Mark the calendar! Friday and Saturday feature a large winter system that will bring severe storms to the southern Plains and the lower Mississippi and Tennessee valleys.

A low-pressure trough colliding with a high-pressure ridge and a low pressure at the surface will initiate a busy end to December’s first full workweek. The surface low moving across the central U.S. will usher in Gulf of Mexico moisture while the high-pressure ridge provides warmer-than-average temperatures.

The collision of the trough and ridge will provide the final lift the atmosphere needs to form severe storms.

The stormy weather begins Friday where a marginal risk – a level one out of five on the severity scale – has been issued. From the northeast Dallas suburbs through southeastern Oklahoma, much of Arkansas, including Little Rock, and to far northwestern Louisiana, isolated severe storm activity is expected to close the week.

The storms pose a nocturnal thunderstorm threat. Since severe activity will then lead into Saturday, Friday night’s storms could begin popping up around Midnight local time. The WeatherRadar is already showing this activity.

By Saturday morning local time, a more organized line of storms will begin to develop. As much as a slight risk for severe storms – level two out of five – has been issued with a marginal surrounding this risk area.

Those from Houston and Lufkin, Texas, all the way to Memphis and Jackson, Tenn., are within the slight risk for isolated to scattered severe storms. At this time, we are looking at a severe wind and hail event. This means gusts greater than 57 mph and hail larger than a quarter are possible within the storms.

Not to be outdone, we have a marginal risk – level one out of five– for excessive rainfall coming with this event on Saturday. The risk area stretches from the central Gulf Coast to the lower Ohio Valley. Two to three inches of rainfall are expected to spread across the risk area.

Due to the punchiness of this system, there are talks from NOAA’s Weather Prediction Center that a slight risk for excessive rainfall – level two out of four – could be added, upping the flood risk. We’ll have updates on that as soon as they come in.

For now, make sure you have at least three ways to receive a weather warning, your app alerts switched on, and a severe weather safety plan in place.