Weather Alert Day: Dangerous cold and accumulating snow expected this weekend

The ABC 17 Stormtrack Weather Team has issued a Weather Alert Day from Friday morning through Monday morning as dangerous cold returns to the region. A low pressure system to our southwest will pull moisture in and bring the potential for accumulating snow to Mid-Missouri.

SETUP:

The upper-level pattern late this week combines the northern jet stream we've been dealing with all week, with an additional jet stream from the South Pacific that develops in conjunction with an upper-level wave that will move in from the southwest.

The confluence of cold and dry air from the north with moist and active flow nudging in from the south is creating potential for a winter storm nearby, potentially impacting mid-Missouri with cold AND measurable snow.

UNCERTAINTY/LIMITING FACTORS:

There is plenty of uncertainty remaining in the forecast, even as we begin to see guidance converge on the likelihood of a system bringing snow across the mid-south, starting in Oklahoma, and trekking to the East Coast. Mid-Missouri currently has a chance to see some of this snow, but several factors give us pause on getting too excited just yet. As mentioned above, the low that develops to our west, orienting the southern jet stream that sends waves of disturbances our way is still off the west coast. This system won't even be sampled very well for modeling until Thursday as it remains out at sea. The northern jet stream that sends small disturbances and weak cold fronts this week is set to make a bigger push of cold air around the same time as our southern moisture. This could combine the cold and moisture we need, but it could also keep critical moisture levels south of mid-Missouri altogether. If we get the moisture we need for snow, we look to likely reside on the northern edge of the system, removed from some of the best lift and moisture, which would set us up for lighter snow totals.

Additionally, the likely present cold and dry air at the lowest levels of the atmosphere could potentially eat away at snow as it falls as well. On the flip side of the coin, colder air could create higher snow-to-liquid ratios that could make snow accumulation more efficient.

As of Wednesday evening, global forecast models have come into better agreement that the low pressure will take more of a northerly track, bringing more moisture north into Missouri, thus bringing the potential for accumulating snow.

TIMING:

It's going to be cold, possibly colder than it has been all season. Timing regarding the cold sets in Friday, behind a cold front that works in early in the morning. High temperatures look likely to come in the morning near 20°, before cooling into the teens by the afternoon, and low single digits if not near zero by Saturday morning. Cold persists until we warm into Sunday afternoon, when temperatures are once again forecast above 20°.

Snow showers are expected to begin across southwest Missouri late Friday night, spilling into Mid-Missouri before dawn Saturday and continuing through late morning or midday Sunday. The highest amounts are expected to be south of Highway 50.

HAZARDS/IMPACTS:

Snowfall amounts will be highest for areas near the Lake of the Ozarks and points south, closer to the center of low pressure in Arkansas. The zone where we're most uncertain about is up along Highway 24, where drier air could eat away at totals more quickly. These amounts will likely change over the coming days as the storm gets sampled by the observation network.

Our greatest confidence is in extreme cold; with frozen pipes, car trouble, and frostbite possible with prolonged exposure this weekend. The window of deepest cold is from Friday morning through Saturday Sunday morning. Wind chills are tough to forecast at this distance, but are likely subzero at times, especially Saturday morning.

Roads will be quite slick with very low visibility between Saturday morning and Sunday morning with snow moving through. Treatment could be tough on Saturday as air temperatures could dip below zero in the morning.

Make sure you have the ABC 17 Stormtrack Weather App to keep an eye on closings and delays through the weekend and get the latest forecast videos as the forecast evolves.