Key Points:
- It looks likely that a winter storm will affect parts of the state, starting Friday afternoon and ending early Saturday.
- Slippery travel is likely across the Upstate Friday afternoon through Saturday morning from a mix of snow, sleet and freezing rain.
- Slippery travel is likely across the southern Upstate, northern Central Savannah River Area, northern Midlands, and Catawba River Area. There is a chance for enough ice buildup from freezing rain to strain trees and power lines in this area.
- There may be slippery bridges and overpasses as far south as I-20 during this time.
- Coastal areas and the southern Midlands and Central Savannah River Area likely see a cold rain with temperatures above freezing.
- There is too much uncertainty at this point to be specific on snow or ice amounts. Any change to the expected storm track or intensity would result in changes to the forecast.
By now you probably have heard the buzz about the potential for a winter storm to affect parts of the state at the end of the week. While the expected storm track is to our south and along our coast, ideal for a snowstorm in some areas of South Carolina, it looks like warm air will intrude aloft and cause a mixed bag of snow and ice from this storm where it's cold enough. There is still uncertainty about how significant and widespread the wintry part of the storm will be, but it looks like we'll see at least minor travel impacts over the northern half of the state.
This loop of GFS model output shows the progression of precipitation and the track of storm center across the Southeast from 7 a.m. Friday to 7 p.m. Saturday. It is a visualization of one reasonable possibility, but should not be considered a forecast, as the model will not get every detail of the storm correct. In fact, it will likely miss several details.
(Green is rain, blue is snow, orange is sleet, and purple is freezing rain)
Image Source: WeatherBELL
I won't get deeply involved in a model versus model discussion here, other than to say they're in general agreement on track, intensity, and timing, with no huge differences. However, a small difference can be a big deal at any given point. For example, a 5,000-foot temperature of 34° versus 32° will be the difference between freezing rain and snow. Some models show most areas north of I-20 impacted by snow and ice, while others show only the I-85 Corridor and north seeing a problematic amount.
The storm should begin early to midafternoon Friday across the Upstate and Central Savannah River Area (CSRA) and spread eastward into the evening. It will wind down close to daybreak on Saturday.
I'm confident in saying that the Upstate is going to see enough snow and ice to make the roads slick. Amounts are in question; it's too early to be specific. It will depend on the storm's track and intensity. A storm tracking further south would bring more widespread snow and ice, while one tracking further north would mean less snow and ice and more rain. A stronger storm would put down more precipitation and more of it would be snow where it's cold enough.
The reasonable range of possibilities puts the southern edge of the risk area near I-20 (extend that along U. S. 76 east of Florence). That far south, a mix of snow, sleet, and freezing rain (perhaps snow and sleet briefly at onset, mostly freezing rain) will likely transition to plan rain as it warms above 32°. Any snow and sleet accumulation along I-20 should be small unless all the models are way off.
Somewhere ... and I can't pinpoint exactly where just yet ... between I-20 and I-85, I think we will see a corridor that gets a significant ice storm, with a quarter-inch or so of ice buildup. That would be enough to strain trees and power lines, and cause slick bridges and overpasses.
The Lowcountry, southern Central Savannah River Area, southern Midlands, and lower Pee Dee will likely get to sit this one out and see only rain. Y'all need the rain; it's been dry down there and a half-inch or so of rain would be nice.
So, be ready for some yucky (though fun if you're not old enough to drive) weather starting Friday afternoon and ending Saturday morning. While it may be impactful across the north, it won't be historic. Also, while it will remain colder than average behind the storm, it won't be cold enough to keep the snow and ice from melting during the day. Except maybe for the area northwest of I-85, it should all be gone by Sunday afternoon. So, don't panic. Don't stampede to the grocery store and clear the shelves; just get what you might need for the weekend. You might be snowed or iced in for a day or lose power for hours if you're in the area at risk, but that's very manageable if you're prepared for a disaster as you should be.
If you need disaster preparedness tips, SCEMD always has you covered. In this case, their Severe Winter Weather Guide will tell you what you need to know.
We should have a decent handle on this storm by Wednesday afternoon, and that's when I plan to send out the next update.