Now onto the "weather" thoughts roaming in my head and there's plenty of room for that. LOL. We really have not had true arctic air in here along with moisture in a very long time due to the mild winter last year. We must remember a few principles that models will not handle well. This is not a classic snow set up for Arkansas. Usually, the cold air is in place when the moisture gets here and winds stay out of the east or northeast. This is a case where the cold air comes in while the moisture is moving through. You can still get ice and snow, but it's not classic and it's much more difficult to forecast.
You MUST remember the nature of arctic air. It's cold, shallow, and very dry. The true nature of it is usually not handled well by ANY computer model. This dry, cold air is underestimated by the models. Once we get into Christmas day, it will be important to look at the surface temperature and dewpoint and compare it to model data. My gut tells me the models will be a few degrees too warm. Rain falling into the layer of dry, cold air will undergo a process called "evaportational cooling". Simply meaning, the rain will cool the air as it falls due to the dryness. This has a tendency to lead to sleet or sleet and rain mixed. That's something we MUST keep an eye on Christmas Day.
Then later, as the colder air works in aloft, the transistion to snow COULD occur depending on what model you look at. Once again, I will not go out on a limb right now due to the differences in the track stated in today's original blog post. Please read that. Some will be happy and others sad. I continue to think northern Arkansas has the best chance for accumulating snow. How much and where the axis of heavy snow is not fully understood until a track is determined. I would rather wait and be right than jump the gun and be wrong.
Check out the maps below from the morning model runs.
|HUGE model differences. Here's the early morning run of the GFS snowfall amounts. The heaviest is up north.|
I have held off on my own forecast for snow amounts for a reason and we are seeing why. Even though we're just 2 days away from this snow/rain event, the models have different tracks. This is a situation where a shift just a few miles means EVERYTHING. Some will be happy and others will be very upset. That's the bottom line. No snow forecast will be absolutely perfect! I continue to maintain as I always have that NORTHERN Arkansas has the best chance for accumulating snow. Areas further south will still likely see SOME snow. I'm very hesitant to put out amounts due to the differences in the NAM vs the GFS. The NAM is trending north with the track ever so slightly and it's enough to cause BIG forecast headaches. This is why forecasting snow is so difficult. We're trying to pinpoint the track of the center of low pressure to the exact position and any deviation from that track can mean the difference between 4 inches and NOTHING.
Here's what we're looking at this morning.