January 25th Winter Weather Event
I am continuing to watch the potential for a moderate winter weather event across the Southeast this Friday and Friday evening. We are going to see an upper level disturbance drop into the northern Plains later this week and then dig into the Ohio Valley and pass through the upper Southeast and mid-Atlantic region.
This is a vigorous shortwave and although it will not tap the Gulf of Mexico, it will have enough moisture and lift to produce a widespread area of light to moderate precipitation. The problem lies in the fact that arctic air is currently in place ahead of it across the eastern US, and this system will not be strong enough to scour that cold air out. In fact a strong cold high pressure will depart to the east during the day on Friday but as the clouds/precipitation moves in a wedge of cold air will set up east of the mountains and prevent a rapid warm-up, and a pool of cold air will be in place for this quick-hitting light to moderate event.
I have drawn my first forecast map for this event. Now there are a lot of zones as I have tried to pin-point the possible effects from this event, I am sure I have overlooked something in some areas, so be kind J.
It looks like a nice moderate snow is on tap for the northern NC mountains, NE TN, SE KY, western Va, and southern WV with 3-6 inches possible, locally more. This would include the Tri-Cities and Boone, NC.
This zone will likely be mostly snow and includes much of Virginia and the northern sections of NC. A general 1-3 inches is likely in this zone and there is the potential for a mix with or change to sleet in southern sections of this zone. This zone include Richmond and Norfolk. There is some potential Norfolk could end up doing well as we see the area of low pressure potentially reform off the NC coast.
The forecast starts to get trickier as we head into the southern zones. This zone will likely see a period of snow as the precipitation starts with perhaps 1-2 inches falling before a changeover to some sleet or freezing rain. If the warmer scenario (GFS) is correct this zone will see more in the way of ice than snow and could see some icing problems, if the colder scenario (Nam and to an extent ECMWF) is correct the zone could see more in the way of snow. Southern sections of this zone have a better chance of less snow and more ice than northern sections. This zone includes Hickory, Raleigh, the Triad, and northern coastal plain.
This is a tricky zone and I confess that I often struggle forecasting for this area of TN and in SW NC as micro-climates and elevation plays a huge role. The NAM is generally colder and would have the snow/ice and ice/rain line further south. In fact the Nam is a nasty ice storm for parts of eastern TN, N Ga, and into NW SC, southern NC. However, the GFS/Euro is a little warmer and further north with these lines which could have a big impact particularly for those areas. Right now, I think this zone will see a wintry mix as the precip arrives with probably a change to rain. However, if the transition is slower than a significant build-up of freezing rain could occur. It appears too early to feel good one way or the other. So for now I will say this zone will see some light to moderate icing, with potential for significant icing and potential for minor icing with a quick change to rain.
This zone includes Upstate SC into the southern piedmont and sandhills of NC. I think this area will likely see a brief period of snow/sleet transition to freezing rain/sleet. This area could see a decent ice event with 0.1 to 0.25 inch glaze possible. A transition to rain as the precip ends is possible but I think the bulk of the event is an ice event.
For now, while I will not rule out a period of wintry weather as the precip begins, this area will likely see mostly rain and not enough wintry weather to make a significant disruption. This could change though.
So there you have it my first call on this. This will likely not be a major event for most folks, but it could offer widespread wintry precipitation and with the cold weather around this weekend, we could see travel problems linger through the weekend for areas that do get some ice and snow. I will update in the morning or via twitter @RaleighWx.