Denver Weather: Snow Arrives By Tonight, Slick Monday Drive Possible

DENVER (CBS4) - A storm system sitting to the west of Colorado today will split into two pieces over the next 24 hours. One of those will bring colder air and produce some snow as it travels across the state.

Snow is expected in the mountains today with rain and snow showers developing in Denver by this afternoon. Any rain that forms should quickly change to all snow by sunset.

The window for steady snowfall is only about 12 hours starting around sunset tonight. Because this weather system has a lot of unstable air with it we could even see thundersnow in a few spots. (that is essentially a thunderstorm that is producing snow) Snowfall rates can exceed 2 inches per hour with thundersnow which makes accurately predicting snow totals almost impossible.

The maps above show the four main computer forecast models we use to determine a forecast. A best practice for models is to look at them all, then make some decisions as you seek the overall message they are trying to convey.

In this case there are a few messages...

Notice the RPM and NAM models try to show subtle bands oriented from southwest to northeast. In fact the NAM model puts a band right across Denver with some higher totals. These models are trying to predict areas of convection or thunderstorms which would produce heavier snow amounts.

We saw a few storms in February that "over-performed" because the right part of the jet stream to enhance snowfall passed directly overhead. A frustrating aspect of forecasting is that we won't really know where bands will develop (if they even do) until the system takes shape later today so be sure to check in with us on CBS4 at 5p for the latest updates.

Because this is an evening and overnight event we will probably see some short-term impacts on the roads and those could linger into the Monday morning rush. We may also see some areas of dense fog develop shortly after the snow ends tomorrow morning.