Just like any winter storm system, the buzz begins several days before it is suppose to happen. If you haven’t heard yet, which we don’t know how you have gone without hearing about it, since many national and local TV stations have been broadcasting about it, there is the potential for a wintry mix including ice by Sunday.
It should be noted, that we are still a few days away from this, but if you have any travel plans Sunday into Monday across western and southern Iowa, you should keep a close eye on the forecast.
A large upper trough lifting out of the desert Southwest late in the weekend into early next week, will be the culprit behind the ice potential. Precipitation will begin to push into the state by late Sunday, but forecasting what form the precipitation will fall, is what needs to be ironed out. Temperatures aloft in the atmosphere will be above freezing. This will allow precipitation to start off in the liquid form. However, as it begins to fall, near the surface, temperatures will be below freezing. For precip to end up as freezing rain, the below freezing layer near the surface needs to be very shallow. If the below freezing layer near the surface extends higher in the atmosphere, this gives the precip a chance to refreeze, which ends up falling as sleet.
This is why it ends up being very difficult to say how much will fall as freezing rain, and how much will fall as sleet. A few degrees plus or minus, will have a big impact on freezing rain totals.
Currently the forecast would support the potential for a decent icing event, south of highway 30. It’s something we’ll be watching closely, so please check back for updates to the forecast through the rest of the week and into the weekend.