CHARLOTTE, N.C — Depending on where you get your weather information, you may have seen the “s”-word reappearing. And no, we’re not talking about spring.
After our unseasonably warm winter and start to the month of March, changes are on the way for this weekend. With that in mind, let's break down what we are looking at in Severe Weather Center 9, and all of the other things we take into consideration when forecasting an early spring wintry event in the Carolinas.
Let's start by saying that, yes, we are monitoring a developing low pressure system that is set to move across the country. That low pressure system, as of Thursday, is over the Pacific Ocean. In fact, it won’t make official landfall until Friday morning.
Until it reaches the coast, we are unable to get the most detailed information on the structure and atmospheric conditions of this developing system. The track can, and will, shift as it moves thousands of miles from the west to east coast.
Currently, the timing for this system to reach the Carolinas is Saturday night into Sunday morning. Various websites and generic weather apps on your cell phones may have thrown out that tiny snowflake icon for Sunday.
The one thing that is certain is a drop in temperature. For the past few days, we’ve been monitoring temperatures dropping into the 30s for both North and South Carolina. Some of us, especially along the Interstate 40 corridor and mountains, look to be cold enough for snow. But sub-freezing temperatures are just one part of the equation.
Enjoying the sunshine and unseasonably warm weather we’ve been feeling this week, especially Wednesday and Thursday? If any snow falls, these warm temps will impact any potential accumulation.
Ground temperatures across the Charlotte metro area are in the upper 60s, meaning snowfall rates would have to be very high for any snow to accumulate on the surface.
And speaking of accumulating snowfall, there is low confidence across our numerous computer models as of Thursday.
Let’s compare two of our main models we use for long range forecasting, the GFS and the European model. As of Thursday afternoon’s update, the GFS model is showing 2-3 inches of snow in the Charlotte metro, with 5-7 inches in the mountains.
The European model is a little different, with up to an inch across the metro, and 2-3 inches for the mountains. This update shows even less accumulating snowfall than Wednesday afternoon's update. Other models, such as the Canadian, also show only a trace for the Charlotte area.
Most of these models update every 6-12 hours, and once we get a couple of days out from the event, we’ll get more of our short-term forecasting tools to use. The main point about comparing these models is that they are still on different pages about something that could happen in the next three to four days.
As seasons shift from winter to spring, models can have difficulty with extremes, especially when we are talking about 70s Thursday, and 30s by Sunday morning, both outside of the norm for early March. They also struggle taking into account the soil temperatures we talked about earlier. A trace of snow, as the European and Canadian suggest, with a soil temperature in the mid-60s spells out puddles, no accumulating snow.
So after all of this, what are the takeaways? Don’t rely strictly on what your phone may say, or what extreme weather graphic may be floating around on the internet. What we know so far includes a major drop in temperatures this weekend, and that precipitation looks possible. Mountains and the I-40 corridor look to see minor snowfall accumulation through Sunday morning. For the Charlotte metro, you may see a few snowflakes flying early Sunday morning, but impacts will stay minor as accumulations look unlikely on roads.
Stay tuned, and as always, make sure you have our free WSOC-TV Weather App as we make any necessary changes.