sides area's of unseasonable cold and rainy weather.
The air will be able to hold more moisture as you increase the temperature too. One case in point is the difference between Antarctica being only a fraction .1grams/volume of air for a dew point(constate) at maybe -30c to a area like Portland that is around 50f that holds like 4-5grams/volume of air for the same. So more extreme rains when and where your not dealing with a super ridge of high pressure!
