KDKA's Ray Petelin explains what inversions are and how they relate to the weather.By Ray Petelin

PITTSBURGH (KDKA) — An inversion is keeping moisture trapped at the surface, with our continued seasonably cool temperatures.

That is a fancy way of saying our weather will not change much tonight or tomorrow. Inversions are a layer of warning air above the surface. This prevents the surface air, which is usually warmer, from rising. As a result, clouds will stick around, and our temperatures at the surface will remain status quo. The temperature is the red line on the left graph.

As the line moves left, it is cooling, and to the right it is warming. The bottom of this Skew-T is the surface, and the top of the graph is the upper levels of the atmosphere. Where the green line (dew point) and the red line touch, that is where you can expect condensation, also known as clouds. That is also the same spot where our temperatures start warming again, or where the inversion is located.

This is the information we get from the twice-daily weather balloon launches.

(Image Credit: Storm Prediction Center, Norman, OK)

Overnight, lows will drop into the mid 20s, and tomorrows highs will make it back to the mid to upper 30s. Not much change in the pattern for Friday. This will be the last day of the mainly gray look to our weather.

(Photo Credit: KDKA Weather Center)

During the day Friday, a bigger system will be passing to our south. It is far enough south that we are not anticipating precipitation in Pittsburgh. The highest ridges of Garrett Couty or Tucker County may see some flakes, but most of the area looks to stay precipitation free. This will likely clear our region in time for a few peeks of sunshine to poke between the clouds later on Friday.

(Photo Credit: KDKA Weather Center)

Once that system clears totally clears the area, our skies will likely follow suit. Partly cloudy conditions will return this weekend and early next week. There will not be much change in the temperatures, though.

(Photo Credit: KDKA Weather Center)

This overall dry and seasonable cool pattern looks “locked in” through most of next week.