A unique setup will enter the mountains of WNC beginning mid week, and there will be a chance from some overrunning precipitation to come into contact with a frozen column. These type of events are notoriously difficult to predict and the northern periphery of precipitation can be under modeled leading up to the event. So with a complicated forecast on tap, I will do my best to dissect the data and pull out the necessary details to show you the possibilities of what could be in store.

GFS Output Regarding Thursday

The GFS model continues to be bullish on the idea of a strong high pressure pushing down from Canada, and a zone of truncation developing between it and low pressure in the Gulf. This zone of truncation where high and low come together will create lift, and precipitation will likely form. Just how far north that precipitation makes it is a great uncertainty, but we have seen several surprise snows from setups just like this. Think back to December 10th of 2017, that overrunning event caught some by surprised who weren’t following AshevilleWX just yet. I am not saying this will be exactly the same, but these type setups lend credit to that possibility. That is why I have my eye on it closely. Below you can see the most recent GFS model output for late Thursday afternoon. As precipitation blossoms late Wednesday night, it will be interesting to see have far north that precipitation makes it. We very well could see light snow showers breaking out around WNC sometime Thursday. But at this moment there is still just too much uncertainty.

Euro Shows Suppression & Cold

The European model shows this system being pushed well far to our south and the moisture never making it anywhere close to WNC. In most cases I give the European model that most weight, but with these overrunning events in the past, we have seen it fail to perform. In fact, we have seen all global models fail to perform up until the snow is falling outside. Below you can see the most recent Euro model from this morning and you can see the massive expansion of high pressure that moves in. Notice how the zone where the high pressure meets the low pressure is farther south compared to the GFS.

That moisture could very well orient over the SW Mountains of WNC and some enhancement could occur. These small details cannot be resolved by these long range models. I will need for the the Nam 3km to get ahold of this system on Monday of Tuesday to get a better idea of how it will unfold. There are other models to consider though, let dive into them now.

ICON German Model Depiction

The most recent 12z ICON run shows that northern edge of precipitation developing at a much more efficient rate compared to previous runs. I believe that this a trend that is setting up, and we will begin to see that northern periphery of precipitation blossom more that compared to what is shown.

as that weak low meanders through the Gulf and then transfers to the Atlantic, very limited warm air is associated aloft. This keeps any warm nose from melting snow as it falls through the atmosphere.

Short Range Models Needed

Recalling back to my forecast on the December 2017 event, I remember seeing similar moisture coming up from the Gulf up against a slightly weaker high. It will be interesting to see how much the trough tilts and how that is affected by the large high pressure to our north. It appears as though WNC will be right on the line as to where precipitation is making it through the atmosphere and where it is drying before it reaches the surface. Stick with me here at Ashevillewx and I will do my best to keep you updated on this system as it approaches and unfolds.