4:45 p.m. Discussion

From Chief Meteorologist Craig Carnesi...

Get ready for a cold night tonight across the area. Winds will calm combined with clear skies and temperatures should drop like a rock.

You've probably heard the term radiational cooling from us before. Here's what happens every day. When the sun rises, short wave radiation comes through the atmosphere and is absorbed by the ground, buildings, our cars, etc. After a short period of time the ground begins to release this energy as longwave radiation. That is how we warm up each day. A good way to feel this is to place your hand close to a sidewalk or driveway in the late afternoon, you can just about feel the heat coming off of the ground. That is the longwave radiation releasing into the atmosphere.

Now, after the sun sets, the ground continues to release the energy. On a night like tonight with clear skies and calm winds, there is absolutely nothing to stop this "radiational cooling" from taking place. Thus, we have colder low temperatures on an night like tonight. This is also why we see our low temperatures taking place just after sunrise. As the sun rises, this is the time we have been the longest without the sun's energy. Thus, this is the coolest we will usually be during a 24 hour period. Now, other factors, like cold fronts, can affect what time of day our low temperatures can take place, and prevent the 24 hour low from occuring right at sunrise.

As we head into Saturday, Southwest winds return the warmth returns as well. Winds will average at about 10 to 20 miles per hour and with this afternoon highs will top out in the middle to upper 60s across the area.

Sunday will be another fire weather concern day. With wind speeds averaging 15 to 25 miles per hour and relative humidity values averagin around 20%, there will be an elevated risk of fire danger.

This is all ahead of another cold front due to arrive Sunday night. This frontal system will also help setup a chance for a few showers. Right now rain chances are only running at or below 20%, but at least there is a chance.

There is also a chance for a few wet snow flakes in the Northern and Western Big Country Sunday night into Monday morning. As an upper level disturbance moves over the cooler air at the surface, we could see a couple of wet snow flakes. I do not expect any accumulations though.

Looking into next week, we may see another couple of fire weather days and a chance of some colder air moving back into the Southern United States. More on that Monday.